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List: kstars-devel
Subject: Re: Optimal Exposure and Noise Calculator
From: Wolfgang Reissenberger <sterne-jaeger () openfuture ! de>
Date: 2023-03-05 6:38:39
Message-ID: F59EDEBC-C41D-478F-8F91-8A873A0251D2 () openfuture ! de
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Joseph,
I'm not sure what type of function we are talking here. Is your intention to \
calculate the optimal exposure time for a single frame or for the target? If its the \
first one, I have the same questions as Hy. For the latter, I'm happy to learn more \
about it.
Wolfgang
—
Wolfgang Reissenberger
www.sterne-jaeger.de
TSA-120 + FSQ-85 + epsilon-160 | Avalon Linear + M-zero | ASI 1600mm pro + 6200mm pro
> Am 05.03.2023 um 06:06 schrieb joseph.mcgee@sbcglobal.net:
>
> Hi All,
>
> Let me explain my reasoning for developing the optimal exposure calculator and \
> noise calculator. I started fairly recently in this A.P. hobby (mid 2019), and had \
> no mentor. Most of the online resources seemed to provide information and \
> suggestions that were geared toward imaging in very dark skies with more advanced \
> equipment than a beginner would own. The typical recommended exposure times I read \
> about were on the order of a many minutes.
> But when I was experimenting with and learning to use my gear, I typically did so \
> in my own backyard (SQM 19.63). I initially spent quite a few frustrating nights \
> trying to find exposure settings that would produce a decent image. As I acquired \
> filters, I had to repeat the learning process. Then when I had the opportunity to \
> travel to a darker site 90 miles from my home, (SQM 21.65), I again had to repeat \
> the learning process. The difference in the exposure times at these two sites was \
> pretty shocking to me.
> I fully grasp that you all have considerable experience with A.P. but this tool is \
> really not intended to provide benefit to folks that have such experience. The \
> target audience for this tool is the newcomer to this hobby (like me three years \
> ago). I would have been thrilled to have tool that says when I'm in my backyard \
> shooting with gain at 100, and no filter, that my exposure time should only be \
> around 45 seconds.
> Now, back to the topic...
>
> Warren,
>
> You raised a suggestion that bias frames could be used to determine sensor read \
> noise. I must be missing some knowledge in this area. I just ran a test with my \
> planetary camera (ASI-178), where I captured a set of bias frames incrementing the \
> gain from 0 to 400 in steps of 50, with an exposure time 32us, (I believe that is \
> the lower limit for the ASI-178). I then used a tool that can assess noise in the \
> image. The noise measured in each image increased as the gain increased; so this \
> did not match the downward trend I expected from the ZWO read-noise graph.
> Perhaps the tool I used for noise assessment was not the best choice.
>
> Can you explain further how I might be able to analyze bias frames to determine \
> read noise?
> Thanks
>
>
>
[Attachment #3 (unknown)]
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charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; \
line-break: after-white-space;" class="">Joseph,<div class="">I'm not sure what type \
of function we are talking here. Is your intention to calculate the optimal exposure \
time for a single frame or for the target? If its the first one, I have the same \
questions as Hy. For the latter, I'm happy to learn more about it.</div><div \
class=""><br class=""></div><div class="">Wolfgang<br class=""><div class=""> <meta \
charset="UTF-8" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: \
rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; \
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class=""><div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode: space; \
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color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; \
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start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: \
0px; -webkit-text-stroke-width: 0px; text-decoration: none;">—</div><div \
style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; \
font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; \
letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
text-decoration: none;">Wolfgang Reissenberger<br class=""><br class=""></div><div \
style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Helvetica; \
font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; \
letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; \
white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; \
text-decoration: none;"><a href="http://www.sterne-jaeger.de" \
class="">www.sterne-jaeger.de</a><br class="">TSA-120 + FSQ-85 + epsilon-160 | Avalon \
Linear + M-zero | ASI 1600mm pro + 6200mm pro</div></div></div></div></div> </div>
<div><br class=""><blockquote type="cite" class=""><div class="">Am 05.03.2023 um \
06:06 schrieb <a href="mailto:joseph.mcgee@sbcglobal.net" \
class="">joseph.mcgee@sbcglobal.net</a>:</div><br \
class="Apple-interchange-newline"><div class=""><div class="">Hi All,<br class=""><br \
class="">Let me explain my reasoning for developing the optimal exposure calculator \
and noise calculator. I started fairly recently in this A.P. hobby (mid 2019), \
and had no mentor. Most of the online resources seemed to provide information and \
suggestions that were geared toward imaging in very dark skies with more advanced \
equipment than a beginner would own. The typical recommended exposure times I \
read about were on the order of a many minutes.<br class=""><br class="">But when I \
was experimenting with and learning to use my gear, I typically did so in my own \
backyard (SQM 19.63). I initially spent quite a few frustrating nights trying \
to find exposure settings that would produce a decent image. As I acquired \
filters, I had to repeat the learning process. Then when I had the opportunity \
to travel to a darker site 90 miles from my home, (SQM 21.65), I again had to repeat \
the learning process. The difference in the exposure times at these two sites \
was pretty shocking to me.<br class=""><br class="">I fully grasp that you all have \
considerable experience with A.P. but this tool is really not intended to provide \
benefit to folks that have such experience. The target audience for this tool \
is the newcomer to this hobby (like me three years ago). I would have been \
thrilled to have tool that says when I'm in my backyard shooting with gain at 100, \
and no filter, that my exposure time should only be around 45 seconds.<br \
class=""><br class="">Now, back to the topic...<br class=""><br class="">Warren,<br \
class=""><br class="">You raised a suggestion that bias frames could be used to \
determine sensor read noise. I must be missing some knowledge in this area. I \
just ran a test with my planetary camera (ASI-178), where I captured a set of bias \
frames incrementing the gain from 0 to 400 in steps of 50, with an exposure time \
32us, (I believe that is the lower limit for the ASI-178). I then used a tool \
that can assess noise in the image. The noise measured in each image increased \
as the gain increased; so this did not match the downward trend I expected from the \
ZWO read-noise graph.<br class=""><br class="">Perhaps the tool I used for noise \
assessment was not the best choice.<br class=""><br class="">Can you explain further \
how I might be able to analyze bias frames to determine read noise?<br class=""><br \
class="">Thanks<br class=""><br class=""><br class=""><br \
class=""></div></div></blockquote></div><br class=""></div></body></html>
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