EI rating for pinhole paper negs?

[Dr Croubie]

I thought this would have been already asked, but there's only 3 pages in the paper neg forum and I can't see the answer (although I'm sure I'll see it as soon as I've asked such a simple question and feel like an ass about it).

Anyway, seeing as I've just been gifted a jobo and enlargers, I'm getting ready for paper developing. One thing I've wanted to try for ages is a suitcase-based pinhole camera using paper negs. I've done it in high school many many years ago, and from what I remember it was along the lines of 'poke a pinhole in a shoebox, take a photo, develop, adjust your exposure time if too dark or light'.
But this time I want to use real calibrated-sized pinhole (i've got a lot from Skink to use), I've got a real lightmeter (digisix), I can calculate focal length and f/aperture, all I need to know is what to rate the paper in EI terms to calculate exposure times.
For the record I'm using Ilford Multigrade iv paper, in Multigrade liquid dev for now (maybe when that's out I'll try bromophen too).

 

[RalphLambrecht]

I thought this would have been already asked, but there's only 3 pages in the paper neg forum and I can't see the answer (although I'm sure I'll see it as soon as I've asked such a simple question and feel like an ass about it).

Anyway, seeing as I've just been gifted a jobo and enlargers, I'm getting ready for paper developing. One thing I've wanted to try for ages is a suitcase-based pinhole camera using paper negs. I've done it in high school many many years ago, and from what I remember it was along the lines of 'poke a pinhole in a shoebox, take a photo, develop, adjust your exposure time if too dark or light'.
But this time I want to use real calibrated-sized pinhole (i've got a lot from Skink to use), I've got a real lightmeter (digisix), I can calculate focal length and f/aperture, all I need to know is what to rate the paper in EI terms to calculate exposure times.
For the record I'm using Ilford Multigrade iv paper, in Multigrade liquid dev for now (maybe when that's out I'll try bromophen too).

witha yellow filter, which will help controlling the contrast in outdoor shots ,I used an EI of 3 for that combination of paper and developer with sucess.

 

[NedL]

I pre-flash my paper ( search on APUG or F295 for lots of good info about that ) and I too rate MGIV at 3 with a yellow filter, or 12 without a filter. But that is for cameras with lenses. With MGIV the yellow filter can also help control contrast as Ralph mentioned.

For pinhole, I make a series of tests and figure out the bright sun "sunny 16" for each camera separately, for the paper I intend to use in it. It's easy to go from there with a light meter. It does not take long to do this testing... just use little scraps of paper and quickly develop them, adjusting time as you go. I usually find that I'll refine that time slightly as I use the camera. So, for each of my cameras, I only need to remember one number: this one is 20s, another is 45s, another is 1m, and so on.

Also remember that the amount of blue light is what matters most. So late in the day, you might want to add a stop to what your meter says, and similarly you might make adjustments depending on the colors in the scene you are photographing. A couple weeks ago I was at the beach and I forgot to reduce the exposure because there was a huge amount of UV reflecting off the water....

Have fun!

 

[MartinP]

The manufacturer of the paper also makes a series of pinhole cameras. For that series of cameras they have a PDF of an exposure calculator, which can be printed on a normal office printer to help with relating a lightmeter reading to the tiny effective aperture of the pinhole. There is a huge amount of information on the IlfordPhoto site - the datasheet for the paper can also be useful.

 

[Jojje]

In his book "Avancerad mörkrumsteknik" from 1988 (available in english) Lars Kjellberg gives masses of information about various papers, including speeds according ANSI. In it he gives speeds between 250-400 depending of filtration for Ilford Multigrade III.

 

[MartinP]

Jojje, take care - the units for those speeds may be the ISO paper system these days, or an out of date measurement system of some sort. Harman give a "film"-speed equivalent to ISO3 for MGIV and that seems about right.

 

[RalphLambrecht]

Jojje, take care - the units for those speeds may be the ISO paper system these days, or an out of date measurement system of some sort. Harman give a "film"-speed equivalent to ISO3 for MGIV and that seems about right.

Yes, EI3 worked for me when using a yellow taking filterand using Dektol1+2 as a developer. if that still gives you too much contrastuse a higher developer dilution.I've been using Dektol up to 1+8.

 

[removed account4]

hi dr c..

paper photography can be dependant on the time of day and season
the iso can be said to be variable seeing its emulsion only responds a certain band/s of light.
have fun with your project and notice the time of day and weather / conditions
it will help you determine your exposures.
paper, dry plate, wetplate &c all require the photographer be more actively involved, and imho so much more fun

i hope you post your resukts in the paper neg group!

john

 

[NedL]

I always forget to look in the groups here at APUG. There's a pinhole group too!

 

[Jojje]

Thanks Martin and Ralph I knew there was a catch - I even double checked Kjellberg's figures! ISO-paper system..?
(I almost always use 120-film with my pinholes.)

 

[removed account4]

this thread might be helpful

(there was a url link here which no longer exists)

that same ilford emulsion might also be as fast as iso 25


re paper speed ratings of 200&c
that is relative to paper speed, not relative to the iso of film

 

[mablo]

Jojje, thanks for the tip. I just reserved for me the book you mentioned above on our library website (helmet).

 

[Dr Croubie]

Well yeah, so I finally got around to trying this out.
0.6mm hole at 200mm gives roughly f/333, near enough to 7 stops down from f/32.
Took the digisix and the suitcase camera out at lunch today, ended up at 2 minutes with ei3, but no filter.
Now I've got a lovely black piece of paper to hang on my wall...

 

[Dr Croubie]

Just did another test strip with a B+W 040 4x Orange filter. Same lightmeter reading, same 2 minutes, same (albeit much smaller this time) nicely black piece of paper.

Either these times are up the creek or I've got a massive light leak somewhere...

 

[MartinP]

Just to confirm that your paper is ok, try developing a piece straight from the box, without exposing it. After fixing, it should be white. If it has any tone at all then you have a problem with the paper.

Just wondering the obvious, you do realise that the paper must be developed in darkness or with a safelight, and that you have checked your safelight is actually safe??

 

[Dr Croubie]

yeah, the paper and the safelight is good (as are the chems), I was enlarging stuff last weekend with the exact same paper.
I'm pretty sure there must be a light leak somewhere in the suitcase, I'll be adding another set of baffles today to see what else I can block out...

 

[NedL]

Um this is still MGIV right? 2 minutes for 200mm "focal" length sounds pretty close to right to me. Even if your exposure was off by 1 or 2 stops whole, you'd still be able see a low contrast very dark image. I think some kind of leak is likely. A good test for light leaks is to load a little strip of paper, put the camera out in the sun, then develop!

 

[Dr Croubie]

So over the llast week I've totally attacked this thing with aquadhere, styrofoam packing, black construction-cardboard, and a can of black spraypaint.

Last night I did 3 images:
- a test strip with the suitcase in the sun for a full 10 minutes, lenscap-shutter on. Completely brand-new chemistry, I tipped dev/stop/fix all down the drain last weekend when my HDPP came out pink. Test strip came out totally white.

- then another square (a 3x5" ripped in half), with an Orange 040 (4x) filter. Digisix gave me ev9 at ei6 in almost-sunset behind cloud. 8-stops below the f/32-mark (7-stops for f/ and 1-stop for ei) gave me 8 minutes at f/344 at ei3 (ie, NOT taking the filter factor into account). Test came out almost completely white again, so I started suspecting the brand new chems. Fogged a strip in front of the safelight (10cms for 10secs usually give a nice mid-grey fog) and that came out greyish so the chems were fine. When it was fixed and I turned the lights on I could just see a tiny faint of grey that would have been a bright reflection off my car in the sun.

- So last one, the other half of the 3x5, I took the Orange filter off, got the same ev9, so did the same 8 minutes (ie, no filter factor and no filter), and got a very nice shot of a tree in front of my house. Shadows were almost white and the sky was totally burned black, lots of contrast (I haven't scanned/inverted to see how well it looks in positive).

So today I loaded it with an 8x10 and packed it in the car, I'll see what I can take a shot of at lunchtime. As I've got the 040 Orange on again (for some reason I don't have a 52mm yellow, only orange and yellow-green) I'll take it 10-stops below the f/32 ei6 reading (7-stops for f/, 1-stop for ei3, then 2-stops for filter) and see how i go. Or should I use a different filter-factor because it's MGiv and has a weird curve?

(if this works I've got some 11x14 MGiv and HDPP coming from B+H, this thing could turn out to be a fun suitcase)

 

[Dr Croubie]

ps, just re-reading all the posts again. So maybe I did the test last night a bit too close to sunset and there wasn't enough blue light around and the Orange filter took out what little there was. So if I do a shot today at almost exactly midday, what's a good starting point for the filter-factor? It's a bit grey and cloudy today, but it might clear up to blue skies in the next 3 hours...

 

[NedL]

My experience with orange filters is that they require a very very long exposure with paper negatives... way higher filter factor than for film. For a yellow filter I use a filter factor of 4 ( 2 full stops ). I'm not sure what it is for orange because I gave up on them early on!

But I'm glad to hear you are starting to have success and it sounds like you will dial it in soon!

 

[Dr Croubie]

Well, after overrunning lunch by 2 hours because I was fixing a production-line test rig (the boys have to come for Sat morning overtime to catch up now), I didn't have time to test an orange filter anyway, so I took it off and just ran unfiltered. Still as cloudy as all hell out there, same ev9 reading, same 8 mins, I'll see what I get out of it when I dev it tomorrrow morning (no darkroom tonight, seeing John Zorn)

 

[NedL]

Gluck

 

[pdeeh]

Yep, ev9 gave me 8 minutes at EI6 for my very first 10x8 pinhole the other day (mid morning, on MGIV RC) and gave a very acceptable image indeed.
Now of course I've run out of MGIV and have a selection of very old graded papers to play with, each of which will require calibration ... sigh

 

[Dr Croubie]

Sigh indeed. I got home on friday and realised I'd left the pack of MGiv paper open. Tested one and there's a strip of black down one edge, the one from the top of the stack is probably a goner.
so, more updates. The 8x10 I shot friday turned out very very black. But not so black from a light leak, there were a few spots of white from some deep shadows. Scanning the hell out of it I got some kind of image, but I definitely need to rate it a stop or two faster than the ei3 when I run with no filter.

Today I took it out again, and this time I found a B+W 52E 2x Yellow-Green filter to put on it. The clouds are still around, but the sun was trying to break through a bit. EV10 at ei6, minus the 7 stops for aperture gave me 2 mins so I went with that (ie, it was ei6 including filter factor, or ei12 minus one stop for the filter).
I got something almost repectable, a little thin and the shadows look totally white, but better than all black. So maybe ei3 including filter factor for the 52E might be the way to go.

I've also bought a different step ring so I can mount a 39mm real Yellow filter on it. I've just looked to see what this one is and all it says is "Ernst Leitz GmbH Wetzlar" and "1" and "Germany" on it. I've never noticed that it doesn't have a filter factor printed on it because it lives on my TTL Bessa. So once I try this one I'll have to experiment again.

 

[NedL]

Even with the filters, it may be a challenge to get those clouds and also get shadow detail.
I rate MGIV at ISO 6 when not flashed, so you are very close. Close enough that remaining differences can be in how you meter and how you develop and different errors in calculating f/ratios... I still think even a yellow-green will have a higher filter factor for paper than for panchromatic film....