Stacking Images

[gjasiewicz]

Thanks Elpajare.

I am glad to see your images and the parameters. I will be sending you mine when I get better hold of that.

I attach the stack of 30 10 secs exposures with 6" F/10 Nexstar 6SE, 2"0.63 reducer, star diagonal and 0.50 reducer before the infinity. So, the FOV is about 47 mins by 1 deg and 3 mins.

I noticed the image may be better with white bar on the histogram about 1/2 way to the right. That is my next experiment and I will try to find a galaxy of mag 10-12.

I think perhaps for this kind of exchange we should move to our personal mails and use the forum rather for technical questions we have.
My address: gjasiewicz@rogers.com

Take care,
George

[gjasiewicz]

Hello Jo and Elpajare,

Regarding the stacking and self terminating the stack sequence after about say 300 secs total, I may be wrong but I think this is the sensor overheating issue. When I was having this happen, the temps at night were min 20C but probably 23-24C. So with an uncooled sensor the heat accumulates and eventually shuts the sensor. Not sure though why I can restart stacking right away and go for another 200-300-400 secs.
Last night the temp was only 14C and the stacking was not shutting easily. I was imaging the surroundings of M57 and I managed to stack more than 100x15 secs images. It stopped stacking after 1,500 secs before 1,600 secs.

My questions are:
1. Is it possible that the sensor overheats easy above say 24C?
2. What is the working temp range for the infinity?

Now, unrelated question is why there is no obvious difference between 10x15 secs stack and 100x15 secs stack? Both stacks attached. Setup: 6" F/10 Nexstar 6 SE, 2" 0.63 focal reducer, 2" star diagonal, 0.5 focal reducer and Atik Infinity. The view angle is about 47 mins by 1deg and 3 mins.
I will do more testing tonight and compare single exposure with a stack of as many as I can stack.

Please provide your view on my findings described above.

Best Regards,
George

[Jo]

Hi George and Elpajare

I'm sorry I've been absent from this thread recently, but I'm glad to see you both sharing your findings and improving your results, it's great to see that happening on the forum.

To revisit some of your earlier questions, in terms of the extra details you'd like to see from us and in the manual, can I clarify that you'd like us to provide better explanations of what the FWHM is and how to use it for image rejection?

Also, I think someone else has also suggested that stacking data be recorded in the saved file, so we'll consider adding that as a feature.

With your comments about filling the chip, do you mean how long you can expose for before the sensor becomes saturated? Naturally, this really depends on your setup and what you're imaging - you can saturate a bright star very quickly, but to capture faint objects, you can go much longer - for example, our 414EX that uses the same sensor as Infinity but in a cooled camera model can be used for exposures of up to and well over 30 minutes if you have a sky and a setup that can handle it!

Also, these sensors don't overheat as such, at least not in the ambient temperature range available. What does happen though is that they'll get noisier and have more hot pixels at higher temperatures.

There should be a difference between a 10x15s stack and a 100x15s stack - I don't think the files attached properly, but I'd be interested to take a look.

I hope that begins to answer some of the questions?

Jo

[elpajare]

Thanks for your help, Jo.

Talking about noise, I have a doubt...

To Jo:

Question: Would have the same noise in a single exposition of 300 seconds that in a multiple exposition of 25 x 12 seconds = 300 seconds exposition?

Another question:  Can you explain some more things about how Histogram works in different situations of faint and bright objects ? Black bar, Orange bar and White bar. The precise regulation of these bars is the 99,9% of success of the final picture.

to George:

I'm working every night about 2 hours at 22º. I have not noticed any increment of noise ( colored dots ).

Nice to know the result of your experiment with single and multiple expositions.

[gjasiewicz]

To Jo,

Jo, when I mentioned the manual, it would be nice to provide more details how to use the camera. The manual covers very high level items that I am sure are sufficient for the experienced users but are not sufficient for newbies like me and I believe the Infinity is focusing on newbies. FWHM is just one item that would be nice to understand how to use it and what level to setup for what images. I read the FWHM theory and I understand that but it does not give me any help with understanding how to apply it and what levels to setup. Histogram that Elpajare mentioned is another example. I think every item that the user can adjust should be explained in details even if they are very basic. Various users have various knowledge and one can understand some items another different ones. There will be also users that know very little overall about astro imaging. I am very technical person and also very well experienced in photography but not in astrophoto and having problem understanding the settings.

I apologize, I simply forgot the attachments. They are attached now. One is 10x15 secs and the other 100x15 secs. That info is also in the file names. FWHM was off.

I know you mentioned the Infinity should be capable of stacking very large number of frames however for some reason mine resets randomly after some number of images. That happens regardless of FWHM setting. I tried levels one, five and 10. The stack of 100 was with FWHM off and even that it reset itself somewhere before 110. I was saving stacks every 10 frames and was hoping that it finally works but unfortunately not.
Earlier in the thread, Ken suggested to turn off Auto Reject. I think he meant to turn off WFHM for I don't see the button Auto Reject.

To answer your last question, yes, you help quite a lot. I also appreciate a lot both of you involvement in helping each other.

To Elpajare,

I did not go out since my last post and did not test single frame against a stack. When I do it I will share with you the findings. Thank you for replying to my ambient temperature concern. I would not expect the chip overheating at 24C. If that was the case the Infinity use would be significantly limited. Also, Jo explained that the heat will not shut down the sensor but will produce more noise.

All the best,
George

The attached images ate not adjusted at all.

[gjasiewicz]

sorry, for some reason only one attachment came through. Here is the second.

[Jo]

There would be a difference in noise between these, particularly in terms of read noise because in the 25 x 12s you’re reading the sensor 25 times instead of just one. Also, you tend to get a better signal to noise ratio in longer exposures.

That said, there are other limitations such as light pollution etc. that mean every setup has a different balance.

It’s difficult to set precise instructions about how to use histogram as every different object taken with a different setup from a different sky will have a slightly different ‘best’ setting. I say ‘best’ because it also comes down to personal preference as well.

The main thing is to try and set it so you’re losing the minimum amount of data. A general piece of advice would be to set the black level a little below the peak curve at the bottom ( - though personally I quite like to go a little lower than this at the expense of a lighter background) Then set your white at a level that doesn’t blow out the image, and slide the orange around to pull out maximum detail depending on your object.

The nice bit about Infinity is how flexible it is, and I really would just say keep playing with it! Get a feel for the settings you like - there really isn't a strict right and wrong here.

I’ll have a think about how we might be able to put together a better guide for beginners explaining the more complicated settings and some far better advice on using the histogram than I may have given there…

I've attached a screenshot of the Auto Reset Stack button, is not showing in your menu? Are you on the latest version of the software?

I see what you mean about them being similar. Did you change the histogram settings between the two? If not, you may be clipping off the additional data gained by the bigger stack. Also, as it's just a star field it may be harder to see the difference - if it was the equivalent experiment on a faint object, it should be much easier to see the benefit of the additional stacking.

Thanks,
Jo

[elpajare]

Thanks Jo. Your advice is very useful.

There are new things in the latest version that are no explained in tutorials, or I have not found:

Image quality , with the two options
Add Q to FWHM
Calc Image movement
Auto reset stack
Use Orig CB

It would be interesting to know what they mean and what are they for.

[gjasiewicz]

Thank you Jo,

I did some more experiments last night and I took 1,10,50, 100 and 130 stacks of Polaris and about 40-50 minutes around it. I can clearly see the better contrast less noise and more clarity especially when enlarging the images. I will start playing now with galaxies, nebulas where I understand you really appreciate the infinity and the stacking.

I fully understand the flexibility of adjustments and peoples likings but for newbies it would be nice to see few simple examples showing what the adjustments do. I will do some more testing as I said and I am sure I will figure it out. Time is the essence.

Yes, I do not see the Auto Reject button so, looks I have an old version of the Atik software. On your website under Atik Resources are only drivers. I do not see Atik app. I also do not see what version I have. I am pretty sure I downloaded the drivers when I originally installed all Atik components.

Please send me a link for the most recent software and if you have newer drivers Please indicate them as well.

Regarding the likings, I did not pay attention in details where I set the bars but I definitely prefer lighter background. By lighter I mean not black but dark dark gray.
Your explanation of how you set the histogram is sufficient for me. Tells me what each bar does and the rest is up to me.

When I have a chance to go out again and do more experiments I will share with you.

Elpajare,
Please let me know if you like to see the samples I mentioned above and I will send them for you.


Best Regards to you both,
George

[gjasiewicz]

Jo,

I found the newer software and have the autoreject button. Please do not bother sending me the link.

Thank you,
George

[elpajare]

George, you have a PM about your offer

[KenT]

Thank you Jo,
saving for a 414, glad you got the updated software George.
As Jo said, play with the controls and see what they do, then see what they can do for you.
Enjoy,
Ken

[gjasiewicz]

Thanks all. I will keep you posted and please keep me with your advices.

What's the PM Elpajare?

[gjasiewicz]

Elpajare, attached are my stacks I described in separate message.

[gjasiewicz]

Elpajare,

I really don't see how to attach multiple files. the attachment function below allows one file only and the button above does not seem to work. So here is the last of the sequence.

George