LTM Summaron 3.5 cm lens tests #1 (follow-up)

[ironringer]

Advertisement (gone after registration)

In follow-up to my April-May thread about "which M adapter to use with a screwmount Summaron 3.5 cm", I now can share scanned negatives from tests I made recently, with Kodak 400TMAX film, using:

a) a borrowed LTM Summaron 3.5 cm s/n 752525 from 1949 (with some issues, see below);

my newly serviced LTM Summaron 3.5 cm s/n 1060111 from 1953 (all optical elements cleaned by Youxin Ye, who works near Boston, USA).

I first tested the borrowed Summaron, that upon inspection showed internal fungus (I think?) inside the rear element, quite visible (see attached pictures).

I attach two reduced-size scans from pictures of a brick wall in shade (my test grid), about 35 feet away, taken at f3.5 and f4, using a tripod and shutter release cable.

The reduced size files, and ISO400 film grain, unfortunately affect our examination of results.

However my initial conclusions are:

1. The large patch of fungus in the lens does not seem to show up in the pictures.

2. Vignetting is visible on the sides and corners - obviously darker than the center, but acceptable for a 60+ year old lens.

3. Resolution-Sharpness: even "wide open" at f3.5 and f4, the focus/sharpness at the edges and corners is (apparently) almost as good as its center performance. I see some difference of sharpness (edge vs center) in the original 6 MB scan files, but not much (probably disguised by the film grain).

4. Overall lens performance (sharpness, contrast) is Fair to Good, certainly adequate for good pictures using film (as the lens was designed for).

5. I believe this lens shows better edge sharpness than the Summaron I had tried in Berlin. HOWEVER comparing resolution of digital files from an M9, versus negative scans of ISO400 film, is not an equal process.

I can send the full-size scan files to others who may wish to review them. I am sure that the negatives scanning process "corrects" for exposure differences, but review of the original film negatives shows they are all properly exposed.

Later this week I will post more tests of this "fungus Summaron" with a real-world scene (not a test grid of a brick wall).

All comments and suggestions are welcome.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[cobbu2]

Interesting, thanks for the post! I'm considering this lens to use as the primary for a Leica Standard Model E I just recently acquired. Very timely indeed! Cheers, Allan

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[ironringer]

Good to discuss with a viewer and future Summaron user.

Looking again at these initial test pictures (with the "fungus Summaron") shot at f3.5 and f4 (I'm not sure which is which, because unfortunately the file names are not retained when they get absorbed into the Forum), the "vignetting" at the upper right may be the darkening effect of the fungus growth in this lens. Other test pictures at f5.6 and f8 show very little vignetting and slightly sharper edges and corners.

Attached here are 3 more test pictures (identified) using Kodak 400TMAX film, taken with the "fungus Summaron", at f3.5, f4, and f5.6, of a nearby bay (a real world scene), at infinity focus, using a tripod and shutter cable release at 1/1000 and 1/500 speeds.

As we see, the "vignetting" (or fungus darkening?) starts to improve at f4, and further improves at f5.6. Examination of the full-size scans of negatives also shows improved sharpness and detail (e.g. tree branches) at the edges and corners, as the lens is stopped down from wide-open to f5.6 and smaller apertures.

Overall even this "fungus Summaron" shows Fair to Good performance (sharpness, contrast) that improves toward f5.6 and smaller apertures. Pretty good for a 60-year-old lens that has internal problems.

I realise that reviewing these reduced-size scans of the actual negatives does not show the REAL picture, but the trends are easy to see.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[jc_braconi]

Page 139 of the Leica Pocket book 8th Edition I can read :

Vignetting is 1.6 stops,and there is no distortion. The lens is a very fine performer and would be rated as very good even according to todays standards. Overall contrast is medium to high and the central definition is quite high, bringing with fine details with clarity.

The zonal areas and the corners are of low contrast and finer detail is recorded with some softness and there is some astigmatism.

Best aperture is 5.6 where excellent image quality is delivered.

 

IMHO it will be wise, if there are fungus in this lens, to have it cleaned or segregated from the other lens you can have.

[cobbu2]

Very useful information and also quite reassuring to see that despite some flaws (not extreme), the Summaron is still a great performer. It's nice to see actual results and is good to know when I finally get around to making a purchase decision. Thanks again! Cheers, Allan