you want coverage? ;-) Re: Nikkor coverage

[Robert Monaghan <rmonagha@xxxxxxxxxxxxxxxx>]

On Fri, 14 Jan 2000 zxiong@xxxxxxxxxxxxxxxxxxxxxx wrote:

> Some simple maths will tell why some 35 mm lens may cover 120 film.
> 
> Any 35 mm lens covers 36 mm of the 56 mm of a 120 film.  If a lens is capable
> of shifting 10 mm, it adds 20 mm to the coverage, which is 35+20=55.

not quite so simple ;-) the diagonal of 24x36 rectangle is circa 43mm, so
most 35mm lenses with full frame coverage must have an image circle of at
least 43mm. Stopping the lens down usually provides more coverage (not 
always, esp. with ultrawides and very wides) too. So covering a vertical 
slit of 55mm is not that unlikely. However, covering the 79mm diagonal of
6x6cm (actually 56mm sq) is generally beyond many 35mm lenses.

However, I have found that many telephoto lenses from 35mm have excess 
coverage, often enough to cover 6x6, making it cheap and easy to convert
to focal plane medium format cameras. Unfortunately, not what we want for 
most panoramic cameras ;-) see http://www.smu.edu/~rmonagha/bronhb.html 

However, I would be interested in any references to actual lens coverage 
of 35mm lenses, esp. in the wide angle lenses, and not just for possible
panoramic lens hacking ;-) Generally, this info isn't published, so you 
have to build a ground glass focusing box or view camera mount to test it
out at different f/stops etc. 

re: fixed lens panoramic coverage lenses...

However, I should alert you to the existence of several medium format 
shift lenses at modest cost, such as the 55mm f/4.5 Arsat shift lens with 
12 mm of shift (on top of being a 6x6cm design lens). Similarly, you can 
remount the 30mm fisheye to give a circular (180 deg diag) view; in fact, 
Roger Hicks created a 4x5 compact body and standard film holder back 
custom camera (in a Brit Jrnl Photogr. article) to fit the 30mm Kiev lens.
A similar roll film holder back with shutter and $180 30mm 6x6 fisheye is
an interesting approach to ultrawide panoramics at $1 per degree ;-) 

finally, these lenses are often less $$ than 35mm ultrawide and shift 
lenses, but with far more coverage for medium format panoramic setups; see 
http://www.smu.edu/~rmonagha/bronfe.html

grins bobm