Alan Imaging Product's 42" lens

[Teddan]

Got a hold of a monstrous 42" lens a number of years ago. I have been trying to find info about this 6,5kg (14,3 lbs) lens but can't find anything.

For one I am trying to figure out the size of the image circle. All that is says on the lens is "Alan 42"

 

[richard ide]

If it is a process camera lens, the angle of view is probably about 45 degrees.

 

[Teddan]

If it is a process camera lens, the angle of view is probably about 45 degrees.

In which case should give me an images circle of......?

 

[Dr Croubie]

42" = 1066mm
2* 1066 * tan(45/2) = 883mm

Which will cover 20x24" paper:
((20*20*25.4*25.4) + (24*24*25.4*25.4))^.5 = 793

That is if, of course, it does cover 45 degrees. But even if it's less you'll easily get a nice 16x20" out of it.

 

[richard ide]

You will also need a minimum of 42" of bellows to focus at infinity.

 

[Dr Croubie]

That reminds me: given that the IC increases with magnification, if you've got 2m of bellows you can possibly even cover 40x48" at 1:1.
If you've got the space and camera, that could make for a nice full-body lifesize portrait (at least sitting, only someone as short as my mum would fit standing up).