Stray light entering pictures.

[Jason A B]

Hi i am new to imaging with a dslr and recently had my canon 700D converted to full spectrum to use with both my 8" Meade SN and a William optics Zenithstar 66mm.

After the mod every pic i take seems to have what i think is stray light entering the bottom left corner of all the pics and gets worse the longer i expose. The same thing happens with both scopes and I have tried everything i can think of to stop this inc covering the viewfinder to taping over any leds that give off light. Last night i tried some shots with different camera lenses i have and it did the same with the 18-55mm but no sign of it with the 75-210 mm even with a 2 min exposure.

The skys here are very dark as i live in the counrty and i have no light pollution near me.

Here are some pics from the last few nights.

The first pic is M13 with the WO Zenithstar

The second with 18-55mm lens

The 3 pic with the 75-210 lens

Last with Meade SN 8"

Has anyone experinced the same problem ?

[Kropster]

Looks suspiciously similar in three of the pics.

Could this be heat from the camera electronics affecting the sensor? So called 'Amp Glow'?

[glowingturnip]

could it be amp glow ?  Shooting with liveview on, or with the LCD activated can heat up the sensor.  Or you could try running the camera off an external power source to eliminate battery heat

[Thalestris24]

Hi Jason and welcome

Hmm... it does seem like some sort of reflection or hidden light source. It seems to have a particular pattern. I don't know the 700d but if it's independent of whether you have a scope or lens then that points to the camera body itself. Perhaps something gets covered or shielded by the 75-210 lens? With my full spectrum 1100d I find the camera is a) much more sensitive and a lot more sensitive to red and infra-red. Hence I use mine with a cls-ccd clip filter. Perhaps the sensitivity to IR is the key as IR will pass through many plastics, possibly including tape that you've used to cover things.

Hope that helps you to locate the source of your problem

Louise

[DaveS]

What was different with the 3rd pic? I don't believe the lens alone would have made a difference. Exposure length? Mounting?

Try taking a series of dark frames and see how they turn out.

[happy-kat]

If it were amp glow why is it not in all 4 images assuming exposure length the same?

What was the aperature used with the 72-210 compared to the other tests?

[Jason A B]

Thanks for all the replys.

This happens even when the first pic is taken and the camera has not been on too long and i have a clip in cls ccd filter in place. I do have live view on and the camera is using its own battery power.

I had taken out the filter when using the camera lenses and the aperature was set to F4 for the 75-210 lens and the same for the 18-55mm.

I took several dark frames with the lens cap on and nothing shows up.

It has me baffled

[Steve Ward]

Could well be light leaking in through the viewfinder ... you'll find a small cap attached to the shoulderstrap that fits over the viewer in place of the soft rubber cup ... 

[Thalestris24]

Yeah +1 for viewfinder. Could be just chance that it didn't show on the 3rd pic.

[Jason A B]

I had the viewfinder covered with the rubber thingy supplied with the camera, it was one of the first things i checked.

Even ended up using black tape just to be sure lol.

[glowingturnip]

my money's on the live view then

[Thalestris24]

Hmm... If there's nothing showing with the lens cap on then maybe you are getting an internal reflection somehow? I don't know what leds the camera has inside or outside. Have you checked with whoever did your mod?

[Jason A B]

I have been chatting to the guy who did the mod and he kindly offered to have a look at it if i can not solve the issue.