Guest Lad98 Posted April 1, 2014 Share Posted April 1, 2014 Hi All I haven't actually taken any picture yet, but before I do I have a Question. I have a Vixen ED81s that is 2" with a 2" to 1.25 adaptor and a Canon EOS 60D. Will it make any difference to my pictures if I use a 1.25 Canon T adaptor instead of a 2" Canon T adaptor. I already have the 1.25 Canon T adaptor but was wondering if I should get the 2" T adaptor instead . Link to comment Share on other sites More sharing options...
Guest Kheldar Posted April 1, 2014 Share Posted April 1, 2014 YES!!! The 1.25" will cut light out ... the 2" whilst cutting a small amount will cut less Get the 2" Link to comment Share on other sites More sharing options...
Guest Lad98 Posted April 1, 2014 Share Posted April 1, 2014 Thanks for the quick reply. I did think the 2" would be better common sense really. 2" T adaptor about to be ordered. Thanks Link to comment Share on other sites More sharing options...
glider Posted April 1, 2014 Share Posted April 1, 2014 Yep, another vote for the 2". The 1.25" will give vignetting, which you don't want. Link to comment Share on other sites More sharing options...
dawson Posted April 2, 2014 Share Posted April 2, 2014 You may still get some vignetting with the 2" but it would likely be much worse with the 1.25". Have a play with the 1.25" in the day time, taking a very single short exposure of the sky (well away from the sun and maybe with a white t-shirt over the end of the scope), and you'll see how much the edge of the image is darkened than the central part of the image: Then you could repeat when you have the 2" nose piece and compare. There are ways to limit the impact of any vignetting in the processing stage but you may already know this anyway. Good luck with it all. It's exciting taking images. The other thing to consider, which you may already do/know, is operating the dslr from a laptop; "they" say once you've done that there is no going back to kneeling on the ground trying to look at the live view screen whilst focusing or framing your shot. Jd Link to comment Share on other sites More sharing options...
Guest Lad98 Posted April 2, 2014 Share Posted April 2, 2014 That's a great idea Dawson, I will do that ,then if I'm ever ask the same question I can explain this comparison Link to comment Share on other sites More sharing options...
dawson Posted April 2, 2014 Share Posted April 2, 2014 Lad98, I just did a really rough and ready comparison of the 1.25" and 2" nose pieces on my Canon 600D on a short tube refractor. There will be so many variables, and I'm sure when the focus tube is drawn right out that will change things again, and your focal length will introduce other variables, but on this rough test I think it is pretty easy to see the vignetting is worse on the 1.25" than the 2". JD https://dl.dropboxusercontent.com/u/1673286/Vignetting%20test.pdf Link to comment Share on other sites More sharing options...
Guest Lad98 Posted April 2, 2014 Share Posted April 2, 2014 Thanks for doing that James. It would seem common sense to go with the 2" and your test just goes to confirm it. Quite a visible difference. My 1st mistake avoided and still not taken a photo. this AP stuff is easy Link to comment Share on other sites More sharing options...
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