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11-09-2009, 12:20 PM   #1
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What does "auto" mean on older manual focus lens?

I have an "Auto Chinon 1:1.9 50mm" and a "Focal MC AUTO 1:2.8 135mm: lens in Pentax k Mount.
My question is- what is auto about them? I've used both on my k1000 in manual (of course) for years but on my recently acquired ZX-50, nothing special seems to happen.
Since I haven't a clue, I am posting this note.
Thank You

11-09-2009, 12:34 PM   #2
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Do they have an "A" on the aperture ring? If so, pressing the little button and setting the aperture to that will allow your newer camera to set the aperture on the body in the same way as it would with an auto focus lens.

If not, I'm equally intrigued as to what it means!
11-09-2009, 12:39 PM   #3
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No, there is no "A" , but I turned them all the way in that direction still with no results.
Thanks!
11-09-2009, 12:43 PM   #4
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The old "auto" meant automatic diaphragm operation. In other words, the camera closes the aperture when you push the shutter, rather than you (e.g. with a preset lens).

Later "auto" meant also open-aperture metering. Later yet, like Matt says, an auto exposure setting on the lens.

11-09-2009, 01:20 PM   #5
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As Nesster said, "Auto" on a lens means automatic aperture. At one time, this designation was important from a marketing perspective to differentiate a lens from those having less sophisticated semi-auto, pre-set, and fully manual apertures. To summarize:
  • All M42 and K-mount lenses labeled as "Auto" have automatic apertures
  • Semi-auto, pre-set, and manual aperture lenses are never labeled as "Auto"
  • All lenses that support open-aperture metering are intrinsically "Auto" regardless of labeling

People have used the term to refer to support of exposure automation and/or focus automation, but when used as part of a lens name it is as above. And finally, to reiterate and repeat and emphasize again...
"Auto" as part of a lens name or as a label on the lens face or barrel does not mean that the lens has the "A" position on the aperture ring and/or the "A" contacts on the mount.
Steve

P.S. While "Auto" is a much abused term, "manual" is even more so. If I had a penny for every time I have seen non-auto-focus lenses referred to as "full manual"...

Last edited by stevebrot; 11-09-2009 at 01:31 PM.
11-09-2009, 02:46 PM   #6
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QuoteOriginally posted by stevebrot Quote
  • All M42 and K-mount lenses labeled as "Auto" have automatic apertures
  • Semi-auto, pre-set, and manual aperture lenses are never labeled as "Auto"
  • All lenses that support open-aperture metering are intrinsically "Auto" regardless of labeling
...
Not quite true. Early Pentax semi-automatic lenses from the late fifties through the early sixties were offically known as "Auto Takumar" lenses. These lenses had a seperate lever to "cock" the aperture. When the shot was taken, the lens stopped down to the selected aperture, but it did not re-open.

Pentax kinda jumped the gun with that name. That's probably one reason why the next generation of lenses (still M42) from Pentax were called "Super Takumar".

To further confuse the issue, a few of the last "Auto Takumar" lenses had fully automatic apertures that DID re-open after exposure. I don't think that the anti-flare coatings were as good as the later Super Takumars and the SMC Takumars.

Semi-auto lenses are somewhat rare, so your list is still a pretty good rule of thumb. The word "auto" on non-Autofocus lenses, clearly refers to some level of aperture automation. For the OP's purposes, that's probably good enough.
11-14-2009, 04:30 PM   #7
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Thank you

I would like to Thank everybody, This was a question that always bugged me but I never though to ask
I'm new here at the Pentax forums But not new at photography (w/film).
My first SLR was a K1000 I bought at K-Mart. That is where I got the Focal F2.8,135mm tele. That's like 30 years ago and they still work great although I have added a zx50 and some Pentax and Sigma zooms. I love my Sigma DL 75-300mm 4-5.6. I use it for my grand-daughters' basketball and my grand-sons' football games.
Yes, Thank You all very much for taking the time to respond!

P.S. The little "confused" smiley looks just like my driver license photo.
11-14-2009, 05:26 PM   #8
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Here ya go - this may have been the very lens?

11-14-2009, 05:58 PM   #9
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QuoteOriginally posted by jonhock Quote
No, there is no "A" , but I turned them all the way in that direction still with no results.
Thanks!
The ZX-50 is unfortunately one of the few Pentax cameras which cannot be used with lenses predating the A series:

The Pentax Camera Lens Compatibility Chart
11-14-2009, 05:59 PM   #10
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The advert really makes this thread!
11-14-2009, 07:27 PM   #11
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Wow, the optical formula in that Focal 135mm f2.8 lens looks very similar to the Pentax A 135mm f2.8.


QuoteOriginally posted by Nesster Quote


A 135/2.8

Edit: I actually have that Focal 28mm f2.8 that I bought new with a K1000.

Last edited by Blue; 11-14-2009 at 07:33 PM.
11-14-2009, 07:58 PM   #12
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QuoteOriginally posted by Nesster Quote

Here ya go - this may have been the very lens?
Or something very similar. The lenses in the ad were only available in M42, Minolta, and Canon mounts (Edit: The ad is copyright 1978).

Steve

Last edited by stevebrot; 11-15-2009 at 11:24 AM.
11-15-2009, 09:22 AM   #13
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QuoteOriginally posted by stevebrot Quote
Or something very similar. The lenses in the ad were only available in M42, Minolta, and Canon mounts.

Steve
I bought my Focal 28mm f2.8 in late 1984 or early 1985 and I got a brochure at the time. Here is a cover and the offerings.




Up until the time of the brochure at least, those lenses were made in Japan, I suspect by Tokina. Sometime after that, they started getting their lenses from Korea like Sears et al.
11-15-2009, 11:33 AM   #14
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QuoteOriginally posted by Blue Quote
...Up until the time of the brochure at least, those lenses were made in Japan, I suspect by Tokina...
The late 70s through mid-80s were the glory days of manual focus 35mm slrs and lenses. The competition was hot and even the off-brands were made and performed to a high standard. There are a few posts (some from you, Blue) on the "Off Brand Club" thread regarding the Focal lenses. It is quite possible that they were made by Tokina. Tamron is another possible suspect.

Steve
11-15-2009, 02:44 PM   #15
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Except that it .....

That would be the one in the upper left corner on Blue's post. Exept that
it has the Pentax K mount instead of the M42. The thing I can't tell from the ad is the fact that this 135 has a built in lens hood. That would be the wide ring in front of the focus ring.
I'll post some pics with it when I get them developed. Some with a Focal 2X and some without.
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