F-mount 50 mm testing

[armand]

I'm doing some basic testing of few lenses that I have and thought I might as well share the results with you, maybe somebody will find this helpful.

The reason is because I took again my Nikon 50/1.8G and wide open it was just not sharp. I tested it against the ancient 50/1.8D which I have since the Nikon D50 days and Voigtlander 58/1.4 manual focus.

1) Lenses on the tripod, target about 2-2.5 m away. Part of my sharpness issue was at longer distances too but I didn't test it here.

2) This is more for center sharpness as the right upper corner is not exactly at the same distance as the center however in the smaller aperture settings that one would use for landscape it is well within the DOF so I'll still show some results.

3) each lens was first shot on live view autofocus except the Voigtlander of course where I just focused manually in liveview wide open, once. Then the lenses were shot with autofocus, the V was focused using the optical viewfinder and the focus indicators. I let the camera autofocus after each shot. The camera was a Nikon D750, I used the mirror delay at 2 sec, no MUP.


Some conclusions

50G
- has issues focusing wide open in autofocus, it might be a calibration issue. It sharpens ok by F2.8 and at F4 is quite sharp. The corners are not that good, they sharpen by F11/F16.

50D
- unexpected huge issues autofocusing in liveview, very soft compared with the regular autofocus, only by F11 it had good sharpness in the central area. Similar with the corners, only F16 was good
- good sharpness since wide open, including corners!

Voigt 58
- a little soft wide open, starts to sharpen nicely by F2.8. Significant visible vignetting wide open.
- corners are soft wide open, start to sharpen by 5.6 and are the best at F8/F11, soften a little by F16
- focusing using the optical viewfinder and focus indicators was as good as using liveview


Comparisons. I'm taking the best performance with each, meaning liveview autofocus for 50G, phase-detection autofocus for 50D, manual autofocus for Voigtlander 58

50G vs 50D

at 1.8
- center: the G has better contrast and is slightly sharper
- corners: the D has significantly better corners

at 2.8
- center: the D narrows the gap but I G is still a little better
- corners: not even close, the D is much better

at 8
- center: about the same, maybe a little more contrast on G; the G is colder than the D
- corners: again, no comparison, D is much better

at 11
- center: same
- corners: D much better


50D vs V58

at 2
-center: the V is sharper  and has better contrast, not a huge difference though
- corner: the 50D is better

at F8 through F16
- center: the V remains sharper and with better contrast, some of it might be related to the longer focal length
- corners: the 50D has better corners but the difference is smaller


Overall conclusions
- to my surprise the 50D is the better option here if you want corner sharpness and being the lightest I think is the best option for landscapes (from these lenses). Just use it at F8-F11 and you are good. For my samples is also the preferred option with autofocus unless I will be able to calibrate the 50G which is a little sharper and has more contrast wide open when focused properly
- the Voigtlander is a close second. Has the best center sharpness once you stop it a little, has the nicest bokeh wide open and the corners are very close to the 50D if you stop to F11

[armand]

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[Rob C]

I've got a Nikkor 1.8/50G too, as well as an old non-af 1.8/50 and the only reason I bought the af lens was because of poor sight these past few years.

It appears that the af version is good at distances from as close as it goes to perhaps fifty yards, but using af on subjects at infinity is dodgy: it can miss very badly, but then that sort of work isn't my thing. I've had two different 1.8/50mm Nikkors and both felt as if the front elements were in a loose fitting of some kind... they could be wobbled by hand, which didn't lend them much belief but, in practice, they both worked well enough. Those two manual lenses were bought a few years apart, the second only because having sold all my 35mm stuff to go totally 6x7, I had to begin from scratch when I realised my mistake.

My favourite, though, was the 2/50 Nikkor that I bought along with my new F back in the day. Shoulda kept it and not been seduced by that silly 1.8 number.

:-)

[fdisilvestro]

I would recommend to do the tests by manual focusing in live view for all lenses. The 50mm Nikon has noticeable focus shift at large apertures that might affect your results