LTM-M adapter focussing issues on M9.

[travellingcello]

Hi all,

I wonder if anybody has any thoughts on my problem - I should say that I am relatively new to rangefinder photography.

I recently found a good deal on a used M9 and have mounted my Canon 50mm 1.4 LTM lens onto it with a knock-off LTM-M adapter.

It focuses fine to infinity and doesn't go past it either. It even lines up at 12 o'clock but I have problems getting it to focus accurately at close-ish focus.

I have figured that if I line up the patch 'accurately' at wide apertures, then I consistently get 'front focus' so at the moment I am compensating for shots under f2.8 for this issue.

I should say that I get the same issue with my Jupiter-8 and Voigtlander 75mm 2.5 too, although less so with the 75mm.

Is it possible that the adapter is fine at infinity but somehow not okay at close distances? Or is my rangefinder mechanism on the M9 itself in need of adjustment ? Or is this what is called focus shift?

Thanks for your help in advance!!



edit: I should say that the frame lines don't really show up properly with the 75mm attached and half shows properly with the Canon on too, even though the adapter says 50/75 on it...

 

[Scrambler]

I wonder how you would detect a small amount of front focus at infinity? One possible explanation is that the adapter is slightly too thick and everything is front focusing but DOF covers it at larger distances.

 

[hepcat]

Before I tried anything else, I think I'd spring for a better LTM-M adapter and see what happens.

 

[jaapv]

Get a voigtlander adapter. These el-cheapo ones are well known for being inaccurate.

 

[Gary Sandhu]

Take a focused photo of measuring tape lying perpendicular to the body of the camera; aperture wide open (say, you focus on the 100cm mark). Stop down and examine the best plane of focus at smaller and smaller apertures. if the focus shifts sufficiently so that the 100cm mark is not in focus at some apertures the you have demonstrated focus shift.
An ill fitting adapter may manifest as photos of a flat target with one or other side not in focus. You may not have infinity focus.

 

[stitchohana]

Im using the fotodiox adapter for my copy of canon 50mm LTM. Previously i see the 75mm frameline instead of 50mm. What i did was to unscrew the adapter from the lens and rescrew it. maybe you can try it out.

🙂

 

[travellingcello]

Thanks for your replies everyone!

Take a focused photo of measuring tape lying perpendicular to the body of the camera; aperture wide open (say, you focus on the 100cm mark). Stop down and examine the best plane of focus at smaller and smaller apertures. if the focus shifts sufficiently so that the 100cm mark is not in focus at some apertures the you have demonstrated focus shift.
An ill fitting adapter may manifest as photos of a flat target with one or other side not in focus. You may not have infinity focus.

I just tried this experiment and I've proven to myself once more that the adapter or lens is front focussing the target - at a distance of 120cm at f1.4 the focus is more than 3cm off on the tape measure.

I took 3 pictures each at apertures 1.4, 2, 2.8 and 4, resetting and focussing as best as I could each time. The results were consistently front focussed but then the focus point moved gradually until at f4 the target was at the centre of focus, or correct focus.

So I now know that not only do I have front focus, I have focus shift too.

So.... have I actually got any closer to working out where the problem is?

Clearly I need to try another adapter, but its harder than it sounds so source a good quality one without spending ridiculous amounts of money where I live at the moment!

Would a good conclusion be at this point that the lens does have focus shift but either the adapter or the lens is out too?

 

[Gary Sandhu]

Don't reset focus between changing apertures. Focus once at f1.4 only. Shifting best focus plane demonstrates focus shift.
The fact that your focus is inaccurate could mean your rangefinder or adapter is off. Try to get another native M mount that you know works to test on. Perhaps there's someone on your area? Or the person you bought the camera from? A helpful store? Or photo club?