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Good news for legacy LONG lens users.


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You may or may not know this already.

MOST long lenses -- 300mm and higher -- are designed to focus PASSED infinity.  They design them this way to counteract thermal expansion of the glass in hot environments.

Normally this is not a concern, but this fact allows you to use these lenses with an adapter on A-mount cameras WITHOUT a converter element -- without any extra glass.

Typically, with an adapter, you can't focus to infinity, but with my long lenses infinity focusing is no problem.  These include an OSAWA 650mm f8.5, Vivitar Series 1 800mm f11, and Honeywell 1250mm f10.5.  I'll have to check out my other telephoto glass -- and you should to!

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I wondered why some of my lenses focussed beyond infinity! I also wondered why astro and landscape photographers often say to set your focus when taking night shots - when the subject was at infinity - I thought you would just turn the focus ring all the way. Now I know better.

I guess all the glass and thermal expansion is why so many long lenses are white rather than black - to reflect the heat away.

 

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Also, if your long lens uses a T-mount, etc. for your older camera -- and MANY did, like my 300mm, 500mm, 650mm, and 1250mm CATS -- you can purchase a T- mount to MAXXUM/SONY/ALPHA for your current camera.  This NEW T-mount will avoid the extra extension that your OLD T-mount created -- and let your older, long lens focus to infinity!

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