Fuji Acros - colour sensitivity and graininess and speed!

[Neil Grant]

I've read that this film has reduced blue sensitivity compared to conventional grain films like FP4. Does this mean I can do away with a yellow contrast filter and still get decent sky contrast? Also, I know the grain is mean to be very fine - would it be as fine as Pan F for example? Presumably 'metering speed' should be about half 'box speed', as with most b/w films.

thanks if you can help.

 

[MDR]

Fuji Acros is sold as panorthochromatic that means enhanced blue sensitivity compared to pure panfilms. Aerial/surveillance films and Kodak technical pan have enhanced red sensitivity e.g. Rollei Retro 400s, Superpan 200, Retro 80S Agfa Aviphot 200 & 400s and Ilford SFX.
E. I is often stated as E.I 80 so not quiet half speed, but the film works quiet well at box speed. It has different grain than Pan-F not necessarily less. The half speed thing is dependant on several factors one being the developer you use, another factor is your camera equipment and finally the enlarger and paper. The E.I. you use should be the result of careful testing and not because someone said so. The biggest advantage of Acros is it's reciprocity characteristics, no adjustment below 120sec exposure time necessary.

 

[flavio81]

Thanks MDR, i also thought Acros had MORE blue sensitivity to other films; at least that's what I see on my photgraphs.

Grain is the finest i've ever seen on a B/W film. I have not used Pan-F, however. Sharpness is also good.

However, nowadays i prefer ILFORD Delta 100 a bit more; Delta 100 has more natural spectral (color) response, and sometimes I think it has better tonality too, while the grain is still fine, although not as fine as with Acros.

 

[Simonh82]

I think Acros is not that dissimilar to other films. Fuji do call it Orthopanchromtaic, and people often say it has lower red sensitivity, rather than higher blue but I don't think either is really the case.

This link contains a useful chart compiled by APUG member Athiril https://www.flickr.com/photos/athiril/6107135683/. It shows the relative spectral sensitivity of a range of films, unfortunately it doesn't include Acros. This image is from the Fuji data sheet.

Comparing the two shows Acros has the same level of red sensitivity, or maybe a tiny shade under, as HP5 and Delta 100 which nobody talks about as having low red sensitivity. Some films have lower blue sensitivity than Acros but Tri-x and Plus-x look like they have similar or higher blue sensitivity so again, I don't think there is a big difference at that end of the spectrum.

Tmax 400 has slightly lower blue sensitivity and I've definitely noticed a slightly better separation of cloud and sky with it than other films but you would still benefit from a yellow filter.

 

[Neil Grant]

. "The E.I. you use should be the result of careful testing and not because someone said so. "

the half 'box speed' thing comes from years of experience with normal b/w films: FP4, PF, HP5. The shadows end up on a straighter part of the film's charactristic curve making for easier printing.

 

[Simonh82]

Also on the subject of graininess, I was printing some in MF (6x6) Acros recently and I really struggled to find focus, the grain was so fine. A 8.5"x8.5" print showed no visible grain even with your nose against it.

 

[DREW WILEY]

ACROS is definitively NOT regular panchromatic. It is classified as Orthopan. This classification is formally stated in the tech sheet and is readily apparent in the published spectral sensitivity chart if you are accustomed to comparing these kinds of things. Remember, what often appears to be only a minor difference at the extremes of the scale to a casual observer can have significant effects in the real world. For all practical purposes, it has less red sensitivity than pan films and slightly higher green sensitivity. This gives it about the same effect in daylight as using a light yellow-green filter on typical pan films. To me, this rendering looks more realistic, so it is one of my favorite films in the mountains. But you need to be careful to never use a red filter deeper than a 25. If you use something like a deep red 29, all it will do is chop off the lower part of the film curve, acting as neutral density. I expose ACROS at 50 and develop it in PMK, and have used it
in formats from 35mm to 8x10, though it tend to like it best in mid-range formats (120 to 4x5). Recently the sheet film version has gotten
quite expensive, and 8x10 is very hard to acquire in the US.

 

[DREW WILEY]

Some of their marketing literature refers to it as pan. And it is, kinda, because it is responsive to all colors of light, but curtails the red end
of the spectrum much more abruptly than what is generally classified as panchromatic. Anyone who works with this film much recognizes that
it is different. And it is not true ortho either, cause it sees some red. The only other orthopan film I'm aware of is the recently discontinued Efke 25, which had higher contrast, a much different curve shape, and serious quality control issues toward the end.