Is there any real utility to ULF?

[Dave Moeller]

The 480 will cover 11x14.... you can 2x enlarge the 11x14, = 22x28.... and still be ahead in the resolution department vs. shooting 20x24 with the 550 XXL (divide the 480's numbers by 2).

Please correct me if I'm wrong, but doesn't this assume a "perfect" enlarging lens? I thought that any time a lens entered the process, whether a taking or enlarging lens, resolution was lost.

Thanks.

[bglick]

Hi Dave, yes, there is lots of variables here, too many to mention. If you scan the film and sharpen it, then 2x, you will probably be a bit ahead, if you enlarge with an inferior enlarging lens, you will loose some rez, but a good enlarging lens at 2x magnification will produce min. losses.

The goal of this exercise was to put an ultra large coverage lens in perspective with LF lenses which most of us are more familiar with.... as this might be the first MTF data provided on a photographic lens that covers 900mm image circle.

[robert]

I'm not trying to get off topic here. But as an old contact printer I've always wondered why if I take a piece of 22x28 paper, I can lay 4 pieces of 11x14 paper on top of it to cover it. Why is it then considered only a 2x enlargement, when it appears that it takes 4 pieces of 11x14 film to cover the surface of a 22x28 piece of film? In other words...if film was elastic and I could take an 11x14 piece and stretch it to the corners of a 22x28...wouldn't I be stretching it to 4 times its size? So does 2x magnification actually mean 2x sq.? .....Just some food for thought. 154 sq" vs. 616 sq" is only a 2x enlargement?...hmmm.

[Marko]

It's not the area, it's the diagonal. The diagonal of 22x28 is only twice the diagonal of 11x14.

[Dave Wooten]

so inverse square? it is also as robert mentiones 4 x's the amount of real estate!

[bglick]

Robert, as mentioned, the enlargement factor is a function of how enlarged the diag. is..... the fact a 2x enlargement produces 4x the area demonstrates just how far film gets pushed. A 6x enlargement (which is not much) is 36x the area.

[sanking]

Robert, as mentioned, the enlargement factor is a function of how enlarged the diag. is..... the fact a 2x enlargement produces 4x the area demonstrates just how far film gets pushed. A 6x enlargement (which is not much) is 36x the area.

The magnification factor was brought in relation to loss of resolution. Basically, every time you double the magnification factor in enlarging or in a scan there is a loss of one-half of the resolution. Consider the following figures, where you begin with a 4X5 negative that has 80 ml of resolution on the film.

Magnification New Size Maximum Possible Resolution
2X 8X10" 40 lppm
4X 16X20" 20 lppm
8X 32X40" 10 lppm
16X 64X80" 5 lppm

I find that these theoretical limits are fairly constant in scanning. In projection printing with an enlarer you are likely to lose some additional resolution.

Sandy King

[Richard K.]

snippet>>> ....... the 550 XXL, which would probably demand use of a ND center filter, ......

IS this the case? I can see maybe on 20x24 (Sandy?) but would a center filter be needed on 16x20 or 12x20 (without movements, you're only about 2/3 of the way into the image circle)?

-Richard

[sanking]

IS this the case? I can see maybe on 20x24 (Sandy?) but would a center filter be needed on 16x20 or 12x20 (without movements, you're only about 2/3 of the way into the image circle)?

-Richard

I am not finding that the 555/11 on 20X24 needs a center filter. There may be some light fall off toward the edge of the, but this is often a good thing when we contact print.

However, I should remark that to this point I have not used the 550/11 very much on 20X24, though I plan to do so a lot in the future. Zebra may have something to say about the light fall off issue.

Sandy

[Kirk Gittings]

The magnification factor was brought in relation to loss of resolution. Basically, every time you double the magnification factor in enlarging or in a scan there is a loss of one-half of the resolution. Consider the following figures, where you begin with a 4X5 negative that has 80 ml of resolution on the film.

Magnification New Size Maximum Possible Resolution
2X 8X10" 40 lppm
4X 16X20" 20 lppm
8X 32X40" 10 lppm
16X 64X80" 5 lppm

I find that these theoretical limits are fairly constant in scanning. In projection printing with an enlarer you are likely to lose some additional resolution.

Sandy King

Along with this, are there any figures about what resolution the eye can perceive at various viewing distances?