Compiled by Q.-Tuan Luong for the Large Format Page
Richard Knoppow (firstname.lastname@example.org) Where the same emulsion is used for both roll and sheet films the resolution is the same. Coating thickness is about the same on both types, its the support which is a lot thicker on sheet film. This is of no consequence for scattering or loss of resolution. Some films do have thinner emulsions, Technical Pan, for example, but again, the emulsion thickness is the same regardless of the format. Film has gotten good enough so there isn't a big jump in quality between 6cm x 6cm and 4x5 as there was in the past. There is still a big jump between 35mm and 6x6 but there used to be another just about as great when going to 4x5, no longer, at least for reasonable size prints. You can still see the difference for prints larger than about 11x14 its just not a stunning as it was many years ago. From: bg174@FreeNet.Carleton.CA (Michael Gudzinowicz) A couple years ago, I compared a few lenses for the 35 mm and 4x5 formats, and the Mamiya 50, 65, 100 and 150 lens (newer models with most recent "M" backs). All negatives were shot on TMX and were of the same scene, and enlarged to 5x7, 16x20 and for 120 The results were somewhat predictable. All were sharp at low magnifications, with granularity detectable at 5X magnification. When the negatives were enlarged to 16x20, most of the 35 mm shots were sharp, though grain detracted from even tone grey areas. All of the Mamiya prints were very sharp, and granularity was just detectable, if you know where to look and had prints from ed Tessars - perhaps unexpected, but present). The visible difference between modern 4x5 lenses and the Mamiyas was minimal. If the Mamiya prints had been enlarged with a diffusion head rather than condenser, they would have been nearly indistinguishable. At 30x40, the modern 4x5 lenses, Mamiya 50 f/6.3 and 100 f/3.5 (last model; all black using 55mm filters) were still sharp when closely examined - granularity was apparent in the MF prints, but wouldn't be noticed at anything resembling a normal viewing diportion of typical handheld 35 mm enlarged to 8 to 11X. The apertures used were f/8 for 35mm; f/11-16 for MF and f/22 for LF. I hadn't cleaned the inner surfaces of the Mamiyas for some time, and performance should be better after removing oil deposited from the shutter. Almost invariably, I've found the 50, 10ilm, and by shooting with less wind (it was a problem). After all of that, the MF and LF results are very similar up to 8x10 or 11x14; at 16x20 modern LF lenses have a slight edge due to reduced granularity and high contrast; above that, modern 4x5 wins due to granularity, though the other lenses are still usable (similar to 35 mm at 16X). I'm accustomed to 8x10 and 11x14 contact prints, and although I don't use those formats any longer, I rarely print larger than 8x10 or 11x14 form 4x5, so "sharpness" is a non-issue for me, despite the emphasis of the post. I'd suggest that you run similar tests on your lenses, and I'd suggest cleaning the surfaces of the cells near the shutter before testing since evaporated oil accumulates over the years, and isn't visible looking through the lenses. Also, use a 10x loupe on the ground glass of the Mamiya or view cameras for focusing. The black Super 23 I used resembles the last of the Universals, but it has 15 degree swings and tilts. The 100 f/3.5 retracts for full movements at infinity focus, and the 150 and 250 have more than sufficient depth of field at their hyperfocal distances tor instance, the 50 on 6x9 is equivalent to a 50 mm shift lens on 6x6 moved 15 mm. Also, the 50 is sharp enough to print a 1 x 3.25" "panorama" offset from center to correct perspective (equivalent to a 20 mm lens field of view in the 35 mm format). All of the Mamiya lenses have minimal distortion (if any) - the 50 is a Biogon design and 65 is a Topogon - both aerial mapping lenses. -------------------------------------------------------------------- From: email@example.com (Barry Sherman) As empirical confirmation of what Michael says, I'll offer my own observations. A friend uses a Pentax 67 for landscape work and I've been consistently impressed with the sharpness and overall image quality that he can achieve with that camera. At 16x20 I usually think that my 4x5 images do, on average, have an edge, but it's not huge and can be easily offset if my taking technique is off at all. And I've seen work done with the monster Fuji 6x8 SLR which is even more impressive. I've seen 20x24's from those 6x8 transparencies which I do think come very close to what I could do with 4x5. It's difficult, of course, to compare different formats unless one has done the kind of side-by-side comparison that Michael did and I trust his results. --------------------------------------------------------------------- From: firstname.lastname@example.org (John Sparks) I think you will see a bigger difference with format for B&W prints than with color prints. I work in B&W almost exclusively and have worked with medium format, 4x5 and 8x10 negatives. In almost all cases, I can see a difference between all three formats in a B&W 16x20 print. This difference is significant enough where I think I can generally pick which format made which print (assuming I can study the print up close in good light and the prints are more or less traditional landscapes with everything sharp and from fine grained film and no unsharp masking was used). In an 11x14 print, 4x5 and 8x10 become harder to distinguish, but large format can generally be distinguished from medium format at this size due to greater granularity from medium format. With 8x10 prints, differences are almost impossible to distinguish. Some subjects make the differences less clear, the more fine details in the subject, the easier it is to distinguish the different formats. When I look at large color prints from medium format or even 35mm, I'm often greatly surprised at the quality possible from fairly small transparencies and to a lesser extent negatives. I think that a combination of lower maximum resolution in the color print materials, smoother "grain" resulting from transparent dye clouds rather than opaque silver grains, greater impact from color with less reliance on fine details, and wider use of unsharp masking are all responsible for making negative/transparency size less important for color than B&W. I don't know where Peter came up with 3.5 for the [maximum enlargment] factor, but it agrees pretty well with my observations (at least for prints from B&W, prints from color allow larger enlargements before I notice differences between formats). I'm not sure if it's exactly a constant. I think the max enlargment factor without ANY loss of quality is smaller for larger negatives (maybe 3X for 8x10, 3.5X for 4x5, maybe 4.5x for 2 1/4" and 5.5X for 35mm). I think this is because lens quality improves slightly with smaller negatives and film plane accuraccy improves more substantially so that things don't improve quite as much as the linear film dimension increase would predict. I find that 16x20 prints from 4x5 (~4X prints) look noticably different from 16x20 prints from 8x10 in most cases. It's definately not grain since I can't see grain in either, at least from fine grain films like Tmax. I doubt it's resolution either (at least not resolution measured by line pairs/mm) since I don't think my eyes can resolve more what you get from a 4X enlargement. I think there is something beyond what the resolution number tell you. Your eyes can detect some of the high-frequency stuff beyond the lp/mm limit. The numbers I've seen for resolution limits in a print that can be seen with the naked eye are about 8 or 10 lp/mm. This seems to match what I can see when looking at a resolution chart with my eyes. However, I think you can tell the difference between a sharp square wave 10 lp/mm and a fuzzy, noisy 10 lp/mm that you get at the film/lens resolution limit. To capture this difference, you need a lot more than 10 lp/mm. From the difference I can see in 16x20 prints (a 2X print from 8x10 or a 4X print from 4x5) or even in 11x14 prints, (a 1.4X or 3X) though this is a much more subtle difference, I'd guess that you need somewhere around 30 lp/mm in the print to get the maximum quality that you can see with a naked eye. I know I want to put my eye right up next to a print (call this 10"-20"), reguardless of print size. Unless there is a barrier that prevents close observation of large prints, I find most people look at prints from about the same distance no matter what size the print is. If you keep your eye about the print diagonal or more from the print (which explains why billboards made from 35mm can look sharp when you drive by them many yards away), I don't see any problems with any size prints from 4x5, but I don't (and I don't see others) looking at prints that way. --------------------------------------------------------------------- Kerry L. Thalmann
So, we keep hearing the argument that modern films and lenses are so good that there is no longer a need to shoot large format (of course, I don't buy into that argument, and it is always presented by those who shoot in smaller formats), but it indeed looks like we need even finer grained films to get a higher degree of enlargement. Modern lenses (and for that matter even many 50 year old large format lenses) are capable of achieving very high on-film resolutions. In the end, it looks like the grain structure of the film may be the limiting factor in determining the maximum enlargement. Of course, this grain structure is a function of the emulsion and will be the same for any emulsion regardless of the format. Finally, the normal viewing distance increases as the size of the print increases. Grain that is objectionable in an 8"x10" print at 1/2 meter may be unnoticed in a 40"x50" viewed from across the room. This is the one relationship I have yet to quantify (I still need a formula for the effects of visible grain as a function of viewing distance). I have made prints up to 30"x40" from 4x5 with acceptable (for me) results, and I regularly make 24"x30" prints. This relationship between visible grain and viewing distance is one more factor that favors the larger formats. Assuming the same emulsions and a constant enlargement factor, the final print size, and thus the normal viewing distance increases as direct function of the film size. So, even though the enlargement factor is similar, at normal viewing distances, a 20"x24" print from a 4x5 original would appear less grainy than an 11"x14" print from 6x7cm. This also explains why, in a gallery setting, I can always tell from across the room, which 20"x24" prints were made from medium format and which from large format. It is not the lack of sharpness of the film or lenses, it is simply the effects of the film grain. The grain is just much more obvious, to my eye, in the prints made from medium format originals.