Film Testing Results (120 T-Max400) Suggestions?

[Todd Barlow]

I have a Mamiya TLR camera with a 55, 80, 135mm. I have done 3 rounds of film testing with the following results.

Round 1 EI - Densitometer tested, no frames with a density near 0.1 (I had set up the test expecting the EI to be less than the ISO400 rating)

Round 2 EI - Densitometer tested, closest frame was closer to 0.1 which gives an EI of something greater than EI800.

Round 3 EI - Densitometer tested, 0.1 + fb + f gave:
EI for T-Max 400 with 55mm = EI 1600
EI for T-Max 400 with 80mm = EI 1200
EI for T-Max 400 with 135mm = EI 1600

55mm film test @ 1/125 (shutter tested and found to be 1/90 all other speeds okay)

80mm film test @ 1/125 (shutter tested and found to be 1/90 all other speeds okay)

135mm film test @ 1/60 (all shutter speeds okay)

Film processed for recommended time in fresh one shot T-Max developer. Film was fresh as well, processed right after shooting the test exposures. Metering was done with a Pentax SpotmeterV.

I expected the shutters to be very slow based on the EI test results, but with the shutters being tested I am at a loss to explain why the EI's are so high.

Any suggestions or comments would be appreciated.

Todd

 

[photobackpacker]

I agree, this is not a result I would expect. Generally, you would expect to see tmax 400 ei to come in around 320 or 250.

Tmax gains or loses very little speed with variation in development process so we can eliminate that as a consideration for the moment.

If I had to make a guess, I would be suspicious of your shutter. You don't say where you live - are you performing the testing outside in cold weather? The variation in shutter speeds you are seeing make me suspicious that your shutter is slow - or inconsistent.

If consistently slow, no problem. I would use the 1200 ei and shoot away. If inconsistent - you have some cleaining/repair work in your future.

I would recommend going out and shoot some real world subjects having a full range of contrasts. Shoot a roll at an EI of 1200 shooting the same subject across the range of shutter settings and aperature. See what you get. It will be revealing and is certainly more entertaining than film testing.

 

[Paddy]

Todd, maybe you could provide a brief review of the methodology for your test.
i.e. Were you inside using 2 blue Photofloods or tungstens, w/ grey card, w/lights at 45deg. angles as in copy art set-up?
Or,... were you outdoors on sunny day, 12 noon, facing north side of building, very open shadow, w/ grey card or even surface?
Did you stop down 4 stops from indicated meter reading to get your Zone I?
What were your actual density readings?

Just asking, so that we can understand your path to results.

 

[Todd Barlow]

Thanks for your feedback.

Based on my earlier test results I thought the shutters must be to blame so I had all three tested.

All speeds on the 55mm tested perfectly except the 1/125 which fired at 1/90.
All speeds on the 80mm tested perfectly except the 1/125 (fires at 1/90), 1/250 (fires at 1/200) and the 1/500 (fires at 1/250)
All speeds on the 135mm tested perfectly.

Again I appreciate any comments.

Todd

 

[Donald Miller]

How did you do this testing? Did you have the lenses focused at infinity? Did you photograph a evenly colored textureless surface? How did you define the EI test exposure?

 

[Todd Barlow]

Todd, maybe you could provide a brief review of the methodology for your test.
i.e. Were you inside using 2 blue Photofloods or tungstens, w/ grey card, w/lights at 45deg. angles as in copy art set-up?
Or,... were you outdoors on sunny day, 12 noon, facing north side of building, very open shadow, w/ grey card or even surface?
Did you stop down 4 stops from indicated meter reading to get your Zone I?
What were your actual density readings?

Just asking, so that we can understand your path to results.

Thanks for your feedback.

- the last set of tests were done inside using the light from the patio doors
- cloudless day outside
- metered against a solid tone card
- tested the evenness in all four corners with the meter
- metered the card picked 1/125 as shutter speed and closed lens 6 stops (to give Zone 1 less 2 stops) exposed and then opened up lens in 1/2 stop increments until I was at Zone 1 plus 2 stops
- Density readings for the 80mm lens are shown below
- Zone V meter reading 1/125 f between 2.8-4
- 1/125 f between 22-32 density .06 (Zone 1 less 2 stops = EI 1600)
- 1/125 f 22 density .10 (Zone 1 less 1 1/2 stops = EI 1200)
- 1/125 f between 16-22 density .18 (Zone 1 less 1 stop = EI 800)
- 1/125 f 16 density .24 (Zone 1 less 1/2 stop = EI 600)

I would appreciate any additional comments you may have.

Thanks

Todd

 

[Todd Barlow]

How did you do this testing? Did you have the lenses focused at infinity? Did you photograph a evenly colored textureless surface? How did you define the EI test exposure?

- Lens at infinity
- I photographed a 20 by 24 dark blue sheet of bristol board
- I filled the frame and metered along the lens axis
- I have listed my exposures and the densities they generated in my previous post (not sure if that would answer your question about how I define the EI test exposure, if not let me know)

Thanks for your help

Todd

 

[photobackpacker]

Todd-

From metered setting, you need close down 4 stops to give you a Zone I

Secondly, a leaf shutter at 125th with lens aperatures of f16 or smaller will cause a 1/3 stop over exposure. I think you have a couple of things working against you here.

Are you explosing the rest of the roll at Zone VI?

 

[Donald Miller]

quote:
"- metered the card picked 1/125 as shutter speed and closed lens 6 stops (to give Zone 1 less 2 stops) exposed and then opened up lens in 1/2 stop increments until I was at Zone 1 plus 2 stops
- Density readings for the 80mm lens are shown below
- Zone V meter reading 1/125 f between 2.8-4
- 1/125 f between 22-32 density .06 (Zone 1 less 2 stops = EI 1600)
- 1/125 f 22 density .10 (Zone 1 less 1 1/2 stops = EI 1200)
- 1/125 f between 16-22 density .18 (Zone 1 less 1 stop = EI 800)
- 1/125 f 16 density .24 (Zone 1 less 1/2 stop = EI 600)"

My response:

O.K. if you are using a Pentax spot meter the Zone V should be a lot more defined then 1/125 between 2.8 and 4. That is a whole stop of variation and your spot meter will give you 1/3 stop readings.

So if we assume that your meter indicated F4 then if you closed the lens down by seven stops as you indicated then that would be F 32 at 1/250 second not F 32 at 1/125 second. You have made a one stop miscalculation in that result.

It might prove beneficial to review your calculations and use your meter to determine the correct Zone V exposure down to the 1/3 stop (it is capable of more precision then one stop variance) that it is capable of showing you and then make the correct calculations.

 

[Paddy]

Ditto to what Donald mentioned. This is why I tend to recommend using 500w blue photofloods, because with controlled lighting, one can inch the lights back and forth until you create exactly the meter reading you want to start with i.e. f/2.8 on the nose. A Sekonic offers even finer readings in 1/10 stop increments, but I use either this or a Pentax digital, now that the Sekonic has been corrected to the Pentax.

Lastly, could you clarify whether or not your density measurements are net readings. (i.e. less fb+f)

The general experience of most of my students for this film in 35mm, has been a speed of between 125-160, and only very occassionally 400 on the nose.

 

[Kirk Keyes]

- I photographed a 20 by 24 dark blue sheet of bristol board

I would suggest that your dark blue board is not close to Zone V. That's why you have the weird film speeds.

You should get a grey board that meters as close to a 18% grey card as possible and try your tests using the grey board as your target.

Kirk - www.keyesphoto.com

 

[Paddy]

Kirk, I don't think that the colour of the board has anything to do with the meter readings, other than to influence one's choice of exposures. Everything a meter is pointed at is 18% grey, as far as the meter is concerned.

There is something else going on here, that isn't entirely eveident. It's usually a case of "lost in translation", especially so when we're communication through this text/forum process.

 

[Todd Barlow]

quote:
"- metered the card picked 1/125 as shutter speed and closed lens 6 stops (to give Zone 1 less 2 stops) exposed and then opened up lens in 1/2 stop increments until I was at Zone 1 plus 2 stops
- Density readings for the 80mm lens are shown below
- Zone V meter reading 1/125 f between 2.8-4
- 1/125 f between 22-32 density .06 (Zone 1 less 2 stops = EI 1600)
- 1/125 f 22 density .10 (Zone 1 less 1 1/2 stops = EI 1200)
- 1/125 f between 16-22 density .18 (Zone 1 less 1 stop = EI 800)
- 1/125 f 16 density .24 (Zone 1 less 1/2 stop = EI 600)"

My response:

O.K. if you are using a Pentax spot meter the Zone V should be a lot more defined then 1/125 between 2.8 and 4. That is a whole stop of variation and your spot meter will give you 1/3 stop readings.

So if we assume that your meter indicated F4 then if you closed the lens down by seven stops as you indicated then that would be F 32 at 1/250 second not F 32 at 1/125 second. You have made a one stop miscalculation in that result.

It might prove beneficial to review your calculations and use your meter to determine the correct Zone V exposure down to the 1/3 stop (it is capable of more precision then one stop variance) that it is capable of showing you and then make the correct calculations.

Donald:
Unfortunately the one thing I did not record was the EV numbers that the meter generated. The Zone V meter reading of the bristol board resulted in an exposure that I selected for Zone V of 1/125 @ an aperture of exactly between f 2.8-4. The Mamiya 80mm does not have 1/2 stop "clicks" so I set it halfway for the exposure.

I had worked out my exposures in a spreadsheet in advance, so I chose the Zone V exposure of 1/125 at between f2.8 and 4 (f2.8 less 1/2 stop or f4 plus 1/2 stop) to be able to maintain the same shutter speed while only having to adjust the aperture.

With that Zone I became 1/125 with aperture set between f16 and f11. I went two more stops to actually start my test exposures to Zone I less 2 stops or 1/125 with the aperture set between f22 and f32.

Did I miss something?

Thanks for your continued help.

Todd

 

[photobackpacker]

Todd:

At what ASA was your meter set?

 

[Todd Barlow]

Todd-

From metered setting, you need close down 4 stops to give you a Zone I

Secondly, a leaf shutter at 125th with lens aperatures of f16 or smaller will cause a 1/3 stop over exposure. I think you have a couple of things working against you here.

Are you explosing the rest of the roll at Zone VI?

Based on the previous tests I needed to start at more than 4 stops so I started at Zone I less 2 additional stops and exposed 9 frames at 1/2 stop intervals until I ended at Zone I plus two stops, the remaining roll had a title page, and 2 blanks for the fb+f measures.

Is there more guidance about the use of small apertures at shutter speeds higher or lower than 1/125. I am not aware of these adjustments that I should be considering.

Thanks again

Todd

 

[Todd Barlow]

I would suggest that your dark blue board is not close to Zone V. That's why you have the weird film speeds.

You should get a grey board that meters as close to a 18% grey card as possible and try your tests using the grey board as your target.

Kirk - www.keyesphoto.com

Kirk:
Thanks for your reply, I had read that the actual colour was not important as long as it was evening lit and was even in texture and colour since the meter would provide an exposure that would result in a Zone V exposure.

Thanks again

Todd

 

[Todd Barlow]

Todd:

At what ASA was your meter set?

Bruce:
To meter the card for the Zone V I set the ASA at 400.

Thanks

Todd

 

[Kirk Keyes]

[...] I had read that the actual colour was not important as long as it was evening lit and was even in texture and colour since the meter would provide an exposure that would result in a Zone V exposure.

Kirk, I don't think that the colour of the board has anything to do with the meter readings, other than to influence one's choice of exposures. Everything a meter is pointed at is 18% grey, as far as the meter is concerned.

There are a couple of reasons a strongly colored board would not make a good target.

First - The color of a target has everything to do with meter readings. The spectral response of your meter will have a bigger affect on the accuracy of your readings if you are using a target that is strongly colored.

I just recently checked several meters using a spectrophotometer as a light source, and 2 of the 4 meters I checked dropped off in response much faster than the other 2 when one measured light in either the red or blue regions. All were very similar (i.e. flat) in thier response to green light. So I might agree that a greenish target may be a good choice, but not a red or blue one.

Second - "Everything a meter is pointed at is 18% grey" That's a good point, so once your meter has converted the reading of your dark blue board into 18%, what correction did you make to correct your meter reading into the Zone that the board actually is? And how did you determine what Zone is the dark blue board. Is it Zone I, II, or III?

If your initial Zone V metering is done off a board that is lighter or darker than Zone V, then your film speeds will be off as well. Isn't that the problem that is going on here? If you are convinced that the color of the board makes no difference and you know the difference in reflection (Zone) between the dark blue board and an 18% grey card, then you could make a correction to the film speed.

I suggest repeating the test with a card that is closer to 18% grey in both color and reflectance.

Kirk - www.keyesphoto.com

 

[nworth]

I'm not really surprised by the differences. First, it's only a third of a stop, which could be experimental error. More likely, the lenses differ in their light passing qualities. This is not unusual. The calibration of the f stops can be off, the coatings may differ, the number of elements and flare can affect the speed test. You may want to check again with a different film and see if the results are consistent.

 

[Peter De Smidt]

I'm going to agree with the idea that 1/3 stop variation isn't that unusual. Not only do shutters vary from one exposure to the next, f-stop settings can as well. Moving the lens from f4 to f8 can lead to a slightly different result than moving from F16 to f8, at least I've noticed this with my enlarging lenses.

I also agree with Kirk: meters and various films have different spectral sensitivities, and using a strongly colored card can throw things off.

The temperature of the light is also very important, since the higher the color tempature the more actinic the light is, at least usually.

All of these small variations can add up. I recommend being conservative in film speed rating. .1 above fb+f is the minimum for zone one. I'd recomend giving at least 1/2 stop more. That way even if your system gives a little less exposure than normal, you'll still have pretty good shadow density.

 

[Todd Barlow]

Film testing update:

I have redone my testing and would again appreciate your feedback:

-Camera: Mamiya C330
-Lens: Mamiya 80mm f2.8 (black version with blue dot)
-Focus: set at infinity
-Meter: Pentax Spotmeter V complete with fresh batteries, set at ASA400
-Density Readings: Used the spotmeter method looking for a frame that read 1/3 EV less than the EV reading of the blank exposure
-Film: Kodak 120 roll film, T-Max 400
-Film exposures: entire roll exposed with title page, 2 blanks and 9 test shots
-Developer: Fresh one shot T-Max developer
-Subject: Kodak 18% reflectance grey card
-Subject lighting: shot indoor, full shade, same meter reading in each corner
-Subject meter reading: EV 6 1/3 = Zone V, 1/60 @ f2.2 (f2.2 = f2 less an additional 1/3 stop)
-Exposure for Zone I: 1/60 @ f9 (f9 = f8 less an additional 1/3 stop)
-Shutter speed: 1/60 used for all exposures, shutter tested 1/60 = 1/60
-Density of blank exposure: 10.89
-Looking for Density of Zone I: 10.56
-Exposure that has a density of 10.56: 1/60 @ f12.3 (f12.3 = f11 less an additional 1/3 stop)
-EI that relates to 1/60 @ f12.3: EI800, which is one stop less than the calculated Zone I exposure = 1 stop faster than Kodaks rating

-Also tested a roll of Ilford FP4+ with following results: EI320 = 1 1/3 stop faster than Ilfords rating

I have learned a tremendous amount about film, exposure etc however I still can not explain why the EI I come up with is a stop faster when the shutter speeds have been checked and found to be accurate. At first I was convinced that I had made some error but the more a retest the more I am convinced that the EI for this lens, meter and film combination is a full stop faster than Kodak's ASA rating and faster than most peoples results. The exposures that I have taken are improving with each experience and I think I will now start to move on to testing for developing time.

Your observations are appreciated.

Todd

 

[photobackpacker]

Todd:

The methodology appears to be sound. Is there a photo shop with a desitometer that would be able to check your densities for you? If not, PM me and I will send you my address. I would be happy to check and record the densities on my McBeth and send them back to you. I think this might be worthwhile. We need to get you out of film testing and out shooting!

Bruce

 

[nworth]

I'm having a hard time interpreting your density values. They do not appear to be conventional density measurements. They look a bit like raw transmission measurements. If that is the case, the density you are using for the Zone I value is somewhat less that what would be expected, which would be somewhere around 8.7. (A density of 0.1 corresponds to about 79 percent transmission.)

 

[Paddy]

I'm having a hard time interpreting your density values. They do not appear to be conventional density measurements.

I'll second this comment. Let's step back again. Your densitometer; what's the make/model, and when was it last calibrated?

Again, as per nworth, your density targets seem a wee bit unusual. In agreement with Hutchings, Barnbaum, etc, I also recommend placing Zone I net density between .10 to .20 above fb+f. A slightly higher Z. I density ensures that shadow densities are placed off of the toe off of the film. i.e. better tonal separation of the shadows.

Only once or twice have I seen an effective personal E.I. with this film above the manufacturer's rated 400 ASA, and even then it was only about 1/3 stop more. As I've previously stated, an e.i. of 125 - 200 is much more the norm for T-Max 400. Still not sure what's going on here.

One last thing: I'll again suggest using controlled lights (500W blue photofloods) in relector bowls. That way you can precisely dial in the exact amount of light for your initial (Zone V) grey card meter reading to give you a whole f/stop, instead of guesstimating fractional f/stops on the lens.

My .02 cents, FWIW.

 

[Ray Heath]

surely this has been done many times, why not go out and take real photographs in the real world