How sharp is your scan ?

The object of this review is perhaps not the most enthralling I’ve ever covered. It is, to be exact, an exposed piece of film, a piece of positive “slide” Agfa film in fact. It isn’t even in colour. It is in fact a Resolution Target (USAF 1951), produced by LaserSoft Imaging. You can read all about it here.

There was a special off on these a few weeks back - they quite often happen - and so it was quite a handy retail therapy opportunity. But apart from feeding the inner consumer, you may well ask “what is the point” ?

Resolution Target (USAF 1951)

Well, there are two points. The first is perhaps the most initially compelling, as it gives you a standard reference target with which, following the detailed instructions, you can determine the actual optical resolution of your scanner. This then gives a warm fuzzy feeling and bragging rights over all your scanner owning friends (or of course it might leave you feeling extremely depressed).

Unless you own hundreds of scanners, that’s pretty much the end of it. I own two, so I was kept happily entertained for over 5 minutes!  But, actually, it isn’t the end of it all, because as the instructions explain, there is something else you can use this target for, which turns out to be very enlightening.

The second use is to experiment with different scanner sharpening settings to determine what the optimum settings are. This was quite an eye-opener. I’d always tended to leave sharpening to Photoshop, and some mumbo-jumbo laden plug-in, as I’m too lazy or stupid to really get the details of all this radius, strength and masking stuff. Using the target in conjunction with Silverfast’s USM tool allowed me to quickly determine the best settings for restoring sharpness lost in the scanning process, without overdoing things. It also revealed that the adaptive “Auto Sharpness” mode in USM actually does a pretty good job.  By way of illustration, if I used USM, I tended (for no really good reason) to keep Power in a range of around 100-150. Auto Sharpness, for a full resolution positive 6x9 MF scan set Power at 300 - it goes up to 500. Zooming in at 1:1, it was clear that 100 was too weak, and 300 was not introducing any artefacts. I don’t know yet if this means I’ll switch to Silverfast USM for capture sharpening, but this experience certainly boosts my confidence in it, and it would be quite a time saver over doing it in Photoshop.

So, if you are interested, one, in seeing how much resolution your scanner actually delivers, and two, making the most of that resolution, this Silverfast Resolution Target (USAF 1951) is a good investment. I’m sure it would be equally useful for Vuescan users, there is nothing that ties it to Silverfast software.

Oh, and my results ? 4096 dpi real optical resolution for the Plustek Opticfilm 120, which while less than the advertised 5300 dpi, is pretty much as good as it gets for desktop film scanners. The revered Nikon Coolscan 8000 / 9000 reputedly do hit their advertised 4000 dpi. And apparently, the Opticfilm 120 could do even better with some way of fine tuning focus.  Anyway, 4096 dpi is quite enough for 35mm and 120 film, and this test confirms what I could see subjectively, comparing with scans from my old Minolta Dual Scan Multi Pro.

My Canon 9000F only managed 2048 dpi, less than half the advertised 4800, but that’s pretty much what I expected.