Am I losing data here? BYE Histogram

[Fordos Moon]

Hi guys,

My histogram is chopped off on the left hand side. Am I losing valuable data or nicely reducing light pollution?!

I believe the histogram should be a quarter to a third the way up. If losing data should I increase exposure time or ISO perhaps?

I am using a modified Canon 1100D with an Astronomik CLS filter.

Many thanks, Bob

[Fordos Moon]

Wrong section or dumb question?!

[JamesF]

I think I'd try to increase the exposure time before raising the ISO setting.

James

[Fordos Moon]

Thanks James - wise words should help keep the noise down, always wondering about longer subs vs more subs but aint that one of the age old questions!

[Fordos Moon]

I think I'd try to increase the exposure time before raising the ISO setting.

James

James if i get out now and get some longer exposure frames, do i need to process the 2 sets separately in DSS and presuming I do - combine images in photoshop?

[JamesF]

I know there's been some discussion about combining subs of different lengths but I can't recall the outcome I'm afraid.  Personally I try to avoid it.

James

[Scott]

In dss, if you put all the lights, darks flats etc into it then if you look downnear the bottom and chose group 1 (I think its called) and do the same with the next exposure length. once you've added all your subs, just continue as normal .

[Scott]

[Fordos Moon]

Much obliged auspom!

[dph1nm]

That's weird. It shouldn't be possible to left clip a Canon - they have a non-zero bias added to avoid negative numbers. Looks like a software issue in ByEOS to me.

NigelM

[Scott]

That's weird. It shouldn't be possible to left clip a Canon - they have a non-zero bias added to avoid negative numbers. Looks like a software issue in ByEOS to me.

NigelM

Is this still the case with a moddified camera and lp filter? I have no idea

[dph1nm]

Is this still the case with a moddified camera and lp filter? I have no idea

Shouldn't make any difference. You can't loose data off the left of the histogram just by putting a filter in, or by modding the camera (which as far as I know does not tamper with the electronics). Even if you had no light hitting the camera you would still get a bias frame histogram, which should peak around the bias (256 for my 1000D -  not sure what it is for the 1100D)  and have a width determined by the read-noise (a few counts).

NigelM

[Fordos Moon]

Oh no this doesnt sound good!