Tuesday, 12 August 2008

Provia v 160ProS

Comparisons are often sought between slide and negative film perhaps especially for landscape photographers. Personally for quite some years I'd mainly tended towards slide for making my "good work" and used negative for snapshots. Just recently I decided to stop speculating and just load both into my film holders and toddle out to see what I could see. I went to a local waterfall and took this image set.

I decided to make the experiment "even" by having the exposures set the same, and alter nothing except which film I exposed. For interest the lens was a Fujinon 90mm f8 and I set it to f16 for the images. I exposed both on the same shutter speed (which means that the negative got a little more exposure than rated as its 160 and the Provia is 100). The Provia looked beautiful as soon as I saw it at the lab (although I as I expected the shadow in the lower left was annoying). The day was generally fine with some fast moving small clouds (I'm on the edge of a plateau here with the altitude being 900Meters or so).

Anyway, to the images, clearly the two scan differently, as you can see from the image at left. I scanned both with my scanner software (epsons scanning software) with all settings to linear both in slide and negative. Clearly the scanner is doing some mask removal there for me). Anwyay, after setting black and white points, I've left them basically as they came out of the scanner.

Now, looking at the images to the left the first thing that strikes (and struk me at the time) was that there is some differences in colour cast between them. Given the nature of the two media (slide being clear and negative having many and varied shades of orange mask to remove) I think they're remarkably similar.

Below is a detail segment screen snapshot of an area in direct sunlight, with some (not very deep) shadows to see if there was much difference.

Looking at these images on my scanner when I first scanned them I found that while there was grain visible on the negative, it seemed sharper to me. I was certainly not expecting that! So I scanned the provia again and it was the same. I've put two segments below. Check out the definition of the railing and the tree tops against the sky.

First the overview showing where the sample was taken:

then the samples:

Provia 1200 dpi segment

Pro160S 1200dpi segment

Now, what's going on here? I don't know, but I'd sure like to. So I started looking at other scans I'd made on this and other scanners (also looking at 35mm film which has sharper lenses {in theory} per mm of film ) and I found the same "look" here appearing on all of the slides. A sort of softness when at the limits of the scanners ability. I didn't have other side by sides to make clear cut comparisons, but it seemed to me that this same 'difference' above was appearing in my images.

So, looking at other images I've scanned it seems to back up this finding.

So this leads me to ask why?

I've got a few theories which I'm tossing around, but I don't know why the negative just looks sharper! One thing which comes to mind is something called the callier effect. Now, normally this is something which is more associated with enlargers. My thoughts are something like this. Perhaps there is something causing scattering of the light which is greater in the slide than in the negative. If this was so it may look like this. Also this would be perhaps observably greater with flatbeds (where the sensor is further away and influenced more from side sourced scatter light) than on a drum scanner (where there is only one sensor)? I sure don't know but its an interesting observation for me. When I get the chance I'd love to get both these drum scanned and make the comparison that way.

Anyway, the result of this (and me looking at my scans) was enough to tip me more towards using negative than positive from now on.

Moving onto the 'colour rendition' I thought that I'd put up my digital reference. This was taken with a 10D using RAW, and was the light metering that I used for all the exposures. The image below is a straight conversion from the RAW with no gamma or curves applied.

At first it looks to me that its between both of these. Sadly there was not a cloud in sight on this image, but forgetting the sky, the rocks water and greens of the foliage look more like the negative to me than the slide. Your interpretation (and monitor) may vary. I've placed below a version of the above with a bit more contrast added.

So, three photographs, and three colour versions. People say that the DSLR's are very neurtral in colour responce, so if that's true then both the films above are "out" by some margin, so this means if you're using a slide as a colour reference for your negative you'd better have a well colour balanced light table to view it, and have your monitor set up well for your photoshop work.

Personally I feel that from here it all comes down to taste, this is after all a pleasing art rather than the scientific application of colorimetry.



Charles Maclauchlan said...

I am a negative film user (Portra is my choice). I don't have any real information about sharpness but I do have an observation. With the costs / steps involved very few of us really immersed ourselves in color printing. This kept us at the mercy of the labs and I believe to to commonly held belief that negative film is OK for snapshots but "Serious" work requires slide film. With digital it's all software not chemicals and negative film has some advantages, not the least of which is the added range it has. I do like slide film but seriously...the sky isn't always brilliant purple now is it.

Slide film is a bit like digital in a way, they each compress the range and "Snap up" the saturation.

Also, although Epson software does do a pretty good job I have found that Silverfast has much truer profiles for negative film and has programmed differences for the various color films available.

Noons said...

Had a similar experience to yours. Started my scanning with Velvia. Progressed to Provia: less contrast, easier to get into the dark bits with my Epson.
Then tried 160S on advice from someone else.
Same observations as yours:a significant difference in sharpness.
So I more or less standardised on 160S.

Then I got hold of a 9000 and a coolscan V. And some new Astia. Fuji has quietly changed Astia to a much more "scannable" film. And they have now done the same to Velvia, both 50 and 100. And Superia 400, of all things!

Fuji has changed all of those to eliminate the "rough" emulsion side that caused some scanners with sharp lighting to lose definition. Andt hey also changed the thickness of the film, so it does not buckle as much and is easier to keep in perfect focus across the whole image.

It is surpsrising how much difference perfect focus in a scanner really makes. The DOF is not as big as the makers claim!

Anyways: if you get a chance, try out new Astia and Velvia 50, also some Superia 400 if you have use for a faster film. Worth a try with a film scanner, don't know if they'd make a big difference for a flatbed.

JaZ said...

I personally expose Provia 100F @160 ISO. Check out the analysys.