Foca PF2B Adjusted Ilford Pan100
"Film d'essai" (test film) of my French range-finder 35 mm camera Foca PF2B (year 1956) after the shutter new adjustments.
I used here a 36 exposure Ilford Pan100 film exposed for 100 ISO using a Minolta Autometer III with a 10° finder for selective measurements privileging the shadow areas. The Foca Oplar lens1:2.8 f=5cm was fitted with a FOCA "AUV"(Anti-UV) filter and a Genaco metal shade hood, both push-on 42mm.
Rue Bodin, March 13, 2023
69001 Lyon
France
After exposure, the film was processed using Adox Adonal (Agfa Rodinal) developer at dilution 1+25, 20°C for 9 min.
The film was then digitalized using a Sony A7 body adapted to a Minolta Auto Bellows III and a Minolta Slide Duplicator using a lens Minolta Bellow Macro Rokkor 50mm f/3.5 at a reproduction ratio of 1:1. The reproduced RAW files obtained were processed in LR prior the the final JPEG editions.
All views of the film are presented in the dedicated album either in the printed framed versions and unframed full-size jpeg.
About the camera and the lens:
The Foca type PF2B (PF for "Petit Format") was constructed in France by the company "Optique & Precision de Levallois" (OPL) starting from 1947. It was manufactured in the Chateaudun OPL factory, route de Jallans, France, in 1956 among a late series of the PF2B. The factory, constructed in 1938, is still at the same place under the name of SAFRAN now producing precision devices for aerospace appliances.
The camera is equipped with the collapsible OPLAR lens (a Tessar formula) 1:2.8 f=5cm. The focal shutter of the PF2B has timing of 1/1000, 1/500, 1/200, 1/100, 1/50 and 1/25s plus the B pose. A slow exposure device below 1/25s could be installed by the aftermarket service and was installed in series for the FOCA PF3 type.
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Object of the adjustments :
Due to the presence the original factory seals on the shutter adjustments, I knew that the camera has never been adjusted of serviced since 1956!
Until now the 1/25s, 1/50s and 1/100s suffered from inconsistent curtains travel speeds causing band inhomogeneities in the exposure. The 1/1000, 1/500 and 1/200s were however coherent. I proceeded here as follows :
1- The shutter being on B setting, proceeding by half turns only on the adjustment screw, I increased the spring tension of the first curtain by 2 half anti-clockwise turns causing more regular and fast opening of the first curtain.
2- Then I did the same on the second curtains to get a similar speed of closure.
3- I checked visually that all speed gives homogenous opening scans from 1/25s to 1/1000 (proceed without the lens mounted).
Likely the 1/25s is still slow but I decided to see the results obtained on a test film. The exposures ae now all homogenous. Following the densities given by the Sony A7 during the digitalization, one could deduce that 1/50s gives +0,3 EV more than expected (ie 1/30s instead of 1/50s) and 1/25s gives +1.3 EV (ie 1/10s instead of 1/25s). After the test film I added 1/2 turn to the first curtains to increase the travel speed.
Foca PF2B Adjusted Ilford Pan100
"Film d'essai" (test film) of my French range-finder 35 mm camera Foca PF2B (year 1956) after the shutter new adjustments.
I used here a 36 exposure Ilford Pan100 film exposed for 100 ISO using a Minolta Autometer III with a 10° finder for selective measurements privileging the shadow areas. The Foca Oplar lens1:2.8 f=5cm was fitted with a FOCA "AUV"(Anti-UV) filter and a Genaco metal shade hood, both push-on 42mm.
Rue Bodin, March 13, 2023
69001 Lyon
France
After exposure, the film was processed using Adox Adonal (Agfa Rodinal) developer at dilution 1+25, 20°C for 9 min.
The film was then digitalized using a Sony A7 body adapted to a Minolta Auto Bellows III and a Minolta Slide Duplicator using a lens Minolta Bellow Macro Rokkor 50mm f/3.5 at a reproduction ratio of 1:1. The reproduced RAW files obtained were processed in LR prior the the final JPEG editions.
All views of the film are presented in the dedicated album either in the printed framed versions and unframed full-size jpeg.
About the camera and the lens:
The Foca type PF2B (PF for "Petit Format") was constructed in France by the company "Optique & Precision de Levallois" (OPL) starting from 1947. It was manufactured in the Chateaudun OPL factory, route de Jallans, France, in 1956 among a late series of the PF2B. The factory, constructed in 1938, is still at the same place under the name of SAFRAN now producing precision devices for aerospace appliances.
The camera is equipped with the collapsible OPLAR lens (a Tessar formula) 1:2.8 f=5cm. The focal shutter of the PF2B has timing of 1/1000, 1/500, 1/200, 1/100, 1/50 and 1/25s plus the B pose. A slow exposure device below 1/25s could be installed by the aftermarket service and was installed in series for the FOCA PF3 type.
-------
Object of the adjustments :
Due to the presence the original factory seals on the shutter adjustments, I knew that the camera has never been adjusted of serviced since 1956!
Until now the 1/25s, 1/50s and 1/100s suffered from inconsistent curtains travel speeds causing band inhomogeneities in the exposure. The 1/1000, 1/500 and 1/200s were however coherent. I proceeded here as follows :
1- The shutter being on B setting, proceeding by half turns only on the adjustment screw, I increased the spring tension of the first curtain by 2 half anti-clockwise turns causing more regular and fast opening of the first curtain.
2- Then I did the same on the second curtains to get a similar speed of closure.
3- I checked visually that all speed gives homogenous opening scans from 1/25s to 1/1000 (proceed without the lens mounted).
Likely the 1/25s is still slow but I decided to see the results obtained on a test film. The exposures ae now all homogenous. Following the densities given by the Sony A7 during the digitalization, one could deduce that 1/50s gives +0,3 EV more than expected (ie 1/30s instead of 1/50s) and 1/25s gives +1.3 EV (ie 1/10s instead of 1/25s). After the test film I added 1/2 turn to the first curtains to increase the travel speed.