Ondu 6x6 Mk II F stop?

[gphoto120]

I bought a used Ondu 6x6 Mk II...does anyone know what f stop the pinhole is for this camera? My exposures have been way off!
Thanks ...

 

[MattKing]

Here is a website link which refers to both a current pinhole size and corresponding f/stop, plus the old pinhole size:
https://ondupinhole.com/products/6x6-pocket

 

[RalphLambrecht]

I bought a used Ondu 6x6 Mk II...does anyone know what f stop the pinhole is for this camera? My exposures have been way off!
Thanks ...

Guess its diameter at 0.25mm, measure the distance to the film plane and calculate but do not forget the Schwarzschild effect.

 

[David Lingham]

There is supposed to be a chart that comes with the camera showing how to translate a f22 exposure reading to a correct exposure for the pinhole size. The chart would seem to indicate a stop size of around f190. Don’t forget that reciprocity has to be added to the transposed reading. I have a 6x6 Zero 2000 that has an aperture of f138, the advice given by them is to meter at f8 then reduce the reading by 8 stops finally adding reciprocity to that number.

 

[gphoto120]

thanks everyone !!!

 

[MattKing]

Guess its diameter at 0.25mm, measure the distance to the film plane and calculate but do not forget the Schwarzschild effect.

That website link says:

1. Focal length:25mm
2. Pinhole diameter:0,15mm ( As of June 2020 ) 0,2mm prior
3. f stop equivalent:167

 

[MellowCat]

I believe all of the earlier Ondu 6x6 Pockets were f/125, the MarkIII version went to the f/167. Maybe email Elvis and ask him? He's always responded to me. hello@ondupinhole.com. Great camera! Also, if you use an iPhone download the Pinhole Assist app, makes all this 1000 times easier, unless you love to manually calculate reciprocity