Swapping 360mm f9 Apo Ronar in Compur 3 for 480mm f9 Apo Ronar

[Ed Bray]

Now I have taken the plunge and bought a 5x7 Camera most of my lenses cover 5x7 anyway (not sure about the 75mm f5.6 SA or the 90mm f8 SA) but my 121mm SA, 150mm Apo Symmar, 180mm Apo Symmar, 210mm Apo Symmar, 240mm Symmar S, 300mm Symmar S, and 360mm Apo Ronar all definitely do.

I would like something a bit longer for head and shoulder shots on 5x7 so am considering getting a Apo Ronar 480mm f9, but these all tend to come without shutters or if a shutter is included it is out of my price range.

As I have a 360mm f9 Apo-Ronar, would it be just a straight swap to use the 480mm f9 Apo-Ronar in the same shutter (Compur 3)? That is, will the aperture scales for one still suit the other?

[Dan Fromm]

Lessee now, 360/9 = 40, 480/9 = 54.4. No.

[Jim Jones]

If the lens cells fit the shutter, simple field math lets you use the 360 scale with the 480 cells. Just give about one stop more exposure than the scale indicates.

[Ed Bray]

Lessee now, 360/9 = 40, 480/9 = 54.4. No.

Ha ha, yes, what a tool!

[Len Middleton]

Ha ha, yes, what a tool!

Seems a little rude, given that Dan was providing the basic math on how aperature is calculated that you did not seem to understand...

[Bob Salomon]

The 90mm 6.8 Grandagon-N MC more then covers 57 so your 90mm 8.0 should also.

[Oren Grad]

...most of my lenses cover 5x7 anyway (not sure about the 75mm f5.6 SA or the 90mm f8 SA)

Vintage Super Angulon Data

(Short answer: at f/22 and infinity focus, 75 not quite, 90 just barely)

[Ed Bray]

Seems a little rude, given that Dan was providing the basic math on how aperature is calculated that you did not seem to understand...

I was meaning that I was a tool, the math was obvious when I'd thought about it.

[Len Middleton]

I was meaning that I was a tool, the math was obvious when I'd thought about it.

Ed, your meaning is a little clearer now.

I misunderstood your earlier intent...