240 Apo Ronar f/9 covers 8x10 with room to spare?

[l2oBiN]

Having both the Fujinon A 240/9 and the Rodenstock Apo Ronar 240/9, I mounted them on an 8x10 to compare the coverage wide open (f/9). Since the Ebony Lens Tables (http://www.ebonycamera.com/articles/lenses.html) state the covering power of the Fujinon and Ronar are 336mm and 212mm respectively, I was expecting the Ronar to evidently lack coverage on 8x10 and the Fujinon to just cover the format. However, it appears that both the Ronar and Fujinon cover 8x10 with room to spare, with the Ronar running out of coverage first resulting from sufficient shift movement.

I am a little perplexed at this apparent inconsistency on the GG and I am wondering the reasons for these observations? Perhaps the apparent coverage could be attributed to circle of illumination rather than acceptable circle of resolving-covering power? As a side note, would the acceptable circle of resolving-covering power increase with stopping down of the aperture?

The following are the details of the Rodenstock Apo Ronar 240/9.
All black Copal 1 shutter with a Rodentock quality seal. It is labelled "Rodenstock Apo-Ronar sinar 1:9 f=240mm" serial number 10 325 9xx (MF date 1981-84 (http://www.ground-glass.net/large-format/rodenstock-lenses-age)). It does not have a "MC" sign on it and this is confirmed by single "yellow-ish" coating. Glass reflections are same on front and back cells and consist of B-S-S-B (B=big; S=small) reflections per cell.

[Dan Fromm]

In the Process Lens Handbook, 212 mm is the diameter of the circle defined by "MTF @ 16 lp/mm > 10%" for the 240/9 Apo Ronar.

[Ken Lee]

The Fujinon A is a plasmat, reportedly corrected for "closer than your average plasmat": somewhere between general purpose lenses (1:10 - 1:20) and macro lenses (1:5 to 1:1).

Whatever its correction, it's f/9 so it's small and light, and it's a plasmat so it has more coverage than a typical process lens.

A rather clever design, and well made, so a great performer at a wide range distances.

[olvrkrg]

In the Process Lens Handbook, 212 mm is the diameter of the circle defined by "MTF @ 16 lp/mm > 10%" for the 240/9 Apo Ronar.

Hello Dan,
is there a chance to get the Process Lens Handbook from somewhere ? I'd need data for Apo-Ronar 150 MC, 240 MC, and 240, 300 and 360 older ones. Many thanks in advance !
regards
Oliver

[Dan Fromm]

Look here https://skydrive.live.com/redir?resid=8D71BC33C77D1008!182&authkey=!AIhF3y6CVJfvYdA for the Apo-Ronar section

[Drew Wiley]

You'd want to compare image quality toward the corners of the field, and then again with full front tilt
relative to near/far focus. I don't own an Apo Ronar, but do have the full spec diagrams, and they certainly replicates the advertised recommendation of only up to 4x5. Process specs or closeup usage
would obviously be different. The Germans tend to be quite conservative in their spec standards, while
Fuji is a bit generous. But the 240A easily accommodates 8x10 with moderate tilt, rise, etc, provided it
is stopped down enough to bypass mechanical vignetting. Like the Apo Ronar, it's superb either close
up or at infinity. Four-element dialytes can have wide coverage (Fujinon C lenses for example), but
Apo-Ronars are classified as relatively narrow coverage.

[john borrelli]

Not to hijack the thread but If the OP has the chance would love to hear a comparison of both lenses actual picture taking abilities.