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06-07-2011, 05:17 AM   #1
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Auto Extension Tubes for K7

Hi,
I've been looking for auto extension tubes for Pentax K7 and couldn't find any. Does anyone have any suggestions?
Thank you.

06-07-2011, 08:27 PM   #2
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Hi liza,probably not much help,but anyway...
if you search for "Pentax Auto-Extension Tube K" you'll probably come up with
set that [was] produced by pentax,has apeture coupling lever but no electrical
contacts for lens info and metering.They're very robust and well made,but would
be 'used' if you found them,been out of production for some time
They also produced another set without coupling lever,might want to be careful.
Pentax never did produce set with any type of electrical interface integral.
Cant tell you alot about 3rd party vendors,(have K set myself)
Believe vivitar made some for awhile,with contacts.Was a set for sale on craigslist
here while back,quite expensive,over $100,somebody snatched them up instantly.
Another option is to pick up old tele-converter with lever and contacts,
remove glass and use.(K-mount of course)
got one for under $10,formerly 2x magnification,with glass removed gives around
23 millimeters of extension,could expect 1.4x,1.7x TC's to be slightly shorter,
so you get a little less extension.Hardest part is finding a "junker" to utilize.
06-08-2011, 01:59 AM   #3
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QuoteOriginally posted by liza1880 Quote
Hi,
I've been looking for auto extension tubes for Pentax K7 and couldn't find any. Does anyone have any suggestions?
Thank you.
As BillM said, Pentax never made extension tubes with contacts. Vivitar made a 3 piece set, AT-23 with contacts and AT-22 without contacts for Pentax K mount cameras. AT-23 is no longer available new and very hard to find. Kenko makes a 3 piece extension tube set with contacts but unfortunately not in Pentax K mount. Kenko extension tube set for Canon and Nikon mounts were priced at well over $200.00 in my local area, so I'd expect you would have to pay near that amount to acquire Vivitar AT-23 extension tube set, that's if you could find one.

The cheaper method could very well be to buy some old Pentax KA mount teleconverters, remove the glass and use them as extension tubes. Three of these TC turned extension tubes would probably be longer and cheaper than a Vivitar AT-23 extension tube set, only drawback will be that they will all roughly be the same size. Sometimes you might just want to extend older telephoto lenses in order to reduce the MFD but if the extension is too long, MFD might get reduced too drastically to be much use.

Thanks,
06-08-2011, 07:54 AM   #4
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Echoing the above: AF is not your friend with closeup and macro shooting (which is what extension tubes are for), so forget AF tubes. AFAIK de-glassed A-type TC's are the cheapest method to get extension whilst keeping aperture automation. I do have a variable-magnification 'macro' TC that I haven't used yet, mainly because it's not A-type, and I have enough other non-A macro solutions to keep me busy.

On extending older teles: I often do this with screwmount glass, whether using a thick-flanged NIF (non-infinity-focus) M39-PK or M42-PK adapter on short lenses, or a short macro tube on longer lenses. A 10mm tube brings the MFD on my TeleTak 200/5.6 down to ~1m and pulls infinity in to ~50m. That's great for many applications. My de-glassed A-type 2x TC's are each ~25mm thick, and so would likely only be generally usable on much longer glass -- my only candidate is the Lil'Bigma 170-500 bazooka. Maybe I'll try that sometime.


Last edited by RioRico; 06-17-2011 at 08:48 AM.
06-15-2011, 09:31 AM   #5
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QuoteOriginally posted by excanonfd Quote
Kenko makes a 3 piece extension tube set with contacts but unfortunately not in Pentax K mount.
Kenko used to make a 3-piece extension tube set for Pentax with all the contacts, and I know because I own such a set. I bought it about 20 years ago at Hunt's Photo in Melrose, MA. (I remember at the time I had some reservations about it because I had never used extension tubes before and only had a K1000, so I couldn't make use of all the contacts at the time. Now I'm very glad I made the purchase!)
06-15-2011, 10:21 PM   #6
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I have seen Kenko extension tubes advertised for Pentax so they made them at one time. Not Af but they had the A contact for auto exposure.
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