November is here, which means the best Black Friday camera deals are now ramping up. But you don’t need to limit your attention to cameras – because plenty of lenses will also see some big discounts over the next few weeks.
Photography isn’t a cheap hobby or career at the best of times, so finding some great discounts can make all the difference, particularly when we’re going through a cost of living crisis.
Black Friday 2022 is on November 25, so we still have a few weeks to go before we know for sure which lenses will be on offer. This is therefore a great time to do some research around what could work for you and your shooting style, so that you know where to look when the day arrives.
I’m currently looking to upgrade to one of the best full-frame cameras, so I’ll need some full-frame lenses to go with it. I primarily shoot seascapes and landscapes, so lenses with a wider focal length will be at the top of my wishlist, followed by a telephoto for those tighter shots and perhaps a prime lens or two.
Whatever style of photography you do, there’s bound to be a lens for you on offer – not to mention that Sony is also offering winter cashback with many UK retailers, giving you the opportunity to save even more money. The company hasn’t said how long the cashback offer will last, but calling it “Winter Cashback” suggests it’s going to be around a good while.
Which Sony lenses were reduced last Black Friday?
Last year’s deals can offer a good guide to what might also be discounted this year. In 2021, we found some great discounts on the best Sony lenses at Adorama, Amazon and B&H, while UK retailer Wex was also offering fantastic savings on Sony lenses. Generally, the more expensive the lens, the bigger the saving, so this could be a great time to splurge on that big lens you’ve always wanted, or to stock up on a few smaller ones while the prices are low.
Taking a look back at last year’s deals, the Sony FE 24-70mm F/2.8 G Master lens was discounted by $400, taking it from $2,199 down to $1,799 – and not only is this lens now a year older, but Sony has also released an updated version of it, so chances are the original model will see even bigger discounts than it did last year.
Similarly, the 70-200mm F/2.8 G Master has also been updated. Last year, this lens was discounted to $2,299 down from $2,599, so there’s a very good possibility that the first version will be much cheaper this year, too.
Do be mindful when looking at offers, though, as some retailers will inflate their prices right before a sale starts, making it look like a better deal than it actually is. CamelCamelCamel (opens in new tab) can be a very useful site for checking price history, and we will of course also be sure to tell you whether a deal is really as good as it seems.
With that caveat out of the way, here are some Sony E-mount lenses to keep an eye out for in the Black Friday sales this year.
The best Sony lenses to look out for on Black Friday
Sony FE 24–70mm F2.8 G Master Lens
If I could only have one lens in my bag, it would be this one. Not only is it a fantastic quality lens, it’s also extremely versatile, covering a good range of focal lengths and making it great for travel and everyday shooting. Sony has released a newer version of this lens, meaning you can pick up the first model for even less. In fact, it’s already reduced on Amazon US. Right now, it’s sitting at $1,698 (down from $2,138), which is already $100 less than the Black Friday deal price last year.
FE 70–200mm F2.8 GM OSS Lens
Another lens worth checking out on Black Friday is Sony’s beast of a telephoto lens – the 70-200mm F/2.8. If you don’t mind the fact that it’s massive and very heavy, this is a great lens to add to your kit, as the quality is just incredible. I’ve shot with this lens before and you can crop a 200mm image down so much and not sacrifice any image quality or detail at all.
Right now, this lens is $1,998 on Amazon US (was $2,433) – already $200 less than last year. For UK buyers, this lens is on Amazon for £1,949. This lens would be a great investment for any style of shooting, but particularly for wildlife or sports photography, and it’s so good that you won’t need to buy another telephoto lens for a very long time.
Sigma 16mm f/1.4 DC DN Contemporary Lens
If you’re happy to look outside of native Sony lenses, you can find some great deals on third-party lenses too. For instance, the Sigma 16mm f/1.4 is on Amazon for $364, down from $620, which is a massive saving already. In the UK, it’s on Amazon for £349, down from £449. This lens would be great for landscape and city shooters, and also for astrophotography due to its wide focal length and fast aperture. It’s a pretty niche focal length, but for the price this would be an absolute bargain.
Sony 16-55mm f/2.8 G Master APS-C Lens
For any Sony shooters who don’t want to make the switch to full-frame just yet, this incredible 16-55mm f/2.8 G Master Lens is probably one of the best lenses you can put on your camera. I bought this model earlier in the year and the quality is astounding. It’s currently on Amazon UK for £1,039, which is full price, however I have seen it drop as low as around £800 in the past, so there’s a good chance it could go lower during Black Friday. All of Sony’s lenses also hold their value really well on the used market, so you could definitely sell it on for a good price when and if you do switch over to full-frame.
Sony 20mm F/1.8 Prime Lens
The 20mm f/1.8 prime lens is a very popular lens among Sony shooters because, although it’s a prime lens, it’s actually quite versatile. While it wouldn’t necessarily be a good choice for wildlife or sport photography, it’s a great lens for any type of travel or photojournalism and it’s also a very popular option for landscapes and cityscapes. Many photographers I know also use this lens when getting into astrophotography, as it’s wide enough to capture foreground and a big chunk of night sky, while the fast aperture means you can let a lot of light in. While professional astrophotographers would probably choose a 14mm lens instead, this model would be a great way to dip your toe into this style of photography. If this lens is reduced on Black Friday, it’s definitely one to consider picking up.
Fabiano Dossantos is a Brazil-born nature photographer currently living in Boston, Massachusetts – USA. In his words about nature photography “I’ve Always loved nature and being outside. Birds, animals, beaches, mountains, forests are an attraction to my eyes. Over the years, I realized that this love for nature, made a perfect marriage with my love for photography. The sunrise and sunset are a divine painting. Photographing nature is a kind of connection with our creator. I am a religious person, and that’s how I fell when I am photographing Nature.”
Thanks, Fabiano for accepting our invitation. Please read on…
#1 Few words about you?
My name is Fabiano Lacerda Dos Santos. I am 48 years old, married and I have two children. I was born in Brazil, in the city of Criciuma, state of Santa Catarina (south, near Argentina). Since i was a child i have always lived in an environment where family members worked in the construction industry. Today I live in Boston, Massachusetts – USA. I have a company that provides services in the construction area.
#2 How did you develop your interest in photography?
My mother has always been passionate for photography. She was a seamstress, but in her spare time, she liked to photograph me and my sister. She was always positioning us correctly, so that, the photo had a good composition. When I was 8 years old, an uncle came to live with my family. He was a professional photographer, and turned his own bedroom into a Darkroom Lab. That’s when my interest in photography started to spark.
For me photography was “magic”, where a piece of paper that was deposited on a tray containing liquids, which I didn’t know what it was, soon turned into an image. This was very fascinating to me. Since then, photography has always been something I enjoyed doing.
#3 How did you get interested in nature photography?
I’ve Always loved nature and being outside. Birds, animals, beaches, mountains, forests are an attraction to my eyes. Over the years, I realized that this love for nature, made a perfect marriage with my love for photography.
The sunrise and sunset are a divine painting. Photographing nature is a kind of connection with our creator. I am a religious person, and that’s how I fell when I am photographing Nature.
#4 What is that catches your eyes to produce such wonderful photographs?
The color, the shadow, glow, the combination of light and colors. Sometimes, I like to photograph what goes unnoticed, what not all eyes perceive. I like to see a beauty where it didn’t exist before the photo.
#5 Could you please share your post-processing techniques?
For every photo, a different situation. I don’t have a strict line of post-processing techniques. Most of my photos are edited in Lightroom. I always try to lower the highlights and shadows and increase white, sometimes color saturation for vibrant colors. That’s all, nothing too special.
#6 Your favorite photographers?
Sebastiao Salgado and Serge Ramelli
#7 One thing you have learned through photography, you would want to share with our readers?
I learned that photography is magic, is Art. We are not only photographers, but Artists, we create Art with what is already an Art. A different way to transform a moment in life into an image.
#8 What is the best compliment you received so far?
To be honest, it’s very gratifying to receive compliments, but the ones that cheer me up the most are when someone says: ” This photo looks like an Art painting”, or ” You should work for a magazine”.
#9 Any favorite photography books?
Photography essentials: A visual Guide. By Serge Ramelli.
#10 What’s your personal motto?
Beauty can be in all things. Transform beauty into Art, the Art of recording a moment in life that will never be repeated.
#11 Other than photography, what are your hobbies and interests?
I like to cook. Just like photography, I think cooking is an open window to invention. I also like to hike, travel and visit new places, but also to return to places already visited that attract me for their beauty.
#12 Thanks again for providing 121 Clicks with this opportunity to interview you. Any final thoughts for our readers?
Photograph everything that you think is beautiful. Your way of seeing the world is peculiar, is your way, not mine. Try to make something peculiar, something that is yours in a new scene created by you, by your angles, your compositions, because this moment will not be repeated. You have the power in your hands to freeze this moment forever.
Copyrights: All the pictures in this post are copyrighted Fabiano Dossantos. Their reproduction, even in part, is forbidden without the explicit approval of the rightful owners.
Anthony Onyango is the 2022 Mkapa Awards Conservation Heroes winner. He will take home a grand prize award of $5,000 (Sh607,000), and a large, specially-commissioned stone elephant sculpture.
The winner was announced at a ceremony and exhibition held at the Kenya National Museum in Nairobi last week.
This year’s competition, which was organised by African Wildlife Foundation and Nature’s Best Photography attracted 9,500 entries from 57 countries including entrants from 16 African countries.
The competing categories include: African Conservation Heroes, Coexistence and Conflict, African Wildlife at Risk, Fragile Wilderness, African Wildlife Behavior, African Wildlife Portraits, Africa’s Backyard Wildlife, Art in Nature, Creative Digital, Mobile, Africa in Motion/Video, and two Youth Photographers of the Year, one inside Africa and one international.
Each of the category winners will receive $1,000 (Sh121,000) and a stone elephant sculpture.
The 77 prints and four videos shortlisted for various prizes will travel to other global locations throughout the year. In addition, all winners’ photographs will be displayed in large-format prints and high-definition video, along with Highly Honoured finalists at the museum in Nairobi through February 2023.
AWF chief executive Kaddu Sebunya said the competition and other strategic partnerships will help define and refine the African conservation agenda for development through these voices.
The awards are named in honour of the late former Tanzanian President, H.E. Benjamin Mkapa, for his dedication to conservation education throughout Africa, and his impactful support of AWF programmes across the continent.
“Nature photography goes beyond just taking a picture but informing and inspiring people to protect nature. It is truly an honour to be among the winners this year and it is a testament that we Africans have what it takes to emerge among the best,” Onyango said after receiving the award.
Which is better: many short exposures or fewer long exposures? 120 x 1 minute exposures or 10 x 12 minute exposures? Questions similar to this one get asked really often and they probably receive all kinds of different answers. People talk about the camera, faintness of the signal, dithering, stacking, light pollution etc. etc. So many factors creep into the discussion that sooner or later it will seem like a personal choice, almost like a matter of opinion. Is this really a matter of opinion and/or complicated? Or can we find some definitive answer to the question if more shorter exposures are better than fewer longer exposures? Actually, it turns out that although there are formulas for ideal (theoretical!) exposure times, personal preferences and opinion and practicality will come into play in reality when determining the exposure you want to be using. Knowing how the subexposure time will impact the SNR of your stacked image will help you to determine the exposure time you choose to use. Please bear with me while we explore the way to determine this optimum exposure time, which will include quite a bit of math. I find that going over the math and actually calculate the SNR for a few different scenarios helps greatly in my understanding of this matter. So I encourage you to follow along with the math. For those who are mostly interested in the key take aways I’ll start with those in a short summary, before diving into details and the math further on.
Key take aways
When you are imaging under light polluted skies, you should not worry about your exposure times. It will make very little to no difference if you are using subexposures of 30sec. or 3minutes. It’s the total integration time that matters. If you are imaging under dark skies, you will benefit from longer exposures in terms of SNR. However, it’s not worth it to go to extremes and keep in mind the cost of throwing out a subexposure due to poor tracking for instance. Only increase exposure time if you can reliable track accurately for that long. If you don’t use darks and/or want to use dithered (bayer) drizzel integration, make sure you get at least 10 to 15 subexposures.
Now that we’ve learned not to worry about subexposure time under light polluted skies and give subexposure time priority under dark skies, let’s see why this is the case and how we arrive at these conclusions.
Read noise and background sky flux
To determine the optimum exposure it basically comes down to these two factors; read noise and the background sky flux. The read noise is the noise that occurs within the electronics of the camera when we convert the electrons coming from the sensor into digital units (ADU) and store them. The background sky flux is the signal coming from the light pollution, moon light and/or air glow. The background is never completely black and the value of the background signal is the background sky flux.
If the read noise is swamped by sky background noise it becomes irrelevant and it doesn’t matter how long our subexposures are
If we wouldn’t have read noise, it wouldn’t matter if we take one very long exposure or many shorter exposures with the same total integration time. If we wouldn’t have background sky noise but do have read noise, the longer exposure would always have better SNR than many shorter exposures. In reality we always have to deal with some sort of mixture of these two scenarios. There will always be some background sky noise and read noise is always a factor to take into account. Especially for us DLSR users. So how should we take those two factors into account? Well, it comes down to determining the point where the sky background noise will make the read noise irrelevant. Whenever this is the case, it doesn’t matter any more if we take many shorter or fewer longer exposures. So if you are imaging under strong light pollution this probably applies to you. Alternatively, if you are using narrowband imaging and/or if you are under truly dark skies, it will be practically impossible to reach this point and so the longer exposures will always be better. Now let’s research why this is the case and look at some test results;
Adding multiple exposures and SNR
Let’s look at what exactly happens to the SNR when we add multiple exposures and when we expose longer. We will dive into some math here and I will try to do this step by step and as clear as possible. I know lot’s of articles will skip steps and rewrite formulas without explaining how or why which I’ll try to avoid.
The SNR is simply the Signal divided by the noise. Sounds simple, but with different noise sources we need to dive in a bit deeper and see how we add noise. But first let’s define the term Signal exactly: S = signal per second (s) * time of the exposure (t) * number of exposures (N). So To be clear; this is the total amount of signal recorded over multiple exposures. Next let’s consider the noise sources we are dealing with here: Object shot noise, sky (shot) noise, dark current noise and read noise. Whenever we are dealing with detecting photons we deal with shot noise. This shot noise is the square root of the number of photons. This noise is also building up over time just like the signal. So in terms of the object shot noise, it is the noise associated with the signal of the object(s) we are imaging and is the square root of the signal.
For sky shot noise it is the square root of the background signal coming from the sky over time.
For the dark current noise it is the square root of the thermal signal (dark current) build up.
The read noise is different in the sense that this doesn’t build up over time but it does occur once for every exposure. This is important to realise. The total read out noise (RonTot) is:
We can sum random, uncorrelated noise by adding them quadratically so we get the following formula for the total amount of noise:
Remember the fact that the shot noise is the square root of the Signal source. So if we add this quadratically we can rewrite the Noise in terms of the signal like this:
Since the number of exposures (N) is present in each term we can rewrite this as:
So the formula for the SNR is:
Notice we have N as a term present in both parts of the division. Since we can rewrite the above formula into:
Now we have written the formula down for SNR in this useful format, we can explore what the impact of the background sky flux and the read noise is on the SNR.
Scenario with no read noise
Maybe you start to see now what we said earlier; if we wouldn’t have read noise it wouldn’t matter how long we expose as long as the total exposure time is the same. Let’s just take out the read noise (RN) out of the above equation. Without read noise the SNR will be:
Since we have t present now in every term we can group it:
which is the same as
and as we’ve seen before we can write this down as
Now we can see it doesn’t matter for the SNR how we fill in values for N and t as long as N*t = the same value. So only total exposure time matters (N*t) and not how we divide it in subexposures. But wait, what about really faint signal? Don’t you need very long exposures for that? Well, not in this case where we don’t have read noise. You just need (very) long total exposure time. If we look at the above formula this is clear, but if we think of stacking and consider that we are averaging there this might seem less intuitive all of a sudden. Because, the average of a few electrons collected by many frames is smaller than the average of a few electrons in one frame right? Well, sure that is correct of course. However, this is only considering signal. And it is not useful to talk about signal alone, we always need to talk about SNR. That alone determines if you will have detected signal that will stand out in an image or not. And if we consider the fact that SNR = simply signal / noise you’ll realise it doesn’t matter in how many frames we detected the signal, since we’ll only end up dividing both terms of the division which doesn’t change anything ((a*b)/(a*c) = (a/a) * (b/c) = 1*(b/c) = (b/c)) So yes, it’s true that if read noise wouldn’t exist it doesn’t matter what exposure time you use and how many exposures you take, all that matters is the total integration time. And even with read noise included in the formula, you can see that once the other values are much much bigger than the read noise, the same will apply; the read noise becomes (almost) irrelevant and we are left in the situation where it doesn’t matter what exposure time you use.
once the other noise values are much much bigger than the read noise, the read noise becomes (almost) irrelevant and we are left in the situation where it doesn’t matter what exposure time you use.
Scenario with little to no sky noise
Alternatively, consider the scenario where we are under a truly dark sky with no light pollution, no moon light and only a little sky glow; we have very little background sky signal (Sky_s). Let’s consider the SNR formula again:
Now let’s say the DarkCurrent_s = 0.15e-/sec (which I found reported for the Nikon D7000), Sky_s = 1e- / sec and read noise = 3e- (Nikon D7000 @ ISO200). If we take a very faint signal that’s similar to the sky flux we will see the following SNR values for different number of exposure times but same total exposure time: Let’s compare scenarios with a total integration time of 120 minutes and compare 120x1min and 12x10min.
Ok, so SNR is higher indeed as expected. What if we take this to the extreme and just take 1 image of 120min?
Hmmm, that’s a really small improvement over the 12x10min exposure. Clearly this is a case of (quickly) diminishing returns. I made a graph showing the SNR gains compared to a 30sec exposure SNR for exposures between 30sec and 120min to show the benefit of exposing longer in this scenario:
This graph paints quite a clear picture I’d say. In case of a dark sky, the gains in SNR while exposing longer is quite big in the beginning and reaches a 10% improvement already at 3,5minutes exposures compared to 30sec exposures. The improvements tail off quickly as well though, reaching only a further 1% improvement at 8 minutes compared to the 30sec exposures. To be clear; in this scenario, the difference between exposing 3.5minutes and 8 minutes (with the same total integration time) is even slightly less than 1% improvement. Please note that these gains are dependant on the signal coming from our target object as well. So if we would take a much fainter object with a flux of only 0.2e- compared to the 1e- we just saw, we get the following graph:
Wow! we can see the same strong curve with diminishing returns, but the SNR improvements for a fainter signal are clearly much much higher! Let’s look at the same minute marks as before: using 3.5 minutes exposures compared to 30sec exposures gives you an SNR improvement of 26.3%. Going from 3.5 minutes to 8 minutes gives you a further improvement of 2.86%. So even though we still see strong diminishing returns, the improvements remain significant up till longer exposures as before. In this scenario, the improvement in SNR between 8 and 15 minutes still is 1%. Please note that we’re talking about signal coming from the sensor here. So this includes scenarios with slow optics as well as using fast optics on very faint signal.
The role of read noise in SNR To make it really clear what the role is of the read noise in the scenario’s we just ran through, let’s take a look at the role of read noise specifically and how it adds up when we add more exposures. Let’s look at the SNR again for the same situation as described before, 12x10min subs versus 120x1min subs and rewrite it a bit just to see what is happening to the noise terms: For the object shot noise, sky noise and dark current noise we get the following: 12x10min:
which is; =
and for the 120x1min this then is; = So you see this is exactly the same, just as we could expect and have seen before in the scenario without read noise.
Now, let’s see what is happening with the read noise; which is simply 12x10min: 120x1min:
So the read noise is growing with the square root of the number of exposures in our integration, while all the other terms simply grow by total exposure time alone. So for a given fixed total exposure time, the read noise will be smallest with the least number of exposures.
Read noise is growing with the square root of the number of exposures in our integration
To see it’s impact in the total noise let’s run the actual numbers. Remember, uncorrelated noise adds up quadratically, so the total noise we get in these situations is; 12x10min: 120x1min:
Now we can clearly see how big the impact is of the read noise in this scenario. Next let’s see what these numbers and the impact of read noise looks like in case of a bright sky. Let’s say sky background flux is 50e-. For the time dependant noise sources we get: =
If we add the read noise: 12x10min: 120x1min:
This is a totally different situation and the read noise could simply be considered irrelevant. In fact, this looks very much like the hypothetical situation without any read noise we saw earlier.
So we can conclude that the exposure time only is relevant when the read noise is relevant. And the read noise is only relevant if the sky is dark enough.
The exposure time only is relevant when the read noise is relevant. And the read noise is only relevant if the sky is dark enough.
Determining optimal exposure time
Now we’ve seen the scenarios above you might wonder what would be applicable to your specific situation. As we just concluded this will be dependant mostly on the brightness of the sky you are imaging under. There are formulas to determine the optimum exposure using the read noise and sky flux as input. There is also a script in PixInsight which you can use to give you an ‘ideal exposure length’. (Scripts->Instrumentation->CalculateSkyLimitedExposure) However, as we’ve seen in the graphs before the benefit in SNR is one of diminishing returns. This means it is not possible to give one absolute answer to the question what the optimal exposure time is. Assumptions need to be made about how much contribution of read noise to the total noise you will tolerate. And the differences in this assumption is often huge (factor 2 differences). Furthermore they don’t take practicalities into account. So I’d like to just show you a few more scenarios and the SNR corresponding gains for longer exposures compared to using 30sec exposures in a situation where we use a total exposure time of 2 hours. I’ve listed the ‘95% improvement mark’ for exposure time for each sky brightness.
The most obvious thing we can learn from this chart is that there is a huge difference how much you benefit from longer exposures under a dark sky versus brighter skies. Furthermore, the 95% improvement mark seems to be awfully close for all scenarios. However, I’m not sure how useful this number is since the next step up in exposure after this mark under a dark sky will still give you 0.05% increase while this improvement is only 0.0012% in the brightest scenario. To make this even more clear; for the brightest scenario the SNR for 30sec. exposure was 11.83, while all the way at the end with one exposure of 120 minutes the SNR was 11.86. So we could safely consider this a scenario where subexposure length is completely irrelevant.
Remember we saw earlier that the SNR improvements were much larger if we are dealing with faint signals. So let’s look at the SNR improvements for different sky brightness with the previously used faint 0.2e- signal
The impact of the sky brightness is very clear again in this chart. Although we do benefit more from longer exposures when dealing with fainter signal also from brighter skies, the difference is negligible for very bright sky and is really huge for the really dark sky.
Based on these graphs we can conclude that if you are imaging under a light polluted sky you should not worry much about your exposure length. Every sky brightness between 5e- and 50e- basically has a total SNR improvement between 0.2% and 2% for which you’ll reach 80% of maximum SNR increase already at 3 minute exposures.
Other practical considerations to take into account
Next to the read noise and background sky flux, we need to take some practical factors into account as well when we want to determine the optimal exposure length. The ability to guide accurately for longer exposures for instance is of course really important, as well as the cost of loss of data if you need to throw out a subexposure. Remember that the total integrated exposure time is most important for SNR, so there is a real significant cost when you need to throw out subexposures. Furthermore you might want to use (bayer) drizzle integration, which will need a minimum amount of (dithered) subexposures to give proper results. These are all very important things to consider which might change things completely in terms of the optimal exposure time for you personally.
Light pollution and narrow band filters
I got asked a lot about the influence of filters. I haven’t tested this out myself, but the book The Astrophotography Manual covers a comparison between different light pollution filters and concluded that in his test it didn’t effect the background sky flux all that much (which was surprising). As always, test it out to know for sure, but I think the effect of light pollution filters is minimal on the read noise contribution to the overall noise. Narrowband filters on the other hand will basically change even a light polluted sky to a dark(er) sky in general. So with narrowband filters you will benefit a lot from longer subexposures. Of course there will always be exceptions to this, like OIII imaging with full moon, and exact details will depend on the speed of your scope and the quantum efficiency of your camera for instance. However, the generalisations will hold true in most situations.
A comparison from a dark site
Let’s look at the following data that I shot while I was in Namibia. There is practically no light pollution there and this was shot without the moon present. The only bit of background sky flux was the sky glow and perhaps a bit of zodiacal light. The data was shot during 3 different nights so some variation is to be expected based on conditions for that particular night. There were no noteworthy differences between those nights so I have no reason to believe this is influencing the comparison much. I had used different exposure lengths: 8, 12 and 15 minutes. For this comparison I made three integrations that all had the total integration time of 120minutes. So 15 frames of 8 minute exposures, 10 frames of 12 minute exposures and 8 frames of 15 minute exposures. No processing is done to these integrations. Just a STF applied to make the data visible. Based on what we learned before we would expect the fewer but longer exposures will have the better SNR. Let’s see if this was the case:
Hard to tell from this wide shot, so let’s zoom in a bit.
Here we can already see some difference in the amount of noise. Let’s zoom in further to have a better look.
The differences in SNR are clearly visible now and we see indeed what we expected: the 8x15min. integration looks (much!) better than the 15x8min. integration. This is even better visible in the dark region of Barnard 44A:
So visually we can already draw the conclusion that we were right: longer exposure has better SNR in this situation where we are clearly read noise limited. Now let’s check the numbers to confirm. First let’s look at the amount of noise:
Noise is higher in longer exposures which is expected. The question is; did the signal grow more than the noise? The SNRWeight measure (to be clear; this is a relative measure and not reflective of the actual SNR differences)
So yes, it clearly did.
Unless you are under dark skies, the subexposure length won’t matter much once you are using 2 to 3 minute exposures.
Conclusion and final considerations on sub exposure time and number of exposures
With all that we learned and the simulations we looked at and the real world dark site test we have quite some information about the optimal subexposure length. However, I bet you still are wondering how this impacts your particular situation and what the optimal subexposure length is. That will remain difficult to answer exactly, and much of the details go right out of the window if we need to take other factors like drizzle integration and guiding errors into account. However, I feel the most important conclusion probably is the fact that the exposure length is only relevant when the read noise is relevant. And the read noise is only relevant when you are imaging under a dark sky. With most moderately to strong light polluted skies, the subexposure length won’t matter much once you are using 2 to 3 minute exposures. Let me know in the comments below if you agree or disagree or still are left with questions at this point!
RICHLANDS, Va. (WVVA) -A new photography studio had its grand opening in Richlands Friday. Magic Moments Photography is one of the winners of Richland’s Pop-up Business campaign where hopeful entrepreneurs can pitch their business ideas to the town. Sharon Horton, the owner of Magic Moments says this business has been her dream since she was around seven.
“It’s had a really good response. Lots of people are, like, excited, and they love the pricing and the fact that we’re offering other retail items like pillows and canvases and Christmas cards, stockings, Christmas ornaments,” says Horton
Horton also says the grand opening was a success with people from all over the county coming to ribbon-cutting.
Polar Bear mother with her two month old cubs curiously surveying the area as they prepare to make the trek from Wapusk National Park to Hudson Bay.
It is three o’clock in the afternoon, I have been waiting four hours for a polar bear with her cubs to emerge from their den. I have three more days left until they close the backcountry lodge where I have been staying the past two weeks. The lodge that has been home these two weeks is called Watchee, a Cree word for forested ridge, located just outside Wapusk National Park located 30 miles south of Churchill, Manitoba in Canada. This will be my fifth visit to Wapusk, primarily to photograph polar bear mothers with their newborn cubs.
This type of photography requires an extreme amount of patience. Days can go by waiting for an opportunity to photograph polar bear mothers and their newborn cubs. This year has been unusual in that we have photographic opportunities almost every day. One day we stayed in the lodge and didn’t go out due to wind chill temperatures around -50 degrees C. It would not be unusual to spend two weeks here and have one or two sightings during the entire two weeks. This year has been, without question, the best year I have had for polar bear photography.
Wapusk is a denning site for polar bear mothers who come to the area in the fall to give birth to their cubs and leave their dens during February and March. Therefore, the middle of February to the mid-March is the prime time to photograph these polar bear mothers with their cubs.
This polar bear mother with her two cubs was photographed after leaving her den and preparing to make the 30 mile trek to Hudson Bay with her three month old cubs in tow. I had been photographing them for three hours as she rested on the snow with her two cubs nestled against her. It was approximately 2:00 in the afternoon when they began to move. She sat up and stretched and watched intently as the cubs played near her side. When playtime was over, she nursed the cubs directly in front of us. All during this time, the mother knew we were watching, but showed no signs of concern or stress. This is mainly due to the park regulations which require that everyone maintain a 100 yard distance from the bears and keep talking, movement, and noise to a minimum. This image was captured just as she was preparing to leave the area. She stood facing us with her two cubs on either side interested to see what we were doing. I hope you enjoy the image. More images to follow.
A lo largo de mis años como astrónomo aficionado son muchas las personas que me han preguntando dónde comprar una estrella o peor aún, me confiesan que han pagado dinero para comprar una. Lo cierto es que detrás de la venta de estrellas hay un intento de estafa.
Muchos de los anuncios de empresas que venden estrellas incluyen un certificado de autenticidad pero lo cierto es que el único organismo con potestad para poner o cambiar nombre a una estrella es la Unión Astronómica Internacional (IAU) y ésta se rige bajo criterios científicos sin ánimo de lucro así que olvídese de que pongan el nombre de su persona amada a una estrella, no va a pasar. Como explican en su página web son muy estrictos con la forma de nombrar objetos celestes y se desvinculan totalmente de las practicas comerciales que consisten en vender nombres de estrellas ficticios.
Si quieres regalar una estrella a una persona querida puedes hacerlo por tu cuenta con un folio y una foto o un dibujo de la estrella que tu quieras, será igual de original y tendrá la misma validez legal que ese supuesto certificado expedido por una empresa privada en Internet, pero mucho más barato.
El timo de la venta de estrellas comenzó en el año 1979 cuando apareció la primera empresa que ofrecía estos servicios, la International Star Registy (ISR). En su página web afirman ser los únicos que tienen registro en la oficina de derechos de autor de los Estados Unidos como si eso fuera algo que les diera relevancia o autoridad. Lo cierto es que nosotros mismos podemos crear el «Atlas de estrellas de Cielos Boreales» y registrarlo como un libro más en tal registro y apuntar los nombres ficticios de nuestro catálogo como cualquier otra publicación de ciencia-ficción. Nadie, excepto nuestra propia conciencia, nos impide cobrar 100 o 200€ por añadir tu nombre al de una estrella en nuestro catálogo personal, no estaríamos haciendo nada ilegal.
Estas empresas ofrecen todo tipo de merchandising para aumentar sus beneficios; cuadros, pulseras, colgantes, tazas… durante estos últimos 40 años han ganado millones de dólares aprovechándose de los incautos que se dejaron engatusar. A menudo han usado incluso a populares actores de Hollywood para promocionar sus servicios.
Otros regalos con estrellas más éticos
Hay otro tipo de regalos basados en las estrellas que son un poco más éticos. Es lo que hacen algunas empresas y creadores particulares al vender cuadros con la representación de la esfera celeste en un día determinado para conmemorar una fecha especial como un aniversario, por ejemplo.
En este caso no te están ofreciendo ningún certificado ficticio, es solo una imagen de cómo se veía el cielo en una noche determinada. Puedes hacer esto tu mismo ayudándote de programas como Stellarium o hacer un planisferio fijo para una fecha determinada.
Otras empresas más originales venden productos que han estado casi en el espacio. Es lo que hace EarthtoSky, que pone colgantes y otros avalorios en globos de helio que llegan a la estratosfera para luego caer de nuevo.
En cualquier caso ¿Por qué regalar una sola estrella si puedes regalar millones de ellas? Regala un telescopio y estarás haciendo el mejor regalo posible para cualquier amante de las estrellas.
KINGSTON, N.Y. — Retired Freeman photographer Bob Haines died Friday, Nov. 4. He was 82.
Haines retired from the Freeman in 2006 after a 39-year career capturing the ups and downs both in Kingston and the Mid-Hudson region, starting in 1967 when the newspaper was still headquartered in a historic building at the foot of Broadway that now houses Mariner’s Harbor Restaurant and apartments.
During his career, Haines photographed everything from local business ribbon cuttings to the Bill Clinton-Boris Yeltsin mini-summit in Hyde Park in 1995. He shot photos of movie stars including Dustin Hoffman and Jessica Lange who were in Ulster County filming the movie “Tootsie”, and of Barbra Streisand and Walter Mathou, during the filming of “Hello Dolly.” He even got the opportunity to photograph his childhood idol, Mickey Mantle, lamenting that he didn’t think to ask anyone to take a photo of him with the baseball great.
In the 2021 interview, Haines recalled the transition from 35mm film to digital photography and how no longer having to wait for film to develop in a dark room took the guesswork out of capturing the essence of the person or situation.
“The hardest part was getting the attitude I wanted to create, to show the mood of what was happening,” Haines said last year.
“I was always behind the camera, never in front of the lens,” he said in a 2021 interview as the Freeman celebrated its 150th anniversary.
High school sports games, he said, were his favorite assignments. “I didn’t know anything about sports,” he said, “but I liked the action.”
“That was all part of the job, I guess, you never knew one day to the next what was going to happen,” Haines said, laughing that he knew every politician in the Freeman’s four-county coverage area by their first name.
Haines said in the 2021 interview that his toughest assignments were photographing people during the darkest moments of their lives, like fatal car crashes, fires where families lost everything or when taking photos of people accused of crimes or those grieving over the loss of loved ones.
After graduating from Kingston High School in 1959, Haines served in the U.S. Navy from 1959 to 1964. While serving, he said he admired photographs of airplanes landing and taking off from aircraft carriers.
He later took a course in a naval photography school that turned into a job taking aerial photos.
A lifelong rail enthusiast and history buff, Haines first picked up a box camera to document the dieselization of area railroads in the 1940s, snapping photos of steam locomotives his father Hildreth ran before they disappeared from area rails for good.
Later in retirement, he collected rare photographs dating back to the 1800s.
Many of Haines’s photos have been featured in Blausweiss Media’s various documentaries and books documenting Kingston’s history like Baluweiss and Karen Berelowitz’s book “The Story of Historic Kingston.”
“I could not have done any of the work with regard to the local history of Kingston without Bob Haines’ participation,” Stephen Blauweiss said.
Blauweiss said he first met Haines while working on the “Lost Rondout: A Story of Urban Renewal” documentary, and he could always count on Haines to come up with another photo or tidbit about area history like the Seal College straight away whenever he called.
“He let us use the little bit of footage we had of the demolition of the Cornell building,” Blauweiss said.
Blauweiss said Haines along with Gene Dauner, documented the final runs of the Ulster and Delaware and Wallkill Valley railroad branches. He noted Haines’ enthusiasm for trains extended to the Kingston Model Railroad Club, where he built many of the buildings. Haines is even featured in Blauweiss Media’s short film “Kingston Model Train Club.”
“There won’t be any more assignments,” Haines said in a September 2006 interview at the time of his retirement.“That is kind of a downer. … It will be like, ‘What now, coach?”
It’s been a busy few months since moving to Reno, starting a lab at UNR, making friends, skiing, biking, and welcoming a small dinosaur (parrot) into our home, but at long last Aubrey and I finally had a chance to do some backpacking over the past two weeks. Here’s a few images from our first trip.
To get back into the swing of hiking and camping we decided to take a short warmup trip to the Desolation Wilderness, an area I’ve heard of often, and probably visited many years ago, but have few memories of. The Desolation Wilderness is southwest of Lake Tahoe (just an hour from our home!), and is mostly known for the plentiful lakes. The largest and most famous, and in many ways most beautiful, is actually a shallow reservoir called Lake Aloha. I’m not sure who decided on the name, but it inspires a tropical hawaiian feeling that is surprisingly appropriate. Aubrey brought along an inner tube floaty and we took turns paddling among the many granite islands. The pine trees almost looked like palm trees, and despite the snowy backdrop, it almost felt like floating in a tropical lagoon.
Summer greenery impatiently appears as the winter snow finally begins to melt away in mid July in the Sierra Nevada.
The warm(ish) waters of lake Aloha and plentiful granite islands make for an almost tropical experience in the Sierra alpine. To get this view point I scrambled up to an overlook of polished granite.
Pollen collects along the shores of Lake Aloha in California’s Desolation Wilderness, arranging itself in gentle curves on the calm water.
I remember in my early days my old astronomy club had a monochrome CCD camera from SBIG, which was used for scientific projects. The club opened its doors to students allowing them to discover new supernovae and other cool features in the night sky involving photometry.
Years passed by and as an amateur astronomer I’ve dealt with DSLRs for the most part of my observing sessions. While DSLRs can be suitable for using them both at day and at night, unfortunately they can’t compete with dedicated astronomy cameras.
CMOS technology has advanced more and mover over the years as well, bringing their sensors to a very competitive level vs. CCD.
In a market the recipe to success is very simple and that comes with manufacturing cost. While CCD manufacturing has struggled enormously to lower its costs, CMOS has prevailed in the technology area and made itself more dominant over the years. Availability and cost efficiency are the two major factors in its success. Both sensors eventually convert light to electrons so the end result will be the same.
Thus, it brings us to the point of my blog entry here. I’ve recently acquired ZWO’s monochrome ASI1600GT. A camera that has a very effective cooling capability, high reliability, built-in filter wheel and lightweight. ZWO has done an awesome job and provided amateur astronomers with a very competitive and strong camera. I can’t wait for the California weather to offer me the chance to try it out very soon!
With my purchase I’ve also acquired a set of OIII (Oxygen), SII (Sulfur), H-alpha (Hydrogen) 7nm narrowband filters with a set of LRGB filters from SVBony as well.