Ideal Exposure Time shows N/A for DSLR


#1

I have a Nikon D5100 and I have set the readout noise and the Camera Gain under the Camera tab in the control panel. There was no listing for DSLR’s iso so I put the Camera Gain under 1x1 binning.

When I take a test or real sub all the Image Statistics are filled out except Binning, Stars Found, Half Flux Radius and Ideal Exposure Time. However, when doing auto focusing all the statistics are filled out except Ideal Exposure Time.

I understand that auto focusing doesn’t give the ideal exposure time but I thought a Frame and Focus or a regular sub would give it. What am I doing wrong? The only thing the log says is “Trying to Display Solved Stars but list is null” for each sub.

I posted this before but the message disappeared during the forum outage so I’ve re-posted.


#2

I know the data shows up when I do centering and when I do any normal imaging. But, I don’t use a DSLR.

http://mainsequencesoftware.com/Content/SGPHelp/SequenceGeneratorPro.html?ImageStatistics.html

What numbers are you using? Maybe the values you found for your DSLR aren’t correct and it’s not displaying the values because they’re incorrect?


#3

Thanks for coming back to me. I use a Read Noise of 3eV and a gain of .3e/ADU. Hope I copied them down correctly.

What surprises me is that the statistics for normal images don’t pick up the other information that I mentioned above. I haven’t heard from any Nikon DSLR owners that it works for them. Actually, I haven’t heard from any Canon owners as well.

So, it could be a bug - or more likely I’m doing something really stupid :slight_smile:


#4

I just re-read the directions. I didn’t right-click on the image and choose calculate HFR. That is probably why I don’t get number of stars found or HFR. Is this also why I’m not getting binning (ISO) or Ideal Exposure Time?


#5

I usually turn inthe button that calculates HFR… But I dunno if it’s required. I have a Nikon, I’ll see tonight if I can get it to do it.


#6

Thanks mads. I would try it but - as usual - its cloudy.


#7

Clear skies for the last few weeks in Western SD :slight_smile: Must be fall.


#8

I finally got a few clear hours and tried calculating HFR on frame and focus and normal imaging. I get everything except the Ideal Exposure Time. As I indicated above, I have set the readout noise and the camera gain, so I’m not sure what else to do. Has anyone else got this to work with a Nikon DSLR or for that matter a Canon DSLR? Thanks.


#9

Hi guys,
I noticed that Ideal Exposure stopped working with my DSLR too with latest SGPro and I might know why.
If you look at Statistics module, instead of binning it shows ISO used to acquire the frame.
Maybe that ruins the calculations?


#10

I noticed when SGP first downloads an image fresh from the camera it shows the binning as the ISO value.

Later, If you load a raw file later back into SGP manually, it no longre shows this value.

I have not tried entering the Binned noise values on a live image, but it does not work with loading up an existing old image.

Next time I will try it on a live download…

PS. This is using camera RAW (NEF) not .FIT.


#11

As far as I know, IET wasn’t intent to work on loaded images, only for the images that just got downloaded from the camera.


#12

Probably not… That statement being true, there is definitely an issue with image statistics being a little confused in that area. I think we decided we were supposed to change the label to “ISO” for DSLRs and that got dropped… your binning is obviously 1x1 so it’s not super useful (unless we extend software binning into sequence images…). Anyhow, that defect aside (we will fix that), Ideal Exposure time is a function of:

  • Actual exposure time for the camera image
  • Mean background ADU
  • Gain (e- / ADU) for that binning (1x1 for you)
  • Readout noise (in e-)

Binning does not affect this calculation. If one of those pieces of data was missing, you would see NA for that field.

True, we do not attempt to calculate ideal exposure time for images taken in the past.


#13

Hi Ken,
that’s what I got, N/A with DSLR with all the parameters in place. With CCD it works fine.


#14

I’d need to see the SGF file you are using with your DSLR since we don’t log everything to do with ideal exposure time.


#15

Sure, Ken, here it is: https://www.dropbox.com/s/ee8k9qf6mkc71jv/M33.sgf?dl=0
Thank you.


#16

Thx. Will need to look into this a bit… will let you know if I find anything.


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