Industar-37

[ridax]

Well, the above table shows quite good UV transparency of the 1967 300mm f/4.5 Xenar that contradicts with my statement that fast tessar type lenses are usually a bit yellowish. But not all tessars are equal, and Schneider obviously paid a lot af attention to the topic those days.... And at least the Industar-37 is not like the Xenar. (But as I said, the 210mm f/4.5 Industar-51 is quite nice, and in 300mm, the slow f/9 Indusatar-11M is even more blue-transparent - when single coated with magnesium fluoride by evaporation (that's the coating that looks pale blue in reflected light). And the same Industar-11M is way more yellowish with the bright purplish-looking 2-layer coating deposited from easther solutions.)

BTW that also means a UV-blocking filter (a real one like the Wratten 2b, not a protector) is a must with color film in sunlight for the highly transparent single-coated lenses like the G-Claron.

210mm APO symmar, Transmission of light wavelengths below 420nm drops off real fast.

The APO-Symmar is optimised for color; it contains rare earth glasses that are far less transparent in the UV, and it is multycoated - the MC is made to transmit as much visible light as possible and almost no UV so that a UV-blocking filter is not needed.

I hate this shutter. It makes so much vibration that even the heavy studio 18x24cm FKP camera from which this shutter comes originally, shakes when the shutter is fired.

I have yet to see a visibly yellowed Tessar, Zeiss or otherwise. Or one that suffers from light loss on wet plate compared to other lenses at the same aperture.

As I said, that's reassuring. Would you please specify the other lenses you have compared your tessars to and the lighting conditions?

[Mark Sawyer]

As I said, that's reassuring. Would you please specify the other lenses you have compared your tessars to and the lighting conditions?

The Tessars I use are Velostigmat Series II, Zeiss, B&L Micro Tessars, Industar-37, Ektar, Commercial Ektar, and a B&J Rembrandt. I often switch between lenses while shooting with strobes, CFL hot lights, and daylight. Other lenses I switch to are mostly Cooke Portrait triplets, Petzvals and process/enlarging lenses (used closed down for still-lifes), though I also wander through a wide variety of others.

Portraits done by strobe are probably the most telling, as I'm always looking for the most light (as wet plate photographers generally are). Switching from an f/4.5 Tessar to an f/4.5 Cooke Portrait Lens never made a difference to the exposure, nor did coated vs. uncoated, though that did make a noticeable difference in contrast. And the strobes give very consistent light throughout a portrait session, (I have a bank of nine Travelite 750's).

[ridax]

Mark, thanks a lot for your explanation. That clarifies quite a bit; my guess is it's all in the light. Quality strobes are still optimized for color slide films so they employ special means to keep their UV radiation low or better nil (though with digital cameras, that's less important as digital matrices are far less sensitive to the UV - and to the visible violet, too). Hot lights and a lot of (though not all) fluorescent lamps are quite poor in the UV, too. Daylight looses a lot of UV passing through the window glass indoors. And daylight also varies too much. Sun tanning is actually available only several months of the year, and only when the clouds are gone away....

It looks like anybody using the lighting conditions similar to your Mark, is free to choose their lenses regardless of the glass tint.

P.S.: I’m a passionate fan of your Pixie series.

[ridax]

Nevertheless, some more observations. On coating: -

The first example: I own six 7.5" f/4.5 Ilex Paragons bought in one batch. The glass is identical in all of them. But all are quite different in their color rendition / violet & UV transmission / grade of yellowishness. Their coating is of the same type but the production quality control was obviously not the best so the coating came out noticeably different on each individual lens.

Another example, this time not about the UV transmission. I tested a number of small format 50mm lenses a couple of decades ago. The f/1.7 Zeiss T* Planar, the f/1.7 and the f/2 Pentax SMC lenses, the 55mm f/2 SMC Takumar, f/1.8 CZJ GDR Pancolars and f/2.8 CZJ GDR Tessars of both the MC and the single-coated versions were all equally excellent in their contrast and flare control but not equal in their optical clarity / transmittance. Both the Zeiss T* and the Pentax SMC lenses required 1/3 of a stop less exposure (for color films; no UV employed) than the CZJ lenses at the same f-stops (and I verified the f-stops were marked pretty accurately in all the lenses tested). That meant the f/1.8 Pancolar was actually exactly equivalent to the f/2 Pentax-M, exposure-vise. My later tests showed the vast majority of the so-called third party lenses were also at least 1/3 of a stop (or more) darker than the industry leaders' pieces of glass.

Go guess how many photographers ever noticed the difference. Perhaps nobody except the ones that used slide films daily. But that difference is real. And if I need a lens as fast as possible should I ignore the fact?

Back to the violet & ultraviolet transmission problem - the coating issue aside....

My 300mm f/4.5 uncoated Ross Express had balsam separation on the edges that looked like a severe haze. Feeling too lazy to undertake the full recementing procedure, I decided to try just heating the rear element along with the cell's barrel in hope that after the balsam melts, the haze would go, and stay so after cooling. It worked - the haze was gone. But there was not enough balsam to cover all the bonded surfaces completely, and several balsamless spots appeared between the cemented surfaces. At least that was better than haze so I was satisfied enough with my lazy method.

The interesting thing was that when I looked through the lens onto a sheet of white paper under the overcast daylight (as I described previously), those balsamless spots looked bluish compared to the overall yellowishness of the Ross Express. That certainly meant the balsam itself was too yellow and added quite a bit to the lens's tint. (It's often thought that as the balsam layer is thin, the balsam color does not matter. But Wratten filters are also quite thin, and still they are filters. So if the balsam is not pale yellow but deep orange, a pretty thin layer is enough to make the lens UV-blind.)

I've also noticed my Turner-Reich to be definitely less transparent to the short-wave light than my Protars and Dagors of the same focal length. And Turner-Reich is infamous for being much more inclined to show balsam separation than Protars and Dagors. My own T-R already has a bit of separation at the edges - just of the same style my Ross Express had.... Could that be the balsam quality problem? It looks like Goerz and Zeiss and Baush&Lomb used a higher grade Canada balsam - less yellowish and less prone to haze and separation - than the grade used by Ross and Gundlach. Still no proof positive on the hypothesis but I am inclined to consider it seriously.

[Murgo]

Got the Industar today. Seems promising, it's not as heavy as I feared. I't still big and heavy but much lighter than for example my medium format Tair 33 300mm.

I experimented with the lens and the camera and at maximum bellows extension I can get infinity focus when holding the lens as it would sit with a regular lens board. When holding it 70mm in front of the lens board plane I get a focusing distance a little less than 2 meters from the film plane (or about 170 cm from the front lens) which I think will be adequate for this lens, if I need to get closer I can always use my 180mm which at full bellows extension will focus at about 70 cm from the film plane. So I'm thinking of making a lens board with a 70mm extension tube which probably would not make the camera too unstable. I may have to install another tripod socket on the bed of the camera to balance it though.

By the way I'm also considering trying the front part of the Tair 33 on the Graflex as it can be screwed off and it contains all the lens elements and the aperture forming a complete "barrel lens" while the rear part is just an extension tube and a focusing mechanism. The front part seems to give a reasonable minimum focusing distance (about 1,5 meters) if held like in a regular lens board and when projecting an image on a piece of white paper it seems the image circle is adequate for 4x5 at least if not using a lot of movements. There may of course be some softness or distortion at the edges of the circle though and as said, the lens is considerably heavier than the Industar 37 but it seems it would be usable with a regular non-extended lens board so I might make one for that one too.

[Murgo]

I got the 3D-printed lens board made, I found a ready made design in Thingiverse for a Speed Graphic lens board ( https://www.thingiverse.com/thing:1763996 ) and modified it to include a 70mm extension tube. I posted my remix back in Thingiverse so if someone wants to give it a try here it it: https://www.thingiverse.com/thing:4896904 .

Seems to work just fine, maybe there's no need to make one in metal after all or maybe I'll print another one from a more rigid material, like for example carbon reinforced filament, though regular PLA seems to be plenty stiff for the purpose.

There's no thread for the lens, it's friction fit, but the layers of the 3D-print act as a kind of "thread" and grab the lens very firmly, it needs to be "screwed" off the extension tube, it can't be simply pulled out so no way it's falling off.

The lens-camera combination is surprisingly rigid and stable, no signs of unwanted wobble at all, and the (heavy) Ravelli video tripod I use for this camera carries the contraption just fine even attached to the standard tripod socket. As indicated by my experimenting with the lens the minimum focusing distance is a couple of meters and there's no signs of vignetting or any other problems visible on the ground glass. Of course I haven't taken any pictures yet.

So seems to work just fine, even though it looks kind of crazy.