Personal Exposure Speed Testing - Folks still doing this?

[JWMster]

I've done some of the Personal Exposure Speed testing and am getting set for some more. Technical (Hornstein) description suggests doing this for every combination of film, camera, lens etc. Sure argues the case for 1 camera, 1 lens 1 film, huh?

But I'm wondering whether this is something folks are doing seriously these days, or simply cutting box speed in half and calling it done? I do wonder how much difference say a 50mm lens will make from an 80mm on the same camera? Thus it may be that the more critical variable after a rough approximation for a film type is the personal development time? Dunno. Just wondering.

 

[Alan9940]

Yep, I still do personal film speed testing and measure with a densitometer. But, hey, I'm old! It is true that film speed can vary slightly based on different shutters, internal camera flare, and other things. If shooting 35mm or MF that doesn't use lens based shutters, then shutter difference is not a problem. But, if shooting LF with several different lenses slight variations in shutter performance can affect film speed. All that said, though, when testing for personal EI I pick a camera/ens combo that has proven through field experience to be working properly and I do one test. Then, I use that EI for that film. But, I won't cross camera size even if same film. For example, if I test 4x5 Delta 100 I'll use that tested speed for my 8x10, also, but I won't use that speed for Delta 100 in one of my MF cameras. I'll test separately for that. Wow, that's a lot of words for something that's pretty simple!

 

[removed account4]

i just over expose my film by 1 stop and bracket once in a while
and process everything the same no matter the film.
i try not to sweat the smalls stuff

===

added later

its always better to over expose than under expose ;
its always a good thing to know how your developer
works with whatever film you use;
AND its always good to know how your camera's shutter works
if it/then are slow/not CLA'd in a while it might be worth getting it/them CLA'd
or buy a timer so you know how they are working ...

 

[Bill Burk]

I regularly test my contrast for process control... but I trust the film speed.

You might test shutter speeds because that has a huge impact. I am looking at some negs that I see are three stops overexposed by the density measurements and I know it was a vintage camera. Sure, I used 2/3 stop less film speed too. That compounded the exposure error. Just illustrates that it's not always half the rated speed if your shutter speeds are off.

 

[Sirius Glass]

No. Given the print film wide light latitude, there is no need to test with present day materials. If you are using sixty year old film then maybe but then the fog will get you anyway.

 

[JWMster]

Okay. Thanks this is what I was beginning to sense. I see some LF folks still do this or talk about "way back when", but for the most part when I begin to talk about this, the "room" goes silent. And yet Minor White, Henry Hornstein, Harry Fearn.... and a host of others not too far back speak about it. The part that seems to interest Thornton more is shortening development time because he suggests we "underexpose, and over develop".

 

[MattKing]

If you use the zone system, and you adjust development to expand or contract contrast, it makes sense. Those development controls need to be combined with precise exposure control.
But if you are not using the zone system, it isn't as necessary.
Intriguingly, many people recommend downrating film an amount that comes very close to the difference between how ISO standards rate film speed, and how film is rated using zone system criteria.
Essentially, the zone system favours shadow detail more, whereas ISO ratings favour highlight and mid-tone rendition.
An ISO rated exposure will probably look better coming out of a machine printer in a commercial lab.

 

[Sirius Glass]

Just shoot box speed unless you really have a good reason to do otherwise. Then fix the way you use a light meter or get your equipment fixed and you will find out that you did not have a good reason, only an excuse.

 

[Trask]

Yes, I do test for film speed with a specific developer, especially if the film is dated. At this point I know how I want to process several films - APX100 (old) being a favorite -- so it's not as if I do it all the time. But I've got some old Pan-X and several 100 foot rolls of 1980s Tri-X that demand testing if I want to do anything reliable with that older film.

 

[E. von Hoegh]

Yes, very carefully in large format. Have you seen the price of one sheet of 8x10 monochrome lately? I want every possible tone and detail on those negatives.
I use my version of the zone system less often on MF, and even more seldom on 35, but the option is there should I choose to.

 

[Andrew O'Neill]

Just shoot box speed unless you really have a good reason to do otherwise. Then fix the way you use a light meter or get your equipment fixed and you will find out that you did not have a good reason, only an excuse.

This doesn't make any sense.

 

[Ian Grant]

Yes I test, but have more than enough experience to fine tune anyway without testing.

A lot depends on the film/developer combination when I used Rodinal and Xttol tests showed best at half box speed with most films. Now I use Pyrocat HD it's close to box speed with all films except Foma which I shoot at half box speed.

Ian

 

[Kawaiithulhu]

I used XTol a lot last year but without giving it some very crunchy lighting to work with I finally found it to be too "flat" somehow, despite the good quality of what it did render.
My last roll was pyrocat, which looks flat to me but ends up nice at the end.

Which is to say that while my testing has been all touchy-feely in the past it's not dependable, so I'm moving towards a more disciplined approach to help increase the number of shots I can depend on being usable.

 

[Kawaiithulhu]

doesn't make any sense

Makes perfect sense. Films are rated against a set standard and if a film isn't working out for you personally it's nice to know why instead of just throwing a blanket statement out that everyone is lying and all films are really slow.

Like Ian said, chemistry has a great effect on speed. Light meters have different spectral sensitivities, metering technique, light flare, mechanical shutters vary, F-stops are close but not directly correlated with light transmission (which is T-stops), and so on with a laundry list of items that can be controlled for not related to the film itself.

 

[tomfrh]

Given the latitude and the ability to correct at subsequent stages I'd never bother. Close enough is good enough. Life's too short to fret over T-stops vs F-stops in still photography!

 

[removed account4]

This doesn't make any sense.

i agree andrew !

if one has a 35mm camera
the 1st roll put through should be bracketed
1 stop over / under what the meter reads
then processed normally and a contact sheet / printed
so one can see the exposures and how they look -- and proceed ...
then bigger format, same film, same developer one knows
what to expect ... no need to throw out 12 sheets of film that costs a fortune
and spend time processing a grey wall ..
film is film no matter the format, its insane to waste it if you know what it looks like.
but unfortunately, that might be a waste of time
part of the problem with "now" is
that people buy used equipment, cheap, on eBay, in classifides, craigs list or gifted to them
they have no clue what the camera's shutter does, or what the schneider app symmar bought for s song
does at 1/125 S or 1/30S. people are too busy buying cheap gear and being all " look what i got ! "
and not spending $$ on a CLA. box speed might work great! but their shutter no so great ///

 

[JWMster]

Well.... this is actually encouraging. I've gone to the trouble of having my 35mm cameras CLA'd and the results there are now excellent... especially hand metered.
Trying exactly to get a more rigorous and similarly dependable output from my "new" Bronica SQ-A and there's been a big adjustment to medium format that has thrown me for more of a loop than expected.
At any rate... although it's one step at a time, I seem to be getting the bugs out of the system. MF seems to cry for film testing much more than 35mm in my view. But maybe it's just a question of getting things dialed in? Find it hard to believe a CLA would be needed though. At least not yet.
But that would seem to be a VERY GOOD reason to do some testing.

 

[Theo Sulphate]

Medium format shouldn't require "loop throwing" regarding exposure. Do you know for certain that the SQ-A's shutter and meter are accurate?

 

[JWMster]

Fairly.... some of the loop throwing is just adjusting to 120 reels where the film is wider but thinner, and forced me to abandon the changing bag in favor of winding in an actual carefully established dark room / closet... due to the humidity buildup in the bag. Odd thing that was! Niggling things like that where 35mm was simply easier. Ditto for scanning which has pushed me to acquire AntiNewton Glass film carriers.... all in an upgrade in process and not a bad move, but with 35mm.... not necessary. So I blame me for these things.... and as it happened coincident with beginning to shoot 120.... there you go.

No, I don't know that the shutters on the SQ-A lenses are 100% accurate. My spot meter has been checked out by Ritter and tested fine (highly recommend him btw for speed and service). I should have the SQ-A tested.... but doesn't that have to be done with the lenses since I think the shutter is in the lens? What do you think?

What I can say is that the Leica M's I've had CLA'd recently have come back spot on and produced great results ever since. Both servicers wondered why I sent them off.... my answer was to eliminate unknown potential variables in the process. Results weren't bad before.... but good as they are now, the detail in a MF neg is going to top them.... once I can get it dialed in.

 

[voceumana]

I did some speed testing about 15 years ago, or so. Interesting results--my Kodak films (with a Zone VI modified meter) all tests at rated speeds, or maybe 1/3 stop faster; Ilford were all 1/3 stop slower. Previously, when I just tested some Kodak films, I also got 1/3 faster than rated. I currently don't have a darkroom, so I haven't tested lately, but will do so when I get one set up.

And, I'll probably use divided developers in the future (at least for roll film), so I expect I'll run at least a simple test to establish a norm. Films have changed a bit since I last tested, but I don't expect much difference in results.

But if I shoot 4x5 and 5x7, I'll definitely test: the film cost is high enough that knowing with certainty is worth it.

Note that the Bronica SQ system uses electronics in the body to control the shutter, but the shutters are in the lens. So the shutter timing control needs only be tested with one lens, and then you can test to be sure all the lenses open/close at the same speed (i.e., if one lens shutter is sluggish compared to another)

A single test roll should be able to do a filme speed test and compare the different lens shutters as follows.

1. Test for film speed as usual, taking maybe 5 or 6 exposures.
2. Then meter the subject for Zone V exposure, and shoot each of your lenses with that exposure, and infinity focus.
Densitometer readings on the different lens options should show the same density, letting you know if any of the shutters operate faster or slower than the others--perhaps needing service.

 

[Peter Schrager]

Blanket statements..you might as well throw a blanket over your camera and take pictures
For LF you should do tests and send out your shutters for CLA
No one here has mentioned doing a proper proof..if you have everything lined up properly and do a proper proof you will know immediately there is a problem
One film one lens one light meter one film developer...otherwise you'll never know anything about ANYTHING in the chain of events.. I still think the zone VI. Handbook is simple and straightforward...if anyone has ever done the exercises including the zone prints they will know more about their materials than 99% of photographers in the world
One reason I use Kodak material in MF./film and xtol is because I get amazing results with full speed. .for 4x5and 5x7 I always downgrade
The film...anyone who tells you they get box speed in a view camera is whacko...just not possible
It's a locked system ..learn it...use it and don't try every developer in the world because it won't make magic pictures
A little discipline goes a long way!

 

[RalphLambrecht]

after having it done a thousand times, it's box speed -2/3 stop for me.

 

[Ian Grant]

Makes perfect sense. Films are rated against a set standard and if a film isn't working out for you personally it's nice to know why instead of just throwing a blanket statement out that everyone is lying and all films are really slow.

Like Ian said, chemistry has a great effect on speed. Light meters have different spectral sensitivities, metering technique, light flare, mechanical shutters vary, F-stops are close but not directly correlated with light transmission (which is T-stops), and so on with a laundry list of items that can be controlled for not related to the film itself.

While films were once tested to supposedly strict standards that changed when Kodak had the ASA portion of the ISO test altered when they introduced Tmax films which failed the then standard ASA/BS testing.

There's other anomalies like the old Adox/EFKE films originally know by their Artificial light DIN specifications like Kb/R/PL 14 which Efke later renamed KB/R/Pl 25 the Tungsten light ASA speed, in fact the Daylight ASA was 40. later 50. Then there's Foma films which need quite different handling to tame their contrast.

So yes all reasons why you say testing is useful.

Ian

 

[E. von Hoegh]

after having it done a thousand times, it's box speed -2/3 stop for me.

That's exactly what I get. For all of '88 and most of 89, when I was learning and using 8x10 a LOT, it was TXP at 200, hc110, and a 30cm Schneider Doppel Anastigmat Symmar in a calibrated Compound.

 

[JWMster]

Peter - I think Fred Picker's book is about the only Zone book I don't have. Thanks to our Amazon Monopoly, it's now on it's way. What I find interesting is the number of different ways folks have derived to come up with testing their film, equipment and personal process. I understand the idea is to encourage, but at the same time the lattitude almost makes detracts from the point of a rigorous benchmarking process.

For my part without a wet darkroom, I've explored how to proceed and been advised that some software provides densistometry readings (by a densitometer sales firm no less). Of course as a Capture One user, I've not found this to be the case... naturally. As my Dad used to say, "You always do things the hard way, huh?" Yep. So perhaps this leaves hybridists in something of a pickle.