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07-08-2009, 03:38 PM   #1
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Infinitely Variable Aperture Super-Takumar?

Anybody ever heard of such an animal? Seller on ebay says he talked to Pentax Japan and they told him there were 50 Super-Takumar 28mm F/3.5 infinitely variable aperture lenses made. In other words there are no clicks for the stops, just a smooth aperture closure from F/3.5 to F/16.

CW

07-08-2009, 03:52 PM   #2
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I saw that listing, not real sure about it. Ive never hear of such a lens, and couldnt find any info. im suspicious... but then I was all but sure the lens with the red serial number that popped up on ebay a year or so ago was a fake... turned out to be real. Im nost sure how much pentax Japan would still know about such lenses. im more skeptical of his call to Pentax than I am the lens itself. maybe someone with the 'holy grail' of Asahi Optical screwmount literature aka 'The ultimate Asahi Pentax Screw Mount Guide' can check on this.
07-08-2009, 04:57 PM   #3
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QuoteOriginally posted by séamuis Quote
I saw that listing, not real sure about it. Ive never hear of such a lens, and couldnt find any info. im suspicious... but then I was all but sure the lens with the red serial number that popped up on ebay a year or so ago was a fake... turned out to be real. Im nost sure how much pentax Japan would still know about such lenses. im more skeptical of his call to Pentax than I am the lens itself. maybe someone with the 'holy grail' of Asahi Optical screwmount literature aka 'The ultimate Asahi Pentax Screw Mount Guide' can check on this.
The "red letter" Pentax-M was real?

Steve
07-08-2009, 05:05 PM   #4
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You know, any lens can have stepless aperture. You just take it apart, and get rid of the ball bearing that makes clicking, and voila! You now have a stepless aperture lens

07-08-2009, 05:17 PM   #5
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QuoteOriginally posted by stevebrot Quote
The "red letter" Pentax-M was real?

Steve
yes.

I saw a photo of one on a website that had pictures from the Pentax Camera Museum. which unfortunately is apparently closing or has already closed...
07-08-2009, 06:04 PM   #6
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QuoteOriginally posted by séamuis Quote
Im nost sure how much pentax Japan would still know about such lenses. im more skeptical of his call to Pentax than I am the lens itself.
That was my thinking also. My understanding is that Pentax didn't keep close records on serial numbers of various runs. But hey, as my wife constantly points out, I'm frequently wrong.

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07-08-2009, 06:30 PM   #7
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Well, one thing is obviously incorrect: the lens is claimed to be super-multi coated. The pictures identify it as a non-SMC lens, and S-M-C lenses start appearing in the 4-million serial range.

Another thing is likely incorrect, as others have pointed out: I doubt "Pentax Japan" would give him this information. Heck, it'd almost be worth the price of the lens just to get the contact information of who could give us the serial numbers of different runs of the lenses.

The lens cap does appear to be authentic, though; I can't say for sure, because I haven't seen many. Most "Asahi Pentax" lens caps have larger "Asahi" lettering, and date from the upper-1-million serial number range; pre-million lens caps are often just "Pentax," but low-1-million lenses are often labeled "Honeywell Pentax" in about the same size as the "Asahi" is written here. Unfortunately, lens caps are rarely sold now with the lens they were shipped with, so my information as well as any implications here are pretty vague.

Anyhow, I have a Takumar 105/2.8 that has an infinitely variable aperture. It isn't a big deal. It would be a big deal if there are no indents at all--which would make aperture setting by touch alone practically impossible.

The seller is offering a no-questions-asked return policy. Perhaps the buyer could take apart the lens to see if it is different from a normal S-T 28/3.5, or if it just is missing a ball bearing?
07-08-2009, 06:31 PM   #8
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QuoteOriginally posted by pbo Quote
You know, any lens can have stepless aperture. You just take it apart, and get rid of the ball bearing that makes clicking, and voila! You now have a stepless aperture lens
Several lenses I have owned allow you to set the aperture between clicks. This is in effect a continuously variable aperture. I have not ever found a real purpose for this.

07-08-2009, 07:10 PM   #9
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I also have an old 50mm M f2 with this 'variable aperture' feature. I prefer to call it the sticky POS though, hmm
07-08-2009, 07:30 PM   #10
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QuoteOriginally posted by pbo Quote
You know, any lens can have stepless aperture. You just take it apart, and get rid of the ball bearing that makes clicking, and voila! You now have a stepless aperture lens
Exactly. I admire the seller's ability to turn this from a liability into a feature.

I have a lens which I think is a C-mount, from some sort of movie or TV camera, with a stepless aperture. That would be a possible use for it. My lens is a 50mm f0.95 but can't be mounted in any useful way.
07-08-2009, 09:50 PM   #11
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the Zeiss Ultron 50mm f1.8 hs steppless aperture.
I really like that, just as presets great to use on dSLR
07-09-2009, 05:08 AM   #12
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QuoteOriginally posted by kuuan Quote
the Zeiss Ultron 50mm f1.8 hs steppless aperture.
I really like that, just as presets great to use on dSLR
absolutely. a preset is a dream on a digital SLR.
07-09-2009, 05:24 PM   #13
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After using a preset aperture lens ... and finding out about infinitely variable aperture .... I think it's actually a really cool feature ... at least you are not limited to a set aperture.
09-10-2009, 12:20 PM   #14
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I wonder how much harder it would have been for Asahi to incorporate two aperture rings, one with stops and one infinite (just like Mir-1B). The idea kinda seems cool to me.
09-10-2009, 08:13 PM   #15
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QuoteOriginally posted by VaSA Quote
I wonder how much harder it would have been for Asahi to incorporate two aperture rings, one with stops and one infinite (just like Mir-1B). The idea kinda seems cool to me.
I have owned two Takumars with exactly that setup. One was the 55mm f/2.2 I purchased with my original (first model made) Asahi Pentax. The other was the 135mm f/3.5 I later purchased. This aperture arrangement is called a preset aperture. One presets the metered aperture on the click stopped ring, and then one can open for focusing and immediately stop down without looking.

They became obsolete when the camera was engineered to do what you had to do with a spare finger with the preset lenses. I don't miss them.
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