Reference: U.S. Navy manual of photography, vol. 1 & 2, 1947 edition.
This is very similar to those holiday jello molds (so popular this time of year) where odd bits of various fruits are suspended in colored (usually green) and flavored gelatin.
The similarity continues in that we know what occurs when the jello mold is dropped or treated in a rough manner. The bits of fruit are displaced to a greater or lesser degree. This same phenomena can be witnessed when viewing student work. When viewing fuzzy pictures be sure to question students on how the film was handled before processing (when film is most susceptible to jarring). Film that has been dropped is seldom worth processing due to the severe migration of silver. Film that has been jarred (this usually occurs from the camera jostling on a neckstrap) will always show a loss of edge sharpness.
If he caught us hold our stainless or aluminum film processing tanks in our hands it was not good for you grade. I would say I learned much from jack on the nature of what is the right way to process film to then apply that towards the rest of my education.
This still has ZERO to do with the ISO not being listed as correct. Because they thought the resulting dies in the film where crap but looked nice at different settings is a non point. Its an aesthetic choice not a as designed to operate based on whatever it was they where shooting for. They're German's the looked up some math and then did that exactly based on what works in a LAB and over exposing it doesn't make the ISO WRONG its makes it an aesthetic choice in how to use that film. It also doesn't mean when they designed the film they did screw it up like the original Kodak Portra's that where just HORRID and then salvage it with marketing on a box. Still doesn't make that right. It makes it aesthetic choice.
ISO is determined at a given amount of exposure such that its above base+fog. In color neg is the same but RGB are measured. Then its just up to the chemist to make sure that the 14 layers of emulsion produce something people want to look at. So if the Agfa was list at the wrong iso based on the ISO criteria then Agfa was out of spec. PERIOD and in theory could have had their ISO mark taken away (unlikely to ever happen) Again what poeple like to look at has zero to do with what the films proper iso is to meet the ISO STANDARD. Now we all know that chemistry and light meters aren't perfect but that is something people should have worked out for their working process. If you want your dmin to be scene referenced black at just above b+f then the ISO IS THE ISO. If you would like a different look then thats on your and your equipment.
I will take my experience and work with people like the multi oscar winning Mr. Miranda over you. Heres why. If you are shooting in light sources that are not what the meter does best then its you issues to know what the spectral response of the film and meter are in relation what they where created and tested for in ISO. So its not really over exposing then is it? Its properly exposing for the spectral sensitivity of the film to that light source. If your meter is NOT designed to meter that light then it would be pretty dumb to count on that being accurate for that light. So You probably have to test to determine what those sensitivities are and the EXPOSE CORRECTLY. You know you can in many cases just use the right type of Grey card. I only have 3 types. Generic grey, Strobe card and a 3200 kelvin card. Then I have a chart of what strobe produce what value on each card that I use regularly as well as the same notes for hot lights, Keno's of most temp, Quartz, tungsten, Plasma (latest coolest thing developed by a friend of mines brother growing in popularity in the film world.)
sound card are accurate to 1/32,000th of a second. use a laser module or an LED, doesn't make any difference, as long as it's colimated to a spot - the only variable is a slight leap and drop with diffraction at the edges and yes I am most certain these cameras were as out as I found, Steve Hodges and I both tested a bunch of cameras and it surprised us both. most surprising was our T90's didn't rate compared the stack of old abused K1000's :)
Karl I don't know about that. When I worked in a camera store in College
we had a shutter speed tester we used to test all used cameras and customer
cameras in for service. I never saw any that where crazy like that. and
I have never seen any of my copal's be off by more then some insignificant
amount and its usually at the long range that they are off. My F5
electric shutter actually has a monitor in the camera that adjust it as it
ages. I know that shutter is/was because when I bought it I ran it on a
tester. All the way to 1/8000th. I think was off by some 10,000th. My
f3 last time it was tested was pretty much dead on as well. Most REAL
camera shops and for sure you repair shop will have a tester and you can
buy them online ebay for $100 bucks but I don't know how accurate they are
but they can go to 1/9999 from what I just found. What I do know is that
a lot of older testers only go to 1/1000th or 1/2000th.
Of course those suffering confirmation bias assured us their new Nikons were bang on perfect and the test gear must have been wrong.go ahead and run your own tests and plot the error factor against the stated shutter speeds, I think you'll be surprised. I built mine using a sound card as its cheap, and the sample rate was vastly superior to any unit you could buy in the day. Steve built his differently, they both agreed. I am always suprised how with the vast capabilities of personal computers available to most people that they are used so little in such ways. all that discussion about the best darkroom timers, contrast analyzers and such.. and yet every day PCs are thrown away because they're 'old'. ridiculous.
I'm sure on that old leaf lens is way out but I would have to see test that
showed the crap result for more then 1/3 stop failure on any shutter in a
respectable camera. Here are test done with a copal
And I am always keen to hear how people test leaf shutters since from their inception they were always recognised as being pretty crazy ..
let me explain. you have your shutter set to 1/125th of a second, your aperture is f45, the shutter begins to open and almost immediately it's allowing fully all the light through the tiny aperture, way before the shutter completes it's wide-open travel. Now you change your aperture to f2 (yes, I had a lovely f2 seiko 150mm 5x7 lens ) so you have to wait for the shutter to be fully open for your aperture to get the full amount of light through.. then it begins to close.
So which one got 1/125th of a second?
and what about at say f16 when there's a zigzag of shutter blades in the way for half the exposure?
see what I'm saying Rand? not so simple.. and each design is affected by the number of blades and the way which they open - and this differs even within a manufacturers designated brand name with different shutter sizes.
The timing test of a Copal #1 by Jean-David Beyer <jdbeyer@xxxxxxxxxxx> shows
that mechanical shutters are very accurate:
I haven't met Mt Beyer, I don't know his test methodology.
However, I agree mechanicals tended to be accurate. I postulated that the permanent magnets used in hybrids such as the F1N and pure electronics may wane in power from being slapped by the actuator (magnets dont like being hit) in the case of faster releases, and layers of lubricant gone sticky may cause the same parts to hold too long. Dont know for sure, but I do know when I service sticky / too-long exposure faults in modern cameras 80% of the time it's solved simply by wiping them with a solvent.might be good advice to those who'd do such a thing.
if you are using an SLR as your meter for large format make sure your
camera is set to adobeRGB.
On a similar note, not sure how your physics is, but selenium cell sensitivity has to be considered when shooting black and white film stocks since their peak sensitivity is away from that of (most) films. but then, the colour of the subject needs to be considered against the film sensitivity as well.. and so forth. I don't know what the current trend in sensors is for the most modern light meters - at one point it was phototransistors, next photodiodes (with peaks in the yellow), then there were 3 colour modules running comparators.. it's all guess work unless you custom build for specifics... or accept that there's always latitude in this sloppy photography world.you can argue that, Iand many others who rigorously test films would argue that getting away from the toe is a better idea. Most photographers don't/wouldn't test there film stocks, many wouldn't know how. I mean, how many pro's do you know who buy 'pro' film because it's 'pro'? conversely how many people do you know who buy blocks of any film and test them? I don't think I ever knew many people who owned sensitometric equipment..
I also don't agree about over exposing neg film. Usually when people
aren't getting exposure to start at base+fog its because you haven't
metered correctly or tested their film batch properly.
But back to why shoot off the curve? Why mess around at a curvey part of what will rapidly become a near linear rise in sensitivity? Trying to eek out the most 'speed' of a film is the only possible reason I could see as valid unless you were using a very tight film like E6. Deriding people for not shooting on the curve is silly. You've got the same gamma up the curve for quite a way - why put up with spotty dark colours where individual grains may/may not have geot enough exposure when you could give it a stop more light and get rich dense colours?
Remember Agfa's much admired Ultra film the 50 ASA with the super rich, dense colours? it wasn't a 50 ASA film. tested, It was actually a 16-180 ASA film (Ilford speed standard). But hey, they sold it and by marking it 50 ASA people 'over' exposed the film and got off the toe - subsequently they got deep rich saturated colours even down in the dark areas.yeah I always bough handfuls of random films and shot/tested them . If I liked them, I bought a block from the local suppliers fridge. cheap pro film. old trick.
Before we shoot a
movie with film we buy the whole movie worth of a batch and then put a hold
an addition 50% to 100% more.
no. see above. some people may do as you say. some people wold rather have denser, richer dark tones. all they are doing is sacrificing the 'speed' that so many people yearned for. Me, I coldn't give a rats for shooting 400 unless I wanted grain for grains sake (even then, 'over' expose a 400 and watch the gain all but disappear ) but most people seemed to love 400 for the speed.
Basically why people
over expose is because their meter is out and has been out and they never
tested their film.
heck, I rememeber being disgusted when I tested one particular 1600 E6 film that had become popular. Inside the box were instructions that it had to be pushed 2 stops to achieve the rated speed. Sorry, pushing does not increase the speed very much at all, it does however change the contrast and I didn't need to pay a premium rate to shift a films contrast!internegs should not mud up, development can/should compensate.. if not the development then the interneg film stock. I used a lot of black and white interneg stock, heck, I shot with it. (of course one has to TEST their film and development before you can go doing that..)
Their reason for doing this was you have a lot
of interneg steps and then prints so the highlights would mud up.
rubbish. please don't tell me you also go around telling folk selenium toning is good for prints?
but Its basically a wives tale.
that bit is true if you are using certain types of scanner with certain types of software. laugh. I remember the other lecturers were all in a pickle over the Nikon scanners inability to scan dense negs.. and I fired up Vuescan and got damned fine results.. 'oh noes! Wee can't use Vuescan.. it's not Nikon, and Nikon is the best!' laugh.
Especially now that you won't probably be printing directly from the
neg but getting is scanned. In that case the extra density in the
highlights will hurt more then help.
I still have my King Conceprt RP 2001 processor, my Hope RA4 24" RA4 machien and my Omega closed-loop 4x5 enlarger and I can mix and make my own chemistry easily enough.. heck, I made everything for the colleges E6 when the national supplier ran dry once.
My scanner is a Sharp JX610 so density is no issue at all. 3 colour pulsed xenon .. it may well take half the night to multipass scan a 8x10, but the result are more than worth it.
