Slow 4x5 sheet film options

I'm looking for a lower iso 4x5 sheet film to make my pinhole exposure times a little more accurate. I currently have 125 iso FP4 film in 4x5 and on bright days I'm getting exposure times of 1.4 seconds, which is really quite tricky to time accurately. I don't want to have to resort to nd or colour filters so I was wondering if anybody knew of any 4x5 film that might be along the lines of a 50 iso or so? I see rollei has a 25 iso film, which I'll likely give a go but it is expensive (cheapest I've seen is about $80 cdn for 25 sheets). I'll pay that if I have to, but if anybody is aware of anything else I'd appreciate being pointed in the right direction. Thanks!

why not try paper negatives ISO is around 6.
alternatively try nd filters
regards
Tony

The slowest 4x5 film that I'm aware of is CMS 20 which, if this size follows my experience with the 35mm version, it needs to be exposed closer to EI12 to maintain good shadow detail.

any film can be exposed at a very slow speed
you just need to develop it accordingly ..

tonyowen said:

why not try paper negatives ISO is around 6.
alternatively try nd filters
regards
Tony

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jnanian said:

any film can be exposed at a very slow speed
you just need to develop it accordingly ..

Click to expand...

The way I develop my film is very different than how most here would do it. I run all my film through a dental xray processor at work. It's fast and convenient and the results I get are acceptable to me.
@tonyowen I'm concerned paper negatives would not develop in my chemistry, or the paper would be damaged by the machine itself- although I have no experience to prove this. This is why I was hoping to stay with film. I also was hoping to stay away from nd / colour filters as I had indicated because removing the lens cap, placing an nd filter and then covering the pinhole back up all for a 1.4 second exposure is far more challenging than what I think my hands are capable of.
@jnanian again, because of my unique means of processing film the only control I have over development is temperature. I can develop between room temperature and 82 F. I also can't find any information about the chemicals as they are still "store brand" dental xray chemicals and the dental supply company has been unable to let me know who manufactures it or provides me with any additional information about it.
@allan9940 Thanks! I'll google cms 20 and look further into that!

ahhh
i'd have suggested processing your film in heavy measured (teaspoon )caffenol c with about a few cc's of whatever
straight print developer you have lying around. sorry to hear you are taped down with store brand xray chemicals ..
good luck figuring this out !

I would suggest you consider permanently attaching an ND filter,either by adhering a suitable sized filter ring to the camera, onto which you would simply screw the ND filter. Then you would only need to remove and refit the lens cap to the ND filter.

Assuming your processing machine is a roller transport type, paper would go through it. I would not suggest you put paper through it though, decades ago I regularly put RC paper through roller transport lithographic film processors; eventually a piece of paper invariably gets stuck, as does film. Paper makes a mess, film just scrunches up (mostly) without much rubbish getting into the baths.

Mick.

Pan F+ @20 is perfect

Forgot! No Pan F+ in 4x5!

I generally use Arista Edu 100 in my pinhole cameras. I rate it at 50 and adjust exposure for its massive reciprocity failure; my exposures are never what I'd call short.

For example, my 5 by 7 is f/180, and a standard sunny day of 80K lux needs an exposure of 31 seconds. The shortest exposure I would use is 11s, on a super bright Australian summer day, when it sometimes gets to 160K lux.

Ces1um said:

I don't want to have to resort to nd or colour filters

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See, I read what your wrote! ... but there aren't many/or any low speed films around in 4x5. This might be the time to try the expired film market. Or Ilford ortho: it is rated 80 in daylight, but only 40 in tungsten. Now back to the filter. Throwing out there as a suggestion using appropriate uniform, midtone developed 4x5 sheet as a filter - sandwich your new film sheet between it and the camera back.

revdoc said:

I generally use Arista Edu 100 in my pinhole cameras. I rate it at 50 and adjust exposure for its massive reciprocity failure; my exposures are never what I'd call short.

For example, my 5 by 7 is f/180, and a standard sunny day of 80K lux needs an exposure of 31 seconds. The shortest exposure I would use is 11s, on a super bright Australian summer day, when it sometimes gets to 160K lux.

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Your thinking agrees with mine -- my first pinhole foray in this millennium I followed the notion "oh, microscopic aperture, I'll get some 400 film." Wrong! When I finished the camera and started to actually try to use it, I found I was getting numbers down around a second or two which seemed awfully short for flipping a flap shutter manually. So I ended up buying a pack of Delta 100 which, with reciprocity adjustment thrown in, got me up into four to six seconds in bright sun and worked pretty well. And then I do most of my pinhole shooting on WPPD and it seems as though 4 out of 5 years it's raining or at least cloudy anyway and the exposures were more like 15 to 20 seconds. I think shooting a 100 film at 50 and pulling development a little should do the job. The last couple of years I've used Fuji HR-T X-ray film which I rate around 50 and have had fairly good results {I've seen folks quote numbers from 25 to 400 for it -- enh -- experiment!!!}

If you are willing to go way down in exposure index consider Arista Ortho Litho 3.0.

It's a high contrast film designed for halftone reproduction, but it is possible to adjust the exposure and development conditions to get continuous tone negatives.

You will have to do some google searches and experimentation to find an appropriate exposure index and development conditions, but a reasonable starting point for exposure index might be about 6, which is going to put your exposure time up around a half minute or more (maybe even several minutes), assuming you are exposing at 1.4 seconds for fp4+.

The beauty of this film is that it is extremely inexpensive ($12 US for 50 sheets, or very roughly 10% of the price you mentioned for the Rollei film), and it has ultra-fine grain. If you are doing landscape or still life photography this might be just the ticket, assuming you are happy with an orthochromatic film. If you are doing portraits (not too likely with your pinhole camera) it is probably not the best choice.

This is why I buy expired 4x5 on eBay. For example, here’s some Vericolor II that expired in the 1970’s that I shot with an ISO of 4... great for pinhole!
https://flic.kr/s/aHskB4SHou

I normally shoot fp4 at 64. that would get your sunny day exposure to 3 seconds, maybe even a bit more for reciprocity failure. That puts you into a manageable range.

But I can't guess if that would work well with your speedy film processor.

Use TMX at EI 50, no change to development. Or use it at EI 25, and reduce development "a bit".