Astrophotography with a 6" Mak Cass

[LRCool (Lyndon)]

Hi everyone,

I'd appreciate some advice regarding my AP dilemma.

I'm using a Canon 7D and a Saxon 6" Maksutov Cassegrain for AP and I'm a little frustrated with the following limitations of my scope;
- The f14 aperture of the telescope. The resultant slow shutter speed and high ISO is affecting image quality far more than I would like.
- The restricted FOV. I would love some clear DSO and wall-poster Luna shots... you know the ones

I have searched for a focal reducer, but Saxon have stated that they do not produce a FR and other brand FRs do not fit the thread on a Saxon Mak Cass! Is there any way around my f14 woes?

If not, I place my AP aspirations above viewing so I would consider selling/trading my Mak Cass for a 2nd hand 100mm ED APO, but I'm concerned that I will miss the FL of the Mak Cass (1900mm to 900mm for the APO). Is a 100mm APO with a 2x barlow comparable to a Mak Cass for viewing purposes?

I'm on the edge and I'd appreciate any advice you can offer.

Thanks in advance!
Lyndon

[Wavytone]

Hi Lyndon,

Your Mak is fine for visual or photographing the moon and planets, even the sun (with a solar filter). But for galaxies and nebulae it is the wrong telescope, you need a focal ratio around f/5, a reflector of some sort.

An ED APO will be around f/7, a bit slower, but reasonable for astrophotography.

IMHO you need two scopes - one optimised for visual, one optimised for photography.

[astronobob (Bob)]

Hi Lyndon,
Also, Re : Is a 100mm APO with a 2x barlow comparable to a Mak Cass for viewing purposes? The 100mm by it self will have an F ratio of 7, maybe 7.5, i havent done the reseach, but close to F7 without being technicle, so, just pointing out that if you added a 2x extender, barlow or what have you, this 2x will in effect slow your ratio down to F14ísh, back to where you started from, , Prob worse as 100mm is 2" less aperture : )
I reccommend any newbies to start off with a shorter F/Length with AP, and visual for that matter, get a good look at the sky with the wider field so can put things into perspective, also easier to find targets, the faster F/ratio will also make targets jump out more, , contrast wise !
Hope this is of help, and all the best ! !

[LRCool (Lyndon)]

Thanks for the advice. Looks like I'll just have to add another scope to the collection!
Kind regards,
Lyndon