Alan Imaging Product's 42" lens

Teddan · Apr 16, 2015

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 · Apr 16, 2015

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

Teddan · Apr 18, 2015

richard ide said:
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 · Apr 18, 2015

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 · Apr 18, 2015

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

Dr Croubie · Apr 18, 2015

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).

Alan Imaging Product's 42" lens

Teddan

richard ide

Teddan

Dr Croubie

richard ide

Dr Croubie

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