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Old 14-01-2009, 11:05 AM
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How do I improve image capture size?

Here's a couple of photos I took recently through my ED80 - one with a film camera and the other with a Canon 350D. As you can see much more of the frame from the film image is taken up with the DSO, while in the digital shot the nebula is pretty tiny.

Is there a simple way to achieve a similar result as the film image with the digital setup?

many thanks gang

niko
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Old 14-01-2009, 12:18 PM
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Hi Niko,
simplest way, providing you have a mount that will handle the increase in guiding accuracy needed is to try using a a good quality 2xs converter or barlow. (longer exposures though)

Next, and getting into a larger cost area, acquire a larger aperture scope. You might have to upgrade your mount!

Another way and maybe counter productive, a smaller chipped, astro dedicated ccd.

BUT, all that aside however, with digital imaging, with what you have, take longer and heaps more exposures, stack them. This will help reduce noise, increase signal and make things easier to find a good balance with stretching and processing to reveal the data that is hidden.
Spend all night on the one object.
The above I mention because with your image of the Tarantula, it lacks all of these things. This area of sky is chock full of very interesting little knots and twists of nebulosity and star clusters etc. Also work on your focus, take your time to get it right.
If your not sure, ask some of the DSLR imagers on this site for some help with your processing and any other advice.

The Ed 80- Orion/ Celestron/ Skywatcher are very capable little scopes and have produced some very fine images from various people, with various cameras since their arrival on the scene.

I'm sure you will find the wider field you have with the ED80/ 350d as is, will produce some pretty pleasing results with many DSOs.

Above all, have fun, it's a learning curve worth the time and effort.

Hope this helps.
Rich
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Old 14-01-2009, 12:58 PM
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Well for a start eta Carinae is 3-4 times bigger than the Tarantula, so you would expect it to fill more of the frame. Also, since the DSLR sensor is smaller than the 35mm film frame, if you used the DSLR on eta, it would fill even more of the frame than for the film
Geoff
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Old 14-01-2009, 12:59 PM
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Hi Niko, It is just one of those things. Firstly the images are of totally different DSO which are of course vastly different in size. The ED80 is really a quite wide field telescope. You could try a good quality barlow lens or Powermate but remember your exposures will also need to be increased to capture the same detail. This is the reason I have 3 telescopes all of different focal lengths.
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Old 14-01-2009, 06:16 PM
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Well all the methods have been mentioned.. Smaller chip = target fills more frame, film is larger than digital therefore on film targets will look smaller in the frame..

Doug's method is great.. 3 different scopes for different jobs.. I have 3 scopes that can be used for imaging also, but the 11" SCT can be used at F/10 or F/6.3 to allow more field of view for bigger targets etc... its good to have a couple of options..
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Old 14-01-2009, 06:43 PM
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As Geoff said, this is arse about. What format film camera was it?. Doesnt make sense.
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Old 14-01-2009, 07:09 PM
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Fred - the reason the image scale was bigger in the film shot was because the film shot was Eta Carine, and the digital shot was the tarantula... Eta C. being massive in comparison, it appears to fill more frame than the digital shot of 2070..
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Old 14-01-2009, 07:50 PM
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oops, Ill go away now
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Old 14-01-2009, 07:52 PM
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not to worry Fred.. I nearly posted the same thing myself.
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Old 15-01-2009, 08:02 PM
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Thanks guys. A someone mentioned many months ago, I have commenced down a slippery slope - so much to learn, so many possibilities. I'll just keep chipping away I guess

niko
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Old 29-01-2009, 12:45 PM
damo_Melbourne (Damian)
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Hi guys,

What about a focal reducer for the ED80?

Im a newbie too so apols if this was a stupid comment but I am taking delivery of an ED80 and HEQ5pro myself and was wondering if the new Mogg adapter for DSLR and the ED80 would be a solution here to Niko's issue or are we talking about different things here?

http://moggadapters.com/astro/adapter.asp
Go to the DSLR Reducer menu option and check out the pics of Eta Carina with and without the reducer

thoughts?

cheers
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Old 29-01-2009, 01:41 PM
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all has been said before, you can get focal reducers but in all honesty i wouldn't bother for the ED 80, as it in itself is a great scope specifically targeted at wider field. Plus a focal reducer will actually make your image wider again...

This is why you have scopes dedicated for different aspects of photography, or different CCD's. for instance the 350d does a great job for fitting in ultra wide fields like Carina, though the DSI is great for galaxy's as they are generally around the 10 arc seconds range.

Choose the gun for the gun fight no use taking a cap gun to a high noon shoot out!
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Old 29-01-2009, 01:44 PM
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[quote=damo_Melbourne;406049]Hi guys,

What about a focal reducer for the ED80?

Im a newbie too so apols if this was a stupid comment but I am taking delivery of an ED80 and HEQ5pro myself and was wondering if the new Mogg adapter for DSLR and the ED80 would be a solution here to Niko's issue or are we talking about different things here?

http://moggadapters.com/astro/adapter.asp
Go to the DSLR Reducer menu option and check out the pics of Eta Carina with and without the reducer

thoughts?

A focal reducer only gives you a wider field of view and I've tried a .5 in a f7 80ED and it don't work maybe a .8 would.

To increase image size need to do as suggested above.

Cheers
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Old 29-01-2009, 02:34 PM
damo_Melbourne (Damian)
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thanks for the replies, I will investigate the barlow option too
cheers
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