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rglasgow
(@rglasgow)
Active Member
Joined: 7 years ago
Posts: 6
28/01/2013 10:22 am  

Someone needs to do something about these clouds! And what's up with the Moon lately? Why does it have to be so bright? I'm looking forward to some clear, dark nights to do some imaging at the observatory.

Speaking of imaging, have you ever given any consideration to building a cold box for your DSLR? My low-end camera (Canon EOS Rebel XS/1000D) suffers from a lot of noise. This isn't readily apparent in daylight images, but plagues my astroimages. I've been reading about cold boxes, and I have the parts to make one, but am a little unclear on whether or not the Peltier cooler and power supply that I have will be adequate. I don't want to get the thing assembled only to find out that it won't work...


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Allan Hall
(@asadmin)
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Joined: 4 years ago
Posts: 70
03/02/2013 12:05 am  

I have thought about the cold box idea, and have even followed a few websites detailing the build, and of course the one from Orion pre-made. The problem I have is I have never seen before and after images, in fact I have asked for such and been ignored. To me this means they probably do not work very well.

Sure, I see lots of "look how clean my darks are now" examples, and nice examples of a single light frame from target A without the box, and a single light frame from target B with the box showing how much cleaner one light is.

Problem is no where I can find has anyone ever shot a full set without the box one night and repeated the process the next night with the box, fully processing both sets and showing the results. Almost makes me want to build one just to see why they won't show real examples!

Allan


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rglasgow
(@rglasgow)
Active Member
Joined: 7 years ago
Posts: 6
03/02/2013 10:33 am  

I've only taken them at their word that it works, but I have seen a significant difference in image quality on my camera when I've shot the same target on cold and warm nights. I have a horrible time with noise during the summer months. The problem is so bad that I often don't bother imaging because I know that I'll not be satisfied with the results. The two attached images (I'm playing with the phpBB interface here) are from a single 30-second dark frame taken at ISO-800. The first file is the unaltered image (as it looks when converted from CR2 to TIFF), and the second is the same image autoleveled in Paint.NET. This image was taken in August 2012, but is probably not my most extreme example.

I ordered a Canon EOS Rebel T3/1100D, which is the next generation of Canon's entry-level DSLR from the one I already have. Many of the reviews I have read state that it has less noise than the XS, so I'm hoping it will perform better. (This one has pictures of dark frames from different Canon cameras: http://ghonis2.ho8.com/T3review/T3review.html ). Still, I think that a cold box might improve performance on warm nights. I've got all of the parts, so I may as well try, right? Maybe I can do the side-by-side test you mentioned and write up a review.

BTW, I'm definitely sold on phpBB, but it will be a little more complicated to implement on the site. Basically, the plugin links to a separate site on which phpBB is installed. I'll probably tackle it later in the week.


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Allan Hall
(@asadmin)
Member Admin
Joined: 4 years ago
Posts: 70
03/02/2013 11:04 pm  

It certainly will not hurt anything to try, especially since you already have the parts. I would be very interested in the results!

Honestly I have no doubt that a cooler camera will produce better images, I am just not sure it is "all that and a bag of chips" for DSLRs like some people say.

But keep me in the loop!

Allan


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rglasgow
(@rglasgow)
Active Member
Joined: 7 years ago
Posts: 6
05/02/2013 9:52 pm  

I got my T3 (1100D) today and took some darks to see how it would perform. Below is the central 300x300 pixel region of a single 30-second exposure at ISO 1600. The shot was taken at approximately 70F. The left side of the image is as it appears when converted to TIFF. The right side is autoleveled to highlight the noise.

For comparison, here is a shot from my XS (1000D). Same central 300x300 pixels, 30 seconds, ISO 1600:

The XS only supports up to ISO 1600, but the T3 also supports ISO 3200 and ISO 6400. Here is a 30 second exposure at ISO 6400:


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rglasgow
(@rglasgow)
Active Member
Joined: 7 years ago
Posts: 6
05/02/2013 9:55 pm  

Oh, and I apologize for bringing on the cloudy nights with my new camera.


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rglasgow
(@rglasgow)
Active Member
Joined: 7 years ago
Posts: 6
05/01/2014 12:01 am  

I haven't bought any new astronomy equipment lately, so I can't be blamed for the clouds this time. Which one of you varmints is responsible for this? 😆

The clouds have driven me back indoors at nights, so I'm filling my spare time with my other hobby: model railroads.


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Allan Hall
(@asadmin)
Member Admin
Joined: 4 years ago
Posts: 70
05/01/2014 12:49 am  

Clouds? Last Saturday had a little break in the clouds, I was the only one at the observatory. Thursday night was pretty clear except to the south, Mike and I both were at the observatory, I left around 9pm I think. Friday night was beautiful, Mike and I were out there all night, I left around 5:30am.

You have to go outside to see there are no clouds 🙂

Allan


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rglasgow
(@rglasgow)
Active Member
Joined: 7 years ago
Posts: 6
05/01/2014 6:46 pm  

True, we've had some good nights. I managed to steal a little telescope time in the front yard the week before last. I got a pretty shot of the Monkey Head Nebula, and a reasonable image of the Heart Nebula. I'm still working on them. I had hoped to go out to the observatory but the past couple of weeks have been very busy. Maybe I'll get to come out one night towards the end of January.


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