Ginette
13-Jan-2014, 01:39
I have a very nice Wista Copal Press shutter #1. It came with an aperture scale. Are some data are available for this shutter as an f scale is already affix to? At the top of the scale I can see this indication W180.
Same as this one (http://www.bhphotovideo.com/c/product/63488-REG/Wista_211341_1_Press_Shutter.html). Mine doesn't have the black tube, don't know what it is? See mine below.
For calculate the good f-stop for a specific focal lengh I think that I need to take exact diameter of each f-stop. Focal Length / diameter = new f-stop Right??
EX: Actual 5.6 on the aperture scale = diameter of the blades 25mm. So for a 300mm it will become 300 / 25 = f12 for a 150mm lens it will be 210 /25 = f8,4
Is this a simple way to calculate an f-stop correction that can be enter in an application like the Reciprocity Timer in terms of a final correction of the time. ex: the calculated 8.4 vs the original 5.6, what is the mathematically coorect operation 8.4/5.6 = 1.5 stop less??
Sorry for my very bad English, hope you can understand what I ask about.
Same as this one (http://www.bhphotovideo.com/c/product/63488-REG/Wista_211341_1_Press_Shutter.html). Mine doesn't have the black tube, don't know what it is? See mine below.
For calculate the good f-stop for a specific focal lengh I think that I need to take exact diameter of each f-stop. Focal Length / diameter = new f-stop Right??
EX: Actual 5.6 on the aperture scale = diameter of the blades 25mm. So for a 300mm it will become 300 / 25 = f12 for a 150mm lens it will be 210 /25 = f8,4
Is this a simple way to calculate an f-stop correction that can be enter in an application like the Reciprocity Timer in terms of a final correction of the time. ex: the calculated 8.4 vs the original 5.6, what is the mathematically coorect operation 8.4/5.6 = 1.5 stop less??
Sorry for my very bad English, hope you can understand what I ask about.