close focus on mount adapted lens

[rbrigham]

Hi

I picked up an interesting macro lens - the Katoptaron TS500 EM a 500mm macro
it has m42 mount and I've bought an m42-EF adaptor for it

its supposed to focus down to 2m but its more like 3.5M
infinity focus is fine
do you think that the adaptor is effecting close focus ?

I would of thought that it effect infinity if that were the case
I was thinking of buying a cheap extension tube set to see if I could bring close focus closer which would normally work

what dose anybody think

stay safe

robin

 

[Bud Hamblen]

If the adapter puts the lens slightly too close to the film or image sensor the lens won't focus on close objects as it should. You can still focus on distant objects. Or it could be that the lens is out of adjustment. This is a very strange lens if it's the one in this instruction leaflet: https://www.pacificrimcamera.com/rl/00914/00914.pdf

 

[rbrigham]

yes thats the one Bud
I'll try and move the camera further from the lens and see what happens

stay safe

robin

 

[Dennis S]

Sometimes those M-42 to EF adapters leaves the lens too far away from the mirror on the camera. I had to do a bit of experimenting but I found the ones that allow the lens to seat on the adapter not on the bottom of the thread mount are the best for my EF cameras. That works with my T thread adapter on a mirror lens I use.

 

[RalphLambrecht]

Hi

I picked up an interesting macro lens - the Katoptaron TS500 EM a 500mm macro
it has m42 mount and I've bought an m42-EF adaptor for it

its supposed to focus down to 2m but its more like 3.5M
infinity focus is fine
do you think that the adaptor is effecting close focus ?

I would of thought that it effect infinity if that were the case
I was thinking of buying a cheap extension tube set to see if I could bring close focus closer which would normally work

what dose anybody think

stay safe

robin

An extension tube should help.

 

[Petrochemist]

If I calculated it right using the thin lens formula that equates to about 0.55mm error which is roughly 1/10 the focusing movement available to the lens.
If infinity focus is at the right point on the scale the adapter shouldn't be out by this much.
If you can focus to infinity but it's NOT at the infinity mark then the adapter is short by roughly 0.5mm. A suitable shim can be made from a disc of metal/plastic/card of the right thickness that fits over the mounts thread & forces the lens to stop screwing into the adapter slightly further away.
I have had other adapters that have been short by similar distances but it is very unusual - The only one I've got was one for a 10mm lens where the error's effect was hugely magnified i needed to focus near the MFD to get infinity at all..