Grain - again.

[pkr1979]

So,

I've been trying to visually compare the difference in grain between Acros II, T-Max 100 and T-Max 400. Zooming in at 100 to 400 % I am still having a hard time telling these films apart grain-vise. It is all scanned at 4000 dpi with a CoolScan 8000. Probably I dont have the best trained eyes, but how trained does your eyes have to be to say which is which based on grain?

Cheers
Peter

 

[wiltw]

Film grain as detected by digital sensels introduces the issue about the optical detection of 'grain' vs the sensel spacing and resolution of the digital matrix.
Your EYE aided with high magnification optical inspection is a better means to evaluate 'graininess'

Abouit grain...

Film grain - Wikipedia

en.wikipedia.org

...characterized by some as "typically ranging from about 0.2 to 2.0 micrometers (µm) for standard films, but can be larger (up to 10 µm or more) in high-speed films and smaller in fine-grain, high-resolution films". There are 25400 micrometers in an inch vs. only 4000 digital dots by the CollScan 8000 in that same inch! At a certain point you will only 'see' the limits of the scan device.

 

[pkr1979]

By the way - its medium format (6x7 cm).

 

[albireo]

So,

I've been trying to visually compare the difference in grain between Acros II, T-Max 100 and T-Max 400. Zooming in at 100 to 400 % I am still having a hard time telling these films apart grain-vise. It is all scanned at 4000 dpi with a CoolScan 8000. Probably I dont have the best trained eyes, but how trained does your eyes have to be to say which is which based on grain?

I use a Coolscan 8000 and can readily detect differences in grain across Tmax 100 and Tmax 400 developed to equal CI.

Which holders are you using? The default Nikon medium format holder is very poor quality and struggles to retain planarity, which might result in focus errors across the frame which might explain the perceived lack of difference in the grain.

 

[pkr1979]

Thanks guys. I use the glass holder.

 

[loccdor]

I can notice a difference in grain between 100 and 400 speeds, but in 6x7 I'd have to go up to Delta 3200 before the grain became obtrusive to me. Unless I was trying to emulate the large format look.

Between the two 100 speed films, I doubt I'd tell their difference by grain, but might by their spectral sensitivity characteristics. I'd prefer Acros for that from all the films you listed but would happily shoot T-Max 400 if I needed the speed in medium format.

 

[albireo]

Thanks guys. I use the glass holder.

That should ensure perfect focus throughout the frame so it sounds like it's not the culprit.

Another idea - when is the last time you performed a mirror clean? A dirty mirror will have a strong impact on retrieved detail.

Also - are you familiar with the Norwegian website where they did an extensive 10 film x 6 dev comparison https://fotoimport.no/filmtest

You can directly compare Tmax 100 vs 400 by selecting e.g. the Tmax 100 tab on the left pane and Tmax 400 on the right

fktmax

Fremkallertabell for Kodak T-max fremkaller

fotoimport.no

(in the example above Tmax dev is selected).

The difference in grain is pretty obvious. They use a Coolscan for these tests, if I remember correctly

 

[Milpool]

Make sure when comparing films developed in the same developer that they are developed to the same gradient and that you are comparing the same densities. Otherwise all bets are off particularly when the differences are expected to be very small, which is the case when comparing TMX, TMY-2 and Acros. One would expect TMX to be very slightly finer grained than Acros but virtually the same for all intents and purposes, and slightly finer grained than TMY-2 but not by very much (TMY-2 is exceedingly fine grained for its speed).