Short Tele lenses on 4X5 at close range

[Chuck_1686]

I use a 180mm Tele-Arton with 6x9 at these distances. This Linhof marked lens has always seemed sharp enough to me. I know in their discription Schneider talks about using this lens for studio work and portraits.

[Emmanuel BIGLER]

To Henry : the additional bellow drag required for focusing in close-up is exactly the same whatever the optical formula can be. Once you've set your lens in the infinity-focus position, after taking advantage of the reduced distance between the lens board and the film due to the telephoto propperties, any additional bellows extension for close up is exactly similar to what you would get with a perfectly symetrical lens : additional extension ( E ) = focal-length ( f ) x magnification ratio (M). This is valid even it the lens is very thick and very asymetric, if you count the additional extension E from the infinity-focus position.

To Robert Zeichner, in principle, a telephoto being a-symmetric, you have to take into account the non-unit pupillar magnification ratio when computing the exposure factor vs. bellows extension. However telephotos are not as asymmetric as retrofocus lenses, so in practice the difference with respect to the approximate formula or method valid for a quasi-symmetric lens is not a real issue.

The general formula for the bellows factor is simple

multiplicative factor for exposure time = (M+M_p)^2 / (M_p)^2

M is the image/object magnification ratio, M_p is the lens pupillar magnification ratio. Most view camera lenses are qausi-symmetric with M_p ~1, hence a simplified formula equal to (M+1)^2.

the M_p factor is given either directly or indirectly in manufacturers' data sheet, it is the ratio of exit/entrance pupil diameters.

for telephotos, M_p is smaller than unity, it can be as small as 0.5 for some telephotos designed for 35mm photography, but I do not think that current LF telephotos reach this figure. For wide-angle retrofocus, M_p may be as big as 2.7 (last version of the Zeiss Distagon® 50mm for 6x6).