Waterhouse stops for a Voigtlander Series II

[Gary L. Quay]

I just bought a Voigtlander Euryscop II Portrait lens No. 5. According to the catalog, it's an f4 lens and has a focal length of 11.5 inches. I need to make waterhouse stops for it. My question is thus: Since the front optic is 3 inches, and each f-stop reduces light by one half, can't I just make waterhouse stops by decreasing the size of the hole by half, i.e. 1.5 inches for f5.6, .75 inches for f8, etc., or is this just wishful thinking?

Thanks!

--Gary

[GSX4]

you need to do the math ..... default lens diameter divided by square root of 2 will give you the correct diameter for the next stop down. Then repeat for each stop downwards.

[Jim Galli]

My approach is simple since I never ever use one of these at infinity. I make the stops mathematically simple, like 5mm, 10mm 15mm 20mm. Then you simply measure center of lens to ground glass in millimeters and divide by the stop number for your effective f-stop. Beautiful lens btw. I have a Serie ii no. 6

[Gary L. Quay]

you need to do the math ..... default lens diameter divided by square root of 2 will give you the correct diameter for the next stop down. Then repeat for each stop downwards.

So, for my 3 inch diameter of the optic, my square root of 2 is 1.41. That gives my a diameter of 2.12 for f5.6, etc. My math skills are rusty, and we're not speaking of a light patina.

Thanks!

--Gary

[Gary L. Quay]

My approach is simple since I never ever use one of these at infinity. I make the stops mathematically simple, like 5mm, 10mm 15mm 20mm. Then you simply measure center of lens to ground glass in millimeters and divide by the stop number for your effective f-stop. Beautiful lens btw. I have a Serie ii no. 6

This would work for me as well, because my Ansco won't even focus this lens at infinity due to repairs to the bellows (gaffer's tape). However, where should I have the lens focused to do the measurement? Also, I'm a little confused about what number you mean when you say "divide by the stop number." Do you mean by the size of the stop opening?

By the way, I admire your work.

Thanks!

--Gary

[GSX4]

Correct Gary... math is on.

[Gary L. Quay]

Correct Gary... math is on.

I made 4 waterhouse stops based on your recommendations. They are f5.6 through f16. I don't suspect that I'll need smaller apertures for portraiture in the studio, especially since I'm looking for softness. They stops aren't perfect, but I think they'll do. I made them out of mat board.



Thanks!

--Gary

[Jim Galli]

This would work for me as well, because my Ansco won't even focus this lens at infinity due to repairs to the bellows (gaffer's tape). However, where should I have the lens focused to do the measurement? Also, I'm a little confused about what number you mean when you say "divide by the stop number." Do you mean by the size of the stop opening?

By the way, I admire your work.

Thanks!

--Gary

You just focus on your picture, however you want it. ie. you focus how you want the picture to be, you measure your draw from center of lens to ground glass and come up with 330mm on this particular picture. You decide to use an aperture that has a 30mm hole. Dive 30 into the 330 and you're at f11. Actually a lot less math than the way you chose to go which is also OK.

[Gary L. Quay]

You just focus on your picture, however you want it. ie. you focus how you want the picture to be, you measure your draw from center of lens to ground glass and come up with 330mm on this particular picture. You decide to use an aperture that has a 30mm hole. Dive 30 into the 330 and you're at f11. Actually a lot less math than the way you chose to go which is also OK.

That's incredibly simple! I didn't quite understand your method until just now, and I was in a hurry to get something done. I really wanted to use the lens, so I did the math. I like learning new things.

I may decide to do it both ways, just to see which one works best. Eventually, I'll make them out of a more durable material, and choose the best option. I really appreciate your input.

--Gary

[GSX4]

glad it worked for you Gary... Now lets see some pictures from the Voigtlander!!!