can I image with a 10" reflector?

[alacant]

Hi

I see that most here use an 80 or 130mm telescope. Is it possible to image with a bigger telescope? Presumably I also have to get an autoguider. I'm getting reasonable 60s unguided shots with a 750mm fl telecope on my eq6.  I wonder if it is worth resurrecting my old sw 254-1200mm to get in closer.

Any comments and advice most gratefully received. TIA

[swag72]

You certainly can!!!

There are inherent difficulties though. There MAY be an issue with reaching focus with your scope (which you will only know by trying) - Then you have the issue of mount accuracy with guiding and also the larger scopes acting like a sail on the mounts .... You may also benefit from guiding with an Off Axis Guider as opposed to a small scope or auto guider.

I guess what I am saying is that it's not easy, but worth trying

[almcl]

Reckon it rather depends on the target, but you should be able to image with the 10",  most of the shots in my album https://stargazerslounge.com/gallery/album/3751-my-quest-for-dsos/ were taken with an 8" (now with a coma corrector which slightly increases the field of view).  Mine aren't the last word in AP, by any means but your big scope should do well, particularly on the smaller, fainter DSOs.  Guiding will certainly help but  see what you can achieve with a good polar alignmrnent and just tracking?  If that doesn't satisfy, it's possible to guide with a £14 web cam strapped to a 9 X 50 finderscope plus a suitable cable/interface.  Of course,  it is also possible to spend  a lot more...

There are several websites which will show the field of view for a given combination of scope, camera &c, one which I rather like is http://www.blackwaterskies.co.uk/p/imagingtoolbox.html 

see if that gives an idea of what you might capture?

[Astrosurf]

It will need to be a very calm night! I also use this FOV calculator: http://www.12dstring.me.uk/fov.htm

Alexxx

[alacant]

Thanks for the encouragement everyone. It's one of the old blue-flimsy-and-goes-out-of-alignment-tube sw. It comes to dslr focus with about 1cm inward to spare. The mirror is gonna have to be cleaned and the focuser can't hold the camera without slipping. I suspect part of the alignment problem is the mirror moving about. You can see it move by tilting the tube. Anyway, as you say, unless I try it I'll never know. Dunno though. Is it so much bigger that a sw 200 so as to cause wind buffet problems?

TIA

[almcl]

1 hour ago, alacant said:

unless I try it I'll never know. Is it so much bigger that a sw 200 so as to cause wind buffet problems?

Think you may have answered your own question there :-)

It depends on how exposed your observing site is.  My dark sky site (on a 1300ft high open moorland plateau) sometimes has me wondering if my 200p is going to get blown over but my back garden, surrounded by houses, 6 ft high fences and trees (not ideal for observing, admittedly) hardly presents a problem at all until the reported wind speed gets above 20 mph or more.

[alacant]

It's something that I've never considered so it's not been an issue before. Clear nights here can have a breeze but I've never noticed it affecting things visually. But the real reason is I'm lazy and I know the reflector is gonna take a lot of time and money. I just looked and the focuser alone is going to set me back over €100. And then I'm half way to a small reflector anyway. Ah, but then I don't get any closer; M3 is still only 5% of the frame... Just thinking out loud. Sorry!

[Waldemar]

A TeleVue 2x PowerMate or a good Barlow can solve your lack of focal length, but it will ask more of your mount in terms of tracking accuracy.
An OAG or guidingscope will solve that problem.

[alacant]

Ah, OK. Didn't think of that. The reflector will give me f4.5 at 1200mm. Wouldn't the barlow also slow the aperture? Currently, I've 760mm@f5 so I'm gonna get 1520mm, f10. That's not going to give me enough light on the sensor, is it?

[Waldemar]

That is correct. To get the same results you will have to use 4 x the exposure time, or make far more subs, not ideal, but your reflector isn't ideal either if I read you right...

Kind of depends on what you want to image.