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Telephoto Mirror lenses

  • 28-04-2006 2:56pm
    #1
    Beano
    Closed Accounts Posts: 3,357 ✭✭✭


    Anybody have any experience with telephoto mirror lenses? They're always up on ebay for what seems like ridiculously cheap prices e.g. there is a 500mm f8 lense up there at the moment for $100. Obviously for that price its not going to beat a €2000 canon L lens but are they still usable?


Comments

  • #2
    Fajitas!
    Registered Users, Registered Users 2 Posts: 16,624 ✭✭✭✭Fajitas!


    If it says they're in perfect condition, I can't see why not!


    Then again, if it says minor damage, or anything like that, I'd say it could be a bit of a fib.


  • #3
    Beano
    Closed Accounts Posts: 3,357 ✭✭✭Beano


    these are all brand new in box. I was more curious about the quality of the lenses really. I did a bit of googling and apparently its terrible.


  • #4
    Fajitas!
    Registered Users, Registered Users 2 Posts: 16,624 ✭✭✭✭Fajitas!


    Whats the lens make? Or a link if possible!


  • #5
    Beano
    Closed Accounts Posts: 3,357 ✭✭✭Beano


    heres the link

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7613431278&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1


  • #6
    ShayHT
    Closed Accounts Posts: 190 ✭✭ShayHT


    I actually bought the same lens (they actually sent a Vivitar rather than the Opteka pictured) of the same company about 4 years ago! I haven't used it in a long time, must dig it out, I remember the ND filters being good to have.

    I'll try take a few shots tomorrow and pop them up. The lens itself is great quality.


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  • #7
    EireRoadUser
    Closed Accounts Posts: 650 ✭✭✭EireRoadUser


    Aren't most of the cheapy zooms just a barrel and a bit of glass.(telescope)


  • #8
    Fenster
    Closed Accounts Posts: 4,763 ✭✭✭Fenster


    What's a telephoto mirror lens when its at home?


  • #9
    joolsveer
    Registered Users, Registered Users 2 Posts: 2,297 ✭✭✭joolsveer


    Fenster wrote:
    What's a telephoto mirror lens when its at home?

    By using a mirror in a long focal length lens the physical size can be reduced significantly. The lenses don't have a diaphragm so the only way of reducing the light received is by using filters. They used be quite popular.


  • #10
    Fajitas!
    Registered Users, Registered Users 2 Posts: 16,624 ✭✭✭✭Fajitas!


    I have to say, a fixed Av of f.8 will seriously limit you.

    What type of photography are you hoping to use them for?


  • #11
    halenger
    Hosted Moderators Posts: 2,094 ✭✭✭halenger


    This looks like a Schmidt-Cassegrain style lens (generally used in telescopes). It would suffer from light fall off and the like due to the central obstruction (the secondary mirror, the thing in the middle at the front). I've never seen one of these in a camera lens I've gotta admit so I've no idea what they'd perform like.

    I have a 400mm spotting scope (normal refractor style scope) that would do similar. Mine's f/5 or f/11 (depending on whether the lens cap is on (minus the centre bit) or not). I didn't buy it for photography purposes but it could be used for some.

    I wouldn't buy it, personally. Note the 't-mount' adapter. That's the adapter I use to connect my cameras to my telescopes. As far as I know that's where it's mostly used.

    A lens like that would have no metering, no auto focus, etc. Be sure you know that before getting into it. You're probably better off buying an old Canon manual focus larger lens, or similar. As Fajitas! asks, what do you intend using it for? Would the 70-300 be too short a reach? Bearing in mind that at 300mm on a Canon dSLR you have effectively a 480mm lens.


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