I have compared Agfa Copex Rapid in Modular UR developed with Ilford Pan F+ in 135.
Originally Posted by hpulley
Huge advantage for the Agfa film, no chance for Ilford. Really big difference in sharpness and resolution.
For the comparison with medium format 6x6 I have chosen 100 - 125 ISO films because I want a comparable speed.
With ISO 40 in 135 I have a comparable speed to ISO 125 in 6x6.
An example to explain:
With 135 40 ISO film I meter for example 1/250 and f4, using a normal 50mm lens.
With 80mm lens on 6x6 I have to stop down about 1,5 stops more to get the same depth of field compared to 135 format with 50mm lens.
I get f5,6-8 at 1/250 in 6x6.
To compensate for stopping down I need film with ISO 125.
So with 135 and 40 ISO I have 1/250s and f4.
With 6x6, same depth of field, same shutter speed, I have to use 1/250s and f5,6-8 (the half stop between it) with an ISO 125 film.
In both cases I have comparable speed and depth of field.
That is the practical reason why I compare the ISO 40 Agfa Copex Rapid / Spur Modular to my ISO 100 - 125 films which I am using in medium format.
In normal outdoor shooting conditions ISO 40 in 135 and ISO 100 - 125 in 6x6 are equivalent concerning shutter speed and depth of field.