takumar focus

[alacant]

Hi everyone. I'm having difficulties knowing whether I have hit infinity focus on a takumar 200mm attached to a modified canon. With other m42 lenses I can focus a little way beyond infinity before I hit the stop, just like on a telescope and so reach focus the same way. With the takumar however, I can focus to what looks like infinity and a tiny bit to what looks like past infinity. Turning down from close focus on Vega, the diminishing circle snaps to a hexagon (the shutter blades) and then continues a tiny fraction of a turn afterwards into the hexagon with a turbulent red halo. Without being able to go either side of focus, I'm not sure I have infinity. The results look OK but I'm wondering if I can get the stars sharper. I've no other 200mm lens shots to compare with so any comments or tips would be most welcome. TIA.

the lens   a raw   processed

[Davey-T]

Are you using a low profile adapter ?

The 200mm SMC Takumer back focus can be adjusted, there was a how to do video on Y'Tube.

Gina has some   so she may be able to help.

Dave

[MattJenko]

I have adjusted my 200mm super takumar and it is quite easy. There are 3 grub screws about half way along the main focus grip ring which you can loosen which releases the focus grip from the lens and you can retighten a quarter turn further round which gives you an extra bit of space to focus past the infinity point. Mine would not quite come to infinity at all when attached to my Canon, but now it goes a fair bit past, allowing me to fiddle until I am happy with the focus.

[alacant]

1 hour ago, MattJenko said:

3 grub screws about half way along the main focus grip

Excellent tip. I can now go either side of infinity. Thanks.

[michaelmorris]

Thanks for the tip about the grub screws. I use test shots with a bahtinov mask (on a very bright star) to get best focus with my Takumar 200mm.