What do you recommend in the way of telescopes etc.. to get into the field of Digiscoping !
I take it you have had a look at the TeleVue Imaging Methods
I linked to in my previous post. I'll split my answer into two parts.
If you want to photograph the Moon in the way I described above then any reasonable aperture telescope (70mm diameter plus refractor or 100mm diameter plus reflecting telescope) could be pressed into service even if it is on a simple fixed mounting. When buying a refracting telescope it is important to get one with the minimum of chromatic aberration so avoid the budget models.
The camera really needs to be mechanically fixed to the telescope to avoid the hand-holding problems I encountered. For afocal imaging ("digiscoping") anything fainter than the Moon you will need the telescope to be fixed to a motor-driven equatorial mount which will counteract the Earth's rotation. Planetary imaging will be a tough challenge requiring long exposures and high magnification and I would guess an absolute minimum would be a reflector of 200mm diameter: N.B.
I am out of my comfort zone here so you will
need to do your own research. Those long exposures will require an accurately aligned and driven mounting. I think you can see where I am going here. Astronomical imaging can make normal photography look cheap!
If you want to use afocal imaging on terrestrial subjects during the day then obviously the requirements are a lot simpler, i.e. a good telescope on a really solid tripod. As you can see from the TeleVue article the focal length of your camera lens is increased by the magnification of the telescope. So when I used a 68x magnification with my 50mm f/1.8 I was effectively using a 3400mm telephoto!
The downside, of course, is that with a 70mm objective that meant I was working at f/48 which might just (!) have been diffraction limited.
The moral here is to decide what your maximum desired effective zoom will be and then make sure the telescope's objective lens has a sufficient diameter to give you the shutter speed you need. If your desired field is terrestrial then there is absolutely no advantage in going for a telescope with a fast aperture other than portability. In order to get the image size up all a fast aperture means is that you pay more for the telescope and more for the short focal length eyepiece and end up with an image which is no brighter on the camera's sensor!
As an example of what this technique could do if you need extreme lenses, say you want to photograph birds (feathered) on the nest. I can't vouch for the quality but you can pick up a 120mm (4.75") Flourite ED Apochromatic f/7.5 refractor for £1500 including 45x and 180x eyepieces. You would have to buy a really solid tripod and some accessories but you could come away with change from £2500. If this telescope feeds a 50mm camera lens then with the 45x eyepiece you are getting a focal length of 2250mm at f/19. Alternatively, strapping the camera directly in front of the prime focus of this telescope you are getting a 900mm f/7.5 lens. OK, it's fixed aperture, manual focus and has no IS but compare the cost (£1500 for the telescope) with the Canon EF 600mm f/4.0L IS USM which retails for over £5300 in the UK. And the Canon can't be "extended" to 2250mm! OK, I know, it's an extreme example and a very specialised application.
Back to the real world! For a good selection of astronomical telescopes in the UK I will take the liberty pointing you to Venturescope
here in the UK. There are other vendors who I am sure are just as good but I have personal experience with them and the owner, Ninian Boyle. He is more than happy to help and knows his stuff (but do your own research first).
P.S. Thanks for the question. In composing my rather lengthy answer I learnt a lot myself and I hope
I haven't made any mistakes in my analysis.