I use a Sony A200 DSLR for astrophotography and had to be content for a while with its limitations. Naturally I wanted to be able to take images of nebulas with that nice red glow. Obviously this meant either buying a dedicated astrocam or modify the camera. First option was too expensive which leaves me the second one. But alas, most DSLR's are Canons. And I couldn't find any articles on moding a Sony. So I found myself on my own in moding this camera. I did a bit of research and I concluded that the Sony A200 sensor is similar to a Canon 350D and so I ordered the appropriate Baader Planetarium filter.
To make the story short I got the sensor off and replaced the original filter with the Baader filter with fantastic results IMO.
Here is a before and after shot and some photos of the camera. The image of Orion in the before shot is about 3 minutes, no darks, no flats, a bit overprocessed to bring out the nebulosity. The after shot is about 1 minute, no darks, no flats. Processed in DSS.
Hi Clem,
I to have a Sony a200 and like you would like to take some astro photo's with, but mine always finish up with the pink glows in each top corner
Would you know what couses it
Cheers
Hi Clem,
I to have a Sony a200 and like you would like to take some astro photo's with, but mine always finish up with the pink glows in each top corner
Would you know what courses it
Cheers
That's almost a two minute exposure @ ISO 800 Ron and it's showing a fair bit of amp glow.
This is caused by the internal circuit (amp) heating up the sensor on long exposures.
If the Sony has In Camera Noise reduction, try using it to minimise the problem.
Yes, Ron, I get them too (amp glow), and I just take care of that problem in post-processing. I am trying to figure out a way to cool the sensor down. It seems to be glued to a metal plate while its electronics "float" about 2mm behind it.
Thanks, Andrew and Simon for the complement.
H, that is not a bad idea , but then I must say one loses the autofocus feature and also the warranty of the camera. Besides, it is very simple to do, no soldering is necessary. Even removing the original filter is a breeze. Applying the new one is the hard part.
Braver than me, much braver. I have the a700, and love it, but for after dark use it is "difficult". I don't seem to suffer "Ron's Glow", but find focus a chore.It would be interesting to compare the un-modded a700 with the a200, are the chips the same/similar?
Gary
That's almost a two minute exposure @ ISO 800 Ron and it's showing a fair bit of amp glow.
This is caused by the internal circuit (amp) heating up the sensor on long exposures.
If the Sony has In Camera Noise reduction, try using it to minimise the problem.
Well done on the mod Clem.
Thanks, Andrew and Clem, I understood it was Amp Glow, but didn't know what caused it
Another question Do all DSLR's get this problem
I don't see other peoples photo's with the glow
Cheers
Thanks, Andrew and Clem, I understood it was Amp Glow, but didn't know what caused it
Another question Do all DSLR's get this problem
I don't see other peoples photo's with the glow
Cheers
There are ways we can deal with amp glow and some cameras handle it better or differently than others.
I did a quick search on your camera model Ron, there should be an option in the menu somewhere that you can set Long exp. NR to ON.
This will work for exposures longer than 1 second.
In your case, say a 2 minute exposure, the camera will finish the exposure then take another exposure of exactly 2 minutes to match but this time the sensor will not be exposed. Instead it will only take a "photo" of the noise and amp glow that is generated, it's like taking a dark frame.
This will then be subtracted from the original 2 minute exposure and it should eliminate most of the problem.
The only downside with In Camera Noise Reduction is that the length of a single exposure is doubled, so in your case, a 2 minute exp will take 4 minutes before the camera will allow you to expose again.
Hope this helps a little and my apologies to Clem for diverting off the topic a bit.
Ron, I am no expert but looking at the sensor of the A200, it has a lot more going on around those corners, so I can only guess that the glow is coming from the way the sensor was built. That is why I am a bit hesitant to do any cooling mod as I don't think that it is going to do much to improve it. I don't know if all DSLR's have this problem. But it is probably safe to say that Nikon and Canon don't. And certainly Hasselblad has no such issues but who uses it for astrophotography??? Hehehe.
Gary, the sensor of a Sony A200 is a CCD type while the A700 is CMOS. Very different. Sony's CMOS sensor is marketed as the Exmor, said to be a very good sensor with a very good SNR. I plan to upgrade my A200 in the future with this. Maybe modify it as well.
But I will be using the modified A200 for quite a while for astrophotography. I am able to fix the problems of signal noise in post processing anyway. There is a built in noise reduction option in the camera which I think is set as default. But I turn this off because, as Andrew said, you can't take an image straight away after a long exposure if you leave the default option on. The most I want to wait is 30 seconds to cool down the sensor before I take the next one. An intervalometer is very useful in this regard.
I don't mind digressing from the topic a bit, Andrew, it makes the thread more interesting.
I have attached a close-up view of the A200 sensor, on the right corner is the place where the amp glow comes from (encircled).
and had to be content for a while with its limitations. Naturally I wanted to be able to take images of nebulas with that nice red glow. Obviously this meant either buying a dedicated astrocam or modify the camera. First option was too expensive which leaves me the second one. But alas, most DSLR's are Canons. And I couldn't find any articles on moding a Sony. So I found myself on my own in moding this camera. I did a bit of research and I concluded that the Sony A200 sensor is similar to a Canon 350D and so I ordered the appropriate Baader Planetarium filter.
, but then I must say one loses the autofocus feature and also the warranty of the camera. Besides, it is very simple to do, no soldering is necessary. Even removing the original filter is a breeze. Applying the new one is the hard part.
