APO scope or high quality lens for DSLR imaging?

[Dodge]

I've been playing around with my Astrotrac travel system and having some fun with my Canon 1100D with stock 18-55 & 50-250 EF-S lenses and a nifty fifty and I'm already finding some limitations (distorted stars in the corners and CA unless stopped down, vignetting etc.) and so I'm debating buying a small APO or perhaps something like the Canon EF 200mm L F2.8.

With the crop factor of the smaller DSLR sensor, the 200mm lens will give me 320mm which will be great for widefield applications, plus it's likely it'll get some use during the daytime.

But I have a lingering doubt as to whether I should instead be buying a small APO. Budget isn't really a problem for me, but I want to do things 'right' from the start. A new EF200L will come in around £650 which is around the same as a small APO with a field flattener. I know the focal length will end up being quite a bit longer, but I have the abillity to guide in RA if necessary.

Other than the ability to look through it, any other reasons I should look at an APO rather than a decent lens?

Many thanks.

[ollypenrice]

I have an EF200L lens and a small apo, a Tak FSQ85, so a good one. The Canon is a great lens but it's fiddly to focus with a CCD and in my case pretty undersampled.

I wouldn't get into crop factors, which don't have any meaning in astro imaging where there is no standard size of chip. You'll get 200mm from the Canon and much more than that from the Apo. You would find the extra FL challenging without dec guiding in my view, especially since I guess you will be going to dark sites which invite long subs to make the most of them.

On a Canon camera the 200L gives some great opportunities.

Olly

[Sp@ce_d]

I'd think the EF200L would be easier to travel with & useful for daytime too of course. I've got one on my wish list even though I have a WO zs66apo. I guess the advantage of having a small scope on the other hand is you can also use it for observing . I think you'd want to guide for best results imaging though.

A couple of work colleagues have recently bought high end Canon gear from these people at a decent UK price & had prompt delivery... http://www.procamera...8L_II_USM_34085