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06-04-2012, 06:04 PM   #31
mee
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QuoteOriginally posted by vicentesagredo Quote
yeah, with A contacts. we're not talking about the cheap chinese tubes
What brand and model?

06-05-2012, 06:48 AM   #32
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those ones PRO Automatic Extension Tube Set for Pentax K-Series Camera for Close Ups | eBay
06-05-2012, 06:51 AM   #33
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Hate to break it to you, but I don't think they have the contacts.
06-05-2012, 07:28 AM   #34
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on the 2nd pic the box says mantains automatic diaphragm...
if not, 25 bucks is still good, they look quite solid

06-05-2012, 07:51 AM   #35
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Which means they will automatically stop down when used with a lens with an aperture ring, when you press the shutter button.
06-05-2012, 07:58 AM   #36
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Should work fine with the green button!
06-05-2012, 08:00 AM   #37
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ah ok i thought i got a deal
06-05-2012, 08:10 AM   #38
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QuoteOriginally posted by newarts Quote
Should work fine with the green button!
Yup..

06-05-2012, 08:49 AM   #39
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QuoteOriginally posted by vicentesagredo Quote
ah ok i thought i got a deal
Why the ?? You did get a good deal!. You deserve at least one

It isn't quite fully auto, but that doesn't matter much for macro which you've got to do mostly manual to get the best results. Use of the green button to set correct exposure will be a big advantage.

Dave

Last edited by newarts; 06-05-2012 at 08:54 AM.
06-05-2012, 09:21 AM   #40
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The ones you bought will be good for any K-mount lens with an aperture ring. The contacts (or Jim's mods) are needed for newer lenses with no aperture ring so you can control it with the camera.
06-05-2012, 11:04 AM   #41
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I still dont get it...the lens would be wide open when I mount it on camera, so focusing and framing will be wide open?
but the shot will be with the aperture selected in the aperture ring?
if that is, its exactly what i was looking for
06-05-2012, 11:19 AM   #42
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QuoteOriginally posted by vicentesagredo Quote
I still dont get it...the lens would be wide open when I mount it on camera, so focusing and framing will be wide open?
but the shot will be with the aperture selected in the aperture ring?
if that is, its exactly what i was looking for
Good. Yes, they should be quite useful.

BUT, let's say you had a DA lens with no aperture ring that you wanted to extend, or like me the Sigma 70mm 2.8 macro -- no ring. The only way to set the aperture is with the dials on the camera body, and for that you need the contacts. That's what people are looking for when they are looking for the ones with electrical contacts for communication with the body. The ones you bought have the mechanical parts only -- which is good, works on a ton of lenses, but not on many of the newer ones. Also some people want autofocus pass-through (a screw-drive on the tube), which I'm not sure any of them have, even the ones with contacts. (Wait, I think the Kenko Uniplus single tube does, doesn't it?) For that, it is useful to remove the glass from a teleconverter with contacts, as many of those have the screw-drive.
06-05-2012, 12:05 PM   #43
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QuoteOriginally posted by vicentesagredo Quote
I still dont get it...the lens would be wide open when I mount it on camera, so focusing and framing will be wide open?
but the shot will be with the aperture selected in the aperture ring?
if that is, its exactly what i was looking for
Exactly. IF the lens has an aperture ring and you set exposure with the green button then you are in business. Except that P-TTL flash isn't available.

Dave
06-05-2012, 01:22 PM   #44
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QuoteOriginally posted by vicentesagredo Quote
I still dont get it...the lens would be wide open when I mount it on camera, so focusing and framing will be wide open?
but the shot will be with the aperture selected in the aperture ring?
if that is, its exactly what i was looking for
Actually, unless you always shoot at the widest aperture (meaning the narrowest depth of field), it doesn't matter if the lens is an M, A, F, FA or DA series. The camera body has no way of knowing what your lens aperture is set at when it meters the scene. My mod will provide the lens information to the camera body and allow you to use a variety of the camera's exposure modes.

You should still do a test shot to check exposure. Apparently M lenses (anything prior to the A series) require a slightly different amount of motion of the lens' stop down lever to reach specific f/stop values. You will never underexpose, but depending on the lens and selected aperture there is a risk of over exposure. Fortunately, unless you blow out the highlights, moderate over exposure can often be fixed in post processing.

I've done the 'A' contact plug on the body and applying the extension tube insulation patches often enough, I can do the whole job in less than 15 minutes. My only tools are a small phillips screwdriver, a bit of aluminum foil, a pair of scissors and magictape. And you can reverse everything in a bit over 5 minutes - although I don't know why you would want to do that routinely.
06-05-2012, 05:48 PM   #45
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Just received my Kenkos from ebay -- the ones that really do have contacts. The 12mm & the 20mm work flawlessly. The 36mm works as far as stopping the aperture down but it asks for focal length and reports the aperture as beginning with f/1.2, so that one must have a broken contact. Which pin would be the likely culprit?

EDIT: Never mind, contact cleaner did the trick.

Last edited by vonBaloney; 06-05-2012 at 06:10 PM.
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