AV mode for flats

[sbradley07]

I searched back thru these threads and found a discussion a couple of years back (when BYN was in beta) about AV mode not working, and that it might be a bug.  I just tried it with my D5300 and latest version of BYN.  It hangs on "Busy" when trying to capture with shutter (and camera) set to AV, and I finally have to kill it. 

Am I doing something wrong, or is AV mode for flats not supported for Nikon cameras?

[admin]

I'm actually drawing a blank

I'm not sure if Nikon can shoot AV without a lens.

[sbradley07]

Ok thanks.

[astroman133]

What that means is that you will need to shoot in Manual and adjust the exposure to get a well-positioned histogram.

[sbradley07]

Thanks astroman.  I've been doing the manual approach, but recently saw some videos where AV was being used, so I thought I'd give it a try.  Looks like it only works for Canon cameras. 

A question on the histogram:  Whenever I take an image, the histogram appears in BYN.  When I do a one-shot "preview", that creates a jpg file.  When I do a "capture", a NEF and a jpg file are created.  For the histogram that's displayed, is there a difference between the histogram of the NEF file vs the jpg file?  I ask because when I open each file in SGP, the pixel stats are very different between the two, and I've read that you want to get the "mean" pixel values to the 20,000 range for flats.  Am I overthinking this and should I just go by what the histogram shows in BYN?

[astroman133]

If BYN is like BYE, the histogram is for the JPG image with a default stretch applied.

[admin]

7 hours ago, astroman133 said:

If BYN is like BYE, the histogram is for the JPG image with a default stretch applied.

It's the same thing for BYN.

[astroman133]

I use an artificial light source (an electroluminescent panel) when shooting flats. Since the light source has a constant brightness I have used the same flats exposure values for several years. 

If I remember correctly, I shot some experimental images and varied the exposure until the histogram from the raw, unstretched image was well centered. I didn't worry much about the exact pixel value.  I did that for each camera/filter/binning combination. I created capture plans with those exposures and have used them ever since.

With my T5i, I used BYE's AV Flat functionality to get an approximate exposure and then tweaked it a bit. I did have to use a different program to examine the histogram of the linear raw image.