Celestron 1100 for imaging

[I_O]

I'm new to the hobby, and recently got started with a Celestron 1100 telescope. I've had a lot of fun so far, but I want to move into astrophotography. The more I read, the more it seems most people are using refractors.

Also, since my mount is not equatorial, I was planning to use lots of short exposures stacked, but I've seen some people saying you won't get the same quality.

I'm beginning to worry that I've invested a substantial amount of money in a dead end.

Are my worries founded? Do I need to start thinking about selling my new scope?

[I_O]

Here's a photo of the Moon with my setup through a cell phone.

[kalasinman]

Moon looks very nice. I started into astro photo last year. There seems to be no one scope for all targets, as they vary so widely in size and brightness.

Normally one would be advised to plan out what one wants to image before buying, but what you have will be fine for planets, and I believe ok for DSOs with the optional wedge.

For DSOs the longer exposure times mean autoguiding is pretty much a requirement. Longer FL scopes like yours make the learning curve to get good guiding steeper, and more critical, I've heard. The requirements for good tracking by the mount are more critical as well.

Subject to correction, you may want to consider guiding with an OAG, as SCTs sometimes have issues with mirror movement, and that would be a way around that.

I'd suggest using a DSLR with it as the chip is larger than most CCDs, even a full frame DSLR for that reason, as that will help widen the FOV. This will help with DSOs.

[Carina Lass]

Use a focal reducer on it and it'll be amazing.

f10 is actually good for globular clusters smaller nebula and planets.

f6.3 (focal reducer) will do the rest

11 inches of glass is a lot of light

[swag72]

What you have will be great for planetary imaging .... is that what you want to do or do you want to move to DSO's?

If the latter then you have a far from ideal setup even with a reducer. DSO's are generally very faint, with a couple of notable exceptions and for this you need long exposures. If you don't have an EQ mount you can not achieve these long exposure times. 30 minutes worth of 1s exposures is not equivalent to 1x30mins. You could invest in a wedge - That will combat the issue of field rotation that your mount cannot currently deal with.

If it's DSO's you are interested in, then get hold of a copy of the book 'Making Every Photon Count' - It is an imagers bible. Read it once..... twice..... and thrice before spending a single bean. Then you will know just what you need and why.

[Leveye]

I'd love to have that scope. I'd keep it. In the end you'll most likely end up with at least 2 maybe 3 imaging scopes. An SCT for planetary and a refractor for DSO would work great. But then a Newt sure is a light bucket and images the faint stuff well and are really affordable. Welcome to astrophotography!

[brantuk]

Once you have achieved imaging with a focal reducer and a wedge - you may well be interested in Hyperstar and Farstar imaging systems for Sct's and deep sky objects. Your scope is smashing and certainly not a dead end.

[Carina Lass]

If you look at the op's post it says polar rig.

I'm presuming that means on a wedge.

[I_O]

I'm interested in planetary imaging as well as getting into deep space later. Are SCTs worse for deep space because the mirrors cause light loss, or because they're harder to guide accurately? Or some other reason? I'd love to know when I'm struggling with blurry images and other issues that it's not the fact I use an SCT.

It sounds like the biggest thing holding me back from DSO is lack of a wedge.

What does OAG stand for?

[ollypenrice]

OAG stands for Off Axis Guider. This is a prism which picks off a bit of light at the edge of the unused light cone from the main scope. This light lands on a small CCD camera which notes the position of a star and sends corrections to the mount if that star drifts, as it will. The virtue of an OAG over a separate guide scope is that if the main mirror moves (as they sometimes do) the OAG will correct for this when a guidescope can't because it can't 'see' the movement. The system is also less prone to differential flexure at long focal lengths.

I'm going to try to answer your main question as reasonably as I can. Your scope is not an easy instrument to use for long exposure deep sky imaging. By using a wedge to make the fork mount equatorial, and by using a focal reducer to widen the field of view and cure some inherent optical defects, you might succeed in getting reasonable deep sky images out of it and you might even get some very good ones. Some people succeed. However, it is a matter of record that many people give up along the way, finding wedges too hard to align, the inherent tracking accuracy of the mount disappointing, the focal length simply too challenging for the mount. I have no means of knowing which camp you would eventually find yourself in but I'm one who eventually gave up and dearly wished he'd left well alone, using the alt-az fork SCT to do what it did well, which was planetary observation and imaging and deep sky observing (though I found the long focal length inhibiting.)

After spending quite a lot of time and money on trying to do deep sky imaging with a wedge mounted Meade LX200 I switched initially to a small piggybacked refractor and then to equatorial refractors and then I started to get results. Given the high cost of the items needed to kit out an Alt Az SCT relative to the cost of an HEQ5 equatorial mount my own inclination would be to 'stop before you start' and go for the small refractor and HEQ5. However, as I said earlier I have no way of knowing whether you'd win or lose the battle to get the SCT imaging well.

As for the Hyperstar system, well, a case of famine or feast. In my view going below F2 is just not sensible, especially in a mass produced instrument. It brings all sorts of problems of its own and is a step too far.

And finally, the amount of glass you have (or the aperture) is, in isolation from a number of other things, neither here nor there in deep sky imaging. Assuming large aperture to be an unambigous virtue in itself will lead you astray. These are images from a little 85mm instrument.

Olly

[Joves]

Olly, the detail in that M42 shot is INSANE!!

[ollypenrice]

Olly, the detail in that M42 shot is INSANE!!

 It gets better when you go up to 140mm aperture and three times the focal length but, of course, you lose field of view. The point is that bigger isn't better, it's just different (and harder.)

Olly

[I_O]

Olly, this is exactly what I needed to know.  I'm glad I can still get started on planetary imaging with what I have.  And I'll start fantasizing about a DSO setup I put more thought into as I learn.

Are people saying SCT are good for planetary because planetary is more forgiving, or because they have some advantage over refractors?  I mean given the choice for planetary imaging, would someone with experience choose a SCT, all else equal?

My guess would be that planetary objects are brighter, making them more suitable for short exposure, which my setup is more suitable for due to the mount?

Thanks for all the answers.  I'll fade back into the vacuum of the forum soon...

[I_O]

A lot of my questions are discussed already in this thread:

http://stargazerslounge.com/topic/237775-refractor-vs-reflector/page-2#entry2579977

[ollypenrice]

In answer to your question about the suitabilty of SCTs for planetary imaging, all you need to know is that Damian Peach uses one. That rather terminates any debate!

http://www.damianpeach.com/

The SCT has enough aperture to support the incredibly long focal lengths needed to resolve planetary detail. If you tried to extend the focal length of a refractor to the several metres used for planetary imaging it simply wouldn't have enough light. The SCT is also very good on-axis (the centre of the image is distortion free) and is easy to collimate. At these focal lengths the seeing (atmospheric turbulence) plays havoc with the incident beam so fast frame cameras are used to shoot many, many frames of which some will be 'lucky' and caught in fleeting moments of stability. These are then stacked and processed.

Olly

[Pete Presland]

As Olly has said your C11 is going to be brilliant for planetary imaging. I use a C9.25 which is also very good, combined with a ASI120mm and some RGB filters and you are up and running.

[dph1nm]

Also, since my mount is not equatorial, I was planning to use lots of short exposures stacked, but I've seen some people saying you won't get the same quality.

It is less efficient (in most circumstances) - so it will take you more exposures to reach a given quality.  How many more is impossible to say, as it will vary with you particular imaging kit and sky conditions.

My main worry with the 1100 would be its focal length, which really means you need a camera with large pixels (or one that can be binned up) otherwise imperfections in the tracking will show up even in short exposures. Such cameras tend to be expensive ...

NigelM