T-Max 100 density and contrast

[alan_rockwood]

I have read in various posts that good T-Max 100 negatives should look thinner than negatives from old technology

films. My question is whether this carries over to densitometry readings, i.e. should a well exposed and well

developed T-Max negative give different densitometry readings than a negative from old technology films?

 

Another way to put it is this. If doing a film test for exposure and development what target values should I look

for in the curves as measured with a densitometer, and are they different from target values for conventional film?

 

Thanks.

[ronald_moravec1]

I never used a densitometer in my life except for school.

 

Yes they look a little thinner, but in order to print they have to match in density regardless of how they look.

 

What you need is a nice full range test target, develove the film and print it. If the whites and blacks come out, you are

home free. If not, 6 exposures on 35mm or another sheet developed longer or shorter will get you closer.

 

Once you have this, use the densitometer and you can use the readings to calibrate for zone system.

[daved1]

Question: should a well exposed and well developed T-Max negative give different densitometry readings than a negative from old technology films?

If both films are exposed in the same camera and development time is adjusted to get the same density reading (over base fog), I don't think there would be much of a difference.

This is just an opinion not tested by me.

[chris_waller]

Yes, they do. I remember the first time I processed a roll of TMX, and nearly freaked because I though the shadows were too thin. However, they printed up perfectly.

[frank.schifano]

They must be less dense overall, because my print exposure times are shorter with TMX than they are with conventional films of equivalent speed. That said, they print nicely and there is no lack of shadow detail in properly exposed negatives.

[profhlynnjones]

To begin with, looking at it visually means nothing. Only the sensitometry is meaningful.

 

World standard #2 paper has a density scale of 1.00 and requires a GBar of .50. Using Kodak's criteria which they foisted on ANSI some years ago with a #2 of 1.20 (formerly #1) , a higher GBar is needed. EK calls for a GBar of .55 while Ilford is at .60. They both like that because the increased development times result in slightly higher film speeds. I ignore them and use the international critera.

 

The practical speed point (not what ANSI talks about that even the manufacturers don't use) is a NET density of .70 in zone 5 (gross density less film base plus fog).

 

Since the last films to be made that have a "Straight Line" portion were Super XX and from Japan, Sakura SSS (Konica). In order to get an "Average Gradient" (we call it GBar) we draw a straight line from zone 2 to zone 8, or practically speaking normal, and minus 3 stops, and plus 3 stops. Draw the curve, draw the line and then decide how far off zone 5 is from 2 through 8. Determine the working film speed from the straight linne above or below the line. That becomes your working film speed while the GBar tells us the contrast. Do this from 3 widely separated points and everything is then known with some simple graphing.

 

Lynn

[alan_rockwood]

Dear Lynn,

 

Very interesting and potentially useful comments. However, I got a little lost starting at the point where you

said "... decide how far off zone 5 is from 2 through 8..."

 

Also, could you explain again how you determine the working film speed? Most things I have read base it on a zone

I density of 0.10 density units above base plus fog, but I think you are using a different method. As I read it

you base film speed on a zone V density of 0.70 density units above base plus fog with the proviso that there be a

certain specified contrast between zones II and VIII.

 

Your recommendation of net density=0.70 at zone V coincides with a suggested value for diffusion enlargers given

on page 77 of the book "The Ansel Adams Guide, Basic techniques of Photography, Book 2" by John Schaefer.

 

By the way, I have a densitometer, and my background is in science, so I appreciate quantitative information such

as this.

 

Thanks.

[nathancraver]

I don't know, but my T-Max 100 negatives look fairly dense to me, they look just like my T-Max 400. The only thin

negatives I've had so far were Tri-X 320, but all of the above print perfectly.

[profhlynnjones]

Hi Alan,

The curves really are curved, no real straight line in modern films. By drawing a line from 2-8 which are absolute limits of printable density, you determine the contrast (GBar). Because much of the time, the zone 5 area will be either above or below that line, at which point you increase or decrease the exposure. This will give perfect grey card density without affecting the contrast. We should always use "Net" density because the film base plus fog is very differnt for different films. Most 35mm films if unexposed and fixed will still have 2/3 of an f stop of density because there is no anti halation backing in virtually all 35mm films. There are slight differences in 120/220 films and sheet films so when you are quality controlling identical emulsions in three kinds of bases that has to be taken into consideration.

 

By the way, I knew Ansel from late 1957 or early 1958 until his death. I was also his contact when we (Calumet) sponsored his book on large format. We had lots of interesting conversations. By the late 60's or very early 70's he switched to an 8 step Zone system which he called Dynamic Range, still later he often worked with his friend Glenn Fishback's 7 zone system. None of these systems worked very well without altering exposure and development. The +/- sytem really only worked reasonably well at around ZV. Attaching some arbitrary ZI density doesn't work well since in all cases there can be not printable density there anyway. However if increases in deep shadow density are needed, Ansel's Zone 2 pre exposure will yield a 150% or more shadow increase while increasing the highlight density only 5 to 8% and while not changing other tones appreciably. I've done lots of testing with Zone 2, 3, &4 pre-exposure as well as "Water Bath" processing. Furthermore I was very lucky to have spent some time with Dr. C.E.K. "Ken" Mees (VP-Kodak Research, author "The Theory of the Photographic Process"). Ken had the remarkable ability to explain complex concepts to we less educated workers.

 

When examining many of the QC considerations, If using a full diffusion enlarger then you have to approach things differently. A true #2 paper has a DS of 1.00 in a condenser or condenser emulating enlarger. A full diffusion enlarger typically will thn yield a #2 DS of from 1.40 to 1.70 (traditional #0 to a bit less than #000 contrat). What most people do in those cases is pile up the density with 2 or 3 stops of over exposure at which point you lose some sharpnes and build lots of grain. Ordinarily, you could simply increase the contrast but unfortunately in most continuous tone films you can't practically get much more contrast than GBar .7 or .8 without using some horrible developer such as D19 or D11 which will foul everything else up.

 

Email me Alan and I'll send you a complete procedure since you have a densitometer and are scientifically inclined.

 

lynn at austincc dot edu

 

Best regards to all,

 

Lynn