UV TOPCOR 28mm f/4

PGraham3 · Oct 1, 2021

I was recently given a pretty clean UV Topcor 28mm f/4 to use on an old, but fully-operational Topcon Unirex that I picked up several years ago in Japan. I understand this may not be a great lens, but I researched around to discover that this 28mm has 6 elements, but I'm curious, would anyone know the exact lens layout design? Double-Gauss, right? I found some diagrams with many brand name double-gauss designs, and Topcor is there, but totally different apertures.
Any ideas?

Paul Howell · Oct 1, 2021

Have no idea, either 6 elements in 4 or 5 groups? I have the 28, 50, 100 and 200, although slow I have found all to sharp at F8.

PGraham3 · Oct 1, 2021

@Paul Howell
Thanks for the tip! I also have the 50mm f2 with it, but it’s not as clean as I’d be comfortable to shoot with. I’ve been looking here and there for a good clean one, but no go.

Would you have a few shots you like that you could share on here taken with the 28mm f4?

Also, 100mm f4 looks like it renders quite nicely. Considering grabbing one sometime.

Thanks for responding!

-Paul G.

Paul Howell · Oct 1, 2021

Sorry it will take a while, my old Canon Flatbed scanner with 35mm negative attachment is set up is not get up, so I will need to dig out a print to scan.

Paul Howell · Oct 1, 2021

BTW, what I've been told is that the reason that Topcon, Kodak, and Kowa leaf shutters lens are slow is that leaf shutter lens have a small throat allowing for limited sized rear lens elements. Others may have different information.

wiltw · Oct 1, 2021

If you notice, the double Gauss lenses are 'normal' FL.

The 28mm FL for the Topcon Auto 100, UNI, etc. had to be a 'retrofocus' design in order to allow space in the body for the reflex mirror to flip up!
While current information indicates the UV Topcor were 6-element lenses (a MYTH!) during the time in which they were 'contemporary' (approx 1964-1970) typicall literature did not portray the optical design groupings for those lenses. About the number of elements myth...my circa 1965 Topcon Auto 100 user manual clearly states:

"Standard lens...53mm...has 6 elements in 4 groups
Wide Angle lens: 35mm...is 6 elements in 5 groups
Telephoto: 100mm, 135mm...have 5 elements"

The 200mm lens came into existence around 1966/67, and the 28mm lens did not come into existence until about 1968 (when I graduated from high school) or later...the 28mm does not appear on the Aug. 1967 price list

wiltw · Oct 1, 2021

Paul Howell said:
BTW, what I've been told is that the reason that Topcon, Kodak, and Kowa leaf shutters lens are slow is that leaf shutter lens have a small throat allowing for limited sized rear lens elements. Others may have different information.

with regard to UV Topcor lenses, the lenses themselves do not house a leaf shutter mechanism...the leaf shutter is located immediately behind the rear element of the lens, in the body's lens mount opening...a behind-the-lens leaf shutter. And the UV Topcor lenses have rear lens barrel all about 21mm in diameter.

Paul Howell · Oct 1, 2021

The rear lens barrel of 21mm had to fit the in body shutter, so the shutter limited the size lens, which is no different from any other shutter? I think the rear lens of my Kowa are about the same size as the Topcon.

AgX · Oct 1, 2021

The Double Gauss design is the typical design for 50-100mm lenses of higher speed than F2.8. (There are other designs as for instance a F2.4 of Ernostar design).

For SLR wide-angle a classic design was that of the Flektogon.

wiltw · Oct 1, 2021

AgX said:
The Double Gauss design is the typical design for 50-100mm lenses of higher speed than F2.8. (There are other designs as for instance a F2.4 of Ernostar design).

For SLR wide-angle a classic design was that of the Flektogon.

A nice diagram of the Flektogon...one could readily envision a similar lens design for the UV Topcor 28mm
https://www.flickr.com/photos/camerawiki/6820638873/in/pool-camerawiki

Dan Fromm · Oct 1, 2021

AgX said:
The Double Gauss design is the typical design for 50-100mm lenses of higher speed than F2.8. (There are other designs as for instance a F2.4 of Ernostar design).

For SLR wide-angle a classic design was that of the Flektogon.

Sigh. More German parochialism. Or is it parochial germanism? Think Angenieux Retrofocus.

Don't forget the 4/4 double Gauss wide angle lenses. All of normal construction, none retrofocus so none suitable for SLRs. Examples: Kodak Wide Field Ektars, Meyer Weitwinkel Aristostigmats.

AgX · Oct 1, 2021

Dan Fromm said:
Sigh. More German parochialism. Or is it parochial germanism? Think Angenieux Retrofocus.

The Flektogons are of the retrofocus type too.
But the Flektogon designs seem more easy to find on the net, thus I chose them.

Flektogons and Angenieux lenses were released the same time.
They differ in their design.

I know of the important work of Pierre Angenieux, but I think this design of his became overestimated. There was a need for such lenses, and of course he was thus not the only one thinking in that direction.

To my understanding the merit of Angenieux and his team was in releasing lenses that withstood the time whereas his competitors where upgrading their lenses.

Apug is filled with posts of american parochialism, often by members ignorant on the matter.

Bronson Dugnutt · Oct 1, 2021

Does it have a filter thread?

AgX · Oct 1, 2021

I see grooves. And if I had to machine grooves (for light light-catching, though with a silver surface not being the best idea) then instead of parallel grooves I would fabricate helical grooves, thus a thread. Thus grooves with a benefit...

Dan Fromm · Oct 2, 2021

AgX said:
I know of the important work of Pierre Angenieux, but I think this design of his became overestimated. There was a need for such lenses, and of course he was thus not the only one thinking in that direction.

Angenieux wasn't even the first. As far as I know the first inverted telephoto lens was invented in 1931 by H. W. Lee of TTH. It (they, actually) was for 3-strip Technicolor cameras.

Apug is filled with posts of american parochialism, often by members ignorant on the matter.

I agree completely. Ignorance seems to be universal.

AgX · Oct 2, 2021

Optics has quite same history. Also having an idea, is not sufficient, there also must be the means to realize it, technically and financially and thus there also has to be a market, at that moment.

I find it amazing what all had been designed and then was put into a drawer or what actually had been realized and as result brought down a plant. One typically looks at such in hindsight, I rather look at such an issue from the perspective back then of the people involved. Sad enough not much of archived relicts exist to yield that perspective, and not much interest exists in such research.

Snowfire · Oct 2, 2021

Does the name mean that this is a quartz lens for UV photography? That is a real treasure if so--such short focal lengths are rare for such optics.

Dan Fromm · Oct 2, 2021

AgX said:
Optics has quite same history. Also having an idea, is not sufficient, there also must be the means to realize it, technically and financially and thus there also has to be a market, at that moment.

I find it amazing what all had been designed and then was put into a drawer or what actually had been realized and as result brought down a plant. One typically looks at such in hindsight, I rather look at such an issue from the perspective back then of the people involved. Sad enough not much of archived relicts exist to yield that perspective, and not much interest exists in such research.

TTH Technicolor lenses come to market from time to time. The 35mm still camera market wasn't ready for such bijoux until after WW II, and by then TTH's focus had shifted to lenses for large format and cinema.

Dan Fromm · Oct 2, 2021

Snowfire said:
Does the name mean that this is a quartz lens for UV photography? That is a real treasure if so--such short focal lengths are rare for such optics.

Absolutely not.

Paul Howell · Oct 2, 2021

UV was name of the mount, Topcon made a consumer grade camera with shutter speed priority exposure, that evolved, the Uni, 100, 100IC (integrated circuit) with a interchangeable lens in body leaf shutter. Topcon also made a mid level and pro level camera that used a Exacta mount, the RE, D, SuperD with focal plan shutter, later one mid level camera with a Pentax K mount.

AgX · Oct 2, 2021

From just the name I would have been mislead into thinking of a lens for UV photography. And I have never come across any UV-mount, not even any Topcon camera. Bu this is due to the differeent development the west-german market for/of japanese SLRs made in contrast to the US and other markets.

wiltw · Oct 2, 2021

Snowfire said:
Does the name mean that this is a quartz lens for UV photography? That is a real treasure if so--such short focal lengths are rare for such optics.

Wikipedia states, "UV stands for Ultra Violet, as the lenses had a UV coating, and did not need a separate UV filter."

The Topcon Auto 100 user manual states,

"Superior lens coating...Special UV filter effect on all interchangeable lenses....All UV Topcor lenses have been speciall coated to cut the ultra-violet (UV) ranys and thus give breath-taking true-to-life color renditions of outdoor scenes at all times, and eliminate the need for an UV filter outdoors for lback-and-white camera work."

Paul Howell · Oct 3, 2021

wiltw said:
Wikipedia states, "UV stands for Ultra Violet, as the lenses had a UV coating, and did not need a separate UV filter."

The Topcon Auto 100 user manual states,

"Superior lens coating...Special UV filter effect on all interchangeable lenses....All UV Topcor lenses have been speciall coated to cut the ultra-violet (UV) ranys and thus give breath-taking true-to-life color renditions of outdoor scenes at all times, and eliminate the need for an UV filter outdoors for lback-and-white camera work."

Thanks for the update, I missed that.

Snowfire · Oct 3, 2021

As someone who has actually dabbled a bit in UV photography, I find the above hype highly amusing:

Much serious b&w film photography was performed through green, yellow, orange, or red filters, which themselves are UV-opaque. The UV transmissivity of the lens did not matter. Those who shot b&w film without such filters were generally amateur snapshooters for whom image quality was not a big issue.

Retrofocus lens designs with many elements and high glass thickness are not generally renowned for high UV transmissivity. There are a few exceptions, but one must actively seek them out.

Ad finally, most filters sold as "UV" filters do so poorly at attenuating actual UV that they are essentially worthless for that purpose--some transmit down to 330 nm! Thus, to argue that there was ever any optical need for such filters is laughable. (Filters sold as "skylight" are a little better in that regard.)

Paul Howell · Oct 3, 2021

I used UV filters with color film, landscapes at a distance when not using a polarizer, help cut the haze.

UV TOPCOR 28mm f/4

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