Simple meniscus orientation question?

Candlejack · Nov 24, 2021

Well. I made a stupid mistake. I was cleaning an old box camera. (Western cyclone senior) and i screwed out the lens to wipe the back. I dropped the piece and it seperated.
Below are the 3 pieces, and im not sure what order and orientation to put them in and of the glass elements should touch.
First and second pic. The screw in piece. Outside first then bottom
3rd and 4th. 3rd pic is rounded/concave., 4th pic/other side is flat.
5th and 6th. Concave on one side.. relatively flat on the other.

Thank yall so much for your help in advance. I feel pretty dumb lol

Donald Qualls · Nov 24, 2021

Are they both positive (magnifying) lenses, or is one a negative lens? Is it possible you've lost one element? I suspect you have a "triplet" which should have a positive front element (largest diameter, convex to the world and flat on the back), a negative middle element (flatter side forward, deeper concave to the rear), an aperture stop, and a positive third element (smaller than the front one, and flatter side toward the stop). A Tessar type is the same thing with the rear positive element replaced by a cemented doublet (which may be difficult to distinguish from a single piece of glass). Based on what you have there, your aperture and rear element might still be in the mount in the camera (behind the shutter, most likely).

If both elements you have are positive, you may instead have a "Periskop" type, two meniscus lenses mounted concave toward each other with the aperture stop between -- but usually those would be identical front and rear elements, and the shutter would be between the elements, almost touching the aperture.

Candlejack · Nov 24, 2021

Donald Qualls said:
Are they both positive (magnifying) lenses, or is one a negative lens? Is it possible you've lost one element? I suspect you have a "triplet" which should have a positive front element (largest diameter, convex to the world and flat on the back), a negative middle element (flatter side forward, deeper concave to the rear), an aperture stop, and a positive third element (smaller than the front one, and flatter side toward the stop). A Tessar type is the same thing with the rear positive element replaced by a cemented doublet (which may be difficult to distinguish from a single piece of glass). Based on what you have there, your aperture and rear element might still be in the mount in the camera (behind the shutter, most likely).

If both elements you have are positive, you may instead have a "Periskop" type, two meniscus lenses mounted concave toward each other with the aperture stop between -- but usually those would be identical front and rear elements, and the shutter would be between the elements, almost touching the aperture.

Thank you for getting back to me.
This whole piece sits behind the simple shutter and aperature. It then screws into the the body behind the faceplate (the back of the faceplate has the shutter.

Candlejack · Nov 24, 2021

Heres the back of the faceplate, that sat in front of all the glass pieces

Candlejack · Nov 24, 2021

This is what it screws into

Donald Qualls · Nov 24, 2021

Are one or both pieces positive lenses (thicker in the middle than the edge, magnifying)?

Candlejack · Nov 24, 2021

Donald Qualls said:
Are one or both pieces positive lenses (thicker in the middle than the edge, magnifying)?

One is magnifying, the other seems to reduce.

Donald Qualls · Nov 24, 2021

The smaller one is negative, right? So for light coming in, the larger lens should be first, with the convex side forward, then the smaller lens behind with the concave (or more concave) side toward the first lens. I think your smaller lens is a cemented doublet, and that worries me a little, because if so, this should be a Tessar type (unusual for a box camera) and there's a double concave middle element missing. I think it's more likely I'm not understanding what you have. Is it possible one of the lenses is from one of the two empty bright-finder openings at the top of the front board?

Candlejack · Nov 24, 2021

This view may help. Hopefully.

The finders all have their glass

Donald Qualls · Nov 24, 2021

Aah. Okay, same diameter, or very nearly so. Most likely one is small enough to drop all the way into the threaded collar, convex first, while the other will hang on a shoulder and should go convex up (i.e. concave sides together). This kind of double meniscus or "Periskop" is usually mounted with aperture and shutter between the lenses; it gives almost perfect aberration correction that way (but is limited to about f/11). Normally, both would be identical positive meniscus, of twice the final focal length (or close to it). If one of these is negative, it'll be the rear one (toward the film) and it may be there mainly to correct field curvature.

Okay, I found this page that says you should have an "achromatic combination meniscus" so both of those pieces may be cemented doublets, but the fit should be the way I described.

Candlejack · Nov 24, 2021

So if i understand correctly, the flat side of the magnifying would face the world like so.

Then the slightly concave negative would rest right behind it. (They dont sit flush though.)

Candlejack · Nov 24, 2021

Donald Qualls said:
Aah. Okay, same diameter, or very nearly so. Most likely one is small enough to drop all the way into the threaded collar, convex first, while the other will hang on a shoulder and should go convex up (i.e. concave sides together). This kind of double meniscus or "Periskop" is usually mounted with aperture and shutter between the lenses; it gives almost perfect aberration correction that way (but is limited to about f/11). Normally, both would be identical positive meniscus, of twice the final focal length (or close to it). If one of these is negative, it'll be the rear one (toward the film) and it may be there mainly to correct field curvature.

Okay, I found this page that says you should have an "achromatic combination meniscus" so both of those pieces may be cemented doublets, but the fit should be the way I described.

Candlejack · Nov 24, 2021

Candlejack said:
So if i understand correctly, the flat side of the magnifying would face the world like so.

Then the slightly concave negative would rest right behind it. (They dont sit flush though.)

It seems to be the right way! I came up with a way to check the old 4x5 box cameras. Parchment paper across a mat, using the cellphone to take a photo since obviously i cant get my head in the box.

Candlejack · Nov 24, 2021

Candlejack said:
It seems to be the right way! I came up with a way to check the old 4x5 box cameras. Parchment paper across a mat, using the cellphone to take a photo since obviously i cant get my head in the box.

Donald Qualls · Nov 24, 2021

I don't know that that's right -- it's hard to be sure, because (probably) the cell phone isn't focusing on the image. Based on your photos, you may need to reverse the front doublet, the put more convex side to the world.

If you have any way to precisely measure the distance from lens to film plane, you could set up the lens outside the camera and project an image of something 15-20 feet away (that's a guess on where the hyperfocal distance would be for that lens).

Candlejack · Nov 24, 2021

Donald Qualls said:
I don't know that that's right -- it's hard to be sure, because (probably) the cell phone isn't focusing on the image. Based on your photos, you may need to reverse the front doublet, the put more convex side to the world.

If you have any way to precisely measure the distance from lens to film plane, you could set up the lens outside the camera and project an image of something 15-20 feet away (that's a guess on where the hyperfocal distance would be for that lens).

Ok. Im gonna take a break from it for a bit. But once i find the right order i can just use rubber cement to keep them in place?

AgX · Nov 24, 2021

Donald Qualls said:
Okay, I found this page that says you should have an "achromatic combination meniscus" so both of those pieces may be cemented doublets, but the fit should be the way I described.

To my understanding a ""achromatic combination meniscus", is a achromate, thus one positive and one negative lens element cemented to each other, though in its whole forming a meniscus.

Candlejack · Nov 24, 2021

AgX said:
To my understanding a ""achromatic combination meniscus", is a achromate, thus one positive and one negative lens element cemented to each other, though in its whole forming a meniscus.

Any idea what order i should put the above pieces in?

AgX · Nov 24, 2021

Well, I am surprised to learn of a box at all that got a lens made up of 3 elements. But if so I would try to form a Cooke-triplet.
However the elements you describe do not fit this design.

Candlejack · Nov 24, 2021

AgX said:
Well, I am surprised to learn of a box at all that got a lens made up of 3 elements. But if so I would try to form a Cooke-triplet.
However the elements you describe do not fit this design.

I only have 2 elements.

Candlejack · Nov 24, 2021

I think mr Donald thought I had 3 at first.

shutterfinger · Nov 24, 2021

A lens description for the Improved Magazine Cyclone is on page 4 and the Senior is on page 5 of this 1895 catalog.
http://piercevaubel.com/cam/catalogs/1898cyclonelp810.htm
It says the Senior has a universal in focus achromatic combination meniscus lens.
The Improved Magazine describes its lens as a combination achromatic meniscus pattern consisting of a positive crown glass lens combined with a negative flint glass lens, corrected for actinic light. IOt states that no better lens for universal focus work can be produced. The Senior likely uses the same lens.
I do not know how to tell the difference between Crown Glass and Flint glass. A positive element should magnify and a negative lens reduce.
What is Actinic light?

Candlejack · Nov 24, 2021

shutterfinger said:
A lens description for the Improved Magazine Cyclone is on page 4 and the Senior is on page 5 of this 1895 catalog.
http://piercevaubel.com/cam/catalogs/1898cyclonelp810.htm
It says the Senior has a universal in focus achromatic combination meniscus lens.
The Improved Magazine describes its lens as a combination achromatic meniscus pattern consisting of a positive crown glass lens combined with a negative flint glass lens, corrected for actinic light. IOt states that no better lens for universal focus work can be produced. The Senior likely uses the same lens.
I do not know how to tell the difference between Crown Glass and Flint glass. A positive element should magnify and a negative lens reduce.
What is Actinic light?

I guess the big question is would the convex or flat side of the positive crown glass face outward?

The actinic light... looking at google it seems to have something to do with bright blue light? I wonder if it has to do with handling UV?

shutterfinger · Nov 24, 2021

Candlejack said:
The actinic light... looking at google it seems to have something to do with bright blue light? I wonder if it has to do with handling UV?

I was being rhetorical, likely referring to the clear bluish light of the day before the industrial revolution pollution turned the sky grey.

Meniscus lens diagram from A Lens Collectors Vade Mecum; light travels the direction of the arrow.

Flat side out.
Transparent tape in strips next t each other on glass or clear acrylic makes a substitute ground glass, tape side to the lens.

AgX · Nov 25, 2021

shutterfinger said:
What is Actinic light?

It means "active" or "effective" light. In our case light for which a photographic emulsion is sensitive. Typically blue light is meant.

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