Fast (maximum aperture 2.8)
How is image quality at full aperture? Many fast lenses (either medium format, small frame or other formats) show at open aperture some weakness.
After a month in use, I can confidently say that the image quality of HD Pentax D-FA 645 2.8 / 90mm is already at full aperture at a very high level. It makes really fun to play with selective focus when you know that there is no quality loss in the final image.
However, at f/2.8 a significant vignetting occurs, but this can easily be corrected in any popular RAW converter or image editing software. Once an appropriate lens-profile from Pentax is available, it can even automatically be adjusted if desired.
Personally, I found the bokeh of the Pentax D FA 645 HD 2.8 / 90mm very pleasant, but this is a very subjective matter so please have a look yourself.
Up to four stops is the promise from Pentax. My experience of the last few weeks shows that this is basically correct, but you should consider the following points:
- You have to work patient and deliberate
- The closer the subject, the lesser the results. For macro photos the effect is practically zero
- Several attempts increase the chance of having a sharp image
The best picture of such a serie is then indeed quite sharp, but not razor-sharp as a photo that was shot with 1/1000 sec or even from a tripod.
Nevertheless, I think the stabilizer is very useful. It allows reasonably sharp images of subjects that would otherwise not have been possible anyway. One can see the effect in the viewfinder also very nice (if the option is enabled in the menu).
For real macro fans unfortunately some bad news from the start. The Pentax HD D-FA 645 2.8 / 90mm Macro ED AW SR has only a reproduction-scale of 1:2. “Real” macro lenses usually have 1:1. Honestly, I am not a specialist for macros, so for me a reproduction-scale of 1:2 is ok.
A word on the auto focus. The Single AF is quite accurate, but in my feel a little bit slow. As usual on macro lenses there is a switch implemented to limit the focus range. You can choose whether to focus only in the macro range (about 16-24 inch), only in the far-range (24 inch to infinity) or in the entire range.
The Continuous AF (C-mode) in my opinion is completely useless. This is, however, not the fault of the lens, but of the Pentax MF autofocus system generally. My advice is to focus manually if required, this will give you more sharp results.
Despite the addition “Macro” in the name I would primarily consider this lens as a brilliant all-rounder with a special qualification for portraiture.
It would be a shame to limit the use of this lens to a tripod. Handheld photography is not only possible but highly recommended. I had/have a lot of fun with this lens knowing, that wide open shots don’t cause a loss of IQ.
The combination of a large sensor with 40 MP, fast and light telephoto lens demands a very precise and deliberate work. Any small imprudence, eg deviation of the camera after focusing on the target, immediately causes a loss of image quality and sharpness. “Point and shoot” is not the way to get the best quality out of this lens.
If you find this little review interesting and/or if you are a Pentax-enthusiast, please also visit the blog travel67 of Chris Willson, a professional photographer in Japan. He published some mini-review of the new Pentax 90mm lens as well.
I hope you enjoy this little review. If you like (or even if you dislike…) please leave a comment.