Problem with longer esposures at night (A100)

Hello all and thanks for reading!

Last October I tried my hand at some astrophotography. Nothing fancy, just setup my camera and was taking long exposures and generally just playing around seeing what worked and what didn't work. At some point my camera shut down and gave a warning that it was overheating. I quit for the evening. I uploaded my shots to my computer and noticed that as the evening went on the outer edge and corners became red.

I used the camera normally since then with no problems (at least none I could detect with my eye), mostly nature photography, some people, etc.

Saturday night I was out in Gettysburg and didn't want to miss the chance to do some pictures of the night sky because of the great views. My first photo was just a 15 second exposure...and the edges were red as could be.

So I'm now wondering if I'm doing something wrong, is my camera damaged in some regard from that night in October, or do I just need a camera better designed for what I want?

I guess these questions have a few purposes. If I need a new camera I'd like to sell my old one, but I would not sell it if its indeed damaged. If I'm just doing something wrong and need to tweek settings or how I do it, that would be a great answer (and cheaper!) as well.

Thanks for taking your time to read this. I can offer more information if it is needed.

Your A100 uses a CCD sensor.

CCD sensors tend to yield their heat into the image when they get really hot. CMOS sensors dont do this.

This is something talked about in Gary Friedman's guide for A700. (EXCELLENT book by the way)

You either got to improve your gear or have the camera checked, maybe there is something wrong that boosts the heat inside the camera.

But all signs point that is a sensor's inherent flaw.
--
My photo comic: http://outofplaceproject.blogspot.com
My Alpha blog: http://alphasight.blogspot.com

Looks like I have some decisions to make then. Hmm...

Neoslash said:

I guess these questions have a few purposes. If I need a new camera
I'd like to sell my old one, but I would not sell it if its indeed
damaged. If I'm just doing something wrong and need to tweek
settings or how I do it, that would be a great answer (and cheaper!)
as well.

Click to expand...

I doubt your camera is damaged, it sounds pretty normal for it. If you have long exposure NR off turning it on will help.

The a700 does much better and folks are actually using it for astrophotography some. Again, even with it the long exposure NR is necessary. That shoots a dark frame of as long an exposure as your main frame and then subtracts that noise from the main image.

For really serious astrophotography you need the specialized cameras. They have sensor cooling to cut down noise and allow really long shots. Of course you will also need a polar guider to match the sky motion too if you get into that.

Walt

There are sites who sell cameras specifically designed for astrophotography.

The newer models and the top of the line cameras use sensors made by...you guessed, Sony CCDs though, but I suppose the camera has a way to prevent sensor overheating.
--
My photo comic: http://outofplaceproject.blogspot.com
My Alpha blog: http://alphasight.blogspot.com

I would eventually love something like that but right now for my budget I'd like to get a well rounded jack of all trades. It sounds like the A700 might be what I'm looking for as a step up from the A100.

Did you have Super Steady Shot off?
If it is left on, the mechanism will overheat and affect the CCD.

--
http://www.flickr.com/photos/shutterspy/

Neoslash wrote:
Snip, snip.....

Neoslash said:

So I'm now wondering if I'm doing something wrong, is my camera
damaged in some regard from that night in October, or do I just need
a camera better designed for what I want?

Click to expand...

I too have the A100.

You didn't do anything wrong. That is normal.

I tinkered with very, very simple astro shots a month or so ago.
Results were like you said.

I then downloaded K3CCD Tools, and tried it. Worked great.
I got rid of all that "burnt out corner" look.

This is what your shot looked something like:



You CAN take a whole pile of shorter images, and "stack" them
to get what you want. Worked fine for me as well. I tried Deep
Sky Stacker (free program) and it worked just fine. I included a Dark
Image in the processing to get rid of a lot of the noise. You can see the
results here:



I didn't use a tripod.... just rested it on the deck at the brother-in-laws
up at Clinton, BC. REALLY dark and clear skies.... very little light pollution
up there!!!

IF the skies here in my part of the world were clearer more often, I
would probably get into experimenting with this more. As it is, I am just
a tinkerer.

There are quite a few programs that allow you to do this. RAWHide is one
that I used as well. Keep in mind, I did this shot with no clue as to what
I was doing!!!!

--
Gil
Sardis, BC
Canada

Oh, I used my Sony/Zeiss 16-80 zoom to take these. I forget
the settings, but NOTHING esoteric, really.

--
Gil
Sardis, BC
Canada

I have Super Steady off whenever its on the tripod. I've read that it can make performance worse than better when its indeed stationary. I never heard of it causing issues beyond that though but I'm glad I've left it off!

I'm leaning toward the 700, it looks like a very nice camera for the cost. I'm just wondering if the price will come down when the 900 comes out, or since they are in a different class, it won't impact pricing at all.

To wait or not to wait? The 900 looks great by way out of my price range and what I need, the glass I have would be a waste on it!

FreeRadical09 said:

There are sites who sell cameras specifically designed for
astrophotography.

The newer models and the top of the line cameras use sensors made
by...you guessed, Sony CCDs though, but I suppose the camera has a
way to prevent sensor overheating.

Click to expand...

The sensors are directly cooled by solid state refrigeration. Generally well below freezing temps. This makes for quite a different sort of camera. And way way lower long shot noise.

Walt

Neoslash said:

I'm leaning toward the 700, it looks like a very nice camera for the
cost. I'm just wondering if the price will come down when the 900
comes out, or since they are in a different class, it won't impact
pricing at all.

Click to expand...

Amazing how many people think the a900 is the a700 replacement. They are definitely two different lines, though the two cameras are comparable in quality.

Note the a700 is not a astrocamera even though it does a better job than the a100. As a still camera for other uses it's definitely better than the a100. Not a surprise as they are two different classes of cameras.

Neoslash said:

To wait or not to wait? The 900 looks great by way out of my price
range and what I need, the glass I have would be a waste on it!

Click to expand...

Actually the a900 is not going to challenge glass as much as many think. The only question will be how good the image from the lens is in the outer parts of the frame, the resolution needed is less than that of the a700.

Walt