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View Full Version : Astrophotography with your telephoto lens



Roger Clark
03-08-2008, 01:17 AM
All,
I'm new to the group. After seeing a couple of really spectacular astrophotos
posted here and seeing the responses, I'd like to make everyone aware that you can take
superb astrophotos with your bird lens (or super-telephotos) and digital cameras.
(Actually pretty much any lens and a camera!)
The attached image of the galaxy M31 was taken with a 1D Mark II and
500 mm f/4 telephoto lens. The key to astrophotography is exposure time.
The attached image was 28.75 minutes of exposure time, but 40 to 60
minutes would be better. All you need is a tracking mount. I use a
Losmandy G11 (about $2,000), so a small addition to all your 1D Mark 3/D3
and 500 to 600 mm f/4 lenses :). You can take multiple short exposures
and add them together, deleting ones with tracking errors, or passing airplanes.

I actually originally bought my 500 f/4 for astrophotography, but I always had an
interest in wildlife, and finding how wonderful the 500 is for wildlife, I've been
doing much more wildlife than astrophotos.

More astrophotos: http://www.clarkvision.com/galleries/gallery.astrophoto-1

Roger

BillPelzmann
03-08-2008, 01:36 AM
Very impressive! Is this the full frame, or did you crop?

Roger Clark
03-08-2008, 01:45 AM
The image is full frame, no crop. More detail: with stacking 23 images and flexure of the system during the exposures, the images did not perfectly line up. so the resulting image is the area that overlaps all the images, or about 98% of the full frame.

M31 is over 2-degrees across, over 4 times the diameter of the full moon,

Oops, I just looked at my data: this image included a 1.4x TC, so taken at f/5.6 and ISO 800.
More info at:
http://www.clarkvision.com/galleries/gallery.astrophoto-1/web/m31.c07.10.2005.Avg23-75s-v1.6-700.html

Roger

Maxis Gamez
03-08-2008, 07:00 AM
Simply AMAZING!

Excellent work!

Roman Kurywczak
03-08-2008, 10:40 AM
Hey Roger,
Very cool! I think I'll be trying this soon. Thanks for the info,
Roman

Alfred Forns
03-08-2008, 08:09 PM
Thanks for the info for making these images Does sound simple but I'm sure in practice will be like anything else

I find these so rewarding and relaxing !!!!! From a "regular" photo point of view might darken all corners just a bit Will help draw the viewer
into the frame even stronger !!!! Big Congrats !!!!

JH Tugs
03-08-2008, 08:40 PM
Great capture, Roger. Are you a registax user, or do you use other stacking software?

I love seeing the great results you can get with astrophotography. I have a friend who captures images using his tracking telescope and a cooled webcam CCD, or something like that, and the results are just stunning. Makes me want to pack up my miserable moon photos and go home ;-)

Fabs Forns
03-08-2008, 10:12 PM
Amazing work and thanks for your explanation of the technique involved, sure to interest a lot of members :)

Roger Clark
03-08-2008, 11:57 PM
> Are you a registax user, or do you use other stacking software?

I use a program called ImagesPlus from www.mlunsold.com

Roger

Robert Amoruso
03-09-2008, 07:50 AM
Roger,

Thanks for posing the coll looking image and all the details on how it was made.

Michael Pancier
03-09-2008, 09:04 AM
perhaps someday I'll consider a tracking mount. I've always wanted to take full sky exposures and obviously this is the way to go. have you done any shots with wide angle or normal lens?

fantastic shot

Chris Ober
03-09-2008, 11:38 AM
Have you ever tried one of the home-made barn-door' tracking mounts? It would take a beefed up version to hold a 500mm I'm sure. I've been meaning on piggy-backing my 500 on top of the Celestron scope and seeing what kind of results I could get. I'll have to freshen up on my polar alignment first :)

Oh, and beautiful shot!

http://www.astronomyboy.com/barndoor/
http://www.tucsonastronomy.org/barndoor.html
http://www.homebuiltastronomy.com/barndoor/index.htm

Roger Clark
03-09-2008, 12:39 PM
> have you done any shots with wide angle or normal lens?

Yes, but I don't have any tracked ones online, but it is far easier to get good results with a shorter lens.
And with a fast shorter lens, one can get stars and foreground subjects for interesting landscapes.

Have you ever tried one of the home-made barn-door' tracking mounts?

I don't have one, but I have been looking into making one for future trips. Many people use them
and get great results with them. For those reading and not knowing what a barn door mount is,
it is a simple two pieces of wood with a hinge on one side and a screw on the other side,
so when you turn the screw, the two peices of wood open or close. You mount one piece
of wood to your tripod, put a tripod head on the other, point the axis of the hinge at the
celestial pole and turn the screw during your exposure to compensate for the earth's rotation.
They can be very light so great for hiking.

Chris, your links are great. I need to build one, which I've been meaning to do for years.

I'll probably bring one with me on my next Tanzania trip.
Roger