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 Post subject: 400D and refractor..
PostPosted: Fri Jan 29, 2010 9:57 am 
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Joined: Fri May 23, 2008 4:46 am
Posts: 150
Location: Hyderabad, India
Hi there,

I am trying to attach my Canon 400D to my small refractor scope of 60mm in diameter and has a focal length of 700mm.

Now, the problem is neither I dont get a clear image (the image looks as if there is a light reflection it or as if there is a white patch it!!)
........ and the corners are heavily vignetted. Should I calculate the image scale produced by the objective lens and then put some diaphram in the middle of the telescope ?

Or is it because the image produced by the objective lens does not cover the whole sensor??

How do I overcome this problem...??

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Phani Kumar

60mm Refractor,
150mm Newtanion Reflector,
18-55 mm Kit Lens, 55-250mm, M42 MC Helios 77M-4 50mm F1.8
Canon 400D.


http://www.flickr.com/photos/phani_astronomy/


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 Post subject:
PostPosted: Fri Jan 29, 2010 11:09 am 
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Joined: Sun Feb 15, 2009 12:59 pm
Posts: 6009
Location: The Netherlands
I don't know too much about scopes, but..are you using it with your lens still mounted, or just the bare sensor?

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I take pictures so quickly, my highschool was "Continuous High".


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 Post subject:
PostPosted: Fri Jan 29, 2010 2:06 pm 
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Joined: Sun May 25, 2008 12:48 pm
Posts: 7999
Location: UK
Got a sample image of the problems? I have had a bright diffuse spot in the middle of my images in some situations, usually opposing any bright source in shot, which I suspect are unwanted light reflections but I never nailed it.

What size is the port which goes to the camera? Maybe that is too small and causing vignetting.

From those specs it's f/11.6 so diffraction shouldn't be a big problem on general softness.

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Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
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 Post subject:
PostPosted: Sat Jan 30, 2010 2:53 am 
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Joined: Fri May 23, 2008 4:46 am
Posts: 150
Location: Hyderabad, India
popo wrote:
Got a sample image of the problems?


Okk.... Let me take some latest pics so that I can compare it with the pics taken with the kit lens and my another scope which is a 6" Newtanion Reflector.
that can give a clear Idea I guess...

I will update in 6 hrs...


thanks

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Phani Kumar

60mm Refractor,
150mm Newtanion Reflector,
18-55 mm Kit Lens, 55-250mm, M42 MC Helios 77M-4 50mm F1.8
Canon 400D.


http://www.flickr.com/photos/phani_astronomy/


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 Post subject:
PostPosted: Sun Jan 31, 2010 5:38 pm 
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Joined: Fri May 23, 2008 4:46 am
Posts: 150
Location: Hyderabad, India
huh! i could not take pics for reference!...

................Meanwhile, I would like to share two other pics that I have taken during the recently happened Astronomical Events

1: The Annular Solar Eclipse on January 15, 2010.. from my place the eclipse was only 80%. It was very cloudy and sometimes the clouds gave way and the Sun revealed itself like never before.. awesome sight that every one should watch!

Image


Now, I WOULD LIKE TO WARN EVERY ONE NOT TO WHO IS SEEING THE FOLLOWING SOLAR PHOTOGRAPHS THAT WATCHING THE SUN DIRECTLY OR VIA ANY OPTICAL INSTRUMENTS IS EXTREEEEEEMLY DANGEROUS AND SHOULD NOT BE ATTEMPTED. PERMANENT AND IRREVERSIBLE DAMAGE WILL OCCUR TO THE RETINA!



The Solar filter was not used for the following pics (because it was very cloudy and nothing was seen with the filter-on, on the objective lens) as the clouds were just enough thick to reveal the Sun without letting the heat pass though.. take look at what I mean..


Image


Image

Note: I have previous experience in solar photography and I knew what to expect on that particular date and time, hence could take the above pics...PLEASE do not attempt what I have done.

-------------------------------------------------------------------------------------



The Moon came very close to Earth, and took some pics of the Moon in RAW. I tried for a HDR. I feel that this is kind of Ok pic... (Later I will post a moon pic thats a 13 photo stack).


Image



regards,

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Phani Kumar

60mm Refractor,
150mm Newtanion Reflector,
18-55 mm Kit Lens, 55-250mm, M42 MC Helios 77M-4 50mm F1.8
Canon 400D.


http://www.flickr.com/photos/phani_astronomy/


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 Post subject:
PostPosted: Mon Feb 15, 2010 8:57 pm 
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Joined: Thu Jul 31, 2008 4:31 am
Posts: 292
It sounds to me like you don't have backtravel to obtain focus. Are you using a 2" tube spacer ?

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Canon T2i (550D)- Tamron 17-50 F2.8 Non-VC, Sigma 70-200mm F2.8 EX DG OS HSM, Canon EF-S 55-250mm F4.5-F5.6
http://www.astronomyphotography.com


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 Post subject:
PostPosted: Sat Feb 20, 2010 4:30 am 
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Joined: Fri May 23, 2008 4:46 am
Posts: 150
Location: Hyderabad, India
Symtex wrote:
It sounds to me like you don't have backtravel to obtain focus. Are you using a 2" tube spacer ?


Hmmm... for the sun pics.. I had to manually focus. So, first pic was not at the correct focus point.

For the Moon, however, to focus correct, I did not have the front travel and yes it was a 2" draw tube.

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Phani Kumar

60mm Refractor,
150mm Newtanion Reflector,
18-55 mm Kit Lens, 55-250mm, M42 MC Helios 77M-4 50mm F1.8
Canon 400D.


http://www.flickr.com/photos/phani_astronomy/


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 Post subject:
PostPosted: Tue Feb 23, 2010 2:25 am 
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Joined: Thu Jul 16, 2009 11:38 pm
Posts: 232
Location: uk
Some good shots there phani

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Canon 400D. BG-E3. canon 18-55mm. canon 28-80mm. sigma 70-300mm APO macro.


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