Help me with a possible lens issue

[wastedimages]

I have a Carl Zeiss Jena 40mm F4.5 from the mid 50's that arrived last week that I took for a test today.
It seems to have an issue with mid to long range shots with pretty much anything past around 15-20ft being very soft.

If we look at the closer stuff first - all shots were taken at F8



From about 8ft away



This one above was at about 12ft away

All looks OK to me.

Now we look at some stuff further away

[ATTACH alt="I was hitting infinity on the focus and my lens scale was telling me that anything from 12ft to infinity should be "acceptably" sharp which it isn't"]3699740[/ATTACH]
I was hitting infinity on the focus and my lens scale was telling me that anything from 12ft to infinity should be "acceptably" sharp which it isn't

Another shot again with focus ring hitting infinity



I know it is an older lens, but these are way softer than I was expecting. I don't think it is the adapter as Im getting the same results with my other M42 adapter as well, and my Pentax 135 is fine with the same adapter. So is my Biotar 58/2 which is sharp at infinity

How can I test this to prove if I have a bad copy of the lens? What is the best method - I don't have test charts and I only have a couple of days before I need to return to sender if there is an issue.

I also want to rule out anything that could be me making a silly mistake, but I (obviously) don't think I am as I have been happily shooting my Zeiss 58/2, Pentax 30/2.8 and Revuenon 58/1.2 without any issues these past few weeks

I can do some more tests at lunch tomorrow if needed

 

[Bosun Higgs]

In that last shot your focus is well short of inifinty.

It could something as simple as an inifinity stop screw set too close, or something more sinister. In any event, it looks likely that the lens has been monkeyed with.

As a crude test you could simply hold the lens closer to the camera while freelensing. If you get sharper distance shots like this, then your infinity setting is off.

 

[SimonOL]

I have a Carl Zeiss Jena 40mm F4.5 from the mid 50's that arrived last week that I took for a test today.
It seems to have an issue with mid to long range shots with pretty much anything past around 15-20ft being very soft.





I know it is an older lens, but these are way softer than I was expecting. I don't think it is the adapter as Im getting the same results with my other M42 adapter as well, and my Pentax 135 is fine with the same adapter. So is my Biotar 58/2 which is sharp at infinity

How can I test this to prove if I have a bad copy of the lens? What is the best method - I don't have test charts and I only have a couple of days before I need to return to sender if there is an issue.

I think the shot above clearly shows the your lens has a problem. No further testing necessary really.

If you explain that you have other M42 lenses which work AOK on your adapter but this lens cannot focus beyond 20ft or so (guesstimate) and send them this image, it says it all.

Unless you're happy taking the lens apart, I wouldn't start trying to repair unless there's a very obvious simple problem or you're really atttached to that particular lens.

I also want to rule out anything that could be me making a silly mistake, but I (obviously) don't think I am as I have been happily shooting my Zeiss 58/2, Pentax 30/2.8 and Revuenon 58/1.2 without any issues these past few weeks
I can do some more tests at lunch tomorrow if needed

 

[wastedimages]

Ok, that has settled it in my mind. There is no way I'm trying to fix it so I will contact the seller and send it back