Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: spotmeter on December 11, 2014, 12:36:25 pm

Title: Zeiss Otus and Sigma Art MTF at all apertures
Post by: spotmeter on December 11, 2014, 12:36:25 pm
I have not been able to find MTF charts for these 50mm lenses, other than wide open, f2 and f4.

Since I usually shoot at smaller apertures, can anyone direct me to any tests of these two lenses across all apertures?

Thanks.
Title: Re: Zeiss Otus and Sigma Art MTF at all apertures
Post by: ErikKaffehr on December 11, 2014, 01:05:40 pm
Hi,

DxO-mark has data for all apertures. In general when stopping down beyond optimum aperture there will not be a lot of difference between lenses as diffraction is the limiting factor. To be more exact, you would meed to multiply MTF with the undiffracted lens with the MTF of diffraction, so a very good lens would have some advantage over a lesser lens even if stopped down.

MTF charts are no good comparison, unless the conditions are specified.

The DxO data seems to be both good and reliable, but they unfortunately are not very clear in the description of the methods used.

The main advantage of the Otus may be the almost total elimination of axial chromatic aberration at maximum aperture. That is nothing that would be obvious in the usual MTF curves.

Best regards
Erik


I have not been able to find MTF charts for these 50mm lenses, other than wide open, f2 and f4.

Since I usually shoot at smaller apertures, can anyone direct me to any tests of these two lenses across all apertures?

Thanks.
Title: Re: Zeiss Otus and Sigma Art MTF at all apertures
Post by: spotmeter on December 11, 2014, 01:12:05 pm
Erik,

Am not able to find data for all apertures on DxO Mark.

Could you send me a link?

Thanks.
Title: Re: Zeiss Otus and Sigma Art MTF at all apertures
Post by: ErikKaffehr on December 11, 2014, 01:26:10 pm
Hi,

This Otus and Sigma Art 55/1.4 tested on Canon 5DIII at DxO-mark.

Note that Otus has an advantage at f/1.4, they are very close at f5.6. The Otus stopped down to f/8 performs below the Sigma Art at f/5.6, both are very similar at f/16.

Unfortunately, the figure doesn't say what is exactly measured.

Best regards
Erik




Erik,

Am not able to find data for all apertures on DxO Mark.

Could you send me a link?

Thanks.
Title: Re: Zeiss Otus and Sigma Art MTF at all apertures
Post by: dwswager on December 11, 2014, 11:07:47 pm
I have not been able to find MTF charts for these 50mm lenses, other than wide open, f2 and f4.

Since I usually shoot at smaller apertures, can anyone direct me to any tests of these two lenses across all apertures?

Thanks.

Erik is right, once a lens get stopped down past about f/8 on a digital camera, diffraction takes over.

http://www.dxomark.com/Lenses/Compare/Side-by-side/Zeiss-Carl-Zeiss-Distagon-T-STAR-Otus-55mm-F14-ZF2-Nikon-on-Nikon-D800-versus-85mm-F1.4-EX-DG-HSM-Nikon-on-Nikon-D3X___1242_792_362_485 (http://www.dxomark.com/Lenses/Compare/Side-by-side/Zeiss-Carl-Zeiss-Distagon-T-STAR-Otus-55mm-F14-ZF2-Nikon-on-Nikon-D800-versus-85mm-F1.4-EX-DG-HSM-Nikon-on-Nikon-D3X___1242_792_362_485)

Go to the measurements tab and then select: Sharpness, Transmission, Distortion, Vignetting, or chromatic aberration  It will show the data at all apertures.