Telescope Camera Mount

[oracledba]

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I'm considering a Celestron CGEM 925 telescope and M/R camera for long exposure astrophotography. Has anyone used this combination? I have an R9 with DMR back, M9 that I could use. The most straight-forward solution seems to be a Canon or Nikon DSLR. I'd rather not have to buy either of these and simply use my Leica bodies. I have the R mounts for the Leica APO Televideo...but not sure that helps in any way.

[gbealnz]

It can be done, but man it's self-abuse really.

The C9.25 will be F10, so slow.

The M9 is not the lowest noise digital out there.

The M9 also only goes to 32 secs according to Wikipedia.

The R9 might seem better, but having done as much astro imaging as I have, believe me digital is simpler. And I started with film.

 

Notwithstanding all that, you will need some form of adapter to fit whichever camera you decide to use. A T adaptor is what you need. I use an M to M43 adapter but I have a 2 inch to M42 eyepiece adapter. If you don't have anything then stick with a 2 inch to T adapter, and get a T ring to fit whichever camera you use.

 

Do what I did, get a used Fuji X-E1, perfect for astro.

Gary

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[aj55]

There is so much more to astrophotography......

 

How do you plan to get into focus? This is VERY critical using a 9.25, even at f/10. A f/6.3 reducer is available form Celestron!

How about guiding?

 

You are far better off using a (modified) Canon 450D or something similar.

Guiding can be done using a videocam or simpel guide ccd with an off-axis guider or guidescope.

 

if you really want LONG exposures - 15 min or longer subs - in order to get a better SNR, a cooled astro ccd is the choice.

 

Also consider lightpollution and the possible need for narrow band filters - which in turn make a monochrome ccd a better choice.

 

choices, choices.... ;-)

 

Clear skies, Arnold

[aj55]

Btw, while on this topic, how about the field of view? With a 9,25 you are only capturing a very, very small piece of sky. Probably a distant galaxy or so.

Very difficult to locate!

You will be amazed how big the interesting nebulae are. I have seen the most beautiful astrophoto's with short tele's (180mm for instance).

 

With a sort tele you can get away much with shorter exposures and - if properly polar aligned - no guiding for several minutes.

 

But then again, perhaps you want to do the planets! Well, in that case buy a video ccd and stack!

 

perhaps I am kicking in open doors, but.......

 

Clear skies, Arnold

[gbealnz]

Arnold,

couldn't agree more, good points, and points I missed.

If anyone asks, I too normally steer them towards the wider field imaging, at least in the early stages.

Still not a walk in the park, but way, way easier than imaging at a couple of meters focal length.

Gary

[oracledba]

Thanks everyone for your input...lots to think about. My R is digital thanks to the DMR (Digital Modul R) and I do have a Vario APO Elmarit R  2.8 70-180 that might be helpful. I don't have any way yet to provide guidance so I'll have to figure that out. 

[gbealnz]

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Hmmmm, R9/DMR. Still a difficult exercise, mainly due to the long focal length, even if a reducer is used.

Then the noise from the DMR is something to consider, I don't figure (but equally, don't really know definitively), it will be low, certainly not as "noise-free" as the later chips, the Fuji's especially. Only one way to find out though, try it.

 

Suggestion is align the C9.25 (you know how to do this?) then piggy-back the R9/DMR and the 70-180 on top. Try some tracked, but unguided shots, say 30 secs, ISO1600, and see. If you have a 50mm or even a 35mm, try that as well.

If that works, then perhaps look at using the 70-180.

 

Report back, let us know what you find. PM me if you want further, off forum.

Gary

[aj55]

One last  suggestion.... if you already happen to have the T to1.25 nosepiece for your Leica then consider buying a SA100 (Staranalyzer) grating which you can screw onto the nosepiece. With this you can shoot spectra of the stars, which as far as I am concerned is far more rewarding and fun than pretty pictures ;-)

And oh, if you calibrate them they can be useful to the professionals too!

 

Arnold

[oracledba]

Vielen Danke!  This is a lot to take in -- but i asked for it -- and great stuff. I think first on the agenda is getting a better mount (azimuth?) so that I can do the polar alignment properly. From what I read the procedure is a bit tedious but straight-forward...and now that I'm retired I have the time.

[gbealnz]

Azimuth? Yikes, no, you need equatorial.

Good luck, don't be afraid to PM me if you get stuck.

Gary

[aj55]

If you are living in or near Germany, may I point you to the ATT in Essen next month?

 

http://www.att-essen.de/index.html

 

This is Europe's largest venue on astronomy with all the makes and vendors present as well as a large secondhand market!

 

Everything you may want to see is there, so a great place to start ;-)

 

Regards Arnold