Magnifax 4 with 80mm lens question

[antielectrons]

Hi,

Anyone know which way round I should insert an 80mm lens in the Magnifax 4 lens cup? Should it be convex or concave (i.e. lens fartherst from film plane or nearest to film plane). My understanding is that it changes depending on the lens focal lengh.

Thanks.

Antonio

 

[David H. Bebbington]

Convex (although concave will work, too, you just won't get enough bellows extension to make small prints).

 

[Marc Leest]

Convex (although concave will work, too, you just won't get enough bellows extension to make small prints).

I agree, I just checked (I have a 4a with a 80mm).

M.

 

[antielectrons]

Thanks guys. I wonder. I am getting about 40 secs for a grade 2 print at 17 mm squaare with a 150w bulb. Perhaps in the concave position times will be shorter as the lens is nearer to the light? Seems to be a fair bit of belows travel left for focussing...

 

[Marc Leest]

Thanks guys. I wonder. I am getting about 40 secs for a grade 2 print at 17 mm squaare with a 150w bulb. Perhaps in the concave position times will be shorter as the lens is nearer to the light? Seems to be a fair bit of belows travel left for focussing...

Strange, I usually have exposure times about 15s. at f8 for a 22x22 (cm) with a 100w bulb...
Dial the ND filter out if appropriate.


M.

 

[antielectrons]

I think maybee the negs I have been using are a bit thick...

 

[David H. Bebbington]

Thanks guys. I wonder. I am getting about 40 secs for a grade 2 print at 17 mm squaare with a 150w bulb. Perhaps in the concave position times will be shorter as the lens is nearer to the light? Seems to be a fair bit of belows travel left for focussing...

For a given print size, the lens will be in focus at exactly the same place whichever way round you have the panel - the only thing that changes is the position of the front of the bellows!