Lens Comparison Tests

[OldBikerPete]

I thought you guys might be interested in a little comparison I recently performed.
I printed a couple of copies of the USAF 1951 Optical test target on a laser printer at A4 size then photographed them from a distance equal to 50 times the focal length of the lens in use. The targets were placed so that one was in the centre and one about 90% out along the diagonal towards one corner. The film in use was 5x4 PORTRA 160 (because that's all I have). I then developed the film and examined the negatives with a microscope. Resolution was calculated from the smallest test element which could just be seen to be composed of alternate dark and light bars.
All of the exposures were on a tripod-mounted Wista 5x4 and the lenses were set at F/11 @ 1/30 or 1/50sec. The targets were placed on a flat surface and the lens was focussed on the centre target. It is probable that the edge values may be degraded due to curvature of field of the lenses.
Schneider Xenar f/4.5 210mm Centre 27 lp/mm Edge 3 lp/mm
Schneider Xenar f/4.5 135mm Centre 47 lp/mm Edge 8 lp/mm
Schneider Symmar-S f/5.6 135mm Centre 47 lp/mm Edge 17 lp/mm
Nikkor-W f/5.6 135mm Centre 53 lp/mm Edge 38 lp/mm
All the Schneider lenses were the older, single-coated variety.

 

[Ray Heath]

g'day Pete

so, for a non technical type, what are your conclusions?

 

[OldBikerPete]

I performed the tests so that I could choose which 135mm lens to keep and because 4 negatives is a neater number for me, I shot the Xenar 210 as well. I know that the xenars resolution falls away from the centre and that they have a curved surface of focus, although I expected their edge performace to be better at f/11 that it was. I chose f/11 because I shoot landscapes and because diffraction effects could be expected to be small at this aperture.
An anecdote which was not part of the test results is that the Symmar-S was visibly darker on the ground glass than all the other lenses. The fact that the f/5.6 Nikkor-W seemed as bright as the f/4.5 Xenars is impressive.
In general the results show that the Nikkor-W 135 is better than the Symmar-S 135 is better than the Xenar 135 is better than the Xenar 210.
Mind you I have taken shots with both Xenars and the Symmar-S and enlarged them to about 28" x 32" in which size they appeared very sharp indeed.

 

[Mick Fagan]

So Pete, which el cheapo 135 are you going to offload to me?

Mick.

 

[OldBikerPete]

So Pete, which el cheapo 135 are you going to offload to me?

Mick.

I could let you have either the Xenar 135 or the Symmar-S 135 (or both) at an exhorbitant price- I gotta get a decent 90mm lens to replace my Optar 90mm f/6.8.