Coverage at 1:1 - double ?

[Ken Lee]

Lens coverage figures are often given for f/22 at infinity. To focus at 1:1, we need twice the focal length.

Does this mean that we get a circle of coverage whose diameter is twice the stated infinity coverage ?

So while a 180mm Fujinon A is said to give 252mm coverage at infinity and f/22, will it give 404mm at f/22, when focused at 1:1 ? If that is the case, would it not make a good closeup lens for 8x10 ?

[Ron Marshall]

Yes, twice as much. Simple geometry with similar triangles

[Leonard Evens]

What remains fixed is the angle of coverage. So if you double the distance from the lens to the film, you double the diameter of the circle of coverage.

[Michael Kadillak]

Give it a go and let us know what you find. I have the same Fuji lens and the prospect sounds promising.

Cheers!

[Ken Lee]

Shucks - I used to have a 180A for use on 4x5 - but sold it when I moved up, thinking that I had no use for it any longer.

Duhh... We live and learn.

[Ken Lee]

I kept my 240A and use it for close work on 5x7 and 8x10: flowers, leaves, etc. The 400mm+ of necessary extension is not a problem on the 8x10 Shen Hao, but it reaches the limit of my old 5x7 Kodak. A 180 or 150 would be much easier, and would still give enormous coverage.

Perhaps others out there were aware of this, and have some nice images to share. 1:1 on 8x10 isn't all that small - but the images be rather nice when they "come out right".