[robert]

I have a Tamron 135mm 2.8 lens with an adaptall adapter.. I'm not sure if the adapter is
one of the better ones or not. The only markings on it are PCS Japan .Is this one of the better ones?

[pepperberry farm]

I have a Tamron 135mm 2.8 lens with an adaptall adapter.. I'm not sure if the adapter is
one of the better ones or not. The only markings on it are PCS Japan .Is this one of the better ones?

does it work on your camera, as in giving you focus confirmation, infinity focus, etc?

[kypfer]

The "better" ones are marked Tamron Japan P/KA and will give fully automatic open aperture metering.
In my limited experience with 3rd-party 'adaptall' adaptors they are totally manual with no aperture control and don't even allow "catch in focus" without modification.
Photographs of the adaptor in question may help confirm details.

I have the Tamron 35-70 Adaptall with the Tamron - Japan adapter and it is just P/K. no A.
Catch in focus works fine but obviously there is no auto anything.

[kypfer]

I have the Tamron 35-70 Adaptall with the Tamron - Japan adapter and it is just P/K. no A.
Catch in focus works fine but obviously there is no auto anything.

… 'cept that the camera will keep the aperture open until exposure time (or during metering with the green button) then close the aperture just to make the exposure.
With the "less expensive" 3rd-party adaptors the aperture only opens and closes by use of the ring on the lens … there's no camera control at all, much like using an M42 lens with appropriate adaptor, but you don't even have the advantage of an a/m switch!

… 'cept that the camera will keep the aperture open until exposure time (or during metering with the green button) then close the aperture just to make the exposure.
With the "less expensive" 3rd-party adaptors the aperture only opens and closes by use of the ring on the lens … there's no camera control at all, much like using an M42 lens with appropriate adaptor, but you don't even have the advantage of an a/m switch!

Ahhhh...thank you!

[marcusBMG]

I think that PCS is an M42 screw thread mount?
Check the review section here - describes and differentiates the adapters available:

Tamron Adaptall Lenses for Pentax: Adaptall Adapters - Pentax Lens Review Database

"Better" rather depends on how you want to use the lens. All the original adapters are good quality. The M42 ones all work the same for adapting to DSLR. Note the point about the iris not being actuated on adaptall-2 and SP adaptall lenses in the M42 mount description.

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Last edited by marcusBMG; 09-04-2022 at 05:28 AM.

[TwoUptons]

I think that PCS is an M42 screw thread mount?
Check the review section here - describes and differentiates the adapters available:

Tamron Adaptall Lenses for Pentax: Adaptall Adapters - Pentax Lens Review Database

I was thinking the same thing... The genuine Adaptall Pentax K adapters I've seen have all been marked P/K or P/KA.

I think the PCS and P/ES are the screw mount ones, with the ES ones doing all the open-aperture stuff on the Spotmatic F.

-Eric

[robert]

]I am ignorant on this subject so excuse me. Here are some photos of the lens and adapter. The lens
seems to work the same as my Pentax screwmount lenses with adapter. The few test photos I've taken seem
very sharp. I'm not sure what the A and M switch do as I just keep it on M. Is there a different adapter I can
use so I could use the bayonet mount? Thanks

---------- Post added 09-04-22 at 11:46 AM ----------

Here are the photos



https://g3.img-dpreview.com/F8EA7DAC345244BBAE963346ABDFF484.jpg

---------- Post added 09-04-22 at 11:47 AM ----------

last one

[kypfer]

]I am ignorant on this subject so excuse me. Here are some photos of the lens and adapter. The lens
seems to work the same as my Pentax screwmount lenses with adapter. The few test photos I've taken seem
very sharp. I'm not sure what the A and M switch do as I just keep it on M. Is there a different adapter I can
use so I could use the bayonet mount? Thanks

Aaaah … ignorance accepted
Your lens is an Adapt-a-matic, not an Adaptall!
Adapt-a-matic lenses pre-date the Adaptall range.
This adaptor system is totally different to and in no way compatible with the Adaptall system.
Nevertheless the lenses are of good quality, both mechanically and optically … just a pity Tamron never made a K-mount for them.
So, yes, use it as you use your other M42 lenses, you'll not be disappointed.
The A/M switch allows for automatic aperture operation on M42 cameras with that capability, which unfortunately doesn't include any K-mount Pentax DSLR
Personally, when working in Manual Mode, I leave the lens on "A" for composition and focussing, to get the brightest viewfinder image, then simply operate the A/M switch to close down the aperture for metering with the Green Button and again at the point of exposure.
If you're happy working with the lens set to "M" and wriggling the aperture ring open and closed, fine. As long as the results are what you want

[UncleVanya]

Aaaah … ignorance accepted
Your lens is an Adapt-a-matic, not an Adaptall!
Adapt-a-matic lenses pre-date the Adaptall range.
This adaptor system is totally different to and in no way compatible with the Adaptall system.
Nevertheless the lenses are of good quality, both mechanically and optically … just a pity Tamron never made a K-mount for them.
So, yes, use it as you use your other M42 lenses, you'll not be disappointed.
The A/M switch allows for automatic aperture operation on M42 cameras with that capability, which unfortunately doesn't include any K-mount Pentax DSLR
Personally, when working in Manual Mode, I leave the lens on "A" for composition and focussing, to get the brightest viewfinder image, then simply operate the A/M switch to close down the aperture for metering with the Green Button and again at the point of exposure.
If you're happy working with the lens set to "M" and wriggling the aperture ring open and closed, fine. As long as the results are what you want

Why is green button needed if you use stop down metering you can shoot in Av mode. Simply put the lens on A to focus and compose and switch the lens to M when ready to shoot. Keep it on Av and shutter speed will be set with no green button efforts.

[kypfer]

Why is green button needed if you use stop down metering you can shoot in Av mode. Simply put the lens on A to focus and compose and switch the lens to M when ready to shoot. Keep it on Av and shutter speed will be set with no green button efforts.

My experience, reflected by some others, is that Av in stop-down mode can be unreliable.
It may be camera, lens or circumstance specific, but I know it can be unreliable occasionally, usually over-exposing if it does get it wrong, whereas Manual Mode with the Green Button has always been totally reliable.
If Av Mode and stop-down works for you, fine, I don't have a problem with that, but I, for one, don't feel comfortable recommending it.

[UncleVanya]

My experience, reflected by some others, is that Av in stop-down mode can be unreliable.
It may be camera, lens or circumstance specific, but I know it can be unreliable occasionally, usually over-exposing if it does get it wrong, whereas Manual Mode with the Green Button has always been totally reliable.
If Av Mode and stop-down works for you, fine, I don't have a problem with that, but I, for one, don't feel comfortable recommending it.

I am aware of some issues with Av and certain A series lenses having exposure issues but I wasn’t aware of M and green button working better with m42 lenses. I knew some recommended optical preview in M over green button. Very interesting - I certainly don’t use this method enough to be expert on it. Thanks for the tactful and helpful reply.