Rodagon-G surprise.

[M Carter]

Been working up to 30" wall projection prints (from 4x5) and realized my 135 Componon-S ain't cutting it; contrast and sharpness are about the same from F8-F16 in the center, but the corner falloff is getting abysmal.

Started hunting for a 150, but I do have a 150-G as I'm working my way from big to bigger. What the heck, stuck it on the board and aligned everything, and... holy cow. It's designed for 10x-40x and optimized for 20x. I'm at about 6x at the 150 focal length, and I simply can't tell test prints apart at F8 from the Componon at 8, 11 or 16. I was afraid it wouldn't even focus or something. I can see sharp grain, damn it!!!

Stuck some paper up in the corner at F8, and as a rough test, I don't see any falloff. I'm testing with scraps of 5x7 RC at various places on the wall (well, alignable vertical easel, that's another story) and sweet jeebus, they look every bit as good as the Componon-S prints.

I guess Rodenstock was either pretty conservative in their specs, or didn't want people thinking a "G" could replace a non-G for many uses. I was about to buy a Componon/Nikkor/Rodenstock 150, a nice surprise to not have to shop and clean and test.

Anyway, just geeking out. Been a happy morning.

 

[ic-racer]

I noticed the same with the “high magnification “ HM Componon 45mm. For all magnifications it is always better than the Componon-S 50mm.

 

[AgX]

The "HM" does not stand for "high magnification", as all Componons are stated to be designed for that range of 2-20x, and even a 1x lens got this designation.
I guess it stands for "high modulation" instead.

 

[ic-racer]

Thank you for the clarification. Of course everything I read has been translated from German language. The reason I always thought "High Magnification" is that the MTF Schneider shows for Componon-S only goes to 12X where the MTF curves for APO HM Componon go to 25X.

 

[DREW WILEY]

You'd need to go to huge mural size to warrant a Rodagon G, and they aren't ideal for smaller work. Old Componon or even Componon S lenses were decent for their respective eras, but are only so-so in comparison to newer options. Anything 135 is likely to exhibit falloff. I prefer a 180 Rodagon for 4x5, but also use an expensive 150 Apo Rodagon N. But all this is relative, and if your 150 G is doing an acceptable job for you, glad to hear it.

 

[M Carter]

if your 150 G is doing an acceptable job for you, glad to hear it.

I was really surprised, holding detail just fine.

 

[markbau]

Interesting thing I’ve noticed is that my Componon S lenses are at their sharpest about a stop down from wide open, my 90mm HM does it’s best work 1/2 way between 8 - 11.
Componon S lenses I still consider to be outstanding lenses.
Another interesting thing is now that I’ve got an Analyser Pro which has a densitometer function. I’ve gone through my lenses and noticed that the f stops are not necessarily spaced exactly. Changing a full f stop should get you a 0.30 reason and a half stop 0.15. Some of mine are 0.12 on the half stops and 0.24 on the full stops.

 

[Lachlan Young]

I was really surprised, holding detail just fine.

Field flatness may be the determining factor as to recommended optimisation range. I think Rodenstock's sales booklets suggested that the 105mm & up Rodagon-G's would match up with their equivalent Apo Sironar-N's, correcting certain aberrations automatically (which implies a significant degree of familial lineage between them). The G series was also considerably costlier than the regular Rodagons - and some (all!) are pretty rare. I did hear an opinion that the 105 Rodagon-G was at least as good at the 105 Apo-EL-Nikkor - though I'll leave that to the people with actual MTF testing facilities.

 

[M Carter]

Field flatness may be the determining factor as to recommended optimisation range. I think Rodenstock's sales booklets suggested that the 105mm & up Rodagon-G's would match up with their equivalent Apo Sironar-N's, correcting certain aberrations automatically (which implies a significant degree of familial lineage between them). The G series was also considerably costlier than the regular Rodagons - and some (all!) are pretty rare. I did hear an opinion that the 105 Rodagon-G was at least as good at the 105 Apo-EL-Nikkor - though I'll leave that to the people with actual MTF testing facilities.

Yep, I don't have much basis for comparison, other than things like "I can do a lith print at 20x24 from a 6x7 neg with a Nikkor 105mm, wide open" - but I'm using a parallel and I make my own "Besalign"-style boards, it's really nice to not need 5-minute print exposures with big lith prints! And lith's contrast control and range makes lens contrast somewhat moot, as long as there's no serious falloff and I'm sharp across the frame, it's all good. The Comp-S 135 has been good for 4x5 negs at reasonable sizes, I was surprised how fast the corners went downhill as size went up. At 30" with good center exposure at F8, corners are almost non-existent; some of that means centering the neg is more critical though (masking carrier).

I lucked out on the G, a Photrio user saw my post about going larger than 20x24 and sold me the 150 for an excellent price. It's like-new in the original box but has been sitting a couple years. I'm working out the infrastructure to get up to 5 or 6', liquid emulsion-coated canvas, but easing into it. I'll have to knock down a wall eventually... my poor wife...

 

[reddesert]

As one goes to larger print sizes, the lens to negative distance decreases significantly (just like focusing a taking lens closer to infinity). This will decrease the coverage in mm for a given angle of coverage. For example, if one has a 135mm lens on 4x5, making a 16x20 print is an enlargement of 4x and the lens is 5/4 * f = 169mm away from the negative; going to a 32x40 print puts the lens 9/8 * f = 152mm away from the negative. Because 135mm is a little short for 4x5 (less than the diagonal of the film), it makes the corners more corner-y, the lens is more likely to show image quality problems and falloff, and the light source may also have some falloff. Longer focal length lenses typically should help decrease these problems.

Curvature of field also depends on focus distance, but I have no quantitative idea how important that is versus the decrease in coverage. Field curvature is probably a reason why enlarging lenses don't always make good taking lenses and vice versa, though.

 

[DREW WILEY]

One problem with large scale work is that it can be clumsier to burn in corners and so forth. One needs either a customized mixing chamber or ground diffuser to offset any lens falloff. So it's more practical to use a longer focal length lens to begin with, with no falloff at typical working apertures. That's often feasible in commercial mural work, because a large room can be utilized for sake of horizontal enlargement. Now a lot of that kind of thing has switched over to very wide inkjet printers instead.

But at more modest scale, I personally don't like printing larger than 30X40 inches, so have two of my 8x10 enlargers in a room with a very high ceiling, which allows me to do a 30X40 vertically with a 360 lens in place, and thus take up less floor space than horizontal projection. On my lesser "little brother" 8x10 color enlarger, which is a more garden variety Durst L184 with a typical Durst Colorhead, only 9 ft tall, I have to resort to a very large mirror box to attain the right angle of incidence over the carrier and into the lens, plus a smaller f-stop and high-end graphics lens to get total evenness of field with certain lenses. I also have different diffusers for different lenses. A lot of forethought goes into it.

 

[Lachlan Young]

centering the neg is more critical though (masking carrier).

Having worked with the Rodagon-G 50mm quite a bit, you very quickly see whether you got the neg dead centre - or not...

There's something quite amazing about a 30x enlargement off 35mm with properly sharp granularity (which is the point of the G) - really messes with people's perceptions about the supposed 'limits' of enlargement.

And for 4x5 I got hold of a WA-Rodagon 120, which resolved any thoughts I might have had about looking for a 150 G.