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Narrowband

Mirror lens? and widefield lens


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Anybody used the 'mirror lens' that are available on ebay i.e. 500.600 and 800mm varrieties, they appear to be mini SCT telescopes to my untrained eyes.

Also what lens due you use for your widefield work, i have a cannon modded 1000d and have used the 18mm end of the 18-55 kit lens and a crappy 35mm prime lens and reasonable 'fastish' 1.8 50mm canon lens. Are the 24/28mm prime lens much good , how about the fisheye for whole sky work, just a lot of investment and was looking for some advice before take the plunge

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I think they will perform poor and require extremely long exposure times because of the high f-ratios. therefore you would need to put it on your EQ5 and even then it will be hard to track. I just ordered a Tamron 17-50 F2.8 for my 500D. Will give it a try on widefield this weekend.

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For normal photography they are at the bottom end of reasonable image quality, fixed aperture and very odd circular (donut) highlights on out of focus subjects. For wide field subjects I'm very pleased with the fast Canon 24mm f1.4L MkII lens on a 5D MkII. Samyang make a 8mm f3.5 fisheye for cropped sensors which is very good quality but a bit slow.

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Thanks for the suggestion, as a folow up to that would the 28mm be 'better ' thoguh because it is a prime lens?
As a general statement prime lens will always out perform equivalent focal length zoom lens and are typically a stop or more faster and will produce higher quality images almost fully open. There is only one zoom that prove this rule wrong to my knowledge but they are very expensive lol
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