I have two ebay sourced m39 to m4/3 adapters and in general I've been satisfied with their quality in operation however, I'm starting to get nagging doubts about their precision.

I've noticed that with wider CV lenses (25mm and 35mm) that I quite often get some smudging down the left hand edge of the image - particularly in the bottom left corner. I'm inclined to think this may have something to do with the tolerance of the adapters (although both have exactly the same effect)

Before I even consider splashing out on either a Novoflex or Voigtlander LEM/MFT adapter (that I will couple with an M converter) I wondered if any here have intimate knowledge of either of these they would be happy to pass on.

I have a generic LTM--->u4/3 adapter and I don't know how it can introduce smudging. But I've read of some Leica RF type u4/3 adapters that have a baffle extension behind it which may or may not adversely affect the rear lens element.

My LTM adapter is machined from one piece metal and it focuses beyond infinity. I find this mildly irritating because I cannot rely on the distance scale on the lens when I want to work fast. With the M bayonet adapter, it can be adjusted with shims but not on a one piece LTM.

I see. I would say that the whole left half is affected. Do you have access to such a tool:
http://en.wikipedia.org/wiki/Vernier_calipers

So you suspect there may be a machining discrepancy from one side to the other?

It is either this, or your LTM lens has taken lots of damage.

Do you have access to such a tool:

The Vernier delivered some interesting results:

One adapter is more than a tenth of a mm thinner than the other - the other has a tenth difference from one side to the other. Have my eye on a Novoflex adapter on ebay at the moment....

The Vernier delivered some interesting results:
....the other has a tenth difference from one side to the other....

That can cause the smudging you illustrated....as an aside, older Barnack Leicas (I, II and III) had "soft bodies", so they used wax paper or very thin metal shims behind the lens flange mount to make sure it is mounted evenly on the body. The later IIIc, f, g and M had a cast alloy chassis which made this step superfluous.

Like I implied above, "shimming" can also be done on a generic M>u4/3 and then use an M>LTM adapter for screw mount lenses. A "tweakablity" not possible from a one piece milled LTM>u4/3 which relies solely on precision machining.

I've read some problems with early Novoflex u4/3 adapters, hopefully resolved by now.....so this is just a suggestion that may save you some bucks.....

Quote

has a tenth difference from one side to the other.

This should not make such a visible difference. Are you sure there are no shiny surfaces inside the adapter?
And also, are you sure there is not too much play when mounted on your PEN?

Well - finally found the time to chase up some brass shim material and it seems the small differences do have a profound effect on focus range and consistency. Using a 0.3mm shim on the 'thin' adapter means I can't hit infinity whilst a 0.2mm still leaves me slightly short - but significant that both deliver a better 'corner-to-corner' result in terms of even sharpness of detail. (unfortunately I don't have any 0.25mm sheet material handy to try that out)

Don't have time to pursue this further over the next week but will leave the 0.2 shim on and post results here when I get the chance but suffice to say that the cheap adapters offered on ebay are definitely not all they are cracked up to be...the 'official' CV version may be 6x the price but might be worth it.

EDITED - I have added a couple of crops to the gallery to show the difference but both are an improvement on the situation before adding shims.

Well - finally found the time to chase up some brass shim material and it seems the small differences do have a profound effect on focus range and consistency. Using a 0.3mm shim on the 'thin' adapter means I can't hit infinity whilst a 0.2mm still leaves me slightly short - but significant that both deliver a better 'corner-to-corner' result in terms of even sharpness of detail. (unfortunately I don't have any 0.25mm sheet material handy to try that out)

Don't have time to pursue this further over the next week but will leave the 0.2 shim on and post results here when I get the chance but suffice to say that the cheap adapters offered on ebay are definitely not all they are cracked up to be...the 'official' CV version may be 6x the price but might be worth it.

I have added a couple of crops to the gallery to show the difference but both are an improvement on the situation before adding shims.

Saw your samples with the CV25/4....maybe that's as good as it gets given that it is an adapted legacy lens. Keep in mind that there are people who actually dismiss the use of legacy lenses wider than a 35mm focal length adapted to a u4/3 body due to telecentricty....hope I understood that well?

I've noticed smeared corners using the CV21/4 and CV15/4.5 + modified M>u4/3 adapter on my E-P1, but as long as they are even.....I'm happy.

I see very little difference,

Sorry adash - not very clear from what I posted.

The main point is that both shims delivered an improvement on the adapter. The skewed focus I mentioned earlier is down to one of the two that has an 'inset' that has the screw thread held in by grub screws; this wasn't set right so the lens plane wasn't even parallel.

The other I've made the shims for is a solid block and machined OK - but just too thin - so infinity was actually reached between the 3 and 6 meter mark on the scale. I have no problem with field curvature in wide lenses - I would expect it - but it needs to be even and the physical scale needs to read right. This was not achieved with either of the cheap adapters which makes them actually a bad buy in my book.

I have now got a Voigtlander (M) version on the way for about half list price so I'll see if that works.

Finally found a reasonably priced Voigtlander M adapter on ebay and that has cured all problems...

Much better corner to corner performance, lenses line up properly on camera (scale at top centre) and read as they should up to infinity.

Now a happy chappy....no messing about with shims.