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09-27-2010, 12:06 PM - 1 Like   #16
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QuoteOriginally posted by Laurentiu Cristofor Quote
That's not what preset means. A Takumar is not a good example of preset lens - it is preset only in M mode
Sorry, but you are not quite correct.

Lenses with a pre-set aperture mechanism feature a lever, switch, or ring that allows you to pre-set the shooting aperture with the lens wide open and quickly stop down by flicking the lever to the stopped down position. The A/M switch on most auto-aperture M42 lenses allows pre-set functionality as a design feature on what is normally an auto-aperture lens. Other lenses, such as my M42 Jupiter 9 have a true pre-set aperture and function only in that or full manual mode.

The eBay Tamron adapter converts the lens to a fully manual aperture with NO pre-set option.

This is a topic where the terms are often misapplied and there is frequent confusion. There are five types of aperture mechanisms common in interchangeable camera lenses:
  • Manual aperture -- Moving the aperture dial/lever results in an immediate change to the aperture size. There is NO aperture linkage between the camera and lens.
  • Pre-set aperture -- There is a mechanism to allow a pre-set of the shooting aperture without changing the aperture size. The lens is stopped down just prior to shooting by moving a lever, switch, or ring and reopened using the same mechanism. Again, there is no coupling between the body and lens. Pre-set lenses are relatively common in vintage types and continue in production today with certain Russian lenses and specialty glass such as tilt/shift lenses. The A/M switch on many auto-aperture M42 lenses allow them to behave as pre-set lenses on cameras lacking the actuator coupling (e.g. K-mount bodies).
  • Semi-automatic aperture -- Allows a pre-set of the shooting aperture with the aperture automatically stopping down at exposure time. The aperture must then be re-opened by moving a lever on the side of the lens to re-enable the auto feature. This type requires an aperture actuator coupling between the body and the lens and was only common for a few years in the late 1950s. Some early Takumars have semi-automatic apertures.
  • Automatic aperture -- The lens automatically stops down at exposure time and reopens after the exposure. Again, there is an actuator coupling between the body and lens. Back in the day, this was considered to be an advanced feature and was often advertised as part of the lens name. A good example would be my M42 Auto-Rikenon 50/1.7. There are many variations of automatic apertures to support various body features via mechanical or electrical contacts.
  • Aperture automation control -- This is a variation on the automatic aperture where the camera body controls the aperture size at exposure time. This feature allows shutter priority and programmed exposure automation. Pentax "A" contact lenses are a good example.


Steve

09-27-2010, 12:16 PM   #17
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QuoteOriginally posted by kangamel Quote
Ta da all done, M42 adaptor now has a bit of plastic added and I can adjust the aperture. Seems to work in M with green button just like my Tak, I am happy with that, and it cost me nothing. But 1- 2 min? find pen, find blade and cut plasic to size - 50 seconds. Getting the Tiny bit of plastic tube onto the pin... lets just say I must be very very clumsy
Problem solved!


Steve
09-27-2010, 01:47 PM   #18
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QuoteOriginally posted by stevebrot Quote
This is a topic where the terms are often misapplied and there is frequent confusion. There are five types of aperture mechanisms common in interchangeable camera lenses:
Thanks for the definitions - I'll try to use these terms now that I learned about them.

I used to refer to the first two categories as "preset" and to bundle the others as "auto", based on the idea that in a preset, you have to take manually an action before shooting to actually get the aperture stopped down, while for auto there is a mechanism that allows the camera/lens combo to do that when the shutter is pressed. A higher level breakdown, if you like, which doesn't get into the messy implementation details.

BTW, I now can say I have a semi-automatic Biotar - so it's not only Takumars that had this system. For this Biotar you had to twist the single aperture ring all the way to lock the aperture wide open - it didn't use a lever on the barrel like the Takumars did.

So, to rectify my statement and bring it in line with the definitions you provided, the ebay adaptall PK adapter makes a Tamron lens into a manual aperture one, which I prefer because it allows me to use it in Av mode.
09-28-2010, 05:36 AM   #19
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QuoteOriginally posted by stevebrot Quote
Sorry, but you are not quite correct.

Lenses with a pre-set aperture mechanism feature a lever, switch, or ring that allows you to pre-set the shooting aperture with the lens wide open and quickly stop down by flicking the lever to the stopped down position. The A/M switch on most auto-aperture M42 lenses allows pre-set functionality as a design feature on what is normally an auto-aperture lens. Other lenses, such as my M42 Jupiter 9 have a true pre-set aperture and function only in that or full manual mode.

The eBay Tamron adapter converts the lens to a fully manual aperture with NO pre-set option.

This is a topic where the terms are often misapplied and there is frequent confusion. There are five types of aperture mechanisms common in interchangeable camera lenses:
  • Manual aperture -- Moving the aperture dial/lever results in an immediate change to the aperture size. There is NO aperture linkage between the camera and lens.
  • Pre-set aperture -- There is a mechanism to allow a pre-set of the shooting aperture without changing the aperture size. The lens is stopped down just prior to shooting by moving a lever, switch, or ring and reopened using the same mechanism. Again, there is no coupling between the body and lens. Pre-set lenses are relatively common in vintage types and continue in production today with certain Russian lenses and specialty glass such as tilt/shift lenses. The A/M switch on many auto-aperture M42 lenses allow them to behave as pre-set lenses on cameras lacking the actuator coupling (e.g. K-mount bodies).
  • Semi-automatic aperture -- Allows a pre-set of the shooting aperture with the aperture automatically stopping down at exposure time. The aperture must then be re-opened by moving a lever on the side of the lens to re-enable the auto feature. This type requires an aperture actuator coupling between the body and the lens and was only common for a few years in the late 1950s. Some early Takumars have semi-automatic apertures.
  • Automatic aperture -- The lens automatically stops down at exposure time and reopens after the exposure. Again, there is an actuator coupling between the body and lens. Back in the day, this was considered to be an advanced feature and was often advertised as part of the lens name. A good example would be my M42 Auto-Rikenon 50/1.7. There are many variations of automatic apertures to support various body features via mechanical or electrical contacts.
  • Aperture automation control -- This is a variation on the automatic aperture where the camera body controls the aperture size at exposure time. This feature allows shutter priority and programmed exposure automation. Pentax "A" contact lenses are a good example.


Steve
steve, a good explanation, but there is one step missing.

You need to add metering into the equation.

Why, because while my Super Tak 50mmF1.5 has an auto diaphram, it only permits stopped down metering, where as my SMC Takumar 135 F3.5 has an aperture ring coupling (like all K mounts) which allowed for open aperture metering. on the Spotmatic F anmd ES II cameras,

This is an important distinction.

also with respect to auto aperture, and this is where the OP got into trouble with his M42 mount, while it was auto aperture, it did not have the auto manual switch and as a result, the lens was always wide open because there was noghing to push the aperture pin in the body or mount.

09-28-2010, 06:38 AM   #20
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QuoteOriginally posted by Lowell Goudge Quote
As for the time to install, it does take longer the first time, but there are some tricks to get the slit in the tube around the pin.

But seriously, how long is really clumsy?
QuoteOriginally posted by Lowell Goudge Quote

...this is where the OP got into trouble with his M42 mount...
Girl clumsy
lost the first bit of plastic on the floor, twice
2nd time it never was found,
cut a second piece, got it on,
then couldn't mount the adaptor to the lens so removed it
Made a third! a tiny bit shorter
struggle struggle tweezers, no tricks, but finally got it on
Bingo..took a few test shots of the cat and my feet and other interesting midnight subjects and posted my victory back here.

It was 1 HOUR from the time I posted I was off to do it, to posting I had done it!

I hope you are getting a laugh Lowell Goudge, I am sooo pleased with the result. thanks again, now I'm off to try and understand all the rest off the stuff brought up in this thread, thanks all.

Mel
09-28-2010, 12:58 PM   #21
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QuoteOriginally posted by kangamel Quote
Girl clumsy
lost the first bit of plastic on the floor, twice
2nd time it never was found,
cut a second piece, got it on,
then couldn't mount the adaptor to the lens so removed it
Made a third! a tiny bit shorter
struggle struggle tweezers, no tricks, but finally got it on
Bingo..took a few test shots of the cat and my feet and other interesting midnight subjects and posted my victory back here.

It was 1 HOUR from the time I posted I was off to do it, to posting I had done it!

I hope you are getting a laugh Lowell Goudge, I am sooo pleased with the result. thanks again, now I'm off to try and understand all the rest off the stuff brought up in this thread, thanks all.

Mel
Mel

maybe I shoudl have started by saying trim your nails
09-28-2010, 02:23 PM   #22
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QuoteOriginally posted by Lowell Goudge Quote
You need to add metering into the equation.

Why, because while my Super Tak 50mmF1.5 has an auto diaphram, it only permits stopped down metering, where as my SMC Takumar 135 F3.5 has an aperture ring coupling (like all K mounts) which allowed for open aperture metering. on the Spotmatic F anmd ES II cameras,

This is an important distinction.
Lowell,
I was tempted to go into that discussion and actually had the text written, but the comment was getting pretty long as it was, so the paragraph was excised. I sort of figured that going into the specifics of coupling for open-aperture metering was a little bit overboard.


Steve
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