EXCERPT page containing first few paragraphs. 2019-08-24 16:36:48
UA_SEARCH_BOT_null @ 220.127.116.11
This page shows how the Pentax-A 120mm f/4 performs on the demanding mosaic target.
I took an immediate liking to the Pentax 120mm f/4. I used a loaner from a reader. It’s solidly built, and it uses an old-style focusing helicoid with plenty of “throw” for fine focus adjustments, all the way to 1:1 on a 44 X 33mm sensor.
I haven’t tried the autofocus FA version, but I doubt that it will compare favorably for manual focus, because AF lenses are usually a compromise in ergonomics, lacking a focusing helicoid.
Using the AF focus assist on the 645D consistently results in front focus and thus a blurred subject. This is true with the 120/4, and with other lenses I tried. Caution advised, and use of fine focus adjust feature might help (not yet tested).
For this test, I focused manually with 3 trials. Not all attempts were as good as the one shown here.
Article continues for subscribers...
Diglloyd Medium Format is by yearly subscription. Subscribe now for about 33 cents a day ($120/year).
BEST DEAL: get full access to ALL 8 PUBLICATIONS for only 68 cents a day ($249.95)!
These systems are hugely expensive, so make the right choice for your own needs (full frame vs medium format).
- In-depth lens evaluations covering behaviors not likely to be found anywhere else, based on real-world field shooting.
- How to configure menus and buttons and best operating practices, gotchas and how-to.
- Real world examples with insights found nowhere else. Make sharper images just by understanding lens and camera behaviors.
- Jaw-dropping image quality found nowhere else utilizing Retina-grade images up to 100 megapixels filling up to 5K display, plus large crops.
- 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.