Developing for older lenses

[Perks]

I recently developed a couple of rolls with my new to me summaron 35/3.
For the first roll I swapped lens mid roll and upon scanning noticed that the shots with the summaron were darker than those on the same roll taken with voigtlander 35/2.5 & 25/4.

I feel they were not just different in tone but appeared under exposed.

I was coincidently reducing development times on that day and did 2 rolls in a tank at 1min less than usual because i felt the negs i was was making were a bit thick (Hp5 @ 320 for 11min in d76, reduced to 10min)

So the reduced time worked great for the lenses I was used to but not so much for the summaron.

I am part way through scanning a roll shot in similar conditions processed for the full 11min and still feel they are a bit under cooked.

I will have to do the onvious thing and try for 12min, but has anyone else noticed this?

It appers most noticeable with skin tones in the shade rather than blocked up deep shadow , so I am somewhat confused.

Any advice or similar experiences appreciated.

 

[radi(c)al_cam]

I recently developed a couple of rolls with my new to me summaron 35/3.
For the first roll I swapped lens mid roll and upon scanning noticed that the shots with the summaron were darker than those on the same roll taken with voigtlander 35/2.5 & 25/4.

I feel they were not just different in tone but appeared under exposed. […]

I’d rather suspect that the Summaron’s aperture blades may be misaligned. Did you check that?

 

[Ko.Fe.]

I have no experience with Summaron 35/3. I used goggled Summaron 35 3.5 and just Summaron 35 3.5 for M mount. I have Jupiter 35 2.8 from fifties experience, twice. None of them required special developing, none gave darker images.
As it mentioned above, check the lens, maybe you are measuring for 3 while it is 3.5 🙂

 

[Perks]

Thats a good idea, but no. They open all the way and I shoukd have mentioned that's it's a metered M6