Bought Magic Lantern

[Raidahl]

Hi,

I bought from ebay uk one magic lanter, it came with lens, height 8,5cm, front lens diameter about 4,5cm
Then there are this condenser lens, which diameter is about 10cm and height 4,8cm
That would be quite nice in front of Sinar

My math is not so good that I could calculate aperture of those lenses, so if anyone could provide me some formula for calculation, I would be very pleased.

[vitality]

some formula for calculation

Focal length divided by diameter of front element (glass) will give you approx. F number (eg. FL - 200mm, front element's diameter - 50mm. 200/50=F4).