Soligor 500mm c/d cat, T2 mount infinity problem

[fatdeeman]

Any ideas?

It has a Pentax k mount fitted which came with the lens and I'm pretty sure my pentax k to 4/3 adapter is fine because all my other lenses reach infinity.

It won't even get close! it won't focus past about 10 meters! Do you think it could be adjusted or is it more likely the t2 mount?

I also have a Soligor 350mm T2 that won't reach infinity either, could both of them really have come supplied with faulty mounts?

I don't know what else to think, it seems the only two lenses I have that won't reach infinity are both t2!

[visualopsins]

$10 T2 adapter for 4/3 camera will allow those lens to reach infinity on camera. Right now PK-4/3 adapter plus PK-T2 adapter length is too long, like extension tube, lens only can focus closer.

[fatdeeman]

I see!

So my chain of adapters is very slightly too thick, enough to disable infinity focus?

I always assumed that if I was using the correct adapters it wouldn't matter if I was using two in a chain because I can use my tamron adaptall lenses this way but I suppose it only takes 0.1 or 0.2mm to throw infinity out.

[visualopsins]

yes, too long adapter effect is closer focus.

something else to check is remove T2 adapter and hold lens onto PK adapter; if now infity focus, lenses are M42 not T2.

[fatdeeman]

I already tried taking off the t2 and putting an m42 adapter on the thread but it wouldn't fit so I'm pretty sure the pitch is different , looks like a cheap t2 to 4/3 adapter is the next step!

[Farside]

[fatdeeman]

Well after a moment of common sense I decided to try the lens on an old pentax body I had lying around and it wouldn't reach infinity on that either, I then replaced the pk mount with an m42 one and tried it on an old practika body and it still wouldn't reach infinity!

After some googling I found other reports of similar problems, all with the t2 version and not the fixed mount versions.

After some research I found a solution!


Like many lenses there is a screw that goes through the focus barrel and is designed to hit a limiter that stops it twisting past infinity at one extreme and past closest focus at the other.

What I did was undo the screw and turn the ring all the way until the lens separated into two parts. Inside the lens there are not one but two limiters, they are very close together so I simply removed the one that is supposed to stop the focus barrel at the infinity end.

I twisted the lens back together and put the screw back through the focus barrel and now the lens can go slightly past indicated infinity but the screw hits the remaining limiter before it reaches the end of the thread.

The result is that the lens now reaches infinity but the focus barrel still stops in exactly the right place at the close focus end!

I'm not sure what the problem was, I assume it was some kind of manufacturing defect but I'm not an expert on these things!