Bausch - Lomb Protar Series VII Aperture scale question

[ilya1963]

Bausch - Lomb Protar Series VII Focus 23-1/8 In No.2448529 Pat. Jan 8, 1895 On Rear Lens: Bausch - Lomb Protar Series VII Focus 18-7/8 In. No.2448528 Pat. Jan. 8, 1895 On Shutter: Copol - No.


I just got this lens from Tooth. Fairy - Ebay seller , beautiful lens it is mounted in copal 3 Aperture scale goes from 5 to 50, 5 being the smalles openinng and 50 is wide open , I wonder is someone knows how those numbers reference to the aperture scale we use now ?
Any help would be very much appreciated...ILYA

 

[Whiteymorange]

According to cameraeccentric.com, B&L were using F stop aperture scale by 1906. The numbers on the shutter may be from another lens?

 

[ilya1963]

According to cameraeccentric.com, B&L were using F stop aperture scale by 1906. The numbers on the shutter may be from another lens?

I just e-mailed Seth directly hopefully he might know, Thank you.

 

[Michael Kadillak]

Bausch - Lomb Protar Series VII Focus 23-1/8 In No.2448529 Pat. Jan 8, 1895 On Rear Lens: Bausch - Lomb Protar Series VII Focus 18-7/8 In. No.2448528 Pat. Jan. 8, 1895 On Shutter: Copol - No.


I just got this lens from Tooth. Fairy - Ebay seller , beautiful lens it is mounted in copal 3 Aperture scale goes from 5 to 50, 5 being the smalles openinng and 50 is wide open , I wonder is someone knows how those numbers reference to the aperture scale we use now ?
Any help would be very much appreciated...ILYA

I saw the lens that you won on that auction house and also believe that the aperture scale may be from another lens. Most protars have a series of f-stop scales that allow you to correctly know with both elements or with a single element what the realized f stop is.

If I remember this was not a cheap lens and you may not want to hear this but you are probably going to have to have the lens looked at by a competent shutter expert and have the appropriate f-stop calibrations made and installed on your shutter to feel confident when you use it.

Just out of curiosity, what is the effective focal length with both elements?

Good Luck!

 

[Jim Noel]

The early Protars were in Compound shutters and had a scale of the diameter of the aperture in mm. The f-stop was computed bythe photographer according to the focal length of the component(s) being used .
At least this is the way the one I owned for several years was set up.

 

[ilya1963]

The early Protars were in Compound shutters and had a scale of the diameter of the aperture in mm. The f-stop was computed bythe photographer according to the focal length of the component(s) being used .
At least this is the way the one I owned for several years was set up.

What is the formula for this please? Ilya

 

[ilya1963]

[If I remember this was not a cheap lens and you may not want to hear this but you are probably going to have to have the lens looked at by a competent shutter expert and have the appropriate f-stop calibrations made and installed on your shutter to feel confident when you use it.

Just out of curiosity, what is the effective focal length with both elements?

Good Luck![/QUOTE]

Michael,I paid 591 dollars for this lens , I have been looking for a 24 inch lens in a shutter for a while and did not want a monster, this is a fairly compact lens for it's focal length...

 

[Michael Kadillak]

[If I remember this was not a cheap lens and you may not want to hear this but you are probably going to have to have the lens looked at by a competent shutter expert and have the appropriate f-stop calibrations made and installed on your shutter to feel confident when you use it.

Just out of curiosity, what is the effective focal length with both elements?

Good Luck!

Michael,I paid 591 dollars for this lens , I have been looking for a 24 inch lens in a shutter for a while and did not want a monster, this is a fairly compact lens for it's focal length...[/QUOTE]

My apologies. I must have been thinking about the Zeiss protar that was sold at the same time for about 3x that amount. B&L used the same formula from Zeiss so you did in fact get a great deal. Good Luck

 

[jimgalli]

I believe what the shutter references is mm. 5mm at the small end, 50mm at the large. That way no matter which combination you have in use, you measure the focus spread and divide the mm into it for your aperture. For instance you're using the 23 7/8 inch lens on a fairly near subject like a steam locomotive wheel. You focus. Measure in mm the distance from the rear lens glass to the ground glass. (try not to get anal about this part, you can be off plus or minus 10mm) Let's say it's 660mm for sake of explaining. Set the mm scale at 15mm. 15 into 660 is 44. You're at f45 for all practical purposes. Works for any combo you install. I have an extra 18 7/8 group for one of those if you want to add it to the casket set.

 

[ilya1963]

Jim, Thank you very much ....Just what I needed
Thank you ...ILYA

 

[ilya1963]

It came with the rear element that is 18 7/8 so thank you for the offer , but I have it already
I do have a question that might sound stupid, but i have never worked with a group lens before so forgive me for my ignorance.
My focal lens of front element is 23 7/8, is it in combination with 18 7/8 rear element or by itself ? and visa versa
and if the answer is - each element could be worked separately, when working with one of those elements in the shutter the blades of the shutter are exposed ,is that OK?
Thank you, ILYA

 

[jimgalli]

With both elements combined you have a focal length of 11 7/8 inch (300mm) f7 lens. To get the other 2 lengths you use the single lenses by themselves. When combined leave the longer focal up front. When using singles use them behind the aperture. Just be careful while the shutter blades are exposed.

Ideally if you removed one of the elements and left the empty barrel up front and then had an orange filter that would spin in that barrel where the lens used to be, you can correct a bunch of chromatic aberations that causes de-focus when using the single groups alone.

 

[QualityCamera]

Hello ILYA,

First congratulations on what I think was a good deal. I was the under bidder and I was interested in buying it for resale. The lens that you purchased was I believe one of many that I sold to the former owner in the early 1990s. The shutter was set up by the late S.K. Grimes. Jims discription for use is accurate. The shutter in fact should be more versatile for you because you can use it with other cells. The cells you have, have a combined focal length of 11 7/8 or about 300mm. So with one lens you have 300mm, 480mm and 600mm focal lengths. Combined 300mm is F7 and the individual cells are F12.5
When using a single cell mount it on the backside of the shutter. Enjoy the lens.

 

[ilya1963]

Gentelmen you are more then kind ...I am greatfull...thank you a bunch for all your input.
ILYA

 

[ilya1963]

Ideally if you removed one of the elements and left the empty barrel up front and then had an orange filter that would spin in that barrel where the lens used to be, you can correct a bunch of chromatic aberations that causes de-focus when using the single groups alone.-Jim
______________________________________________________
Do you know by chance what size thread copal three has?
ILYA

 

[jimgalli]

Ideally if you removed one of the elements and left the empty barrel up front and then had an orange filter that would spin in that barrel where the lens used to be, you can correct a bunch of chromatic aberations that causes de-focus when using the single groups alone.-Jim
______________________________________________________
Do you know by chance what size thread copal three has?
ILYA

58mm but I don't know if the thread pitch is the same as filter threads. Might be finer pitch.

 

[ilya1963]

Thanks once again...

 

[ilya1963]

I want to add something to this thread... I bought this lens to have a 24 inch lens in a shutter that is not too big , but what I got is a beautiful painting 12 inch lens when not stoped down is soft and sharp at the same time...

Maybe it's just a new toy , but I have not touched my other lenses for three months now

Did i say how much i like this lens ?

ILYA