Metrogon 6" lens vs. other 6" lenses.

[Mark Sawyer]

Six inch (154mm) Metrogon aerial camera lenses come up for auction an ebay about once a month. They appear to be a rather unique design, with bulbous glass protruding way out the front of the mount. Does anyone know how an image made with one of these lenses would compare with an image from a more conventional lens of similar focal length, say, a 159mm EWA Wollensak?

[Richard Boulware]

When I flew photo-recon with the U.S.Navy we had a B&L Tri-metrogon system that used three matched lenses that photographed horizon to horizon on a vertical axis at the same time. Shutters were electric and the lenses were engraved with each focal length to a tolerance of four decimal points...if memory serves. Lens coverage from each lens was matched to very fine tolerances. Controls for the camera units were on the cockpit left with exposure counters and intervalometer included and routing electrical switching to the pickle switch on the "stick". System could shoot semi-auto or full auto using the intervalometer to calculate exposure interval for 60% forward image overlap. (calculating true altitude and a/c true air speed.).....and yes, for our recon purposes, the lenses were very sharp. But...they were designed for a different purpose and that must be taken into consideration for your needs. Hope this helps.

Richard Boulware - Denver

[John Berry ( Roadkill )]

I bought one off the bay and had it mounted in an aphex shutter. Make sure you get the complete nose peice as there are different appature locations for same focal length, depending on which lens you have. If you only have the cells you wont know the spacing or location of appature. It is very sharp. Shooting grand vistas the mountains on the horizen are quite small. I find it works best for me when I'm getting in up close say 10' out to about 30' on 8X10. Then again I kinda like to push the perspective. I don't see that I will be using it as much as the 240 G-claron, but sometimes it's just the ticket. I shoot B&W and I didn't find any objectional falloff without the center filters. I'm into it about $600

[Mark Sawyer]

Thanks, Richard and John! It's good to hear first hand that they're quite sharp; I was presuming they would be, given their original application and the military's budget. Still, I wonder about that design, sort of like a Goerz Hypergon, but at a not-so-wide-angle. Why did they go to all the expense and trouble, when a more conventional design would have worked?

John, was that an expensive custom mounting job, or did it actually fit your Aphex (Alphax?) shutter? I'm presuming it must be disassembled and machined to fit any sort of shutter, probably why you're into it for $600...

Interesting that the fall-off isn't too bad; I have a few Metrogon center filters, but they look pretty low quality- thick, with a laminated sheet between two pieces of glass, with one showing pretty bad separation.

[John Berry ( Roadkill )]

You can check out this page. http://www.metrogon.20megsfree.com/index.html It is where you will find most of the info available. $200.00 of that was for the shutter. I payed $125 for the lens, $25 for the mounting ring and $300 for the machining to fit the elements into the shutter. Compared to others I don't know as I haven't tried anything else. I do like haveing a 6.3 lens when looking at the ground glass. It is a chunk of change but not when compared to a 165 SA.

[John_4185]

To add to John Berry's excellent information - for those who might want a center filter, you might go to www.surplusshed.com and use ther eMail inquiry to find one. Fred is the chap who usually gets the inquires and he's been very helpfull. They have more inventory not listed and he knows it all. The K2 colored center filter used to be rather common.

[Mark Sawyer]

BTW, the yellow Metrogon center filters have the usual fuzzy dark area in the middle. The red Metrogon filters (at least the ones I have) have a dark mnay-pointed star shape in the middle, which I suppose goes sufficiently out-of-focus when you have it close to the front element. Funky, but I guess it works...

I prefer the yellow, and find it an economical, if not elegant, alternative to the usual $300 center filters on the few occassions I've wanted one. And of course you need to come up with your own mounting system.

As jj said, you can usually get the filters throuh the Surplus Shed for around $25.

John- great site for the Metrogon! Thanks! It's good to see any info on them.

[Jim Galli]

I think what you may find as far as comparison is that the Metrogon (Zeiss Biogon formula?) is designed to be as sharp as it will ever be wide open where normal wide field lenses usually must be stopped down quite a lot. Also they were designed for 9.5X9.5 framing with no concern for further coverage. An educated guess is that they'll cover an 8X10 very similar to how a 75 biogon covers 4X5 which isn't by much. I'll confess that while I own one, it's never been used by me. The good news is that I have multiple hundreds of images in our archives made with that lens and they are very sharp corner to corner.

[Dan Fromm]

Jimbo, buy yourself a copy of the Vade Mecum. It will help you spot more good opportunities.

More seriously, the M'gon ain't a B'gon.

Cheers,

[John_4185]

[b]JG:[/b[ . An educated guess is that they'll cover an 8X10 very similar to how a 75 biogon covers 4X5 which isn't by much.

I presume we are still talking about aerial application lenses.

Which Biogon? The marked 75mm is not the same as the one marked 3". Would you happen to have the little 75mm lens? I wouldn't mind having one to compare to two others of equal (nominal) focal length.

BTW: See any Biogons listed here?
edclxs22.cr.usgs.gov/osl/camusgs.txt (http://edclxs22.cr.usgs.gov/osl/camusgs.txt)

[Michael S. Briggs]

The Metrogon is not a Biogon-type design. The Metrogon is a simple double-Gausse type (see page 119 of Kingslake's A History of the Photographic Lens). He describes the 6 inch focal length as covering 9 x 9 inches with vignetting that required a center filter.

On page 150--151 he describes the Biogon type lens, with its more uniform illumination, and comments "The new lens quickly replaced the Topogon and Metrogon as the standard lens for aerial photography and photogrammetry."