100 Iso 135 = 400 Iso 120?

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Denton

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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
 
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.
 
6262673982_a05839c0a1_z.jpg


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

What do you mean by this?
 
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.
 
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.
 
"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!
 
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.
 
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.
 
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?
 
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
 
sanmich said:
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)
Click to expand...

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

Cheers,

Michiel
 
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?😉
 
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!
 
xenohip said:
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!
Click to expand...

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

Still Calculating...

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
 
OK, got DOF wrong.

OK, got DOF wrong.

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

Denton
 
f16sunshine said:
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.
Click to expand...

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!
 
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