EXCERPT page containing first few paragraphs. 2024-04-19 13:44:25
UA_SEARCH_BOT_compatible_botmozilla/5.0 applewebkit/537.36 (khtml, like gecko; compatible; claudebot/1.0; +claudebot@anthropic.com) @ 18.117.72.224
For full access, subscribe here. Or click title to login. 
Modulation Transfer Function (MTF)
The Sigma-supplied MTF chart indicates a lens with very good contrast wide open, indicating well-controlled aberrations. It’s not clear if MTF is computed or measured. Zeiss measures MTF and doesn’t ship a lens unless it meets specifications—computed MTF means that’s the best possible result, and real lenses might not perform as well.
The red lines are at 10 line pairs/mm and the green lines are at 30 line pairs/mm. The Sigma description states that the MTF chart is wide open (f/1.4), which is an outstanding MTF curve for an f/1.4 lens, and field shots do tend to confirm it. Compared to the Zeiss ZF 50/1.4 Planar MTF chart, the Sigma maintains notably higher contrast over much of the field at 10 lp/mm, a remarkable performance. Beyond that it’s hard to be sure; Sigma’s results may be computed (not measured) and are at 10/30 lp/mm vs 10/20/40 lp/mm for the Zeiss. Interpolating, fine detail MTF is probably a bit better with the Sigma at f/1.4.
Article continues for subscribers...
Diglloyd Advanced DSLR is by yearly subscription. Subscribe now for about 16 cents a day ($60/year).
BEST DEAL: get full access to ALL 8 PUBLICATIONS for about 75 cents a day!
Diglloyd DAP is DSLR-oriented, but also contains workflow and other topics. Much of the focus is on Canon and Nikon but also Pentax and Pentax medium format.
Special emphasis is placed on lens evaluation, focusing on Canon and Nikon and Sigma lenses, but with a few others like Rokinon/Samyang.
- Make better images by learning how to get the best results right away.
- Save money by choosing the right lens for your needs the first time, particularly some of the new Sigma Art lenses vs Nikon and Canon.
- Workflow discusses image organization, raw conversion and post processing. Many examples show processing parameters for direct insight into how the image was converted.
- Jaw-dropping image quality found nowhere else utilizing Retina-grade images up to full camera resolution, plus large crops [past 2 years or so].
- Real world examples with insights found nowhere else. Make sharper images just by understanding lens behavior you won’t read about elsewhere.
- Aperture series from wide open through stopped down, showing the full range of lens performance and bokeh.
- Optical quality analysis of field curvature, focus shift, sharpness, flare, distortion, and performance in the field.
Want a preview? Click on any page below to see an excerpt as well as extensive blog coverage, for example on Nikon or on Canon or on Pentax.
