Mastering SharpCap's Smart Histogram: Optimize Exposure Without Sacrificing Signal-to-Noise Ratio

Welcome back to Hidden Light Photography, the place where we capture the universe together! 🌌 Today, we're diving deeper into SharpCap's Smart Histogram. This tool is a game-changer for those seeking the best possible signal to noise ratio in their astro images!
I'll walk through how to get a more realistic exposure recommendations for those whose mounts can't handle the longer recommended exposure time.ensuring you capture the most stunning images of the cosmos. 🌠 The best part? You won't be sacrificing your signal-to-noise ratio! 📈 Don't forget to like, comment, and subscribe for more astrophotography tutorials and tips. If you have any questions, feel free to comment below or email me at [e-mail]. Let's capture the universe together! 🚀🔭
Want to learn how to perform your camera sensor analysis for the Smart Histogram? Check out this video:
• Maximize Your Astropho...
00:00 Introduction
01:32 Explanation of Smart Histogram Options
05:06 Let’s See it in Action
#SharpCap
#SmartHistogram
#signaltonoise
#hiddenlightphotography

[@matthewkendall5235]

Very interesting Tony - most analysis of astro photography video analysing S/N using ZWO cameras in Bortle 2- 8 skies on LRGB tend to end up use 10 - 30 second shots in Bortle 5-8 skies and 60 - 90 second shots in Bortle 2-3 and then say triple this for Narrowband. This is the first video I have seen using much longer duration shots - with the analysis trained for our exact gear - in our skies for our targets.
I generally image magnitude 8 - 10 galaxies in Bortle 6.5 skies using ZWO cameras (71MC-c and 1600MM-c) and William Optics (95, 110 and 132mm OTAs) - and often guess at a sequence of 2-4 minute subs in LRGB - and do that until I have 10 - 20 hours of data. My old Vixen Atlux + SS2K-pc can easily do 10 - 30 minute subs at much longer focal length than my 3 OTAs - so I will certainly now look at exactly what SharpCap Pro recommends for my targets, gear and night skies.
Great find - thank you!

[@Hidden.Light.Photography]

This is definitely a very useful tool and does a very good job. The use of broadband filters will have less exposure time recommendations than their narrowband counterpart. I use this exclusively for exposure recommendations and build this into my set up workflow just due to the reliability and proven results.

[@moneyoffsoftware]

Thank you for another excellent tutorial Tony. I can't wait to try it out, if only the sky would clear up in the UK. The weather has been awful for the past few months.

[@Hidden.Light.Photography]

Thank you! I am fighting the same thing. It has been cloudy here for the last 3 or so months. I shot this video right after my remake of NINA polar alignment since I had a very small break in the clouds and right as I finished this one I lost my hole and the entire area was cloud covered haha.

[@AstroNerd]

Thank you for posting this video. Very informative.

[@Hidden.Light.Photography]

Thank you and you are very welcome! Are you currently using SharpCap or looking into it?

[@AstroNerd]

@@Hidden.Light.Photography SharpCap is awesome, the best program out now for Live Stacking. I’ve been using Sharp cap since around 2016/2017 (ver. 2.8 I think) when I had a modified LN300 camera (Astro Video Systems MK-IV). I moved up to an ASI385 Cooled and then an ASI533 MC Pro which I’m still using and really love that camera! I’m thinking about using the Smart Histogram to set the baseline histogram and then jump over to LiveStacking for the EAA.

[@Hidden.Light.Photography]

SharpCap is definitely a great tool and you won’t be disappointed with the Smart Histogram! I use it for all of my exposure recommendations

[@PeterClarke55]

Hi Tony, I am really learning and enjoying your vids and really glad to have found you. Coming from a very light polluted part of England on the west coast I cannot take longer than 150 sec exposures. So I noticed that you set the 20min exposure on the process but surely this will dictate those longer exposures that you are finding in the results. Would it not be better to reduce the max exposure to say 5 mins and see what results you obtain. Again thank you for your videos and really look forward to the new shoots coming out. Clear skies and Thank You..

[@Hidden.Light.Photography]

Thank you! This is a really good question!! The short answer is no. The explanation is SharpCap doesn’t care what you put there. It is looking for the best signal to noise based off of your integration time, color channel read noise limit, choice between max dynamic range/unity gain and sensor capabilities as measured by the sensor analysis. What will end up happening if you choose a tighter tolerance on the exposure times is it will error out saying that it cannot find a suitable exposure time within the parameters so you will have to change one of the other parameters anyway.

[@KJRitch]

Do you find after using this tool, especially if you image from one primary location, you build some experience and know you will be always using a certain gain and exposure. I notice that Unity gain is set but gain 0 was recommended. How does Sharpcap know what is Unity gain? I have a ASI071MC Pro but I'm not sure what is the Unity gain. Is it where Gain(e-/ADU) = 1.0 on the graph for the camera spec, in that case 90 is my Unity gain? Thanks

[@Hidden.Light.Photography]

You do gain experience when you’ve been in the same spot for awhile and using the same equipment in the sense you can judge pretty well what you’ll need. There’s a lot of calculations the SharpCap algorithm uses to determine gain and exposures including sky conditions such as brightness along with your total intended integration time as set in the smart histogram and the amount of noise you want to allow in your final image (the more you stack, the less the final noise will be). Before you use the smart histogram, you’re going to want to run a sensor analysis so SharpCap knows your particular camera. Sometimes, it’ll already have the camera data installed, but this is generic for the camera brand/model and it’s best to think of the sensor as a finger print. To get the best results, you’re going to want to run the analysis so you have your personal cameras sensor “reactions” analyzed. When you choose unity gain, that’s a parameter so SharpCap can aim to get as close as possible to unity gain. The easiest way to think of this is to think of the gain setting as an artificial value to brighten or darken the image. The higher the gain setting, the more noise you are introducing, but the brighter the image, thus less sub exposure is needed (I.e (using easy numbers) to get a well exposed sub frame you’d have 60s at gain 100. Increase the gain to 150 and you’d need 30s for the same type of exposure but you’ll have more noise. Set gain to 50 and you’d need 90s for same type of exposure but this would have less noise. These aren’t real numbers. Just an example to explain principal). Let’s say you have 10 hours of integration, unity gain and noise readout of 3% and you are lined up with your target and push measure, SharpCap will start taking exposures with different gain and exposures, dial into your sensor analysis and do the calculations based on the current sky conditions compared to your camera’s capability and figure out exactly what you need in order to get you the best possible final image with a noise level of no more than 3% of the camera’s lowest read noise capability for a total integration time of 10 hours and the lowest possible gain setting which will minimize the noise. Keep in mind, as gain is increased, you are in turn lowering the full well capacity which causes pixels to saturate more and increases the noise within the image. Unity gain is 1 electron per ADU. Now, the same is true for selecting dynamic range, except SharpCap won’t necessarily choose the lowest possible gain setting since it is not aiming for unity gain, but rather utilizing the dynamic range of the camera. Since gain isn’t as important with this, SharpCap isn’t looking for lowest gain to accomplish your goals.
Keep in mind, it is very easy to overthink exposures. SharpCap is very good if you are looking to absolutely maximize your image’s potential. In the end, if you threw your gain to between 75-100 and did a few test exposures on your target until you got your histogram with a gap off of the left side (maybe a 1/8 or less) and ran it, you would be just fine. You can figure out the unity gain of your camera with the math you mentioned and I believe it’s something along the lines of FWC/bit depth and then you need you figure out how much gain takes away from FWC and run it that way until FWC equals bit depth, but once you start figuring the other variables such as sky brightness and how the light from DSO is hitting your sensor plus the noise you get from a live environment it is pages of math and that’s where SharpCap comes in because Robyn Glover did the math for us :)
I really hope this helps