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05-28-2014, 11:50 AM   #1
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Extension tubes with DA lenses

Is there a way to shoot at different apertures with DA lenses mounted to extension tubes? Feeling dumb.

05-28-2014, 12:01 PM   #2
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Only if the extension tubes have 'A' contacts. Which is pretty rare. I think there is a set from Jessups that will work if you can find them. Some folks (including me) have resorted to buying a (relatively) inexpensive 2x teleconverter and removing the glass. You end up with a fixed length extension tube that will work with DA lenses.

There is also a Macro teleconverter from Vivitar and others that has the 'A' contacts and a variable length helicoid, you can remove the glass from these to get a variable extension tube. These can be purchased relatively cheaply sometimes, but other times they go for a lot so you have to know your price. This is also available in a non-'A' contact version so shop carefully. Here is the review link: Vivitar 2x Macro Focusing Teleconverter Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

Last edited by jatrax; 05-28-2014 at 12:02 PM. Reason: added sentence
05-28-2014, 12:07 PM   #3
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There are no dumb questions here.

We all have to learn, but the answer is a conditional yes. The condition being that the extension tubes have electrical contacts and such tubes for Pentax are scarse.

However, many have de-glassed cheap teleconverters for Pentax-A lenses and used those as extension tubes.

EDIT: OK, I see that jatrax came in first, but I will let my answer stand anyway.
05-28-2014, 12:13 PM   #4
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There's also, if you're in a bind, the "fold up a little piece of paper and jam it into the aperture control lever" method, and I suppose the "tape a piece of black paper onto your lens and cut a hole the size and shape of the aperture you want" would work if the lens aperture was wide open instead of shut down.

05-28-2014, 12:14 PM   #5
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No, I have the cheapos with no contacts. They will work fine on my M lenses. I'm assuming Pentax has no ability to lock in aperture using a depth of field preview like Canon has?

---------- Post added 05-28-14 at 03:23 PM ----------

Okay, so I consulted Emanual and he said I can set the Raw button to give me an Optical(dof) preview. If that will lock the aperature on the lens maybe I can take it off, put the tubes on, reapply lens and viola?
05-28-2014, 12:23 PM   #6
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QuoteOriginally posted by Bunch Quote
No, I have the cheapos with no contacts. They will work fine on my M lenses. I'm assuming Pentax has no ability to lock in aperture using a depth of field preview like Canon has?

---------- Post added 05-28-14 at 03:23 PM ----------

Okay, so I consulted Emanual and he said I can set the Raw button to give me an Optical(dof) preview. If that will lock the aperature on the lens maybe I can take it off, put the tubes on, reapply lens and viola?
Right, if your lenses have no aperture ring and you use manual tubes, there's no way to control the aperture. It would be just like trying to use a DA lens on a manual film camera- every shot would be taken at the smallest aperture setting.

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05-28-2014, 12:27 PM   #7
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There's definitely a work around for this with Canon and I think Nikon with the DOF preview method I mentioned above. I do not know if a K-30 will behave the same way with the Optical Preview option.

---------- Post added 05-28-14 at 03:45 PM ----------

Unfortunately, even if this works it seems like a lot of trouble. I should've just saved the $10 to put towards a M 100mm f4 Macro.
05-28-2014, 01:30 PM - 1 Like   #8
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Keep the extension tubes. When you decide to buy a nice old M42 lens, mount the adapter on an extension tube first, so that when (not if) it gets stuck you'll be able to release it and practice taking it off before it gets stuck on your camera.

It will save you from this:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/263114-holy-crap-help.html

05-28-2014, 02:16 PM   #9
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I have heard of people setting the aperture with the lens directly on the body (e.g. set f/5.6 in Av or M), then removing the lens without powering down, then inserting the tubes. This should leave the aperture wherever it was set. I have not tried it (all my lenses have aperture rings), but it may be worth experimenting with.
05-28-2014, 02:29 PM   #10
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QuoteOriginally posted by OregonJim Quote
I have heard of people setting the aperture with the lens directly on the body (e.g. set f/5.6 in Av or M), then removing the lens without powering down, then inserting the tubes. This should leave the aperture wherever it was set. I have not tried it (all my lenses have aperture rings), but it may be worth experimenting with.
You have to do a DOF preview while removing the lens or it won't work. Changing the aperture setting in the camera only changes the aperture at the moment the photo is snapped, and while the DOF preview button is pressed.
05-28-2014, 02:39 PM   #11
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QuoteOriginally posted by narual Quote
You have to do a DOF preview while removing the lens or it won't work. Changing the aperture setting in the camera only changes the aperture at the moment the photo is snapped, and while the DOF preview button is pressed.
You are correct - I forgot to mention that you actually have to stop down the lens (using DOF preview) before detatching it from the body.
05-28-2014, 04:15 PM   #12
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best option i've managed to come up with.

QuoteOriginally posted by narual Quote
You have to do a DOF preview while removing the lens or it won't work. Changing the aperture setting in the camera only changes the aperture at the moment the photo is snapped, and while the DOF preview button is pressed.
dof preview or not, it won't work. you're thinking of canon lenses.
05-29-2014, 06:00 AM   #13
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QuoteOriginally posted by maltfalc Quote
best option i've managed to come up with.

dof preview or not, it won't work. you're thinking of canon lenses.
Never tried it with a canon. Worked fine with my nikon. Pretty sure it worked on my K5 when I wanted to reverse mount my sigma 10-20, but I certainly could be mistaken.
05-29-2014, 07:44 AM   #14
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Just saw this post: https://www.pentaxforums.com/forums/16-pentax-news-rumors/264093-new-auto-ext...ml#post2831256 thought I would add it here since it might be of use to people interested in extension tubes. First time I have seen new production tubes with AF and auto exposure.
05-29-2014, 08:39 AM   #15
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QuoteOriginally posted by narual Quote
Never tried it with a canon. Worked fine with my nikon. Pretty sure it worked on my K5 when I wanted to reverse mount my sigma 10-20, but I certainly could be mistaken.
the subject is DA lenses, which neither your nikon nor your sigma lens are. DA lenses have a spring loaded aperture lever and no aperture ring, so they stay stopped down all the way when not connected to a camera.
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