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06-17-2009, 05:28 AM   #1
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PKA AUTO FOCUS extension tubes ?

Hi

This extention tube above is A or AF ?
(I don't know enought to figure it out by the contacts )

I mean, does it auto focus or only gives the reading by the contacts ?

Thanks in advance.


Last edited by netuser; 01-27-2010 at 03:51 AM.
06-17-2009, 05:34 AM   #2
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That's a PKA version. No AF with it.
06-17-2009, 05:41 AM   #3
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QuoteOriginally posted by wildlifephotog Quote
That's a PKA version. No AF with it.
Damn , so the contacts are only for the readings to the camera

Seems hard to find one with AF
06-17-2009, 06:19 AM   #4
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To do macro, you do not use AF at all. So I would care if the extensions tubes don't have AF.

06-17-2009, 07:37 AM   #5
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QuoteOriginally posted by YJD Quote
To do macro, you do not use AF at all. So I would care if the extensions tubes don't have AF.
Yes, it's just I tried one from canon on a 70-200 f2.8 and it makes the lens focus closer giving great shots.

Might be also good to consider a cheap AF converter without the inside glass ?
06-17-2009, 09:37 PM   #6
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QuoteOriginally posted by YJD Quote
To do macro, you do not use AF at all. So I would care if the extensions tubes don't have AF.
"At all" is a bit strong. With critters and buggs that move, AF is usefull. At least the AF with the SMC Pentax-DFA 100mm f2.8 macro is precise enough to be usefull. I also have a tube with KA contacts, SDM contacts and screwdrive autofocus gear, and it works well both on SDM lenses and screwdrive lenses such as the DFA 100 macro (which gives me about 2:1 and the AF is still usefull). But I agree, on stationary objects such as flowers MF is easier to use.

QuoteOriginally posted by rnetuser Quote
Hi

This extention tube above is A or AF ?
(I don't know enought to figure it out by the contacts )

I mean, does it auto focus or only gives the reading by the contacts ?

Thanks in advance.
Please not that there is only six contacts on the tubes in the picture you show. It should mean that they are for the first early KA mount of 1983. They will transfer min and max apperture to the camera and enable P and Tv modes, but the 7th contact that was later added is missing, and with that its functionality. The chip in the lens will be unable to tell the camera the focal length, distance to subject, exact apperture, lens dimension, and modular transfer function (apperture of highest resolution). There are later tubes with all 7 contacts, both second hand and in new production.
06-21-2009, 08:51 AM   #7
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QuoteOriginally posted by netuser Quote
Yes, it's just I tried one from canon on a 70-200 f2.8 and it makes the lens focus closer giving great shots.

Might be also good to consider a cheap AF converter without the inside glass ?
The Kenko Uniplus 25 will autofocus and auto meter. It works very well with my Tamron 70-200mm

Kenko 25mm Uniplus Tube DG AF Extension Tube for Canon - eBay (item 330338823733 end time Jun-26-09 09:58:53 PDT)
06-21-2009, 09:12 AM   #8
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To bad they don't sell one for Pentax mount.

06-21-2009, 09:26 AM   #9
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QuoteOriginally posted by Eaglerapids Quote
To bad they don't sell one for Pentax mount.
2 are available in k mount

https://www.pentaxforums.com/forums/photographers-marketplace/41255-sale-kenk...brand-new.html

or

http://www.clubsnap.com/forums/showthread.php?t=436172
07-10-2009, 11:12 PM   #10
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QuoteOriginally posted by YJD Quote
To do macro, you do not use AF at all. So I would care if the extensions tubes don't have AF.
Agree.....actually,even the "A" is a bit unneeded. I use my M42 tubes /bellows on my K mount Pentax or Chinon and intend to shoot full manual usually (though Aperture Priority works well. Don't WANT Prog modes in Macro. Tight macro...you focus by leaning IN and BACK mostly.
07-10-2009, 11:38 PM   #11
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A pleasant part of macro..is you can do VERY well with "Old School". You don't WANT to hurry..or be noisy..or fuss about with modes and buttons and such. BASIC is the zen. You can study the options for 10 min before popping a shot.

I have a Minolta X 700+ Novoflex Auto Bellows + Novoflexar 100mm bellows lens.....THAT rig can do shots

My M42 baby is a Mamiya DTL with spot meter. I have 2 sets of tubes and an auto bellows,a SMC Pentax Tak 135,a Novoflexar 105mm,A Mamiya 50 1.4, a Bigass 300 4.0 Sigma.....all work fine on the M42 with tubes or bellows.

Easy...is using the Pentax 100 4.0 Macro K Mt on the Chinon (also spotmeter) or the ZX 5 Pentax...which ...having TTL flas (pop) lets me slave up the big Vivitar on a bracket for some "fancy" flash tricks.

the Tamron SP 35-80 zoom has about the best macro of any zoom....versatile.

Being various "Pentax Mounts" I reckon any of that can do well on a K10/K20,but ironically..it's hard to beat the trusty old Mamiya for Macros.

The FUNNY part......you can get a Mamiya+Tubes+Bellows+cable release+a couple of NICE lenses....for about $100......which is cheaper than autofocus tubes alone.

Or.....you can hunt down a Tamron 90 2.5 macro SP,and the SP 2x and that gets GREAT 1:1 mac (at 180mm)...adapts to various mounts.
07-13-2009, 02:48 PM   #12
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I use manual exposure and manual focus when using my macro lens. Having a K10D, I would lose an essential function with an AF macro lens.

Snap-in-focus requires the use of a manual lens on any body other than the K20 or K-7. In this mode, all that is needed is to put the camera into AF.S and set the lens focus to the distance (or magnification using the scales on a macro lens) and press the shutter release fully down while keeping the ( ) in the middle of the viewfinder on whatever you want in focus. The camera will take the image when it detects focus. With the K20 and K-7 you can do this using the AF/MF switch on the lens and a menu setting.

Manual Exposure is essential when chasing bugs around the garden or moose in the woods. I set the exposure using sunny-16 or by metering on a suitable subject. I don't want the camera to underexpose (as it wanted to with this image) or overexpose as it would when the subject is in front of dark green foliage or with dark woods in the background.

Here's a sample shot of what I mean - Least Skipper (we think - definitely a skipper, probably a least based on range and the striped antennae) on a pansy. Exposure would vary violently depending on the background. The lovely lady (one inch from nose to tail) was flickering about - that's where the name comes from - and never stands still for more than half a second. Trying to keep it in focus and relying on auto exposure would be extremely difficult.

07-13-2009, 09:53 PM   #13
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Except that is the same person and they only had 2 posts here and never responded to any of our PMs etc. Why Kenko quit producing this for Pentax mount is a mystery to me.

Marc L'Anguille has a set of the AF Kenko ext tubes. He also has the FA* 200mm f4 macro. He may have traded his soul to the devil or something to end up with both.

At any rate, I have concluded that the only certain way to get an AF ext tube for PKA is to remove the glass from a teleconverter.
07-13-2009, 11:15 PM   #14
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This one is better off in the lens forum.
07-14-2009, 01:16 AM   #15
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QuoteOriginally posted by Blue Quote
...............

At any rate, I have concluded that the only certain way to get an AF ext tube for PKA is to remove the glass from a teleconverter.
I'm following this path now.

Any AF teleconverter will do ? I think there was a thread on the forum about that DIY project but can't find it now
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