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Message: <blockquote data-quote="dreamline" data-source="post: 1244976" data-attributes="member: 67769">I have been following this thread with great interest. From Paul's and Jules' pictures, it seems that digiscoping is a viable alternative to using a long telephoto (which I cannot afford, let alone justify...) so a big thank you is in order to all the contributors so far.Firstly some background. I'm a regular user of a Canon 30D so I'm familiar with f/stops, aperture and speed etc. I tend to carry out a lot of bird photography in Autumn/Winter and I find my Sigma 70-300 limiting. It's too short for a lot of the 'sit and wait' subjects. (My haunt is a series of gravel pits with regular anglers - and passing 'angler traffic' means the birds will rarely come within range. |<|) The best shots are often on the far bank. So a longer lens would be pretty useful...Now, for the thing that's been puzzling me and the point of the post. I had all but decided on a short tube refractor (Vixen or similar with an F/5 focal ratio), when I saw a review for an Orion 127 Mak, praising its quality and construction and crucially, its light-gathering ability and low light performance as a spotting scope. Aha, I thought, here we have a good dual-purpose scope, suitable for digiscoping, which won't need too short a focal-length eyepiece to produce reasonable magnification, and will be suitable for the odd bit of astronomical use to boot. However, I notice it has a focal ratio of around F/12.How can a scope have good low-light performance with such a small ratio? From a photography perspective, during winter F/12 would be almost unusable for wildlife, even at ISO 1600. I'd estimate shutter speeds slower than 1/30 would be required, especially against the far bank, and that won't be fast enough to freeze any motion.So, have I missed something here? I would have equated good low-light performance with a faster focal ratio, and I suspect I will eventually go with my original choice. Just thought I'd ask to satisfy my curiosity (and in case I may be able to make the perfect compromise.)|<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big grin    :D" loading="lazy" data-shortname=":D" />|Bernie</blockquote>

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