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11-09-2009, 12:35 PM   #1
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What does "auto" mean on older manual focus lenses?

First thing-I posted this in the "camera" forum and then I read the "what goes in here" post from Adam "the administrator".
I apologize for that.

I have 2 lenses that have auto in the name. A "Focal MC AUTO 1:2.8 135mm" and an "Auto Chinon 1:1.9 50mm" I have used them for years on my Pentax K1000 in manual (of course) but when I put them on my Pentax ZX-50 (I just purchased on Ebay (of course), nothing special happens. I've tried AV, TV, Manual, and Auto with no results.
Any One have any ideas on that?
Thank You

11-09-2009, 12:55 PM   #2
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Without seeing a picture of the lenses I can only guess that they're auto aperture lenses.

So you can change the f-stop on the body instead of the lens, or a camera with full auto will be able to control the aperture for you.
11-09-2009, 12:58 PM   #3
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It usually means that the camera can close the aperture when taking a picture. For framing and metering the aperture is usually fully open otherwise the viewfinder can be very dark. When you take a photo the camera closes the aperture to the pre set value (set either manually or by the camera) and then alows it to open again. Olde lenses in which the camera can operate the aperture are usually marked as Auto. There are also pre set aperture lenses in which the camera cannot operate the aperture at all and the operator must do it.
11-09-2009, 12:59 PM   #4
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QuoteOriginally posted by jonhock Quote
First thing-I posted this in the "camera" forum and then I read the "what goes in here" post from Adam "the administrator".
I apologize for that.
I have 2 lenses that have auto in the name. A "Focal MC AUTO 1:2.8 135mm" and an "Auto Chinon 1:1.9 50mm" I have used them for years on my Pentax K1000 in manual (of course) but when I put them on my Pentax ZX-50 (I just purchased on Ebay (of course), nothing special happens. I've tried AV, TV, Manual, and Auto with no results.
Any One have any ideas on that?
Thank You
Nesster gave you the correct definitions in the other thread.

The AUTO on those lenses means that the aperture stops down automatically. That was a mechanical operation and it just wont work with an electronic camera.
You can still use them by stopping down manually.

See also: General Photography - Techniques and Styles. for a kind of automation.

Mickey


Last edited by mickeyobe; 11-09-2009 at 01:09 PM.
11-09-2009, 01:34 PM   #5
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See my comment on the "other" thread...

Steve
11-14-2009, 04:39 PM   #6
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I just posted a "Thank you to everybody" note in the "Pentax film SLR" discussion section.
Seriously, The pentax forums have been a great help lately and I'm sure I can come up with some more questions.
Thanks again!
11-14-2009, 05:00 PM   #7
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QuoteOriginally posted by jonhock Quote
I just posted a "Thank you to everybody" note in the "Pentax film SLR" discussion section.
Seriously, The pentax forums have been a great help lately and I'm sure I can come up with some more questions.
Thanks again!
first, good first question!! And second, I find the folks here really nice and lots of great help to be had.

I'm new here as well and a good way to get to know folks here was to post over here:

Welcomes and Introductions - PentaxForums.com

I got to know folks and, more importantly, let folks know how goofy I can be when the good meds kick in. hehehehe...
11-15-2009, 02:27 PM   #8
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1.4 Takumar Pentax 50mm

Yeah Brecklundin, me too. (the goofy part, that is)
As long as we are on the subject, I have been looking at 50mm Takumars-1.4 for close ups with a set of Hoya's (+1,+2,&+4) I've had since the 70's and now I am wondering about the "auto" switch on them.
Does any one know if this is an "auto" as discussed in this thread or is it an "auto" like auto aperture setting (with the little button on the f~stop ring)? After all these years, one might think one (one as in "I") may know this stuff, but apparently one doesn"t!
Also... would the 1.4 Takumar be a great bit different than my 1.9 Chinon 50mm?
Stan

11-15-2009, 05:24 PM   #9
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QuoteOriginally posted by jonhock Quote
Yeah Brecklundin, me too. (the goofy part, that is)
As long as we are on the subject, I have been looking at 50mm Takumars-1.4 for close ups with a set of Hoya's (+1,+2,&+4) I've had since the 70's and now I am wondering about the "auto" switch on them.
Does any one know if this is an "auto" as discussed in this thread or is it an "auto" like auto aperture setting (with the little button on the f~stop ring)? After all these years, one might think one (one as in "I") may know this stuff, but apparently one doesn"t!
Also... would the 1.4 Takumar be a great bit different than my 1.9 Chinon 50mm?
Stan
On Takumars (at least on Super, SMC, S-M-C) the Auto switch means that when you fire the shutter the camera will close the aperture to whatever diaphragm setting you have set on the aperture dial. Also this works only on m42 bodies, not on K if you're using the adapter.
11-16-2009, 02:06 AM   #10
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Any good suggestions on jamming the pin to make a lens manual? Was considering a toothpick or superglue, but my hands.dll is somewhat buggy, so if someone knows a better way
11-16-2009, 03:09 AM   #11
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If the lens has an A/M switch then just switch it to M and this has the effect of jamming the pin in. If not, the best way of loacking in the pin depends on the specific lens (and how easy it is to remove the mount).
11-17-2009, 02:12 AM   #12
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QuoteOriginally posted by MattGunn Quote
If the lens has an A/M switch then just switch it to M and this has the effect of jamming the pin in. If not, the best way of loacking in the pin depends on the specific lens (and how easy it is to remove the mount).
So, removing the mount is necessary? The lens is an auto-only M42 Tokina. Thanks!
11-17-2009, 10:36 AM   #13
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QuoteOriginally posted by Blaze Quote
Any good suggestions on jamming the pin to make a lens manual? Was considering a toothpick or superglue, but my hands.dll is somewhat buggy, so if someone knows a better way
You could get an M42-K adapter that engages the stop down pin
Hin's Tech Corner: m42 adapter for auto-mount m42 lens

or try Big Dave's epoxy trick

https://www.pentaxforums.com/forums/339429-post10.html
11-17-2009, 11:32 AM   #14
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QuoteOriginally posted by troyz Quote
You could get an M42-K adapter that engages the stop down pin
Hin's Tech Corner: m42 adapter for auto-mount m42 lens

or try Big Dave's epoxy trick

https://www.pentaxforums.com/forums/339429-post10.html
The alternative adapter is an interesting idea, but Hin does mention the machining being imperfect. Plus it would cost almost as much as the lens in question
Gonna try epoxy or stick something under the pin (like Hin suggests) for now.
11-17-2009, 01:11 PM   #15
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QuoteOriginally posted by Blaze Quote
So, removing the mount is necessary? The lens is an auto-only M42 Tokina. Thanks!
No
If the mount comes off easily then it is often quite easy to take the pin out, put a short length of tube over it and put it all back together again. In this way the lens is converted to manual but it is straightforward to remove the bit of tube and restore the lens should you decide to part with it. Generally if I am modifying a lens then I will try to do it reversibly in case I decide to sell it on (like I'm ever going to willingly part with any of my glass...)
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