Assessing film speed and development time without a darkroom.

[JohnF]

good luck with that !

you might become good friends with your lab / the people who develop your film into negatives

I shoot only black and white and develop it myself at home

[Doremus Scudder]

I think the point jnantz is making is a good one, though. Many labs would be happy to give you densitometer readings for a minimal charge. You might just track one down and see if you can bring/send in your test negatives for readings.

Doremus

[jnantz]

I shoot only black and white and develop it myself at home

I thought you said you didn't have darkroom facilities

Is there any technique available to me to achieve my objective in the absence of darkroom facilities?

sorry for my misunderstanding !

I think the point jnantz is making is a good one, though. Many labs would be happy to give you densitometer readings for a minimal charge. You might just track one down and see if you can bring/send in your test negatives for readings.

Doremus

exactly !

==
but ... do you actually need to have densitometry readings ? I know a lot of photography people love to talk about log curves they plotted, and data and base plus fog lingo but is it really necessary for your application?
in actuality you might be able to get away with just exposing your film, bracketing it, bracketing your development photographing/scanning and seeing which ones you like the best / easiest for you to work with without getting bogged down in gymnastics. time shooting, film and chemistry is expensive, and even though a lab would probably do it for you at a minimal charge, it still adds up and you might not really need to know the readings for you to know your own optimal exposure, optimal iso, optimal film processing times &c. the info manufacturers give is pretty much on target for most applications ( and chemistry makers like Sprint Systems have up to date info on every film made on their website ) ...
I hate to admit how long I have been making photographs but I've never done densitometry or sensitometry readings, I've just shot and printed and proceeded from there blindly ...
ignorance is bliss.. ( especially when you are making photographs on a shoestring budget, and you don't go to cocktail parties where people talk about B+F values, curves plotted, logs, shoulders &c )
good luck !

[Tin Can]

Yes

Just do it

Shoot process repeat

I thought you said you didn't have darkroom facilities


sorry for my misunderstanding !



exactly !

==
but ... do you actually need to have densitometry readings ? I know a lot of photography people love to talk about log curves they plotted, and data and base plus fog lingo but is it really necessary for your application?
in actuality you might be able to get away with just exposing your film, bracketing it, bracketing your development photographing/scanning and seeing which ones you like the best / easiest for you to work with without getting bogged down in gymnastics. time shooting, film and chemistry is expensive, and even though a lab would probably do it for you at a minimal charge, it still adds up and you might not really need to know the readings for you to know your own optimal exposure, optimal iso, optimal film processing times &c. the info manufacturers give is pretty much on target for most applications ( and chemistry makers like Sprint Systems have up to date info on every film made on their website ) ...
I hate to admit how long I have been making photographs but I've never done densitometry or sensitometry readings, I've just shot and printed and proceeded from there blindly ...
ignorance is bliss.. ( especially when you are making photographs on a shoestring budget, and you don't go to cocktail parties where people talk about B+F values, curves plotted, logs, shoulders &c )
good luck !

[Drew Wiley]

Just bracket, bracket, bracket? For heaven's sake, this is a large format forum. Is everybody here rich enough for that volume of sheet film? Sounds like a snipe hunt; and at least some form of map up front might be helpful before getting lost.

[LabRat]

Remember the old foto rule "Expose for the shadows, develop for the highlights"... In this case it means there must be enough exposure to give the darkest (thinnest) area some information, but development controls the maximum density of the brightest highlights...

So your testing will include the level where the bottom of the shadow areas will be visible in the thin areas of your neg... (There is very little change in this area during duration of development, and this area is the EI of the exposed film)... But the highlight areas have the most chemical activity, and can "run away" with overdevelopment... So your developing time is about those areas...

Developing just long enough where the highlights don't block up in Dmax where there is still some transparency through them is where they should be... If you exposed a sheet for this highlight exposure, you develop so you can just barely see through it when held up to a light is correct...

You can eventually do some calibration tests, but you will find the above very close for normal negs/exposure...

Steve K

[Tin Can]

Some here suggest using 1/2 Box ASA/ISO speed as starting point for SHEET film

I shoot Ilford HP5 which is factory rated at 400, at 200 ASA/ISO

Many more will suggest insanely complicated exposure systems, contraction/expansion, ZONES

BUT you better check your actual shutter speed, they vary

Plus or Minus 20/30 % is NORMAL

Bellows factor will get you often and early

[Michael R]

Agreed.

Drew mentions having a map instead of flying blind, which of course makes sense, but when it comes to exposure the map is already given to us in the form of ISO speed.

Cutting ISO speed in half for sheet film essentially puts the former safety factor from the standard (pre-1960) back in, which is fine. It will also line you up very closely with Zone System speeds without having to do any testing because the Zone System EI is 2/3 stop lower than ISO.

Some here suggest using 1/2 Box ASA/ISO speed as starting point for SHEET film

I shoot Ilford HP5 which is factory rated at 400, at 200 ASA/ISO

Many more will suggest insanely complicated exposure systems, contraction/expansion, ZONES

BUT you better check your actual shutter speed, they vary

Plus or Minus 20/30 % is NORMAL

Bellows factor will get you often and early

[jnantz]

Just bracket, bracket, bracket? For heaven's sake, this is a large format forum. Is everybody here rich enough for that volume of sheet film? Sounds like a snipe hunt; and at least some form of map up front might be helpful before getting lost.

yes, ... 3 sheets of film, bracketed like a test strip with a dark slide. Each developed a little different.
your exaggerations area too funny, Drew, 3 sheets of 4x5 will make someone poor or it's like a snipe hunt?
exposing 12+ sheets of film to map out exposure / development for each film won't make someone broke, LOL, that's too funny.

.. yes, quite right, this is the LF forum a place where people will drop IDK $3,000 or $6,000 on a lens or camera body ...
I don't think 3 sheets of film and IDK 40cents worth of developer will break anyone's bank. even if the person is like most, on a shoestring budget.

BUT you better check your actual shutter speed, they vary

<...>
Bellows factor will get you often and early

BINGO

[Alan Klein]

How do you use the densitometer on a scanner and what does it mean? I have an Epson V850 scanner and a lab develops my film. I shoot Tmax for BW and various chromes for color.