Would older lenses benefit from 6-bit coding of similar newer lenses?

[colorflow]

Please point me to the right thread if this has already been discussed.

I have a number of older Leica lenses which are not included on the list of coded lenses. These include Lux 35 11870, Lux 50 11114, Cron 35 8 element, Elmarit 90 11129, and Cron 90 11023. Would they benefit by coding them with codes of similar later lenses?

Thanks,
Alan

[carstenw]

Some do benefit. The ones which have been tested and known to benefit are listed in the table in my signature. There aren't many so far. You can try coding the lenses with a black marker, as described on the same page, and test the lenses. You need to shoot a completely evenly lit white wall, for example, and check out vignetting before and after. The articles found on Sean Reid's site show examples. Note that this is a pay-site. Well worth it though, and there are many subscribers here.

http://www.reidreviews.com/

[sean_reid]

Thanks Carsten. What I'm finding, as a rule of thumb, is the following. If a lens A vignettes as much as, or more than, modern Leica lens B (that a given code is designed for) then A will likely benefit from coding as B. The cyan drift (red vignetting) correction will likely be most strongly associated with focal length/field of view although not all lenses of the same focal length show the same cyan drift patterns.

I'll know more when I can start testing lenses using firmware 1.10 (which should be able to correct for the cyan vignetting caused by 486 filters on wide lenses) but as of now, I have yet to come across a lens that didn't benefit from being hand-coded. A given lens may not be corrected as completely as the intended lens (say, a 24/2.8 Elmarit Aspherical) but it will almost always show less vignetting and less cyan drift.

The tricky one, so far, has been 28 Ultron because it vignettes less at F/8 than either of the current Leica 28s.

Cheers,

Sean

[colorflow]

Thanks Sean and Carsten, I am having great fun coding these lenses. Am having trouble with my 28mm Cron ASPH which keeps showing up as 35mm. Also it appears that I need to shift the template for some lenses but not for others. I am havinh so much fun and wish there are more hours in the day.

Alan

[scho]

Originally Posted by sean_reid

The tricky one, so far, has been 28 Ultron because it vignettes less at F/8 than either of the current Leica 28s.

Cheers,

Sean

Sean,

Would you recommend using the Ultron un-coded when using a 486 filter for color landscape work (eg. stopped down to f/8 - f/11)?

Carl

[sean_reid]

Carl,

That's a great question and I think I could go either way on that lens. I'd suggest trying it uncoded first (with the filter) and see if the cyan drift is noticeable or problematic for your work. If so, maybe you'd want to code it and then develop an action in Photoshop that darkens the corners of the files just a touch. That lens is really impressive with respect to vignetting.

Or...you could code it and then turn off the lens recognition when desired. You could try some A/B comparisons with that feature on and off and see what you think.

Cheers,

Sean

[jaapv]

There is an interesting thing - code a ZI 21 Biogon and it won't be recognised because it brings on the wrong framelines. Push the selector lever: bingo. On a coded Leica lens: push the lever: recognition gone. Might be nice in B&W to induce some vignetting. Sean: Why does Leica recommend turning lens recognition off for uncoded lenses? I have yet to see any adverse effect from not doing so.

[sean_reid]

Originally Posted by jaapv

There is an interesting thing - code a ZI 21 Biogon and it won't be recognised because it brings on the wrong framelines. Push the selector lever: bingo. On a coded Leica lens: push the lever: recognition gone. Might be nice in B&W to induce some vignetting. Sean: Why does Leica recommend turning lens recognition off for uncoded lenses? I have yet to see any adverse effect from not doing so.

Hi Jaap,

No idea...I leave it on almost all the time.

Cheers,

Sean

[carstenw]

Jaap and Sean, with lenses with screws or cutouts over the lens-sensor, it is conceivable that it would pick up a black field somewhere, thus choosing some false lens and applying wrong corrections. It would have to be quite a coincidence, as the framelines would have to be right for that lens, but it is possible.

[sean_reid]

Originally Posted by carstenw

Jaap and Sean, with lenses with screws or cutouts over the lens-sensor, it is conceivable that it would pick up a black field somewhere, thus choosing some false lens and applying wrong corrections. It would have to be quite a coincidence, as the framelines would have to be right for that lens, but it is possible.

Perhaps, but I've never seen it happen.

Cheers,

Sean

[carstenw]

Some report that the Zeiss 21 has this problem, I think. There is a screw there which sometimes gets detected as black, although it is meant to be white. I don't have this lens, so I can't confirm. I don't know which version either.