100 Iso 135 = 400 Iso 120?

[Denton]

I know, confusing title. Basically, I love the fine detail of TMAX 100 in 135. I think 8x10 in this format/speed is equivalent to anything digital. My question is whether the increased format size in 120 at ISO 400 will give me the same fine detail that 100ISO gives me in 135?

Also, I've heard folks say 120 vs. 135 has superior tonal separations, myth or reality?

I'm seriously thinking of picking up the GF670 before the weekend since I think my Epson 750 would rather eat 120 than 135 BW!
Thanks!
denton

[Tom A]

I have been using Tmax-2 400 in 120, developed in HC 110, diluted 1:60 for 12.5 min. Grain is extremely fine - looks like a good 100 iso film. Less of a "primadonna" than the old style Tmax 400. Not as flexible as TriX/HP5+ - but worth the extra care. I use it with the Bessa III and Bessa 667W - mainly on AE.

[Tom A]

http://farm7.static.flickr.com/6153/6262673982_a05839c0a1_z.jpg

New York, last week. Bessa 667W and Tmax-2 400 in HC 110/1:60/ 12.5 min

[Tom A]

http://farm3.static.flickr.com/2646/4011432323_8d2c641005_z.jpg?zz=1

Bessa III, Tmax-2 400 in Pyrocat HD developer. This is probably the best "soup" for the Tmax-2 400, but a bit more sensitive to exposure, agitation etc.

[tomalophicon]

I know, confusing title. Basically, I love the fine detail of TMAX 100 in 135. I think 8x10 in this format/speed is equivalent to anything digital. My question is whether the increased format size in 120 at ISO 400 will give me the same fine detail that 100ISO gives me in 135?

Also, I've heard folks say 120 vs. 135 has superior tonal separations, myth or reality?

I'm seriously thinking of picking up the GF670 before the weekend since I think my Epson 750 would rather eat 120 than 135 BW!
Thanks!
denton

What do you mean by this?

[f16sunshine]

Thanks for the samples Tom. I love the Tmax-2 400 in 120 as well and develop it mostly with Tmax dev (or Rodinal if I want it to look a bit more rustic). I'm curious about your comment since I have never tried Pyrocat HD. Do you think the results are comparable to using Tmax Dev? Is the grain finer or tones smoother using Pyrocat ? Thanks for the reply.

[pvdhaar]

100 Iso 135 = 400 Iso 120?

In my experience, yes. Not only for detail, but also for exposure lattitude. Rollfilm is much more forgiving when it comes to underexposure, so you can get away with the same number of stops between 100 Iso 135 and 400 Iso 120.

[jpberger]

"whether the increased format size in 120 at ISO 400 will give me the same fine detail that 100ISO gives me in 135?"

Quite likely, if not more,-- but the real point is better tonality

"Also, I've heard folks say 120 vs. 135 has superior tonal separations, myth or reality?"

Big time!

[Ezzie]

I agree. But of course depending on how much you enlarge. If you enlarge to the same size, 120 400 ISO outperforms 135 100 ISO (same emulsion), both wrt grain and to a greater degree tonality.

[Roger Hicks]

100 Iso 135 = 400 Iso 120? Yeah, pretty much, from a grain point of view. The tonality will be different, though. Most people would probably prefer the ISO 400 120 tonality.

Cheers,

R.

[sanmich]

I am wondering the same thing.

I don't feel comfortable with medium format.
I use a Tri-X fed koni omega system very seldom for the occasional landscape.
I feel TX is a must because of the smaller apertures and what I feel a lower stability during the shutter release (compared to a Leica with soft release)
I was thinking that maybe delta 100 behind a good lens could be a good replacement in terms of resolution. I know that the DOF effect is not comparable, but I don't care too much.
Did anyone ever reach a conclusion about this?

[Michiel Fokkema]

If you print at the same size I'd say yes, more or less.
But there is also less DoF in MF so you probably need the increased iso to offset the lower shutterspeed. Tonality in MF is superior.

Cheers,


Michiel

[Ezzie]

Boring thread, we all agree. ;)

[Michiel Fokkema]

I am wondering the same thing.

I don't feel comfortable with medium format.

I feel TX is a must because of the smaller apertures and what I feel a lower stability during the shutter release (compared to a Leica with soft release)


Really depends on your camera. A leaf shutter without reflex mirror will even be more stable then a Leica shutter.

Cheers,

Michiel

[sanmich]

ok, just to make a fool of myself, I tried to play with numbers I don't understand,namely film RMS.

Tmax 100 is announced at RMS=8, while TX is 17.

a 6x9 neg requires ~2.5 less enlargement than a 35mm frame, thus it seems that in terms of grain effects, a TX on 6x9 has much more grain than a tmax 100 frame in 35mm (each RMS unit multiplies whatever is measured in the grain by a factor of two, right?)

Now that I have made clear that I understand nothing about that stuff, can someone correct me so we learn something today?;)

[xenohip]

This is IMHO a very interesting question, and leads to a general principle that might be called "depth of field invariant image quality".

A 35mm normal lens ~45mm at f5.6 will give the same depth of field as a medium format normal lens ~80mm at f11, and as a 4x5 ~150mm lens at f22. If you take three images on ISO 100, 400 and 3200 film in the three formats with apertures adjusted to equalize depth of field, your shutter speeds will be equal, your field of view and perspective will be equal, and I believe your image quality will be approximately equal as well-- grain, tonality, sharpness, etc.

So if you adjust aperture to equate DOF across different formats, and make the necessary adjustment in ISO to give equal shutter speed, the image quality will be roughly equivalent. The perspective, DOF and motion blur from the shutter will be equal and the images will be, in rough terms, identical.

This can be extended to digital. A Canon S95 at 10mm f2.8 and 7D at 30mm f8 and 5DmkII at 45mm f11 all have the same DOF. If you shoot at ISO 100, 800 and 1600 respectively to equalize the shutter speeds, I believe that again you will get approximately equivalent image quality, and thus (roughly) identical images.

If you go along with all of this (I pretty much do-- it's one of two main reasons that I stopped shooting medium format, along with the fact that a large number of my favorite images were shot on delta 3200 in 35mm format anyway, and an even larger number have the characteristic that image quality per se plays almost no part in the strength of the images) then you can translate image quality to an f-stop scale. This allows one to say, for example, that digital color is about 2 stops better than film color but digital color converted to B&W is a stop or two behind B&W film.

True digital B&W without bayer demosaic, without anti-alias filters, without color filters on the sensor elements, etc. would be in a different league entirely, but the camera manufacturers don't seem to see the opportunity there, and that's a subject for a different thread anyway!

[besk]

This is IMHO a very interesting question, and leads to a general principle that might be called "depth of field invariant image quality".

A 35mm normal lens ~45mm at f5.6 will give the same depth of field as a medium format normal lens ~80mm at f11, and as a 4x5 ~150mm lens at f22. If you take three images on ISO 100, 400 and 3200 film in the three formats with apertures adjusted to equalize depth of field, your shutter speeds will be equal, your field of view and perspective will be equal, and I believe your image quality will be approximately equal as well-- grain, tonality, sharpness, etc.

So if you adjust aperture to equate DOF across different formats, and make the necessary adjustment in ISO to give equal shutter speed, the image quality will be roughly equivalent. The perspective, DOF and motion blur from the shutter will be equal and the images will be, in rough terms, identical.

This can be extended to digital. A Canon S95 at 10mm f2.8 and 7D at 30mm f8 and 5DmkII at 45mm f11 all have the same DOF. If you shoot at ISO 100, 800 and 1600 respectively to equalize the shutter speeds, I believe that again you will get approximately equivalent image quality, and thus (roughly) identical images.

If you go along with all of this (I pretty much do-- it's one of two main reasons that I stopped shooting medium format, along with the fact that a large number of my favorite images were shot on delta 3200 in 35mm format anyway, and an even larger number have the characteristic that image quality per se plays almost no part in the strength of the images) then you can translate image quality to an f-stop scale. This allows one to say, for example, that digital color is about 2 stops better than film color but digital color converted to B&W is a stop or two behind B&W film.

True digital B&W without bayer demosaic, without anti-alias filters, without color filters on the sensor elements, etc. would be in a different league entirely, but the camera manufacturers don't seem to see the opportunity there, and that's a subject for a different thread anyway!

Those are good points. Thanks for making the effort to equate the differences of the different formats.

[Denton]

Thanks for the input Tom. That Manhattan shot look suspiciously close to a very large and excellent camera store, perhaps only a 0.7 mile walk due west?

I'll have to do more research to figure if the math works out, but the impressions are positive. Of course, composition and subject trump grain and technical detail, at least in my book.

OK, am I correct in figuring the 80mm GF670 at 6x7 will have a horizontal FOV of 39 degrees and at 10 ft subject distance we are talking 2ft DOF at max aperture of f3.5. The equivalent in 35mm seems like a 50mm lens at 5 ft would have the same image size, but DOF now would be 2ft only at f11. Or have I made an error? I"m wondering how a MF performs DOF wise when he same image size is projected on the film.
Denton

[Denton]

I realize my error in calculating decreased DOF for same images size, 135 relative to 120.

Denton

[Tom A]

Thanks for the samples Tom. I love the Tmax-2 400 in 120 as well and develop it mostly with Tmax dev (or Rodinal if I want it to look a bit more rustic). I'm curious about your comment since I have never tried Pyrocat HD. Do you think the results are comparable to using Tmax Dev? Is the grain finer or tones smoother using Pyrocat ? Thanks for the reply.

The Pyrocat HD gives the impression of better sharpness, grain is not super fine but with something like 120 film - you really dont notice it. It is a bit more finicky to develop than plain old HC 110/D76/Rodinal etc - I tend to go in Pyrocat "kicks" and do a couple of 100 rolls with it and then go back to more normal "soups" Haven't had one of those urges for a while - maybe in the spring!

[xenohip]

One more note on the image quality invariance: DOF scales according to the absolute physical dimension of the aperture, for a given angle of view. The 40mm lens at f4 on 35mm format and the 80mm lens at f8 on medium format both have an aperture dimension of 10mm diameter (at least in simple, if not compound, lens terms). Therefore both lenses gather the same amount of light per unit time. If the ISO of the capture medium is adjusted to equalize the shutter speeds (i.e. 100 ISO 135 = 400 ISO 120) then the two images are formed from an equal number of photons. It makes good sense that the image quality would be similar.

[semilog]

ok, just to make a fool of myself, I tried to play with numbers I don't understand,namely film RMS.

Tmax 100 is announced at RMS=8, while TX is 17.

a 6x9 neg requires ~2.5 less enlargement than a 35mm frame, thus it seems that in terms of grain effects, a TX on 6x9 has much more grain than a tmax 100 frame in 35mm (each RMS unit multiplies whatever is measured in the grain by a factor of two, right?)

Now that I have made clear that I understand nothing about that stuff, can someone correct me so we learn something today?;)

Note that RMS is a measure of grain, not resolving power.

For resolution you need to look at the film's MTF data. TMAX100 is indeed spectactular, Fuji ACROS is equivalent, and I'd venture to guess that Delta 100 is right in there with the others. Assuming that the camera is held stable and shutter/mirror movement are well-damped, the next most important cause of image blur is usually inaccurate focus. After that, it's film flatness. 35mm generally does better than MF for flatness, which helps 35 to close some (but not all) of the gap with MF. Another thing that can wreck 35mm sharpness is overexposure/overdevelopment. Thin negatives are generally sharper. This is often overlooked.

Assuming you've got all of that under control, you then need to get the detail back out of the negative. It's a lot easier to get good enlargements from MF negatives than from 35mm, but with good gear and technique it can be done. Holding the film flat is critical. I love the half-glass carrier for the V35 enlarger.

If you're scanning, MF wins again, and in a big way.

Really it's at the enlarging/scanning stage where MF has the biggest advantages. But 35 can be awfully good with exacting technique. Here's one of my better examples: ACROS developed in XTOL 1+1, scanned on a Polaroid 4000. Click on the picture to see bigger versions of same. Note that scanning tends to accentuate grain vs. enlargements, one reason why MF scans look better than 35. A drum scan would be better, and a good enlargement better still. Even so there is a lot of detail in this image.

My impression of carefully-handled ACROS is that it can approach the quality of Tri-X or HP5 shot on 645 format. TMAX400-2 on 645 would probably be superior. Soon I'll be out of Neopan 400, and ACROS and TMAX400-2 will be my exclusive choices for 35mm B&W.

http://semilog.smugmug.com/Travel/Santa-Cruz-Aug-2010/20100903-scan681/994319497_RX5Cf-L.jpg (http://semilog.smugmug.com/Travel/Santa-Cruz-Aug-2010/13626334_HsBK4D#994319497_RX5Cf-A-LB)

[Denton]

On reflection, someone's head projected onto the film plane with an 80mm lens is the same whether it's MF or 35mm film. The film and image are the same as well as the DOF if the subject-lens distance does not change. But, I need to get half the distance with MF to fill the frame to the same degree, so that's the difference. I can ignore most of the math.

The critical thing is how large, in real dimensions, will the image take on the film plane.

[sanmich]

Note that RMS is a measure of grain, not resolving power.


Isn't the grain size the only thing limiting the actual image resolution on the film?

A lot of detail in this shot indeed.
handheld?
RF or SLR?

[semilog]

Isn't the grain size the only thing limiting the actual image resolution on the film?

No, because the specific way in which the grain clumps has huge effects on both resolution and perceived sharpness. That's why Kodak and Fuji provide information about both grain (RMS) and modulation transfer (related to resolution). There's a big literature on this subject. For digital cameras, Falk Lumo has written a beautiful and terse (though somewhat technical) summary of what image sharpness (http://www.falklumo.com/lumolabs/articles/sharpness/index.html) is. The bottom line is that edge effects added by either signal processing or film chemistry and grain geometry (which should be seen as a form of signal processing) can alter both the MTF response and the perceived sharpness.

Kodachrome was sort of a poster child for edge effects that gave it very high resolution and extremely high perceived sharpness despite having more grain than some competing slide and negative films. This is a major reason why I loved Kodachrome.

Here's an example of huge grain and high perceived sharpness: Delta 3200, exposed and then forgotten in a box stored in an attic for over ten years, then developed in XTOL. Again, click for bigger versions.

http://semilog.smugmug.com/Street/Streetphotos/20100807-scan526/962065855_TtNtk-S.jpg (http://semilog.smugmug.com/Street/Streetphotos/4684443_WJ5V82#962065855_TtNtk-A-LB)

See also the Wikipedia entry for acutance (http://en.wikipedia.org/wiki/Acutance).

A lot of detail in this shot (the shot of Lick Observatory, above) indeed. handheld? RF or SLR?

Handheld M6 and 35/2.8 C Biogon. Probably f/5.6 or 6.3 at 1/1000 on a very bright, clear summer day in central California.

[Turtle]

120 (6x7) TriX or HP5 is grainless on a 8x10 and I would roughly say that both can be broadly comparable to a fine grained 100 film, like D100. I prefer the look of the former most of the time, however. A 'lowly stressed' big neg from an old emulsion always seems to look better to my eyes than the ultra low grain films. I just dont like modern films much.

Also, the comment earlier about 120 film having more exposure latitude confused me. I don't find this to be true at all - they are the same if the enlargement factor is the same. In terms of what ends up on film, there is no difference that I have noticed.

[pvdhaar]

Also, the comment earlier about 120 film having more exposure latitude confused me. I don't find this to be true at all - they are the same if the enlargement factor is the same. In terms of what ends up on film, there is no difference that I have noticed.
When the enlargement factor is the same, then you're absolutely right. It's just that you don't have to enlarge 120 the same amount to get to a specific print size. And there lies the catch. The lower magnification factor required means that especially shadow areas remain cleaner..

[Turtle]

I'm still not sure I agree with you or understand how this can be so. Shadow areas surely respond no differently in any format and even tho 120 is enlarged less, I do not see what qualitative effect this has on shadows in the context of latitute. If they are overexposed they are printed down, if under, they are going to look bad regardless of format, surely?

When the enlargement factor is the same, then you're absolutely right. It's just that you don't have to enlarge 120 the same amount to get to a specific print size. And there lies the catch. The lower magnification factor required means that especially shadow areas remain cleaner..