Actual coverage of 150 mm Sironar S

What is the actual maximum image circle of Rodenstock 150 mm APO

Sironar S lens? Literature states it as 231 mm but some

manufacturers can be a bit conservative. I am comtemplating to get a

6x24 camera with this lens and would thus need about 246 mm

coverage. This is just 15 mm more than stated and when the lens is

commonly focused down to 3-5m in actual use, the circle would be

bigger still.

<p>Hi Ilkka,</p>

 

<p>I have the 150mm Sironar S albeit as a Sinaron SE. I'm pretty sure that Rodenstock are correctly reporting the effective coverage. I seem to recall reading somewhere that Fuji were a little conservative with reporting coverage with some of their lenses and the 150mm f/6.3 springs to mind.</p>

 

<p>I think to be safe and the fact that I see you shooting panos and architecture that you'll probably still like to make some use of shift etc. So, have you considered the Rodenstock 150mm Sironar W which covers 252mm and apparently is just as spectacular as the S.</p>

 

<p>They don't sell them new anymore from memory but I know someone who was selling one around a month ago and can put you in touch if you like.</p>

 

<p>Cheers...John.</p>

The 150 Sironar S is the sharpest and best 4x5 LF lens I have. I never used it with formats larger than 4x5 or 6x12, so I cannot state if it covers something as wide as 6x24. I did a lot of work with a Nikkor 150 SW and the 4x10 pano format (about as wide as the 6x24 format), and it has a tremendous amount of coverage with movements to spare. The Nikkor is much, much larger, significantly heavier and more expensive than the Sironar S, so that's probably not an option.

 

I once tested all my 4x5 lenses on my 8x10 camera, shooting a brick wall at infinity focus at f/22, to see the actual usable image circle of each lens on the larger sheet of film. I was surprised by the results; many of the lenses yielded larger image circles than advertised, though image quality really suffered at the extreme edges.

 

And focusing closer than infinity really amplifies the image circle of any lens, to the point that I've done close-ups with my 90 f/8 Super Angulon on 8x10 with no problem.

231mm is the 150 Sironar-S's rated image circle at infinity focus at f/22. If you plan on using your 6x24 camera exclusively at focusing distances of 3-5 meters, or stop down farther than f/22, then the usable image circle will be larger. I don't have my 4x5 and 150 Sironar-S handy to do an exact measurement, but if we assume that 25% more bellows extension is required for close focusing, then you would position the lens at roughly 187mm of extension to focus at 3m. If we charitably assume that the 180mm APO Sironar S (which, like the 150, has an angle of view of 75 degrees) has the same angle of coverage as the 150, then the 150 at 3m should have a usable image circle of at least 276mm (rated image circle of the 180 Sironar-S). These are rough guestimates but I think they are probably not too far off.

 

Obviously the safest solution is to get a 5x7 or 8x10 camera and lens and do an actual test. A 4x5 camera with rear shift would also do the trick.

Thank you for the replies so far. The reason I am asking specifically on 150 S is that I have the lens, but I don't have it with me now, so I can't check the coverage. And I have a chance to buy a reasonably priced 6x24 body. To cover 6x24 I would just need a little bit more coverage than advertised and if Rodenstock is at all conservative, it should be enough, especially when focused a bit closer than infinity. I can accept a small decrease in corner image quality as it is often sky anyway or can be cropped a bit.

According to Rodenstock Spec sheet you will be ok for image quality at f/22 out to 250mm coverage. (it is the limit MTF is plotted, you can

see why they spec 231 as image quality is dropping fast). The light falloff though is only

graphed for f/16 and shows some falloff > cos. out that far.

I suspect you would have some darkening in the extreme corners

but not a total vignette. f/22 and smaller apertures looks like it

would work....just barely.

Thanks. That's what I sort of thought. I will try it out before buying just to be sure.

Illumination was more of a coverage reason than resolution, IF you are looking at ancient spec sheets. Many folks didnt enlarge as much, and illumination NOT super resolution was the criteria for "cvoverage".

The standard regarding lens coverage is: Infinity at f22. If focusing closer than that, the image circle gets greater.

 

Lynn