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Larry Huhn
12-Nov-2016, 05:53
I am interested in exploring the process of building or adapting lenses for my Toyo 45 or my Hasselblad. Can anyone recommend a group here or Facebook or websites? Thanks!


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Dan Fromm
12-Nov-2016, 06:44
What do you mean by adapting? And which lenses or types of lenses are you thinking about adapting?

I asked the first question because I've hung unlikely lenses in front of press and view cameras. Most mounted up in the usual way. The ones that didn't either had to be put in shutter, which can involve machining, or wouldn't pass through the camera's front standard.

I asked the second question because hanging lenses in front of a press/field/technical/view camera isn't a big deal. Hanging lenses in front of a 'blad can be somewhat more involved.

mdarnton
12-Nov-2016, 07:02
I think the idea of building a lens from scratch works better in the soft focus realm. In your basement you probably will not be able to reach even the level of sophistication of a commercial maker in the 1880s for building a sharp, flat-field lens. But if you are into SF, there are tons of interesting possibilities. The best place to start will definitely be 4x5, unless you have some extra Hasselblad lenses you are OK with gutting just to get the shutter, which would be necessary for any kind of real functionality on a Blad body. Then once you have the shutter, there's the problem of closely matching the focal length the shutter was designed for, if you want the result to focus.

There used to be a lens designer hanging around the APUG forum, talking about lens building and offering up some designs, but I haven't been there in a while, so he may be gone.

Brook Martin
12-Nov-2016, 07:32
I am interested in any forms or groups on lens building as well. I have been working on this and have had some success. I run a kiln department for an architectural glass studio for the day job so I have access to a bit more than the average garage.

Dan Fromm
12-Nov-2016, 07:35
Brook, I don't think there are any forms or groups. Amateur astronomers make concave mirrors, sometimes lenses. Look for astronomy forums.

But there is a book. https://www.amazon.com/Primitive-Photography-Cameras-Calotypes-Alternative/dp/0240804619

Larry Huhn
12-Nov-2016, 08:01
What do you mean by adapting? And which lenses or types of lenses are you thinking about adapting?

I asked the first question because I've hung unlikely lenses in front of press and view cameras. Most mounted up in the usual way. The ones that didn't either had to be put in shutter, which can involve machining, or wouldn't pass through the camera's front standard.

I asked the second question because hanging lenses in front of a press/field/technical/view camera isn't a big deal. Hanging lenses in front of a 'blad can be somewhat more involved.

Dan, thanks for reply. By adapting I mean using projector lenses and such. My Hasselblad is a 201f so it has a focal plane shutter. I was thinking I could use a short extension tube for a mount and go from there. I am interested in soft focus lenses. Thanks


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Larry Huhn
12-Nov-2016, 08:04
I think the idea of building a lens from scratch works better in the soft focus realm. In your basement you probably will not be able to reach even the level of sophistication of a commercial maker in the 1880s for building a sharp, flat-field lens. But if you are into SF, there are tons of interesting possibilities. The best place to start will definitely be 4x5, unless you have some extra Hasselblad lenses you are OK with gutting just to get the shutter, which would be necessary for any kind of real functionality on a Blad body. Then once you have the shutter, there's the problem of closely matching the focal length the shutter was designed for, if you want the result to focus.

There used to be a lens designer hanging around the APUG forum, talking about lens building and offering up some designs, but I haven't been there in a while, so he may be gone.

Thanks for the reply. My Hasselblad is a 201f with a focal plane shutter. I was thinking of using an extension tube as a mount because it would be pretty cheap.


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Larry Huhn
12-Nov-2016, 08:05
Brook, I don't think there are any forms or groups. Amateur astronomers make concave mirrors, sometimes lenses. Look for astronomy forums.

But there is a book. https://www.amazon.com/Primitive-Photography-Cameras-Calotypes-Alternative/dp/0240804619

Thanks Dan, I will check out this book.


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Dan Fromm
12-Nov-2016, 08:11
Projector lenses? Oy!

Oy for two reasons. Projector lenses for 35 mm projectors cover 4x5 only very close up. Projector lenses for larger formats, such as lenses from opaque projectors/epidiascopes, run large to gigantic.

All are in barrel without diaphragm. Putting them in shutter can be problematic because they're typically not lenses in cells that screw into barrels, instead they're lenses in tubes. I hope you see the difference.

Shutters? Large leaf shutters, e.g., Packards, Luc and such, or roller blind shutters such as Thornton-Pickard, behind or in front of the lens. I don't know whether y'r Toyo 45 can mount a Packard or Sinar-Copal behind the standard.

mdarnton
12-Nov-2016, 08:48
If you can get a lens on the board, you can mount a Packard in front. I'm using a cheap barndoor set (setscrew type, doors removed, Packard taped where the doors were--http://www.adorama.com/ltbbd.html?gclid=CjwKEAiAmJvBBRDKpP724LigwngSJAAYRJXB_7VdItrxrXzgvCm35ji01P02W_FnyV4-hlxDcn_12BoC3h_w_wcB) to mount a Packard to the front of my Verito and other lenses of similar size. For the Blad, you might find a bellows to be the most functional for mounting various lenses, rather than tubes.

DrTang
12-Nov-2016, 10:53
unless you have some extra Hasselblad lenses you are OK with gutting just to get the shutter, which would be necessary for any kind of real functionality on a Blad body..

I gut RB67 lenses to mount crazy stuff on - to use on my RB67 body

scratched up lenses are cheap on ebay and rb67 systems are way cheap

Bob Salomon
12-Nov-2016, 10:58
Projector lenses? Oy!

Oy for two reasons. Projector lenses for 35 mm projectors cover 4x5 only very close up. Projector lenses for larger formats, such as lenses from opaque projectors/epidiascopes, run large to gigantic.

All are in barrel without diaphragm. Putting them in shutter can be problematic because they're typically not lenses in cells that screw into barrels, instead they're lenses in tubes. I hope you see the difference.

Shutters? Large leaf shutters, e.g., Packards, Luc and such, or roller blind shutters such as Thornton-Pickard, behind or in front of the lens. I don't know whether y'r Toyo 45 can mount a Packard or Sinar-Copal behind the standard.
Dan, their are 35mm projector lenses that do have aperture rings built in, among others were some Rollie, Schneider, Baruch & Lomb and, I believe, Braun. There can be many others. They used the aperture to compensate for poorly exposed slides that otherwise would have projected too washed out in the screen. But they were not calibrated in f stops.

Dan Fromm
12-Nov-2016, 11:22
Bob, thanks for the correction.

Drew Bedo
16-Nov-2016, 06:15
I'm the realm of ill-informed speculation:

Incomplete or damaged antique brass lenses often come up on auction sites at "reasonable" prices. I would think that a friendly optician's technician could replicate the glass elements to rebuild one. this might be an entry level step to scratch building a lens.

Just be sure that the doner parts are not bits of some priceless collectable!

Steven Tribe
16-Nov-2016, 11:34
I'm the realm of ill-informed speculation:

Incomplete or damaged antique brass lenses often come up on auction sites at "reasonable" prices. I would think that a friendly optician's technician could replicate the glass elements to rebuild one. this might be an entry level step to scratch building a lens.

Just be sure that the doner parts are not bits of some priceless collectable!

Yes "ill-informed speculation", mostly!

In theory, this very sensible.
In practice, extremely difficult.
Glass is not just glass. Even pre-Jena glass varies a lot (mostly refractive index). It depended mostly on the sources of sand used in manufacture. So French crown glass is different from English crown glass. After 1890, many new glass types became available and were quickly adopted by lens makers. New blanks of traditional type optical glass are no longer available. As you mention, a solution might be to use orphaned lens glass from the same country and same period. You just have to find a suitable diameter and a thickness which will allowing grinding down to the right radii. Telescope makers do have a kind of rites of passage where they make a mirror surface or refracting lens as part of their initiation into the brotherhood - but there is large supporting network that we don't have.

I have two examples which do provide some optimism, though.
The first is an aplanat, a Voigtlander series II F.4 which has just a single cell. I have replaced the missing cell with an orphan aplanat cell - slightly shorter focal length. The reason I dared do this, is because there is a tradition for casket sets of aplanats where cells of different focal lengths are installed in the same barrel (But not including wide-angle cells).

Another example is the petzval design, whose front and rear cells can be used independently from each other and where I know that the precise distance between these cells is not very critical for optical performance. Whilst the production of the rear pair requires a lot of work, the replacement of the front achromat can be done, I think, with success. I am in the process of attempting to recreate a 40cm french Petzval by using a commercially available telescope achromat which has the right diameter and focal length.

I have also seen working Petzvals where the edge ink writing shows that two different makers were responsible for the rear and front lenses!

ruilourosa
17-Nov-2016, 01:25
Hello

This has been a discussion for some time! You can make simple lens very easely, although people from the realm of "real lenses" will say NO! this cannot be done and resolution will be the same as you get with you 110 "wreck, wreck" camera!

Well building a simple meniscus is a really easy thing just buy a close up +1 +2 or whatever focal distance you need build a barrel, put a waterhouse stop in front and you are done!

Building a Steinheil Periskop is easy too, just put another close up in the barrel concave to concave and a stop in between!

A rapid rectilinear is easy too!!! just buy two achromatic close up lenses and replace the above simple close ups!

Distance between the elements is somewhat critical but you can experiment and try first in digital via adapters...

You can also dismantle some cheap zoom lenses and salvage the elements and try!!!

I have some lenses that have very nice quality!!!! they are all long focus lenses, around 600 or 800 mm made out of achromatic close ups

Well try try try! and study some older designs, some are really simple! aim towards symmetry, itīs easyer!

Cheers

Rui Lourosa

mdarnton
17-Nov-2016, 03:32
I have another example of why this is a hard task. I have a 11-1/2" Verito. It's made to be used with or without the front element. I noticed that the front element is simply a +1. but a very thick one, so I thought, I wonder what I can change it into with various closeup lenses substituted in front. Of course, the first I tried was a +1, just to see what happened. Disaster, totally different lens, unusable. even as a soft focus.

Though those old lens elements may have been done by different people, that doesn't mean that they weren't made to any particular specs. :-)

I have also notice that all two-element achromat close-up lenses are not created equal. Used alone, they have different characteristic looks.

Mark Sawyer
17-Nov-2016, 11:01
Building a Steinheil Periskop is easy too, just put another close up in the barrel concave to concave and a stop in between!

A rapid rectilinear is easy too!!! just buy two achromatic close up lenses and replace the above simple close ups!



Such a home-built lens might have the same configuration as a Periskop or Rapid Rectilinear, but it wouldn't have the same look in the image. A lot of calculations went into those lenses by some very bright (yes, pun intended) optical designers, giving very fine optics. Saying two achromats make a Rapid Rectilinear is like saying letting grape juice go bad makes a fine wine.

But people don't make their own lenses to get a lens that looks like all the others. Vive la difference!

Yep, I went through my lens-making phase too:

http://i55.photobucket.com/albums/g139/Owen21k/L1020490.jpg (http://s55.photobucket.com/user/Owen21k/media/L1020490.jpg.html)

http://i55.photobucket.com/albums/g139/Owen21k/L1020498-1.jpg (http://s55.photobucket.com/user/Owen21k/media/L1020498-1.jpg.html)

http://i55.photobucket.com/albums/g139/Owen21k/Wolly3xconv.jpg (http://s55.photobucket.com/user/Owen21k/media/Wolly3xconv.jpg.html)

ruilourosa
19-Nov-2016, 14:48
All true!!! but basing things in a design is good enough for me!

Try: achromat close ups from leica and minolta, the one with the longest focal distances (0,75 and 0,92 diopter) gave me the best results with the separation of a diameter!

I maybe got lucky because the results are quite good!!!
Cheers

Rui Lourosa

Tim Meisburger
20-Nov-2016, 05:40
Is there a formula for the separation of lenses for a periskop? I bought two lenses from Surplus Shed (PMN, Dia: 42.4, Focal: 4000) to make a lens specifically to shoot the moon on 4x5. I figure 2000mm should give a usable size. Besides a larger f stop, what are the advantages of the periskop design (if any)?

Nodda Duma
20-Nov-2016, 08:02
The periskop is a symmetrical version of the landscape lens, meaning the prescription layout is roughly a mirror image around the stop. The landscape lens is a single meniscus in front of or behind the stop. Symmetry reduces the odd aberrations (coma, distortion, lateral color).

Spherical aberration is minimized by the lens shape.

Distance from the stop to the lens is chosen to compensate for field curvature. Typically the distance is set to flatten sagittal field curvature since it is less pleasing to the eye than longitudinal.

The ideal lens shape and distance from the stop can be calculated from the corresponding aberration formulae.

Alternatively, it takes only an hour or so to bang out an optical design in Zemax: 15 minutes to get the Periskop solution and 45 minutes of tinkering with better corrected variations before undoing and saving the Periskop solution. :)

Note as a landscape lens derivative, the design family is more appropriate for wider fields of view i.e. landscapes rather than portraits.

Jim Jones
20-Nov-2016, 08:05
Tim, the main advantages of the Periskop design are probably wider coverage, not better performance of a small distant subject like the Moon. A two element 2000mm achromatic telescope objective should give better performance than two 4000mm meniscus lenses used in the Periskop design. Surplus Shed doesn't list such an objective now.

Tim Meisburger
20-Nov-2016, 13:37
Thanks Jim. That makes sense, but I already ordered the lenses. If it doesn't work, I'm only out fifteen bucks (including shipping). Using the periskop design will at least increase speed, bringing me to something less than f/64 wide open. Nodda explained above how to calculate the distance between the lenses, but I didn't really understand it, so I'll just scale a diagram of a periskop (I'm guessing an inch and a half). Hopefully that will get me close enough to get an image.

Nodda Duma
26-Nov-2016, 20:16
Tim, you don't have to calculate the distance, just adjust the distance until the image on the ground glass looks "good" and pleasing to the eye. This will very likely be the distance for corrected sagittal field curvature. Pay attention to the off-axis image for this. Make sure to keep the distances from the iris to front lens and to rear lens the same.

If you knew the specifications of the lenses -- radii of curvature and thickness -- then I could model in Zemax and give you a starting point. But scaling from a layout is a good idea and will get you close. Hopefully you have a way to accurately adjust their positions without decentering.

Nodda Duma
26-Nov-2016, 20:27
.

There used to be a lens designer hanging around the APUG forum, talking about lens building and offering up some designs, but I haven't been there in a while, so he may be gone.

That was me. I'm still around. :)

mdarnton
27-Nov-2016, 12:09
Yup, that was you. Thanks for showing up!