Sinaron S Lens question regarding APO

[Rudy Torres]

My first question in these forums.
Are all Sinaron S lenses APO. The Sinaron S lens I just got does not have APO on the barrel. I'm not familiar with Sinar's history with regards to marketing these re-branded Rodenstock lenses.
Hope you all can help. Thanks

- Rudy / El Paso Texas

[Emmanuel BIGLER]

This is the correspondence between Sinar names and Rodenstock lenses fabricated for Sinar.

Your lens is identical to the Rodenstock apo sironar N

Sinaron-S = Apo-Sironar-N 72°
Sinaron-SE = Apo-Sironar-S 75°
Sinaron-WS = Apo-Sironar-W 80°

Sinaron-W = Grandagon-N 102-105°
Sinaron-WE = Apo Grandagon 110-120°

Apo-Sinaron = Apo-Ronar 48°

[Rudy Torres]

Thanks for the reply, Mr. Bigler

- Rudy / El Paso, Texas

[Songyun]

Just to stir it a little bit, Did Rodenstock make Sinaron S lens back in the 80s when they made Sironar-N lens (instead of Apo-sironar-N)?

[Rudy Torres]

From the stand point of value to the buyer, when Sinar started this private label venture with Rodenstock, you would think they would mark the lenses as APO on the barrel. Hell, they at least were wise enough to mark the MC for multi-coated. Why not APO. So, that was why I asked the question. I just bought a Sinaron S Lens on Ebay and the title listed it as an APO. Only one picture of the lens was on the listing so I couldn't see the letters on the other side of the lens. When I asked the Ebay member about the APO issue his response was the same as Mr. Bigler's. But red flags (so to speak) are still popping up in my head.

- Rudy

[rachase]

I had similar doubts about the Sinaron-S 135 lens I picked up a few years ago though the results with it seemed very good. Late last year, I decided to 'upgrade' to an APO Sironar-S 135 after hearing by many that it is one of the best with the idea of selling the Sinaron. After using the Sironar-S for a few months, it is now not so clear to me which should be the one to get rid of; I feel the Sinaron-S may have given me slightly better results. It definitely merits side by side comparison tests with the Sironar. I shoot both color and black and white and don't really need the few additional millimeters of coverage that the Sironar-S affords.
I too have heard that all Sinaron-S's are really APO Sironar-N's but I can't say that authoritatively.

[John Schneider]

Rather than banter around hearsay, get the definitive facts. Do a search here for posts involving Sironar, Sinaron, etc. made by Bob Salomon, who is the "voice" for the official US importer for Rodenstock, HP Marketing. You find that his posts echo what Emmanuel Bigler said supra, and probably quite a bit more. Bob is a wealth of information but sometimes a little terse, so you don't get the entire answer at once (which, come to think about it, is good pedagogy).

[Emmanuel BIGLER]

The above correspondence table between Sinaron lenses and Rodenstock products applies for sure to the Sinar-branded lenses sold at the end of the last century. Say, to be sure, 1990 onwards.
I have at home a German compilation of professional photo equipment catalogues of the nineties, and both Rodenstock and Sinaron lenses are listed with their specifications. No need to be an optical enginneer or a photographic Sherlock Holmes to translate the schwytzertütsch dialect spoken in Schaffhausen into the Bavarian dialect spoken in Munich : the Rosetta Stone is in this German compilation book !
Hence the table of correspondence I have listed above is, as far as one can be sure, fairly reliable, at least based on this German document, and for the end of the XX-st century.

Now there are two other questions :
- why apo ?
- is the apo sironar S realy better than the apo sironar N ?

The answer to the first question ; "apo" is related to to the existence for a certain period of time at the end of the XX-st century of a (now obsolete) German standard:
Din 19040 Blatt 5 : Allgemeine optische Begriffe in der Photografie

This standard, which I have never read, is supposed to be the legal and technical basis allowing German manufacturers to label "apo" certain of their lenses.
However, the standard no longer exists, and when you read recent Rodenstock catalogue, their explanation about the meaning of apo is quite vague and does not refer to this standard.

Bob Salomon is definitely the authority here who could clarifiy this but there is a good probability that some already existing excellent view camera lenses could be labeled "apo" according to the DIN 19040 Blatt 5 standard without any change inside.
For example a good Sironar N could probably be transformed into an apo sironar N according to the standard. But the lens could also be improved. I do not know !

There is no obligation for manufacturers to explain in detail the successive internal upgrades of their lenses. And there is no obligation for them to put clearly for the customer any correspondence between their patents and their commercial lens names. And secret know-how is also very important in the harsh industrial competition.
So we should not be surprised to be at guess as far as the technical history of Rodenstock lenses is concerned.
The only technical document which is really proper to a lens design, except the patent of course, is the FTM curve, and for the last generations of German lenses, those data are available. So by reading the MTF curve anybody can say if a certain lens, identified by a commercial name and officially listed, has been changed with respect to a previous design or not.

This brings us to the second question : are apo sironar S better than apo sironar N (alias Sinaron S, alias Caltar II)
The answer can be found, at least on a theoretical point of view (those who actually take pictures with their lenses can stop reading here ;) ) by comparing side by side the Official MTF Curves for the 3 apo sironar, the N, the S and the W.
The following comparative FTM plot for the 150 mm apo sironar series has been recomputed from the official Rodenstock specs by myself; I have followed a good advice by Arne Croell who has the German brochures and who showed me the same kind of diagrams.
http://www.cijoint.fr/cj200904/cijF0OLuAc.pdf

@f/22, it is extremely difficult to differenciate the FTM of the 3 lenses at the centre of the field. The major difference being that N, S and W have an increasing image circle, no surprise. It should be noted, however that the image circle advertised on the brochures coresponds to a very low contrast limit @ f/22.

My understanding is simply that those lenses represent the state of the art for a classical 6/4, (not a 100° wide angle: the grandagon N 6.8 series are also a 6/4, but very, very different) , like the Symmars, Sironars, Nikkor-W and other designs covering 70° and sligtly above.
It is extremely difficult to do better, the Rodenstock engineers by designing the W series have compromised a little bit on the FTM at the centre in order to gain 5-8° of image circle..

The practical conclusion is that the apo sironar N, suffering on the market from the (justified) reputation of the S and W series is sold new or used at bargain prices... so do not hesitate to buy one and be happy with your 72° instead of 75 or 80; and simply compute the premium you'll have to pay per additional degree of angle, if you succumb to the hard pressure of those damn' internet discussion groups who endlessly advertise : S or W ! S or W! S or W! ;);)