In 4x5 format when do you need ISO100 over Iso 400?

[stradibarrius]

With LF, it seems to me, that grain is not really an issue so under what circumstances would you select 100 speed over 400???

[jp]

I use iso 400 film (tmy2) 95% of the time.

Reasons for slower film: desire to use a wider aperture in bright daylight. different spectral response (tmy2 is naturally light yellow filtered), slower shutter speeds (such as if a shutter doesn't go past 1/100 second) or if you want a slower speed to capture motion and you don't have ND filters.

[Ken Lee]

grain is not really an issue

Doesn't that depend on the degree of enlargement ?

[Leigh]

I have never purchased any film faster than 100 ASA for LF work in over 50 years of doing it.

It's all about quality.

- Leigh

*Technically, Ilford FP4+ is ASA 125, but I shoot it at 100.

[E. von Hoegh]

With LF, it seems to me, that grain is not really an issue so under what circumstances would you select 100 speed over 400???

Always. It's my standard film for 4x5.

[Light Guru]

Just like with other formats of film it depends on what you are shooting.

[MIke Sherck]

Films are not all the same except for speed. FP4+ has a very different look than does HP5+. For that matter, TMX looks different than does TMY. Film speed isn't the only criteria.

Mike

[unixrevolution]

I typically use 400 speed, but that's a function of my wanting to use my Graflex handheld occasionally, and wanting to take portraits without people holding still for too long. I do love a good, sharp 100 speed film.

[Peter Gomena]

If you're working in a studio and need two more stops of depth of field for a flash-lit shot, (and can't use multiple pops of the flash) you can reach for the faster film. If you're in the field and there's a light breeze and you dont want grass and leaves moving, you can reach for the faster film.

My first choice these days if an IS0 100 film. If conditions call for a higher shutter speed, I always pack some 400 ISO film. If I'm shooting smaller formats on windy days, days that are too windy or wet for LF, I always pack some IS0 400 film.

T-Max 400 is so fine-grained for a high-speed film that I don't think twice about using it. My standard film for years was Tri-X 320, and if handled well, it's rare to see grain, especially in smaller enlargements.

So why use 100 ISO film at all? It still has finer resolution and grain than faster film. Other characteristics are different, too, such as reciprocity characteristics and gradation. It's good to have a choice.

[Drew Wiley]

I generally choose a film first for its curve characteristics and specific spectral sensitivity, then for speed. While I often shoot TMY in 4X5, there are times I find
the grain a bit too apparent in smooth tones, esp if enlarged beyond 16x20 or if the neg needs to be masked to enhance microcontrast. I've always hated the look
of Tri-X, which seems like buckshot blown out of a blunderbuss (though there are obviously quite a few people who have done wonderful work it). Once I get to
8x10 film size, TMY is a dream. But I've never been a one-film guy.