It has now been a little more than a month since I received my new Hasselblad H6D-100c and I have got to test it out properly, at least in the field. One of the things I was most curious about was how my lenses performed on this new, physically larger sensor.
Most H-system lenses (denoted HC) were designed for full frame medium-format which corresponds to medium format 120 film. Often called 645, referring to the full size of the film of 6×4.5 cm, the true image area of the film most often is around 42x55mm. Thus, the HC-lenses image circle covers this area and are designed to be sharp in the edges and don’t make too much vignetting even on a sensor this size. However, more recent H-series lenses were made to work optimally for a slightly smaller sensor (37x49mm) that was widely used in the early days of digital medium format. These lenses, (denoted HCD), makes a slightly smaller image-circle than the HC-lenses and are the 24mm, 28mm and the 35-90 zoom. I own, and have grown to be very fond of, the hcd 28 and the hcd 35-90. Little has been known about how these HCD-lenses performed on the new full-frame sensor, and concerns have been raised regarding both sharpness and vignetting.
So, I have now tested my new full-frame H6D-100c with the HCD 28 and the HCD35-90. Basically I am happy with the results. The short message is that the there is no real cut-off of the corners. The vignetting is pretty significant, but easily corrected in both Phocus and Lightroom. Sharpness is good but not excellent in extreme corners, but very good in corners. As a landscape-photographer, the sharpness and vignetting does not represent any problem at all in most real-life situations as long as software profile-correction is used. However, this is just my opinion. You can have a look at the images below and judge for yourself.
All images are taken from a tripod, mirror lock-up, manual focus in live-view. Iso 64. Daylight temperature. Aperture as denoted and shutter-times from approximately 0.5-2 sec. Images are processed in Lightroom, raw-conversion only, no raw-sharpening, no other corrections. Standard lightroom lens-profile correction where this is noted. Images are not cropped and are all 11600×8700 pixels. Exported as 3000×3000 max quality jpgs with medium output-sharpening for screen. The lightsource is a huge window with slightly overcast daylight from the left. I wish I could have found a scene more evenly lit by daylight, but that is not very easy in Norway this time of year…
To summarize, I would say that vignetting is not a significant problem as long as you use profile correction. I have tried out both Phocus and Lightroom. Phocus does a slightly better job, with a little bit more evened-out result after my taste, but nothing that will make me change my standard workflow from Ligthroom. The only concern is on severly underexposed images (more than 2-3 stops) at iso 1600 and upwards, where I have found that the vignette correction may give some slight color noise (not shown here). This is not unexpected at all, but should be known when shooting with these lenses on very high iso. Regarding sharpness, I am happy with the HCD 28, at least from f8 and upwards where I usually shoot (f 11 – 16 is my go-to aperture on these lenses). The sharpness in extreme corners using the HCD 35-90 @35 is somewhat compromised at f8. It is better at longer focal lenghts and good in the not-so-very extreme corners. I know my lens has a slight issue from f8 and wider on close distance of the upper left, but this is very rarely a concern as I mostly shoot landscapes on longer distances and wider apertures.
I have also done some testing using filters, both a regular UV-filter that I use for my Lee 100mm push-on holder and a slim polarizer from Nisi. I will try to process and post these images sometime during next week.
Hope you found this helpful. Let me know if there are any specific tests you want me to do, and I will try to make room for it within a week or two.