hi! for first I must repeatthat my english language is not good, so please forgive my errors..I try to explaine.. I'm using C5 and Canon550 in direct focus, I mean without eyepieces and mirror (the image is not inverted). Before I used Skywatcher 90 (1250mm,f=14) and now that I'm using C5 I can tell you that the quality and the colors of my pictures are really better. I bought it for 475€ two months ago, in a famous internet site in Germany. It's cheap if you think that you can have 1250mm and f=10. Well, I never tried by lens scope, but I know the similar quality needs big names, like Kowa or other...how much for them? of course this is a decision to take, but if you start now maybe it's better to save money and make experience. I'm happy of my pictures, I know it's not easy to take good pic but this is good satisfaction to me when I take good one. Anyway, the best problem is the manual focus: for example, if the subject is near (I'm talking around 10-15 meters), you know that if the bird is long 10cm, you will have focus only on the head of it (I'm sorry I don't know the right word..depth...?). If the subject is really far (around 250-500meters), you have better focus (ehmm...1 meter?bit more?) but the air could distort the subject, in particular if you work near a river. So...little subject in medium distance? hard to advise...
if you decide to use eyepiece (with zoom?why not...) all change but the price too, and the quality goes really down (everything between the light and the camera will be a filter). In past I took pictures by eyepiece GSO 32mm (1250/32=39x),it's cheap eyepiece so I can see distorsion, you can see some of my pictures in
http://hobbydigiscoping.blogspot.com/
the good solution could be a focal reduction 0,63x, it resolve focus sensibility and light too, just you could have black bord but you can crop after, anyway it's really expensive (around 250€?)
What I can say is just that I love mirror scope, and digiscoping for me is all what is around the single picture: find a good place, be patient and wait the right moment surrounded by nature,really good moment for relax. The mirror is not easy, but this is what I love, because if I want to take easily a good picture, it's sufficent to use google images, eheh...
Ah, the last things: I have an EF 70-300 IS USM Canon that, used on the "not full frame sensor", gives to me a theoric 112-480mm (1,6x factor for not full frames cameras, EF not EF-S), for no more than 500€, with autofocus and stabilizer too: I think if you need this focal, maybe it's better if you don't buy a telescope, right? other important thing is that the Canon 600 has not fixed display that 550 doesn't have...good! the angolation for take pictures sometime is terrible for your neck, the 600 can resolve you many problems, eheh...
I would like to tell you more about my experiences but my not so good language is really limit to me, I'm sorry, my blog is in italian but please write me if you have questions about...
See you, bye! Stefano