glend
13-03-2016, 09:29 AM
Background: This is from my Mono DSLR camera that I have been working on for some time now. I finally have a sensor that is producing reasonable results but there is a problem which may not be related to the sensor surface itself.
Test: Last night, I took a series of four test lights of Eta C, all shot with the Canon 450D with mono sensor, ISO 1600, all same duration (300"), through my RC08 (no filter other than a front mounted UV/IR Cut). The attached light is one of the four light subs and they are all identical.
Also attached is one of four Darks shot just after the Lights, all are identical, shot on the same scope and camera with same settings and duration.
I have also attached one Offset Bias Frame, one of four also shot through the same setup at 1/4000". Note that the camera cooler was turned off during this test session, so these were shot on a warm night (about 22C), so noise will feature in the Light and Dark. Also the sensor still has some cleanup to be done on the surface and on the border, there is evidence of small bits of the Bayer Matrix coating still on the surface - ignore these. There was some thin high cloud around and this may have impacted the Light slightly.
Questions:
1. The thin line through the Light is puzzling, the sensor is obviously detecting data as there are some stars right on the line showing up. What could cause the line? Note I did have the sensor 'shield' off at the time (which is an earthed aluminium cover that encloses the back of the sensor board assembly). Is this simply internal signal from the camera electronics that the shield would have cancelled out?
2. In both the Light and the Dark there is a narrow vertical light beam on the left centre that rises from a sunburst sort of light source at the bottom. I suspect this is a light leak. I had my Teleskop-Express EOS filter drawer on the front of the camera but there was no filter in it at the time. It is possible that light could have leaked through the drawer sides or front as there were a few small light sources in the observatory (Red leds on heater controller, computer screen, etc).
3. The Bias Offset Frame shows none of the horizontal line or vertical light problems but this is consistent with the very short duration of the frame (1/4000').
My plan is to reshoot, when I can, without the filter drawer (just an EOS bayonet and T- Adaptor) to try and confirm the filter drawer as the light leak source. I also plan on reinstalling the sensor board shield for a retest to see if it impacts that dark line across the Light.
Any advice from the experts?
Thanks for looking.
Test: Last night, I took a series of four test lights of Eta C, all shot with the Canon 450D with mono sensor, ISO 1600, all same duration (300"), through my RC08 (no filter other than a front mounted UV/IR Cut). The attached light is one of the four light subs and they are all identical.
Also attached is one of four Darks shot just after the Lights, all are identical, shot on the same scope and camera with same settings and duration.
I have also attached one Offset Bias Frame, one of four also shot through the same setup at 1/4000". Note that the camera cooler was turned off during this test session, so these were shot on a warm night (about 22C), so noise will feature in the Light and Dark. Also the sensor still has some cleanup to be done on the surface and on the border, there is evidence of small bits of the Bayer Matrix coating still on the surface - ignore these. There was some thin high cloud around and this may have impacted the Light slightly.
Questions:
1. The thin line through the Light is puzzling, the sensor is obviously detecting data as there are some stars right on the line showing up. What could cause the line? Note I did have the sensor 'shield' off at the time (which is an earthed aluminium cover that encloses the back of the sensor board assembly). Is this simply internal signal from the camera electronics that the shield would have cancelled out?
2. In both the Light and the Dark there is a narrow vertical light beam on the left centre that rises from a sunburst sort of light source at the bottom. I suspect this is a light leak. I had my Teleskop-Express EOS filter drawer on the front of the camera but there was no filter in it at the time. It is possible that light could have leaked through the drawer sides or front as there were a few small light sources in the observatory (Red leds on heater controller, computer screen, etc).
3. The Bias Offset Frame shows none of the horizontal line or vertical light problems but this is consistent with the very short duration of the frame (1/4000').
My plan is to reshoot, when I can, without the filter drawer (just an EOS bayonet and T- Adaptor) to try and confirm the filter drawer as the light leak source. I also plan on reinstalling the sensor board shield for a retest to see if it impacts that dark line across the Light.
Any advice from the experts?
Thanks for looking.