[Levi]

Hi All,
I know someone here wil be able to answer my question.
I just picked up a used Tamron 90mm sp 1:2 macro adaptal mount.
And the camera absolutely refuses to allow the lens to stop down.
It also doesn't recognize the aperature the lens is set for.
First let me say that It's not an "enable aperature ring" problem. I have other manual focus "A" lenses and they work fine.
I've removed the adaptall adapter and inspected it, and re-assembled it a couple of times, and can't find a problem or make it work.
The only way I can make it stop down is to use the old trick of partially detaching the lens, then it works fine with the aperature ring, in full auto exposure mode.
The lens is indeed very sharp (I knew it would be), and I really want it to be a keeper. So before I take it back to the shop and see if the guy there knows what the problem is, and possibly excange it, I thought I would let you guys have a try.
Thanks in advance for any possible help you can give me.
Levi

[Nesster]

Questions:
1) is it a K/A or K adaptall mount?
3) do you have the appropriate menu item set to 'allow aperture ring'?
2) if K/A have you set the lens to "A" = which can be a bit tricky
4) If K, you'll have to use the aperture ring and manual stop down metering

The K / k/a mounts tend to be a bit fiddly, you have to make sure the 'ears' of the mount fit the slots on the lens... but you probably know that.

[stevebrot]

A few questions:

1) What adaptall mount do you have? PK/A (with the electrical contact) is the only one that will work like an "A" lens. The PK version works like a "K" or "M" lens (wide open in AV, green button metering in M mode).

2) If you are using PK/A mount, can you actuate the diaphragm with the lens off the camera by flicking the lever? The reason I ask is that I have seen adaptall mounts where the mechanism jams when mounted on the lens (i.e. defective mount).

3) Is the mount properly attached to the camera with both "tabs" seated in their indents on the lens?

Steve

[stevebrot]

Nesster beat me by 1 minute!!

[Levi]

It is a K/A mount (with contacts)
And the tabs are locked in the appropriate locations.
I guess that means it's the mount that's screwed up.
I'll monkey around with it and see if I can make it work.
I'm sure I could turn it into a manual only/stopdown metering lens, But it would be nice if I could make it fully functional.
Levi

[Mike.P®]

I have a Tamron 90mm F2/8 that uses the Adaptall 2 pka mount and it was doing the same thing when I first got it.
What I had to do was scratch away slightly at one of the screws on the pka mount as apparently there is a problem sometimes with one of the contacts.

Problem with Tamron adaptall mount: Pentax SLR Talk Forum: Digital Photography Review

[Levi]

Ok,
It works now,
but I'm not sure that I did anything to fix it.
One small but interesting note:
the lens is and F1:2.5, and the camera registers an f1:2.4 as the max. aperature

[Nesster]

Mine does that too.

[Blue]

Do you have the 52B or 52bb? I have one of each. I have the matching extension tube 18F for the 52B which makes it 1:1 and does not loose much in F stops. I have the 0F1 2x converter that I use with the 52bb which makes it a 180mm 1:1. For now I only have the P/k adapter and am looking for a pka but the prices are rediculous on them. I really like thes lenses.