What exposure time should I use?! Let's answer that!

What exposure time to use for astrophotography is a recurrent question, especially with the waves of CMOS astrocameras now on the market. In this video, I answer this question, from my happy go lucky point of view! Well, that's how I roll, sorry for being lazy!
More seriously, as always, I may be wrong - so let me know in the comments how you determine your exposure time, and if you have any suggestions or if I made some glaring mistakes! This hobby is a continuous learning opportunity, that's one of the things that's great about it.
I am planning to have a video explaining shot noise and thermal noise as well and stacking - and stress the importance of SNR as what we are after!
Dr Robin Glover videos: • Deep Sky Astrophotogra...
And the follow-up: • Choosing the right gai...
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#astrophotography

[@SKYST0RY]

When I tried the exposure calculator, I thought I had accidentally discovered the event horizon of a black hole as it was recommending infinite exposure. Then I realized I had left my lens cap on.

[@aniket789]

😂

[@MrMrduke1975]

😂😂😂😂 awesome!! That made my night!

[@thebst6408]

Helo cuiv whats the best exposure for the hyperstar?

[@danielmills2992]

Cuiv! another cracking video, thank you for all your knowledge and info! Clear skies brother

[@CuivTheLazyGeek]

My pleasure Daniel, and thanks for watching! Clear skies to you too!

[@jean-clauderoussil4830]

You not so much lazy, you give me good instructions to do the best of my camera, keep going, god bless you!!!

[@jimmydigital00]

I am so happy I found your channel. Very informative. Thank you

[@CuivTheLazyGeek]

Thank you for finding the channel, and welcome! :) Glad to know the channel is being useful!

[@johndaley9188]

I asked about exposure time on one of your newer videos. Did a search on your earlier videos and of course, found this one. I don't plan on using NINA but winging it seems to be the best approach. There's no magical, use this for all. I'm going to look at it as part of my learning curve. Thanks for your insight and being able to express your knowledge. It has helped me a lot.

[@miodragpetkovic6142]

You are The Legend Geek not Lazy... Superb and so inspirated videos. Keep going and full suport.

[@lpalbou]

Good video, but just a small addition. While there are many advantages to expose as little as you need (be sure any of the R,G,B channel are just detached from the left border of the histogram), you may have some cons: you have to stretch your data more, and with that, any imperfections in the data. I am thinking particularly of some sensor banding and pattern issues. They are not always filtered out from flats (even though you can see them here too) and I find that exposing slightly more is better (being 1/4 or 1/5 detached from the left side).

[@elmikol2443]

Another outstanding video Cuiv! I like your sense of humor!

[@CuivTheLazyGeek]

Thank you :D

[@angusfraser5562]

I got this working, I did the SmartCap analysis. What is not obvious is where the sensor analysis is stored. After some seraching I found out it is in your gome user directory under appdata/roaming/SharpCap/SensorAnalysis. To see appdata you will have to show hidden files in your home directory. Now I poinjt at the sky and get a suggested exposure time which is remarkable good and WAY shorter than I would do if I were doing by eye. Thanks for the video as always great content.

[@billneedham5785]

very helpfull. thanks Bill

[@steppen57]

I enjoyed your video and how you presented it. I also live and image from a bright city. This is very useful. I have been wondering for ages - how can I determine the exposure time. At the end, you last comment ... play it by ear! That’s the way I think if you live in a city. Thanks!

[@MrGChuff]

Phew (flops onto chair, cloth in hand, dabbing beads of sweat from ones forehead) ADU and exposure length explained in a simple bite size way. Thanks a million from a mono newbie

[@CuivTheLazyGeek]

You are quite welcome! I am very glad this was useful! Good luck on your monochrome journey, it's going to be a lot of fun :)

[@AnakChan]

Great review. I didn't know N.I.N.A. had a calculator. Taking lots of small exposures do require a decent PC setup behind it. I only have the ASIAir Pro and last week, was contemplating taking pictures of Homunculus Nebula - then realised, to take 100ms exposures with the ASI6200MM (62MP producing 122MB files) was probably NOT a good idea :D.

[@CuivTheLazyGeek]

Hahaha! We've had another user on the NINA Discord with similar issues with the 6200MM (needed to subframe to get good HFR estimates)! You would need a server farm to process a few thousands of frames from that monster of a camera! How are you liking the camera by the way?

[@kayedsss]

Thank you very much for the great information, I have a question, I live in Bortle 6 area and I have the nextstar 8se with 6.3 FR, the L optolong pro and the asi294mc pro, at F6.3 still the 30 seconds rule of thumb applies?

[@yangyunbo1]

thanks cuiv,i will try this function in nina.BTW nina has inproved a lot,i just used the 1.8.10 version but the 1.10 beta looks much better than before

[@CuivTheLazyGeek]

Oh yes, NINA 1.10 Beta is light years ahead of 1.8 versions! So many things have been enhanced. Thanks for the feedback!

[@ericbelanger1262]

Merci pour les excellents tutoriels :) un beau bonjour du Québec :):) merci encore

[@yellowlynx]

Cuiv, you can try and use a red transparent paper over the lamp you are using while filming. That can reduce the effect of light leaking into your scope.

[@johnjames378]

Again I learned more good stuff.

[@suzannebeers6238]

Great videos thank you! it's there a way to relate exposure time to target magnitude in a " mathematical" way?

[@ricardoibargoyen4331]

Very very interesting. Thanks!!!

[@CuivTheLazyGeek]

My pleasure, glad it was useful!

[@allenbaylus3378]

Put my scope up a few weeks ago in a clear night. First time with my SCT in a year. I was shooting M101. 5 min looked ok. 2 min and 1 min looked faint. Shot a few hours at 1 minute expecting to stack then with less star streaking. PI decided that it was not interested in my under exposed pics. I later realized that I left my L-Extreme in the filter drawer. Still I should have reviewed this before shooting.

[@rv3211]

Great video as usual. You say you have 1 e- per ADU and that your FW is just a count of ADUs, then 2^14. What about if your gain gave you a value of 1.5 or 2, how would you calculate that?

[@dravenack]

You have explained the best I have seen and I have read a lot always leading me to confusion…and I tried asking on an astrophotography forum and those assholes just rip me a new one for not being as smart as them..so thanks

[@CuivTheLazyGeek]

My pleasure! I'm glad I can help!!

[@alessandrogaldiero7796]

Hi Cuiv, interesting video... I've never shot from home with my setup, I'm usually in the mountains where I don't worry about doing long exposures. At home I have a bortle 8/9 sky, using unit gain of an asi 294 osc with asiair pro can you show me an "ideal" histogram of how it should be? Obviously, it is important to keep in mind not to saturate the stellar nuclei. Thank you

[@starpartyguy5605]

I am only imaging at Cherry Springs state Park, Bortles 3. For years I used SBIG cameras, all with Kodak ccd chips. When I was getting started, I asked around for exposure time suggestions. I kept hearing 10 minute subs. I’ve been doing this for 10 years. Now I move to the Sony cmos chip in a QHY 268m. And since I’m using a c9.25 at f/10, I am binning at 2x2. Obviously I don’t need to use 10 minute subs. So I cut it to 3. I can’t imagine using exposures shorter than that.

[@broady64]

just got my ASI533, you're my goto channel for info. As usual well explained and easy to understand, even to an idiot like me :-)

[@starwatcher]

Excellent. Thanks.

[@CuivTheLazyGeek]

Thank you!

[@shaunozs1ra92]

Thanks for another great video. I live under Bortle-8 skies and knowing Tokyo I am amazed at the images you are getting. I used the now aged Celestron 8300 one shot colour camera and really struggle to get faint detail out of my images. When I get the faint data I invariably have blown out cores and have to HDR stack etc. I am not in a position to purchase a mono camera, plus a filter set, plus, plus, plus, at the moment (I saw your great review of the ASI) Do you attribute the images that you are managing to capture just down to kit or are there some obvious issues that I should be checking before making the expensive leap of a mono conversion?

[@CuivTheLazyGeek]

I was drooling over that camera for a while - every forum thread was about the KAF-8300 sensor! I looked around and it seems that camera has a gain of around 0.4 e/ADU, with 16 bits ADC (e.g. 65,000 ADU or so), a full well of 25,000 electrons, and a much higher read noise of around 7-8 electrons. So that read noise is very significant. What does the optimal exposure calculator in NINA tell you in terms of exposure time, based on the above? You could be in a situation where LP is so bad that for that sensor, if you're swamping the read noise, you are also saturating the stars. By the way, are the star cores really saturated when the image is still linear? Or do they appear saturated after you stretch in PixInsight or equivalent? In which case, you may want to use something like the MaskedStretch to avoid over-stretching the stars in processing.

[@shaunozs1ra92]

@@CuivTheLazyGeek Thanks for your reply. I think you have hit the nail on the head with the sensitivity of the sensor. To get any sort of nebulosity captured the stars are saturated straight out of the camera. I also use a unmodified Canon 1Ds MkIII & 1D MkIV, whilst the star saturation is still present it is much lower. Unfortunately I do not use NINA, I am about to change shortly. Currently I only use Celestron AFX and and Canon Utility-2 for capturing. I have going to look at the ZWO you reviewed in one of your videos as I am not going to be able to move home for the next 5 years so I have to find some solution to my dilemma.

[@M0XCR]

Loving your content, just starting to give N.I.N.A. a try after using nebulosity for the last 8 years, it’s like starting over again 😊

[@CuivTheLazyGeek]

Oooh Nebulosity - I bought that a long time ago! I need to find my license to that. It was when I had no idea what people meant by "stretching" the image. Huh. I should do a video on that. I will probably as part of my upcoming lazy approach to AP series!

[@BrokenPik]

@staterboy What would i do with my Meade DSI Pro II if it was not for Nebulosity 4. love it.

[@M0XCR]

Mitch it is a cracking bit of software and I must admit it is a bit like a safety blanket, I keep going back to it when I can’t figure out what to do with NINA.

[@BrokenPik]

@@M0XCR u could do like i did at first...i would wait for full moon clear nights and just learn 1 or 2 settings in NINA , eventually adding more till i got comfortable...

[@CuivTheLazyGeek]

@@BrokenPik Meade DSI Pro II. This is the reason I bought Nebulosity in the first place! :D

[@alanrichards7667]

I was just thinking I started this hobby with a Atik Horizon OSC and there software limits your exposure to 120 seconds, you can overnight it and expose for 2 hours if you like but they know with the sensor they have and there gain settings over 120 seconds will over fill the well, so they recommend low gain for max dynamic range, I think they are playing to the beginner, make it simple. My feeling is that max exposure is were a unstreched image will show maybe 1 star or no stars but yet start it's baseline over the bias.

[@CuivTheLazyGeek]

The Atik Horizon is basically the ASI1600MC, right? Yeah I wouldn't use it at zero gain... The read noise is then really too high, too much of a tax to pay with each exposure. The Unity Gain (which in itself doesn't really mean anything besides 1 electron / ADU) for the 1600MM/MC is actually very well placed - sure you have less DR, but you have much less read noise (and the read noise curve starts decreasing less quickly from that gain onward), so you can actually afford to expose less long. I think they may have suggested 0 gain as a way to make their CCD users comfortable! 0 gain means high read noise and long exposures, just like CCD! But I've never used zero gain with my 1600MM :)

[@Pletharoe]

Hey Cuiv, love these tutorials, and I've switched to NINA too. Question if I may, why is your gain level selection always set to empty? is it automatically controlled by the driver or something? keep up the great work!

[@CuivTheLazyGeek]

Empty in the sequence, but set in the camera tab!

[@alanrichards7667]

Think of it this way, you have a 12 oz glass a 6 oz glass and a 1 oz glass out in the rain, after 1/2 hr the 1 oz glass is full and the other 2 are 1/6 and 1/12 full as it continues to rain the glasses keep filling except for the 1 oz which over fills, now think of the 1 oz glass as high gain and the 12 oz as low gain or exposure time. Most people think that if they expose for 5 min they are getting better results because there single frame has more detail in it but in many cases it's like the 1oz glass which is overfilling, sure the bottom looks good but were is the top it's in the 6 and 12 oz glass. They have full dynamic range and the 1 oz glass has low end range but loses it in the high end. The best results will be to fill the glass (any one) 90% full and shoot more exposures. So from my house I go out and shoot 100 exposures at 30 sec the dynamic range is good but no shadow detail so I shoot 100 more and it's there so now I know for my sky and moon I need to shoot 200 at 30, from a dark sight I might get away with 100 at 30 but in either case you would get full dynamic range. Secondly as for banding in images if you stretch your bias and the histogram shows it to fall into a range of 0 to 500 lets say your lights have to start above 500 (600 - 1000) is better if the light starts it base point at 250 you get banding in you image it is not a software or driver problem it's exposure.

[@CuivTheLazyGeek]

Thanks for that as well! When you say "the best results will be to fill the glass (any one) 90% full and shoot more exposures", it sounds like advocating ETTR photography, which tends to saturate/clip point source lights such as stars, which are (in theory) affected by aperture rather than focal ratio. In the end the optimal exposure time is determined by the point at which the read noise of your sensor is swamped by the shot noise from your target and the sky glow. So your sub-exposure times will be much longer in dark zones (or in narrowband) than in suburban environments, as the read noise is then much more difficult to swamp (but that's a good thing!). Then, since we are hunting for SNR, we can increase the total exposure time as much as possible - the signal will grow linearly, while shot noise will grow as a square root (although with each exposure, we pay the read noise tax). So the longer the total exposure time, the more we increase our SNR (assuming we've swamped the read noise! Which is indeed represented by the bias, but the bias mean will represent the offset directly and the read noise - e.g. the random uncertainty in the bias - indirectly, so in itself doesn't tell you where you should be exposing, thus Dr Glover's concept of the optimal exposure time). As the SNR increases, we can then stretch the image more and more, as the fainter objects or strands of nebulosity can then be extracted from the shot noise. The necessary total exposure time to do that will depend both on the target, the sky conditions, and what the imager wants to accomplish.

[@basfinnis]

What if I have a pint glass as opposed to your shot glass?

[@testboga5991]

You want to use the median to not get screwed over by extreme values. Median is the correct value.

[@raeiqmusachi]

your channel is great, you’re like a funny professor who actually is interesting to listen. keep it up. what is your knowledge background? how do you know all this... tell us your secrets oh wizard

[@CuivTheLazyGeek]

Hahaha, thank you! I'm originally trained as an engineer, but more on the computer science side of things. So it helps a lot!

[@raeiqmusachi]

Very nice, subscribed

[@alanrichards7667]

You need to shoot a a gain that gives you the max. dynamic range, and a exposure greater that the bias but not over exposing the image when stretched. Less is more and more is less in exposure don't be fooled into thinking because your shadows look good you have the best exposure. Atik software and Meade capture are 2 programs that have a stretched histogram when capturing if using one of these you would take a bias look were it stops increase light exposure till it stars to the right of the bias and the last bit of detail in the light is well short of the end at the right. then shoot enough frames to get good shadow detail. Image stacking while exposing works well here as in the Atik software, wish NINA had it works also with ZWO ASIAIR

[@CuivTheLazyGeek]

Thank you! I have another video looking at the DR and the read noise, which explains those concepts and how they will link to an optimal/minimal exposure that would swamp the read noise (10 * read noise squared / sky glow flux, as per Dr Glover's advice) - in the end you need to first choose the gain that will work for you, or maybe iterate until you find the gain that gives you an exposure time your mount and material can support. You do not always need to maximize DR (a lot of which can be recovered while stacking), otherwise you'd be shooting at gain 0 all the time with the 1600MM for example - you want to choose a judicious gain that minimizes read noise while preserving as much DR as possible. For example I consciously choose to go to gain 200 with my 1600MM when shooting ultra-narrowband, to keep read noise low and exposure time relatively low - although I sacrifice DR while doing so (but I recover some of it when stacking). Overall, once you have chosen your gain, the rule really is to expose long enough that the read noise is swamped in each exposure, and you can expose for longer than that as long as there is no pixel saturation. That minimum / optimal exposure time is determined by the shot noise contained in target and sky glow (e.g. does that shot noise swamp the read noise sufficiently, so that read noise is then insignificant compared to shot noise?). Right now I think the best way to do live stacking when using NINA is just to use DeepSkyStacker, which is also free!

[@garypowers9649]

hi Quiv, I am 8.00 mins into the Video again and have a question on the Gain value you mention of 101, when i did a camera sensor analysis (ref : SharpCap) my unity gain value for a Hypercam 269C came out at 565 ( calculated from a Graph i plotted) . ? - should i be using this figure in place of the 101 you mention, i am not sure, PS: your videos are a great help to me starting AstroPhotography and especially with NINA also. thanks

[@CuivTheLazyGeek]

Remember that unity gain in and of itself means nothing - just that we count 1 electron per ADU. From an astrophotographer's point of view, this fact is "meh" at best - it just so happens that manufacturers have placed unity gain in interesting places. Now for the Hypercam 269C, your sensor analysis seems to agree with AstroStace's (www.astrostace.com/post/altair-hypercam-269c-review), but from what I see in here, there seems a switch to lower read noise/HGC at around gain 250? My first impulse upon looking at this graph would be to use the camera at gain 300 or maybe 350 or so, see what type of exposure times this gives me. Glad my videos are helpful, and clear skies!

[@grindingyanus]

Hi thanks a lot for all your videos, your tips and your really good mood ! Is there any reason to set gain at 101 and not 100 (sorry if I miss the answer in another video). I'll receive my 2600mc pro and looking for the optimal gain. Thanks !

[@CuivTheLazyGeek]

Just paranoia! I prefer to be absolutely sure I'm triggering High Gain Conversion!

[@SKYST0RY]

I noticed no gain is noted in the imaging panel. If you leave it blank, does NINA go to the default gain setting?

[@tomroberts3851]

Cuiv, thanks so much for your videos, they're awesome and I too am using a ZWO Asi 533 MC Pro :) Just like you mentioned, I'm not keen on 1s exposures, however, with my Optolong L-enhance filter, I'm trying to work out the advantages of say a 90 s exposure vs. a 300s exposure. To date, I can't see any real advantage of going for the longer 300 s exposure? Could you offer some advice? I'm experiencing a little star bloating too, hence why I'd quite like to drop my exposure time. Thanks man!

[@Kyle_Hubbard]

Ten months no answer, OOF.

[@tomroberts3851]

@@Kyle_Hubbard sad face :(

[@WalidFeghali]

I'd also like to know this!

[@mode1charlie170]

See Alan Richard comment and reply above…

[@cryptoalchemist10minutes44]

Just need one thing to make your Nina video's complete. Polar align :) If I can skip Sharpcap I would be happy!

[@CuivTheLazyGeek]

I have to admit, I am addicted to Sharpcap's PA - I pay for the pro license literally for the PA... But I'll give NINA's method a spin sometime soon!

[@newforestobservatory9322]

I have taken 1-hour subs on a Sky90 @ f#4.5 with a SX M26C OSC CCD and the results were excellent. Provided you are not plagued by bad light pollution, the answer to how long should my subs be is long enough to get at least 12 subs to stack at the end of your imaging session. I note the CMOS camera I've just got (ASI2600MC-Pro) won't go beyond 33 minutes for a sub - that's interesting.

[@CuivTheLazyGeek]

I disagree on the number of subs - it's all about integration time! My 30 second subs in broadband will never show enough SNR with 12 subs :D Longer subs are fine as long as they don't saturate the sensor. But if I can I'll go for shorter subs every time (as long as read noise is swamped), as I can afford to lose subs to wind, etc. without feeling bad :)

[@newforestobservatory9322]

@@CuivTheLazyGeek Yes, you're absolutely right - I was sloppy in the way I worded that :) I meant 12 subs is fine when you're taking subs of order 15 - 20-minutes. 12 x 30-second subs isn't going to look great :)

[@0815mkl]

hmm just a question. at 3:28 you say the measurement is in ADU and for your camera the maximum is 16.384 but the measurement of the max value for this image shows 35417. Could it be that even though the sensor has a 14 bit depth the data itself is transferred as 16 bit numbers (and so with 65535 as maximum value)? That would mean your value of 4265 is an ADU value of 1066 (or 1/4 of the shown values). At 3:55 the maximum value after 30 seconds is 65535 with the brightest pixel being fully saturated. just realized that it even shows 16bit depth directly above the histogram.

[@DebashishGhoshOfficial]

If this tool gives me a minimum exposure time to swamp the noise floor, then how do I calculate the maximum exposure time before stars get over-exposed?

[@tycho_escher]

Very useful. Do you ever use light pollution filters with your 533mc?

[@CuivTheLazyGeek]

I haven't yet! I will have to get to it at some point though... But the only LP filter I own is a 2 inch Optolong CLS-CCD filter... Not sure it is super good compared to something like an IDAS. But I'll get there, I'm sure!

[@ricardoibargoyen4331]

Hello!! Just a question (stupid question I think 🙃) : I dont see the calculator in imaging tab. I have 1.9 version. Thanks and keep going!!

[@CuivTheLazyGeek]

There is no stupid question :) Oooh I am not sure whether it was in 1.9. 1.10 is now in Release Candidate mode (so almost stable version), so I'd really recommend it! It should have the calculator icon in there. Good luck & clear skies!

[@ricardoibargoyen4331]

@@CuivTheLazyGeek Thanks!!! Waiting for go with the equipment and try NINA seriously.

[@bricktrainfan]

I been watching your videos for a bit and really value the information you ass on. But for someone going under the moniker of "Te Lazy Geek" you went through a bunch of work to get exposure time. 😆Cheers

[@CuivTheLazyGeek]

Short term work for long term laziness:)

[@MCDanyification]

Question: What does the number in the bracket (min/max) mean? is that the amount of pix that have these numbers? I´m curious :) ohhh... and thx for the great vid :)

[@CuivTheLazyGeek]

An excellent question! And your answer is the right one, well done :) If you see a lot of pixels with a max value equal to the max ADU value, you know you're clipping stuff! And if you see a lot of very dark pixels, you may want to increase your offset.

[@ricardoibargoyen4331]

Hello!! Just a question with NINA. When you have an image in Imaging, can you select a point with the mouse in the image and slew the telescope there like in APT?? Thanks!!!

[@CuivTheLazyGeek]

Unfortunately no... You'd have to go into the Framing Wizard, and load the image from file or cache, or maybe simply from a catalog, center the image on where you want to slew and plate-solve to, and then NINA will do the rest.

[@ricardoibargoyen4331]

@@CuivTheLazyGeek Thanks again!

[@darrenwarne9005]

Are you supposed to aim at your target or just a random patch of sky? I tried it and came up with 52" when I tried that exposure the histogram was clipped. End up at 240" to get the histogram off the left edge. I did use sharpcap analysis. Great video as always

[@CuivTheLazyGeek]

It's better to aim at your target, so you estimate the total sky flux to overwhelm the read noise. What camera do you use?

[@darrenwarne9005]

@@CuivTheLazyGeek , altair 269C hypercam is what I was working with on an ED102t Cf . I also have an ASI533, ASI1600MC-C and 1600MM-P. I like the 533 btw

[@aughtago]

you say that maybe ALL ZWO cameras convert 14 bit to look like 16bit to NINA, I think by watching a previous video you may even have the same camera as i do (ASI 294 MC PRO) , yet when i look at the manual it only indicates 14 bit. I am very new and a little confused.

[@Master0fDe5a5ter]

Cuiv, from your point of view use bin or no bin (asi533 celestron 9.25 @f6.3) bin 2 is normal a good resolution but most people say, that bining "destroys" the color what do you think?

[@CuivTheLazyGeek]

I personally do not bin my CMOS cameras - if binning, I would do it as part of the processing, not as part of the capture. I am not sure how the software binning on ZWO cameras works (nor the hardware binning), and I don't really trust it. Binning in post does increase SNR, but wouldn't kill the color since it averages the R, G, B values of each post-debayer pixels. But one thing to remember is that by debayering, there is some loss of resolution - so an image that would be oversampled with a monochrome sensor may be just right or undersampled with an equivalent bayered sensor. So if you're just slightly oversampled, there is a risk with binning. Of course you could drizzle and then bin - honestly I have no idea how much SNR would then be recovered! This is an area I'm not an expert in, so take everything above with a healthy fistful of salt.

[@shaunozs1ra92]

I am interested in the binning issue too. My reason being that I don't own a monochrome camera and my CCD will only work in monochrome when binned for the reasons that Cuiv mentions below. Due to the amount of light pollution I was thinking that a mono with filtering maybe a better solution. I know that resolution may suffer but I am tired of washed out images because of the high noise floor.

[@Philobr]

Does this process also apply to dslrs?

[@chrishanson3497]

HI Cuiv. Do you have any filters in while running the optimization test or should I remove my L-ehanced filter?

[@CuivTheLazyGeek]

I have the imaging train I will be using including the filter - otherwise the results won't be accurate

[@cucubits]

Should I be worried that I'm exposing way too long if I'm doing 600s subs with an L-Enhance filter (also with an ASI533) from a similarly light polluted city? The individual subs do look bad (green tint) but the histogram is there at around 30% from the left. Haven't processed yet, need more clear nights to gather data, but I'm slightly worried that I went overboard with individual exposure times.

[@CuivTheLazyGeek]

You're fine at 600s if your star cores are not over-saturated. The only thing is that you are exposing yourself to more risk of losing imaging time from wind and vibrations!

[@davidemaino7868]

Hi there. Great video. Just a quick question. I live in bortle 7/8 region and the large part of the sky is from my front yard (balcony) where I have street lights. I’m using a DSLR Astro mod. Do you think your suggested approach is valid also in my case? Do I have to take as much as I can from single exposure without saturating it? Thanks.

[@connolly3000]

Did you ever find an answer to this question mate? New to astro myself with a modded Sony A7III. My shots are blown out by light pollution but I don't seem to gather any Ha data on shorter exposures. Is that because I need tonnes more of them? I'm not quite sure how it all works

[@davidemaino7868]

@@connolly3000 I found out that on the back balcony without street lights I can get subs of about 120/180 secs. On the front one I was able to shoot M33 for about 2.5/hours with 90 secs subs with a good result.

[@connolly3000]

@@davidemaino7868 Thanks for the reply! Do you find light pollution hard to work with in post or are you mainly shooting DSO? It’s more widefield I’m having issues with, there’s an atmospheric glow that blows out the shots, it’s hard to pull Ha data from barnards loop etc with the shots being blown. Is it possible to shorten the exposures to not blow the light pollution haze out and still gather data from the shot? If so would it take like thousands of shots to do it or would I be better driving further afield. It takes me over an hour for a bortle 4 sky 🤦🏻‍♂️

[@davidemaino7868]

@@connolly3000 let me share with you this video. It is in italian but I think the core would be usable. kzbin.info/www/bejne/eIKwnHSdl96bi7M

[@connolly3000]

@@davidemaino7868 Thank you! The subtitle translate might work 😅 I’ll check it out when I have time to read the subs too. Appreciate you taking the time to reply to me! 🙏🏻

[@BrokenPik]

Had to pause to read your message , dont you just love crows... another informative episode...

[@CuivTheLazyGeek]

Hahaha, I'm glad someone did pause! Crows are indeed far too smart - and vindictive too!

[@BrokenPik]

@@CuivTheLazyGeek Yea and those clothes hangers are expensive , so, come on birds, give it a rest... Lol

[@dankahraman354]

Cuiv I am still trying to see where the "lazy" is...;)

[@CuivTheLazyGeek]

Hehehe many people have been telling me that! I explain that I am selectively lazy :) For astrophotography I definitely am lazy!

[@dankahraman354]

@@CuivTheLazyGeek I think it is being smart which comes from experience..you learn to be very concise. Be careful though: My teacher had a nervous breakdown and he had been doing this for 40 years. I don't want it to happen to you or to me. Ours is a very demanding hobby and it will have you going in all directions in trying to solve one problem versus another as well as looking for constant improvements...

[@allen4564]

I can't seem to get a histogram with my Canon T2i. Does NINA support this? If it does I'm not sure what I could be doing wrong. I believe that my camera has a bit depth of 14 so I tried going to options and setting it to 14 bit there but when I look at the Statistics it still says 16. Don't know if that has anything to do with it.

[@CuivTheLazyGeek]

Mmmh, I haven't used DSLRs with NINA so I can't tell for sure. The T2i is quite old but still should be supported by Canon's SDK. Do you actually get a picture from the camera into NINA? This is one instance where you likely will get much better support on the official NINA Discord, which you can access here: discord.gg/fwpmHU4 . I really hope you get this cleared up!

[@cweinert2727]

You say you can expose to whatever time you want as long as your star cores are not overexposed. How do you determine that during test shots? And do you mean don't overexpose any stars or just the "bright" ones? Like named stars only, usually magnitude brighter than 3.5.??

[@CuivTheLazyGeek]

Excellent question - and difficult to answer too. I actually typically don't care that much about blowing out star cores of super bright stars (for example when imaging the horse and flame nebulae), so in the end it all depends on what you are willing to accept. My tolerance for blown out star cores is pretty high (I don't care too much), so if bright stars are overexposed... well so be it. It really depends on the end user - and there is no set rule. So the 1/3rd histogram rule of thumb is generally a good compromise... I wouldn't worry too much about it! I hope this helps, and clear skies!

[@doctorschulte9751]

What control Software are you using.

[@CuivTheLazyGeek]

I use N.I.N.A., which is free and open source - you can find it at nighttime-imaging.eu/ . I have a series of video tutorials about it if you look at my playlists too!

[@rashie]

👍👍

[@Farathus]

Hmm maybe I don't understand something, but this sounds to me like you're throwing away all of that bit depth of your sensor. The sensor has 14 bits stretched from dark to bright, but you're only exposing for a few seconds so you're only filling that full 16000 deep well to 4000 let's say. The final image is stacked, but all stacking is doing is averaging over all frames to reduce shot noise. So the final image will only contain values between 0 and 4000. That's 12 of your possible 14 bit. Shouldn't you expose long enough that you optimally fill that well to use the entire bit depth you have?

[@cryptoalchemist10minutes44]

Awesome another thing I learnt. I estimate you will be monetized in another 10 video's time. 2,000 subscrivers end of June! Thats where you can buy some goodies to review :)

[@CuivTheLazyGeek]

10 videos only?! Well, if it's exponential growth.....! Thanks for the encouragement!

[@tomtoka]

I dont get it at all, I watched the video may times and i dont get it . I am using asiaair pro,

[@thefourgrapples2810]

I am a subscriber. Although I have never seen a crow carry a clothes hanger, I have seen a swallow carry a coconut.

[@CuivTheLazyGeek]

Was it a European swallow or an African swallow? :)

[@MathewKelson]

I hit the like button mostly for the crow 😂

[@CuivTheLazyGeek]

Curse that crow! :D

[@woody5109]

Nina…Mac or pc?

[@lachezarkrastev7123]

Actually you are overthinking here :)

[@timmoody7600]

You started with an exposure of 10s and then increased it to 30s. but in your video on the Sunflower galaxy you expose at 120s. Why is that?

[@CuivTheLazyGeek]

Wow, I have no idea by now. I probably wanted fewer subs to stack.

[@timmoody7600]

@@CuivTheLazyGeek Sorry, I went back and looked at my notes and I think you did indeed shoot at 30s at f/3.8, faster than my f/6.3. You get nice results and as you say have lots of subs to stack (756 out of over 1000 in that case). I was shooting at 300s as many of the other videos I follow seem to use such exposures.

[@jodyschultz5870]

You know Cuiv, the thing I hate about you, is that as someone that is originally from the UK, I can tell you that your command of the English language and your vocabulary is vastly superior to the majority of English people.

[@jesuschrist2284]

Are you only doing 10sec subs then?

[@alegomanYTPs]

words and letters and numbers and e=mc squared or whatever, yeah, no. I'll stick to my dslr, intervalometer, press start go inside for a nap, done.

[@alegomanYTPs]

aaaand I bought a asi533 HERE WE GOO ALGEBRA

[@dankahraman354]

Cuiv, it is time for you to ditch Pixinsight and move to Star Tools...

[@CuivTheLazyGeek]

I used StarTools when it was first released, and struggled a lot with it - I need to try it again at some point, but I fear I've become too used to PixInsight! Next on my plan is trying APP (because of the pre-processing features), and trying Startools again after that!

[@dankahraman354]

@@CuivTheLazyGeek Yes I find it difficult as well but remember that Pixinsight isn't easy either. There is a good tutorial on it here>>kzbin.info/www/bejne/iaqQfHWhrZmJbNU, but the presenter goes too fast...I will use it but it will probably take me several hours stopping and starting presentation. I had a friend process my M20 (50 subs of 10 seconds each) and the colour he got with Star Tools cannot be matched in PI.

[@CuivTheLazyGeek]

@@dankahraman354 Thank you! I will look into it! I have to say most of my color issues (at least for LRGB or OSC) were solved in PixInsight by the excellent PhotometricColorCalibration. I'll look at the tutorial and try it out though!

[@dankahraman354]

@@CuivTheLazyGeek There are former Pixinsight users who are migrating to Star Tools. There must be a reason.

[@CuivTheLazyGeek]

@@dankahraman354 There must be - but then each person is different :)

[@Psychlist1972]

Sorry about your clothes hangers :)

[@CuivTheLazyGeek]

Hahaha, thank you! :D

[@-Jeremiah-]

TWICE?

[@mrpoopybutthole666]

thanks! I also heard that long exposures like 10 min can be even more noisy than short exposures, because of a thermal noise, is it true?

[@CuivTheLazyGeek]

For an uncooled camera if comparing a single 10 minute exposure to a 1 minute exposure, the 10 minute exp will have far more thermal noise. But if you take 10 1 minute exposures in a row, the camera sensor will still warm up equivalently, so in theory the thermal noise in a stack of 10 1 minute exposures and in a single 10 minute exposure would be roughly the same

[@mrpoopybutthole666]

@@CuivTheLazyGeek thank you!