Convertible Sironar Coverage?

[Steve Hamley]

Folks,

Here's an interesting question for my fellow lensaholics.

I recently purchased a 210mm convertible Sironar, and it has a nicely working original shutter and clean glass with no separation, so I lucked out there.

Today I was testing a friend's "junk" lenses and had the 8x10 set up, and when I was done, I put the Sironar on the 8x10 just out of curiosity. To my surprise, it illuminated the GG quite nicely, but figured it would be visibly soft at the edges, so I pulled out the blackjacket and stopped it down to f:32. Surprise again, it seems quite sharp at the edges of the 8x10 GG. Much more so than my friend's older 21cm Dagor-type convertible Symmar.

So does anyone else have a similar experience with a convertible Sironar? I know the convertible Symmars are supposed to have larger usable ICs than specified. Do I have a sleeper here?

Thanks!

Steve

[erie patsellis]

If you're happy with the results (though I'd try it on film to be sure), then it's a good thing. My 210 Convertible covered 8x10 nicely, without any softness at f22.

[Steve Hamley]

Thanks Erie,

I just popped it on the 8x20 and it has a circle of illumination of about 14", with a quite rapid (almost immediate) drop off as you'd expect from a modern plasmat. It also seems relatively sharp within a small distance of the edge, also expected of a modern lens. A 14" circle makes it an 80 degree lens and if I carve off an inch of IC assuming the last 1/2 inch isn't sharp. then it's a 75 degree lens. Of course as you note, film has the final say.

Anyway, 13"/330mm of sharp coverage or even a little less would be consistent with your observation.

Cheers,

Steve

[IanG]

The Symmar isn't really a Dagor type lens, although it is symmetrical - the Symm - comes from symmetrical. A very small number weren't and were sold a triple convertibles but they used the same cells as the symmetrical lenses, it was like using a 135mm cell with a 150mm cell.

The early Sironar was technically a triple convertible and they are nowhere near symmetrical, Rodenstock recommended using just the front cell as a soft portrait lens at wider apertures and the rear cell stopped down for more critical work. Mine's on loan in Italy and I've not field tested split it but it converts to a 450mm, to long for my field cameras.

The 210 should split to around 630mm, it's always three times the Focal length of the prime lens. At 630mm it should cover 10x8.

The sharp fall off is probably vignetting, and deliberate, my 210 Rodagon enlarger lens does the same, I haven't tried my 210 Symmar on my 10x8 yet.

Ian

[Peter K]

The Symmar isn't really a Dagor type lens, although it is symmetrical - the Symm - comes from symmetrical.
No Symmar from 1950 up to now is symmetrical. But Schneider used the name from a pre-WWII lens. This f6.8 Symmar was a symmetrical Dagor type lens.

Peter K

[Steve Hamley]

Ian,

The Schneider Double Anastigmat Symmar f:6.8 ser 184008 has two brights and two ghosts per cell. Plasmats have 4 brights and one ghost per cell.

My 210mm Sironar converts to 400mm and the aperture scales "halve", f:11 becomes f:22.

Cheers,

Steve

[IanG]

In a separate post Bob "the fish" from HP quotes a Rodenstock resource and assumes the 420mmm of the split 210mm Sirinar is a typo. Maybe he's wrong but all the other Sironars split to 3 times the Prime's FL :)


Ian,
The Schneider Double Anastigmat Symmar f:6.8 ser 184008 has two brights and two ghosts per cell. Plasmats have 4 brights and one ghost per cell.


Maybe but they are quite different lens designs.

Ian

[Steve Hamley]

Ian,

May be. The shutter is obviously factory and has an aperture scale labeled "400mm".

Cheers,

Steve

[Ole Tjugen]

No Symmar from 1950 up to now is symmetrical. But Schneider used the name from a pre-WWII lens. This f6.8 Symmar was a symmetrical Dagor type lens.

Peter K

The early Dagor-type Symmars were unsymmetrical as well - and were sold as triple convertibles.

[Peter K]

The early Dagor-type Symmars were unsymmetrical as well - and were sold as triple convertibles.
Ole, do you know the exact focal lenght ratios? As I know it is about 1 : 1.95 : 2.05.

[Ole Tjugen]

Peter, all I can find right now is this (from the Vade Mecum):
a f6.8/240mm lens No2,944,55x from early 1952, coated and in shutter. It had cells of f13/465 and f12/375, ie it was a true 3 focus lens.

Edit: Ludwig David, in "Photographisches Praktikum", 9th edition, 1932, says that "Vorder- und Hinterglied mit kleiner Blende als Landschaftslinsen verwendbar". And that's all.

[Peter K]

Ole, in a Schneider brochure from the thirties one can read:

"Die Einzelglieder lassen sich mit mittleren Blenden als Landschaftsobjektiv von nahezu doppelten Brennweiten des ganzen Systems verwenden."

The same one can read here. (http://www.cameraeccentric.com/html/info/schneider_3.html)

[Ole Tjugen]

So that was changed, too? Seems like the later "Dagor-Symmars" have about the same cell power distribution as the early convertible Angulons...

[Bob Salomon]

In a separate post Bob "the fish" from HP

Ian

Ian, I do not describe anyone by other then his/her name and/or title.

We represent Rodenstock among other companies. If you can't be civil enough to use just my name or position you should keep your extraneous comments to yourself.

You, I or any other person is not a "fish".

A correction and apology of your offensive comment is not only appreciated, it is expected.

[IanG]

Apologies Bob Salomon, a post mad jokingly can be offensive, I'm sorry, the forum software doesn't allow editing the post now.

But you raised an interesting point the early 240mm seems to be different, all the other early Sironar's split to 3 times their focal length. You posted giving the correct info but questioning if it was a typo. It seems perhaps it isn't a typo.

It's strange that just one lens out of the early range is different, and it also appears to be similar to the later design of the complete range.

Ian

[Bob Salomon]

Apologies Bob Salomon, a post mad jokingly can be offensive, I'm sorry, the forum software doesn't allow editing the post now.

But you raised an interesting point the early 240mm seems to be different, all the other early Sironar's split to 3 times their focal length. You posted giving the correct info but questioning if it was a typo. It seems perhaps it isn't a typo.

It's strange that just one lens out of the early range is different, and it also appears to be similar to the later design of the complete range.

Ian

Ian,

Apology accepted.

I quoted the printed info that we have on the old Sironar lenses. I have no further info then that as I have not used that lens since the early 60's.

[IanG]

It would be interesting to know why the early 240mm lens is the odd one out.

Perhaps Bob if you get a chance you could ask Rodenstock, but then is there anyone there old enough to know, it's unlikely :D

Personally I don't know anyone who uses these lenses split, I know in discussion with professional friends none used a convertible Symmar or Sironar split they all thought the results were too poor quality.

In 40+ years of photography I think I've only ever seen one image made with split Sironar/Symmar.

Ian

[Bob Salomon]

It would be interesting to know why the early 240mm lens is the odd one out.

Perhaps Bob if you get a chance you could ask Rodenstock, but then is there anyone there old enough to know, it's unlikely :D

Personally I don't know anyone who uses these lenses split, I know in discussion with professional friends none used a convertible Symmar or Sironar split they all thought the results were too poor quality.

In 40+ years of photography I think I've only ever seen one image made with split Sironar/Symmar.

Ian

There isn't anyone at Linos who was at Rodenstock when the Sironar was made.

[IanG]

There isn't anyone at Linos who was at Rodenstock when the Sironar was made.

That's what I thought, so we have to keep guessing :)

Ian

[Ole Tjugen]

... Personally I don't know anyone who uses these lenses split, I know in discussion with professional friends none used a convertible Symmar or Sironar split they all thought the results were too poor quality...

Sharp coverage drops drastically, and there is quite a lot of "colour fringeing" in the corners of a 4x5" shot with a converted 150mm Symmar. Central sharpness is very good, and the corners aren't really bad enough to be "wonky and interesting".

There's an example here: http://flickr.com/photos/71733804@N00/438377619/

[Steve Hamley]

Here's the latest update.

For the combined lens, I measured the distance from the front of the front standard (close to where the iris is) to the rear of the rear standard. Not scientific, but I'm interested in the differences. I got 200mm. The rear cell is then 153mm longer. The front cell is 140mm longer. So it appears nearly symmetric.

The rear cell seems softer than the front just trying to focus on the GG at infinity. The converted glass alone does exactly what Ole says, sharpness falls off rapidly, and from looking at an 8x10 GG you'd be lucky to get sharp corners in 5x7. You could probably get a usable 4x5 in a pinch. The basis for these statements on coverage is that if it looks O.K. on the GG, it might or might not be very good on film, especially if enlarging, but if it's observably unsharp on the GG, it's definitely not going to be good on film.

Cheers,

Steve