Lens differences

[Brent]

I did a search on lens differences and found out much needed information but still could not find out the difference in Sironar and Grandagon. I am looking to buy a 90mm f 6.8.

Thanks

Brent

[Ernest Purdum]

The Sironar series (there are several versions of Sironars) are general-usage lenses with moderately wide angles of view so as to allow full use of view camera movements. The Grandagon lenses work at very wide angles, up too 105 degrees. The f6.8 version is a less expensive six glass design as compared to the eight glass f4.5 version. Rodenstock lists the 90mm size as working at 102 degrees and covering a 221mm image circle at infinity and f22.

[Brent]

So working with a 4x5 will my movements be limited with the grandagon lens due to the extra coverage area?

Brent

[N Dhananjay]

Your lens needs to provide enough coverage to cover the size of film you are using. If it provides extra coverage, there is scope to utilize movements. Now obviously the shorter the focal length, the closer the lens sits to the film and the more steep the angle of coverage needs to be in order to cover the film and provide extra coverage for movements. The Sironars are a general lens design that works at providing good amounts of coverage in certain focal lengths. Now if the same design was used for shorter focal lengths, it would not provide enough coverage for the same size of film. Therefore, for very short focal length lenses, you need different designs - thus, the Grandagon. The Grandagons is a different design that provides more coverage and thus even at the shorter focal length provides sufficient coverage to cover the film and provide room for movements.

In short, you are unlikely to be limited in your movements (using 4x5 film) as long as you select Sironars in the 150 mm range, and the Grandagon in the 75-90 mm range.

Hope this helps. Cheers, DJ

[Ernest Purdum]

Brent, you might do well to buy a book (comparatively cheap) before buying a lens (expensive). This could give you far more information regarding lens selection than is feasible here. You can find several very useful ones by searchin on this forum.

[Michael S. Briggs]

Rodenstock, which is part of Linos, has expanded the information available on their website. For LF lenses, http://www.linos.de/en/prod/obj_analoge_fotogr.html.
The html pages describe the currently available lenses and the pdf files add tables with their specifications. For example, the 90 mm f6.8 Grandagon-N covers a circle with a diameter of 221 mm -- this will allow rise / shift movements of 67 / 50 mm with 4x5 film.





The 90 mm f6.8 Grandagon-N has an angular coverage of 102 degrees. In comparison, most of the Apo-Sironar-S lenses cover 75 degrees. Within reason, more coverage is better because it allows larger movements without the film being placed outside the circle of coverage. Each lens projects a cone of coverage -- for a given focal length, a large angle of coverage means a larger diameter circle of coverage. For the same angle, as the focal length is increased the apex of the cone is moved farther from the film and the diameter of the circle of coverage increases.





AFAIK, no Sironar has even been made with a 90 mm focal length, so your choice is easy. Even if there were a 90 mm Sironar, it wouldn't have enough coverage for 4x5.





There have been various versions of the Sironar series over the years. The Linos site has info on the ones still in production. If you are considering buying used, you can search the web for information about previous models.