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Paul Kinzer
30-May-2017, 21:51
I'm cheap. And I sometimes make things. I could not bring myself to pay $80 for a decent ground glass loupe; one that allowed me to leave the viewing hoods on my Graflock holders, which I use on all my LF cameras (4x5 Speed and Crown Graphics and 5x7 Rittreck View). So I ordered this lens (http://www.surplusshed.com/pages/item/l13517.html) from the Surplus Shed, and made my own loupe around it. I chose the lens for both its diameter and focal length. I figured that a focal length of 150mm would allow me to make a loupe that would both magnify just the right amount, and keep the lens far enough out from the ground glass. I figured the diameter would be big enough for nice, wide views, and also fit into some combination of PVC plumbing fixtures. I was guessing on all counts, but I guessed right!

The photos will show most of what I did. I went to my local hardware store and found all that I needed. I was surprised, since I live in a small town (population 1500) and our hardware store is accordingly tiny and low-stocked. I just walked through the plumbing aisle, and found some 1-1/4 adapters that fit together over the lens, and another that slid into this combination to provide the proper focusing distance against the ground glass.

Here's an image of the raw materials.

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And here's another, showing the order they go together. The red arrow shows the distance I found for best focus on the slip-fit piece. I marked it with a pencil and then used PVC sealant to glue it in place. It works very fast, so care is needed to get it in and straight quickly. I've re-habbed five homes, so it was withing my skill set!

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I then screwed the front piece on (without the lens), sanded the smooth surfaces on the inside, taped up the outside, and spray painted the interior with 'chalk board' black paint to reduce reflections. It actually worked fine without this, but hey, why not make it better?

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Here it is, complete:

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Paul Kinzer
30-May-2017, 22:07
I've made similar things for my astronomy habit, including complete telescopes, and I usually sand off the printed bits on the outside. But I chose not to on this piece, first because I just don't care; and, second, because the writing, and the ridges, provide something to grip.

Here's the loupe next to one of my cameras. You can see that it will hold my eye at a good distance.

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The lens is actually recessed inside the loupe about one inch (25mm), which is the perfect distance, it turns out, for my eye to focus well (what in astronomy parlance is called 'eye relief').

This loupe design would not work were it not for the fact that I'm quite near-sighted. With my glasses off, it works great; but with them on, I need to hold the loupe out from the glass by a centimeter or so. I could have found some other bits at the hardware store that would have worked, but I may have needed to cut something. I'm glad it was this easy!

The loupe is also not very powerful: it only magnifies by about 2x -2.5x. But it does the most important thing I want a loupe for: it allows me to get a close, sharp, bright view of the ground glass, which I find much more important than magnification. The clear aperture of the lens is 32mm (about 1-1/4 inches, just like the plumbing fitting specifies.)

Here's an image of the coated glass. It's a cemented achromat, and it looks multi-coated to me, though the Surplus Shed doesn't claim it is.

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And finally, here's an image looking through it. Very sharp right across the field of view:

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Paul Kinzer
30-May-2017, 22:10
Oh! Total cost, including shipping for the lens: less than $20. I could probably have made it cheaper yet by scrounging in my boxes for a lens, and in my garage for plumbing bits, but I wanted it just so for the purpose it would serve, and I scrounge enough.

Andy Eads
31-May-2017, 10:09
An old 2" movie projector lens works well and has it's own barrel. Or, use a viewfinder magnifier from an SLR such as a Nikon F series or the equivalent Canon. I'm using a DW6 magnifier. It has the qualities of covering about a 2" diagonal with no distortion. I've also cannibalized old Polaroid film recorders for their copy lenses and pressed them into service. Have fun with this!

Nukatpiat
31-May-2017, 10:55
I like it. Good idea on the chalkboard paint! I am going to try that. Mine are all projector lenses from secondhand stores. I like them better than commercial offerings.

Sent from my Moto G (5) Plus using Tapatalk

Paul Kinzer
31-May-2017, 15:34
Good thinking on the projector lenses. I have a couple of them somewhere, and will check them out. This was just a fun project to try, and the results were so easy and successful that I wanted to share it.

Taija71A
31-May-2017, 19:35
Paul, look for an old SMC Pentax Takumar or Super-Takumar 50mm f/1.4 Lens.
There of course are many, different variants of this respective Lens.

https://www.pentaxforums.com/lensreviews/SMC-S-M-C-Super-Takumar-50mm-F1.4.html

But, for $20+ and a little bit of DIY Effort... You will now have a far 'Superior' (7 Element) DIY Loupe. :D
Have fun... Thank-you!

-Tim.
__________

Paul Kinzer
31-May-2017, 22:02
For me, getting the physical length right was the important thing. I have an (almost) embarrassing number of lenses floating around my home, garage, and observatory, but none that would bring the lens out to the proper distance from the ground glass, save for -- possibly -- one of my projector lenses. I will dig that out and see how well it works. Still, it won't top this one because this one is just ideal for my eyes and my cameras. It's also lightweight and fits really well in my hand.

B.S.Kumar
1-Jun-2017, 01:33
A long time ago, I made one from an old M42 mount 50mm lens, but it was awkward to use because the balance simply wasn't there.

Kumar

Drew Bedo
1-Jun-2017, 05:52
Years ago I pestered my optomitist till he made up a pair of prescription reading glasses so powerful that theworking distance was maybe 4 inches. Tthey hung on my neck and could be poped on and off leaving my hands free when under the dark cloth.

At another time I used a jeweler's hedset magnifier the same way under the dark cloth.

Paul Kinzer
1-Jun-2017, 09:38
Hmmm.... They sell reading glasses at drug stores. I should check them out.

These are all fun, inexpensive, easily checked ideas.

jim10219
4-Jun-2017, 21:09
I just use a $5 thread counter. It folds up small, yet folds out to set the focal length, and has a good level of magnification. If you lose or damage it, you can pick up another one in any number of stores for not much money, so you don't have to be delicate with it. It's hard for me to imagine wanting anything more from a GG loupe.

Drew Bedo
5-Jun-2017, 06:10
Hmmm.... They sell reading glasses at drug stores. I should check them out.

These are all fun, inexpensive, easily checked ideas.


Try the drug store cheaters, but I think they need to be a bit stronger. Mine were prescription and Stronger than regular.

Eventually I went to "normal" prescription readers under the Jewelers magnifying head set called "Opti-Visor".

online
11-Jun-2017, 04:55
Mine are all projector lenses from secondhand stores. I like them better than commercial offerings.