75mm Biogon sharpness-quality.

[Richard Boulware]

For jj. and anyone else interested, I did check the optical quality of the 75mm Biogon with the 75mm Grandagon-N, last year.

My Biogon is one of the third, and final production runs of this classic lens. Mine has the three rows of tiny square chromed friction patterns on the ring that controls shutter speeds. (Thanks to my friend J.P.Mose for this information).

In direct shooting of a target at a distance of about two and one half city blocks distance, negs were made of both lenses, on T-Max 100, processed in Pyro. Optimum sharpness occurred with both lenses at the classic optical philosophy at two stops down from maximum aperture. The target was a distant townhouse and the leaves of the shutters on the townhouse windows.

Observations were made on what I call 'micro contrast' which I term, the ability of the lens to separate grey tones at extreme enlargements. Negatives were viewed through a 20X binocular medical dissecting microscope over a tungsten light stage within the microscope unit.

My observations are correct, I think, for these two specific lenses only. Lenses can be like identical twins....looking alike, but each having different personalities.

The best way I can give you my observation opinions is to invent some kind of artificial scale to give you an opinion and reference. By doing this...I imagine a quality scale for both resolution and contrast....running from one, to one-hundred. Although each quality...contrast and resolution should be examined separately, I will lump them both together. In my observation, the Grandagon-N 75mm would be scored a 96 on a 100 scale. The 75mm Zeiss Biogon would score abou 93 on a 100 scale. Slightly less for this Zeiss lens, but amazing nevertheless for a lens of this age.

The quality of the Gradagon-N is superb, with multicoating and modern computer design, but I am amazed that the Zeiss lens could even come this close.

Just one mans opinion that I thought I would share with this group.

[Steve Hamley]

Thank you for the report Richard. Seeing old glass doing this well is a pleasure.

Steve

[David A. Goldfarb]

Thanks, Richard. How is falloff of illumination on the Biogon compared to the Grandagon-N?

[John_4185]

I have only a crummy Epson 3200 flatbed scanner, so forgive.

Here's a 38mm Biogon shot for comparison purposes:
elearning.winona.edu/staff%5Fo/jjs/compare/

And here's a 3" Biogon on 4x5
elearning.winona.edu/staff%5Fo/jjs/f/ (click around on the blow-up of the lower left corner)

Pretty sloppy scanning. I'm really not very good at that stuff.

[David A. Goldfarb]

Thanks, JJ. Looks pretty good, probably better than the Grandagon-N, though I think the Grandagon-N has more coverage.

[Brian Vuillemenot]

Hi Richard,

Good to read- was this the f4.5 or the f6.8 Grandagon?

[John_4185]

though I think the Grandagon-N has more coverage.

Does the Grandagon have as little light fall-off and distortion?

FWIW, this particular Biogon has a circle of coverage of probably around 7", which ain't much, but then Biogons are like that.

[Richard Boulware]

Answers to some of the questions. : 1. David A. Goldfarb. Biogon fall of is non-existent on my 75mm Biogon.. Focusing image on GG is bright and crisp, and same for test negative. Grandagon-N is much the same, although I thought a caught a hint of fall off. The Grandagon-N fall off ...if it is there,....is so slight as to not warrant a reshoot on a gray card, and hauling out my densitometer. Center filters?.....don't waste your hard earned bucks. Guess I am one of those guys who thinks that some illumination fall off in very wide lenses is a creative tool that can be creatively exploited to the advantage of the photographer. No worries, Mate.

Certainly the 75mm Grandagon-N has more coverage, but decades of experience has taught me that 90% of camera front standard tilts are totally unnecessary when shooting landscapes. It's kind of like going elephant hunting with a howitzer. Nice to have the potential but rarely used.

Brian Vuillemenot: The Grandagon-N was a 4.5, brand new, right out of the box. A very fine lens, as one would expect from Rodenstock.

Perhaps I could have done a optical lab, optical bench test, but I like to test lenses in real life, not in some damned lab. No test charts for me. Just shoot something with great detail, at great distance, and use a damned good microscope to evaluate. The image area I was viewing and rating was about 1mm on the negative. That's good enough for me.

Merry Christmas.

[David A. Goldfarb]

Thanks again for the responses. I have the 75mm/4.5 Grandagon-N, so I know how it performs, but was more curious about the comparison to the Biogon of legend. I have a Schneider III center filter that I use with a few different lenses, and I usually use it with the 75mm as well, but even without it, the Grandagon-N is still pretty good. Here's a shot with the 75mm/4.5 Grandagon-N at f:16 on Type 55 with a B+W 022 (medium yellow) filter, no center filter, and about 1.5-2 cm front fall with my Tech V mounted upside down, and the darkening of the lower corners is visible, but not too bad really--

[Richard Boulware]

jj. Thanks for posting that scan. Sharp enough? I would certainly hope so. I had three Hasselblads when I had my big studio. Once I got the Hasselblad SWC knocked out of my hands, while on assignment in Los Angeles. Luckily I had insurance, and some connections with the guys at Hasselblad. I had the honor of watching a factory technician remove the lens and replace the incredibly intricate magnesium assembly (I think...magnesium) which holds the lens elements. Amazing. Machined out of a solid piece of metal, the three dimensional rig which holds the elements of the 38mm Biogon together is intricate and complex enough to be called...metal art. I left with a new appreciation of why Hasselblad SWC cost so much.