Backyardeos clipping blacks?

[Lognic04]

Hi all,
On the weekend i went to go image using backyardeos, and looking at the preview i was really questioning what was going on (unstretched the background was black), exposure was iso 800,f6.3 and 50 seconds, there is definitely something wrong. after stretching there was data there but some pixels were clipped to black. Strange!
any advice? i used the same settings a few days earlier and the image came out nice, but this time i was saving to pc, but i wouldnt think thats the problem
:help::question::thanx:
(i will be away for the next 3 days so i cant check this post :sadeyes:)

[Lognic04]

Ideas anyone?

[JA]

Somehow underexposed??? Did the histogram indicate underexposure? Was the camera set to JPEG instead of RAW, reducing dynamic range and/or causing posterization? Or other similar BYEOS settings? Posting an image may make it easier to comment

Best
JA

[ZeroID]

BYEOS doesn't manage exposure, that's up to you to find\use suitable settings. BYEOS only manages the hardware, timing and controls delays etc.

[doppler]

Have you tried saving to camera again to compare pics. Raw shouldn't change anything but if you shoot jpeg there might be a difference in compression methods between camera and computer. I can vaguely recall having a similar problem where the shots saved on the laptop looked different to the camera saved ones. (the camera saved ones looked better).

[JA]

If Backyard EOS is directed to do something to the exposure, then Backyard EOS directs the camera to change the exposure via shutter speed or sensitivity, it's not AUTO of course, so it's not management in that sense; however, it's in control and it doesn't mean there couldn't be something wrong with the Backyard EOS settings, be they default or user selected.

Best
JA

[Lognic04]

It definitely wasn't in JPEG. The exposure was 45sec, iso 800 and 6.3. I don't see anything wrong with that?

[JA]

Did the histogram indicate any underexposure, however small? It would be good to post the pic. You said that it imaged Ok 3 days ago with the same exposure settings. Was this for the same target?

Best
JA

[Lognic04]

211084
This is the picture of eta carina saving to camera, looks good, histogram included
211085
This is the picture of the cone nebula, almost the same settings, but the histogram is clipping.

[Lognic04]

and yes there is definitely some clipping in the second picture

[JA]

The image and the histogram clearly show the underexposure. The histogram is too far to the left and is the reason for the compressed/clipped black in the image. Monitor this (the histogram) next time and increase the exposure to fix.

Another thought: Do you have the date and time stamp of both images? If so, check these against the moon's position. The difference in exposure between these images may be due to stray light/moon glow or other light source.

Best
JA

[DJT]

Hi

The cone nebula is not a bright object. It's worse than the Rosette in that respect.

Were you imaging from Melbourne?If so there would be LP issues and your exposure time is far too short given the lack of surface brightness. Looking at your equipment list I assume this was with a camera lens rather than a scope?

I tried this from Sydney with a 102mm scope and a dslr a few years ago also using BYE and with 5 minute subs plus a clip-in CLS filter you can hardly see a thing. It's a tricky object for which you really need a dark site to do well with in my view.

Phew, 3 paragraphs...