mirror lens

Did you read the article? Seems to explain it ok!
 
duttytd said:
As I said I'm thick. Tech talking me don't get on to well.
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basic differences are

a) Mirror lenses tend to be fixed aperture (usually F8 or F11)

b) shooting into the sun you get lotsa of little donuts in the back ground

c) in short they are crap

d) but they're a lot cheaper than a normal lens of the same focal length

simple enough ?? :lol:
 
schmidtc.gif

This is how a mirror lens works.

A 'normal' lens works by letting the light 'straight' through!
 
A telephoto lens has a longer focal length than a wide angle. The more the 'telephotoness' the lens has the longer it will be. A 1000mm lens will be about 1000mm long if made using conventional techniques. A bit unwieldy, you will agree.

A glass lens bends light as it passes through its curved surfaces. A curved mirror also bends light and acts like a lens, for example a magnifying shaving mirror. By using two mirrors opposite each other it is possible to simulate a long lens in a short package. The disadvantages are the lens will have a fixed aperture, usually quite slow like f/8/or f/11, and out of focus elements are doughnut like rather than pleasing circles.
 
duttytd said:
Kinda lol. Should I try and save a litter longer for a normal one of the same focal length as it will produce better quality pics?
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yes.
 
An adjustable aperture is the biggest advantage of a normal lens. Unless you buy a really cheap lens, in all likelihood the image quality will be better with a normal lens too.
 
duttytd said:
Kinda lol. Should I try and save a litter longer for a normal one of the same focal length as it will produce better quality pics?
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yes

the sigma 135-400 isnt bad (its not brilliant but its a damn sight better than a mirror lens) and if you are rocking a nikon or a canon you can normally get one second hand for a tad over 200 notes
 
duttytd said:
Ok cheers. Iv got a Canon so will look for one.
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have a look here http://www.mifsuds.com/acatalog/Used_Canon_EOS_Lenses.html

down the bottom of the list - theres a sigma 135-400 for £349, a 170-500 for £399, or a tamron 200-400 for £249

any of those would be better than a mirror IMO, tho of the 3 i'd say the 170-500 was the best if you can go that high ( that said none of them are truly awesome, they come in the 'ok' bracket - most of my long lens shots were taken with a 170-500, for truly awesome you want something like the sigma 150-500 OS, 50-500 OS, 120-300 F2.8, or Canon 100-400 IS or 400 prime but those are a lot more wedge)

btw dont be tempted by a cheap sigma 400 prime - most of the old ones arent compatible with DSLRs
 
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