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02-13-2012, 04:41 AM   #1
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Idiot's guide to extension tubes

Sorry if this question has been asked before - I'm sure it has, but I'm getting lost with the conflicting information I've found.

I have 2 fully manual lenses I would like to use with extension tubes, one Pentax and another 3rd party lens. Neither have the 'A' setting on the aperture ring.

I'm used to using manual lenses with stop down metering so no problems there. Where I'm confused is whether or not I can use fully manual extension tubes or whether I need to get ones with a mechanical aperture linkage. I've found a decent set of Pentax branded tubes, but these are fully manual with no aperture lever on the mount.

I assumed that these would be o.k., but have read a number of articles that imply that these won't work properly even with M lenses.

Can someone let me have an idiot's guide to what I can or can't do with manual tubes and what, if anything, would be gained by getting a set with aperture linkage.

Thanks very much

02-13-2012, 05:27 AM - 1 Like   #2
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If you just use an M lens on a camera in M mode, then you can still focus and compose with the aperture fully open and bright, but with manual extension tubes when you change the aperture it actually changes immediately.
That leaves you two possibilities (unless of course you only shoot with aperture fully open all the time):
1. Stop down and then focus with the quite dark viewfinder.
2. Focus with the aperture fully open and then close it down trying not to move the camera in process (doable on a sturdy tripod and static subject).
02-13-2012, 05:39 AM   #3
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Thanks - let me see if I have got this right, then.

With only manual tubes if I set the aperture on the ring to f16, say, the aperture on the lens will immediately close to f16 leaving the image dark in the viewfinder. If I get a set of auto tubes (with manual aperture linkage) then setting the aperture ring to f16 will leave the aperture wide open to focus and compose. At what point will the aperture close to f16, when I use the green button to stop down meter or when I take the photo? ie. when will the image in viewfinder go dark?

At the moment with my manual lenses I set the aperture on the ring, focus and compose, use the green button to meter, recompose and focus, take the picture. With a set of tubes with aperture linkage I can still do this, with a manual set I need to work wide open or do as you suggest above?

Is that right??? Sorry for being thick!

So basically the manual tubes aren't much use unless I shoot fairly wide open all the time? Should have said I have a K-r if that makes any difference.

Last edited by milamber; 02-13-2012 at 05:45 AM.
02-13-2012, 05:44 AM   #4
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Yes, exactly.
It's certainly not impossible to use manual tubes, I have used them without problems, it's just good to know that chasing butterflies is not an option.

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