Auto Tamron 21 /4.5...with issue(s)

[mo]

I have not been in this section for awhile..

I traded lenses with a fellow member and received this lens (I knew it had issues so that is not a concern)
It still functions although with a the obvious mount issues, it seems to work quite well.There is some play (movement) at the front of the lens...I can change the aperture by holding onto the front of the lens and turn it to open and close the aperture (I am sure it is not supposed to do that).

I have 3 questions...

Is this lens repairable? and is it worth spending the money to fix it?...lastly should I just leave it as is and enjoy having a 21mm lens

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#5 Note where the N & S stickers are this should be covered by another ring.

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The weather is lousy at the moment these are just quick snaps to give you an idea of the images it takes.

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[luisalegria]

Hi Mo,

It looks pretty complete from your pictures.
Mine looks the same with the mount removed.
The only bit missing on yours is that mine has glass in the rear filter.
I have actually started using it to hold in a red or yellow gel filter cut to fit.

You do have the M42 mount, right ?

If so I think the problem may be that someone has been monkeying with the aperture
ring somehow. Whatever problems there are are not on the surface but internal.
I bet there's a loose setscrew or two in there.

[mo]

Hi Luis,thanks for checking this out.

Yes I have the M42 screw mount adapter.The lens is missing the bottom ring that has the letters SRT on it that sits below the two screws that you can see below the Aperture numbers.....image #5

Have you had your lens dismantled at all?... to know how hard it may be to disassemble? I am assuming that all adaptamatics would have the same internal set up for their mount end?

[luisalegria]

I dont have anything there on the spots labelled N,S, or SRT.
These are locations where supplemental items like Nikon ears or an extra strip for the Minolta aperture indicator lug go.
They arent needed for the M42 mounts.
The Adaptamatic mounts on the lens side do vary, but they shold be similar.
I have a spare 28mm thats not working - stuck aperture. If I find it I'll have a look and maybe post something about the internals.

[mo]

Thank you, I would really appreciate any helpful insights.

This is the back of the 135/2.8 showing the missing ring... its actually SRT.TO...my mistake.. I don't know what the letters mean.Do all your adaptamatics have the ring? I am probably getting this all wrong but I am curious to know if it is missing a ring even though as you said it is probably something inside that is of more concern


This first "missing" ring starting from the left of the image.


The SRT.TO mark on the "missing" ring.


luis you have got me thinking so....
I am sitting here looking at both the 135mm and the 21mm.The 21mm has the serial 632507 and does have a different back end.....the 135 has the serial number 641849 the ring that has the SRT.TO has also on the opposite side the letters MA....near these sets of letters are 2 holes which can only be seen when you are looking straight down the back end of the lens.The older 21mm has way more holes than the 135mm,8 sets of holes...maybe there was a slight change in the mount between the 2 lenses?

[luisalegria]

The Adaptamatic adapters were sometimes not just an adapter - they came with other bits that had to be screwed directly on the lens body, on that ring labelled "SRT-TO" and etc. In the case of SRT-TO specifically, thats where the additional part goes for the Minolta adapter, which is a flexible ring carrying a lug that mates with the Minolta SRT body open-aperture metering mechanism.

The Nikon adapter came with the "ears" (also used for open aperture metering) that likewise screwed in to the section labelled "N", etc. There are other holes and slots for the various other mounts that supported external open aperture metering linkages, like Miranda. There are also a couple of others I am not recalling.

Not all Adaptamatic lenses are drilled or marked for all these other "extras" on the lens mounts.

If you just have the Pentax screw mount adapter, there is no missing ring.
The Adaptamatic Pentax/M42 mount does not support open aperture metering, so there is no extra part to screw into any of these holes.

[mo]

I have a lot to learn,Thanks so much for taking the time to explain things.It just shows the engineering beauty of these lenses.