Infinity v close focus (lens on tubes)

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bt_photo
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Joined: Wed Jun 06, 2018 10:43 am
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Infinity v close focus (lens on tubes)

Post by bt_photo »

Hi folks.

Sorry if this has been posted somewhere before. I'm new here (hello :smt039 ) and couldn't find anything.

When using a lens on extension tubes, does it make any difference to image quality where the lens is focused? (infinity, close focus, or in the middle) - if you are moving the camera to focus...

Thanks :)

rjlittlefield
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Post by rjlittlefield »

Welcome aboard! :D

The general rule is to drag any lens away from its design space as little as possible.

If you're extending the lens just a little, then the best bet is to turn the ring to its own closest focus, then add minimal extension behind it.

If you're adding lots of extension, taking the lens beyond 1:1, then probably it's better to reverse the lens and set the focus ring to whatever best matches the distance between lens and sensor.

The other general rule is that there are always exceptions. For critical work, be sure to run a real-world test.

--Rik

bt_photo
Posts: 2
Joined: Wed Jun 06, 2018 10:43 am
Location: England
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Post by bt_photo »

Hi Rik.

I've been using a focus rail for indoor still things, so the whole setup moves. Will try more experimenting today... :-)

Thanks,
Brian

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