WBPP diagnostic message

M

Muskoka

Well-known member
New Pixinsight trial user here. Using the WBPP Script v2.1.2. I have loaded my lights, flats, darks, and bias. All settings are on default.

When I click on the Diagnostic tab I'm getting the message below, not sure if it's ok to proceed or not? I'm processing 329 120 second lights, with calibration frames, so I'm assuming it's going to take a while. I don't want to start if things aren't correct. I see it's just a warning, but I don't know why I'm getting a warning?


==== PRE-PROCESS CONFIGURATION

==== Flat frames (filter = NoFilter, binning = 1, exposure = 0.60s, keywords = [], mode = pre-processing, frames = 50 (50 active))

Warning: No Master Dark will be used to calibrate the frames, the Master Bias will be used instead..

==== POST-PROCESS CONFIGURATION
 
Hi @Muskoka, this message informs you that flats will be only bias-subtracted. Since WBPP detects the presence of dark frames but is not able to find a proper matching group of dark frames with an exposure corresponding to the flats exposure then it will use the bias only.

This is perfectly fine in most of the cases when your flats are very short, you just have to ensure that all parameters used to shot the flats have been used to shot the biases (gain, offset the most important).

The warning is shown because by default for any flat group the option to auto-match the darks is enabled. If you disable that checkbox for your flats then the warning will go away since it means that you don't want to use darks at all for your flats, so WBPP does not have to warn you anymore

Robyx
 
There are no default settings. This is important to understand. WBPP communicates what you have set up (and what it will do) in the control panel in a number of ways. It is up to you to choose the correct configuration to calibrate your images.
If you have not reviewed it, please see this series on the top of calibration and how to make it work in WBPP:


-adam
 
Thanks you for the quick response, and explanation. New to astrophotography (almost a year), so please bear with me.

Still something I don't understand. Am I not correct when I say that a flat exposure, and dark exposure, will "never" be the same? You say it's not able to find a matching group of darks with an exposure corresponding to the flats? Isn't that a situation that's never going to happen anyways?

All my lights, and calibration frames are taken in Nina, same gain and offset. Darks are the same exposure as the lights. Flats exposure is whatever Nina decides, based on your settings in the flat wizard. Bias are taken at the fastest speed possible.

Guess I still don't see why a warning is necessary, one that makes me question whether what I'm doing is correct or not. As far as I'm concerned my lights, and calibration frames, are exactly the way then need to be, should be, so why is there a warning? I also don't see the checkbox you mention about auto-match the darks? I've looked around, and can't find it?
 
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ngc1535 said:
There are no default settings. This is important to understand. WBPP communicates what you have set up (and what it will do) in the control panel in a number of ways. It is up to you to choose the correct configuration to calibrate your images.
If you have not reviewed it, please see this series on the top of calibration and how to make it work in WBPP:


-adam
Click to expand...

When I said default, I should have said after a push of the reset button.
 
ngc1535 said:
There are no default settings.
Click to expand...
I think this is just going to confuse folks.
If I "reset" WBPP, select "+Files", load some files, and press "Run", WBPP will (usually) processs the files. The configuration of setting used in this context is the "default settings" - that is what "default settings" means, so of course there are default settings. I suspect the real intent was "you should never accept the default settings without confirming that they are appropriate - the default settings will, more often than not, be the wrong settings".
 
Muskoka said:
Still something I don't understand. Am I not correct when I say that a flat exposure, and dark exposure, will "never" be the same? You say it's not able to find a matching group of darks with an exposure corresponding to the flats? Isn't that a situation that's never going to happen anyways?
Click to expand...

what do you mean by "the same" here? the exposure length (in time) of a dark and a flat can certainly be the same. generally speaking calibration frames have to match light frames in temperature, duration, gain and offset. of course what's recorded on the sensor is different between darks and other frames, but that's kind of the point - to be able to remove signal that is specific to the sensor itself from the object and/or flat signal.

rob
 
Thank you Fred. I understand what your saying, and yes, my settings could very well be wrong. All I was looking for was a way to get back to ground zero, "defaults", and I figured the reset button would do that.
 
Muskoka said:
Isn't that a situation that's never going to happen anyways?
Click to expand...
I take "dark flats" at exactly the same exposure as my flats, so they match exactly. If you don't take "dark flats" you won't have matching darks.
If you use sky flats (with varying exposure), you may need dark flats with an approximate match (but still typically much shorter than your darks).
If your flats are very short exposure, and you have captured bias frames, then flat calibration with bias only will often be fine.
 
fredvanner said:
- the default settings will, more often than not, be the wrong settings".
Click to expand...

Commonly "default" implies they are the "common" setting or average- or should work because they are carefully chosen. So in my opinion, I would refer to many settings in PixInsight to be initial settings- but *not* default since as you highlight in support of my argument they will "more often than not, be the wrong settings."

-adam
 
pfile said:
what do you mean by "the same" here? the exposure length (in time) of a dark and a flat can certainly be the same. generally speaking calibration frames have to match light frames in temperature, duration, gain and offset. of course what's recorded on the sensor is different between darks and other frames, but that's kind of the point - to be able to remove signal that is specific to the sensor itself from the object and/or flat signal.

rob
Click to expand...

Again, I'm new, and learning. Having used the Flat/Dark Flat wizard in Nina numerous times, the flats and dark flats, are never close to an exposure of a dark. Darks exposure match my lights.

My flats / dark flats are always around, or under 1 second, using the flat wizard in Nina, nowhere near the exposure of a dark? Is something not correct in the Nina flat/dark flat wizard?

Is this statement from above not suggesting that my darks and flats should have the same exposure length? That's never been the case using the Nina flat wizard.

" Since WBPP detects the presence of dark frames but is not able to find a proper matching group of dark frames with an exposure corresponding to the flats exposure then it will use the bias only. "

What does "dark frames with an exposure corresponding to the flats exposure" mean then? To me it's saying they need to be the same exposure length?
 
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fredvanner said:
I take "dark flats" at exactly the same exposure as my flats, so they match exactly. If you don't take "dark flats" you won't have matching darks.
If you use sky flats (with varying exposure), you may need dark flats with an approximate match (but still typically much shorter than your darks).
If your flats are very short exposure, and you have captured bias frames, then flat calibration with bias only will often be fine.
Click to expand...

Yes my "dark flats" exposures are exactly the same length as my "flats", but never the same length as my "darks", certainly not when using the wizard in Nina.
 
Sorry. In the context of WBPP "dark flats" are darks. They should be loaded and processed exactly as dark files.
You will end up with two master darks, one for your darks and one for your dark flats. WBPP will then pick the appropriate master dark for your flats and lights.
 
fredvanner said:
Sorry. In the context of WBPP "dark flats" are darks. They should be loaded and processed exactly as dark files.
You will end up with two master darks, one for your darks and one for your dark flats. WBPP will then pick the appropriate master dark for your flats and lights.
Click to expand...

Thanks Fred, that did the trick. I have lights obviously, darks, bias, and dark flats / flats, using the wizard in Nina.

I wasn't loading the dark flats, I was using the darks I took from a regular sequence in Nina. After reading what you said I selected my dark flats "in the "darks" tab, and now I don't get any warnings. I take it I'm good to go doing things that way. Load dark flats instead of darks?

The only thing I find strange is it was suggested to me at another site that dark flats take the place of, or replace, bias frames. I was told you use bias, or dark flats, so one would assume that the dark flats I took would go in the bias tab? I'm happy to do whatever Pixinsight needs, I just need to be sure I'm doing things correctly, which I think you have straightened me out on.

" You don't need both bias and darkFlat. It's one or the other " That statement says to me that you can use a dark flat in place of a bias.
 
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ok i see - terminology. "dark flats" or "flat darks" are still darks. the inclusion of the word "flat" is meant to indicate that they match the exposure length / temperature / gain / offset of the flats rather than the lights.

but they don't have to be called anything other than darks - WBPP does not really care about that and only detects that the frame is a dark frame (from the filename or from FITS headers) and then tries to match it with whatever it's trying to calibrate (a flat or a light.)

rob
 
Thank you for the help everyone. I've loaded everything into the script, no errors or warnings under diagnostics, guess we'll see what it spits out.

Edit:

Actually there is a warning in the Control Panel under Light.

WARNINGS

Light frame's exposure differs from the Master Dark's exposure.

You can add a compatible Master Bias and optimize the Master Dark in order to achieve a better dark current estimation.

Do I need to deal with this in some way before I proceed?

This seems overly complicated. I'm going to list what I have as far as lights and calibration. Can someone tell me what combination from what I have listed will make Pixinsight happy?

Lights are 120 seconds.
Darks are 120 seconds.
Flats are 0.60 seconds
Dark Flats are 0.60 seconds
Bias are listed as 0.00 seconds.

All at the same gain and offset, all taken in Nina. Camera is Asi533mc Pro. Zenithstar Z61, Z61a flattener.
 
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so at this point the question is how much does the master dark exposure differ from the lights? if it is some small amount (say, 5-10s) it is probably no big deal. you can open the master dark and one of the lights and use File > Fits Header to look at the FITS keywords. the relevant one is EXPTIME. see how much they differ.

if the difference is huge, you can either make new darks that match your lights, or do as the warning says and create a master bias. this allows WBPP to "optimize" the master dark (which means to scale it so that the noise in the dark is comparable to the noise in the light being calibrated.) this would happen automatically behind the scenes on a light-by-light basis. but it can't be done without a master bias file.

rob
 
pfile said:
so at this point the question is how much does the master dark exposure differ from the lights? if it is some small amount (say, 5-10s) it is probably no big deal. you can open the master dark and one of the lights and use File > Fits Header to look at the FITS keywords. the relevant one is EXPTIME. see how much they differ.

if the difference is huge, you can either make new darks that match your lights, or do as the warning says and create a master bias. this allows WBPP to "optimize" the master dark (which means to scale it so that the noise in the dark is comparable to the noise in the light being calibrated.) this would happen automatically behind the scenes on a light-by-light basis. but it can't be done without a master bias file.

rob
Click to expand...

I think I may have added some data as you were typing your reply? My darks always match my lights. Only difference is when I put the cap on the telescope.

I guess my question is still the same. My calibration frames are always going to be very similar to the list in my post above. Is that not going to work for Pixinsight? Everything is done in Nina, using the provided tools, but If I can't easily use that stuff in Pixinsight I see no point in going any further. I hope that makes sense?

It's appearing to me that calibration frames coming directly from Nina can't just be placed/used in Pixinsight without further processing. Is that the correct way of looking at it?
 
Muskoka,

It isn't complicated. One of the reasons the control panel was made was to be able to capture a screenshot and share it so it is easier to assist. YOur Lights and Darks are NOT 120 seconds according to the script. So, post the screenshot and I can explain.

-adam
 
Muskoka said:
I think I may have added some data as you were typing your reply? My darks always match my lights. Only difference is when I put the cap on the telescope.

I guess my question is still the same. My calibration frames are always going to be very similar to the list in my post above. Is that not going to work for Pixinsight? Everything is done in Nina, using the provided tools, but If I can't easily use that stuff in Pixinsight I see no point in going any further. I hope that makes sense?

It's appearing to me that calibration frames coming directly from Nina can't just be placed/used in Pixinsight without further processing. Is that the correct way of looking at it?
Click to expand...

i agree with adam, this stuff isn't that hard and there's no reason to give up so soon. something's gone wrong somewhere along the line but the solution will be simple...

just post the screenshot he asked for and this can be resolved i'm sure.

rob
 
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