Home made ground glass focusing loupe

[Just Josh]

Hello LF community, this is my first post. I hope someone finds this helpful just as I have found everyone else's info here extremely valuable towards bettering my passion.
Up until this point I have been using a cheapo 8x plastic loupe for focusing on the ground glass. It works ok in bright situations but is very soft around its edges and not very well suited for focusing in dim situations. On a recent outing frustration got the best of me and I thought to myself 'there has to be a better solution out there that does not require what little money most of us have.'
After tooling around the web for ideas on what to use as a gg focusing aid I ended up finding a few things (reading glasses and 80mm enlarging lens being my two fav) that I settled on trying with stuff I have around my house. The reading glasses did a decent job but I found myself getting lost in the focus as to where my head needs to be in relation to the gg for a perfect focus ability at the knob. If you dont have that issue then the reading glasses are probably a good solution for you. The enlarging lens used in reverse to its proper mounting orientation against the gg works fine as well but I found that my viewing area was tiny and dim. Unsatisfied I started digging around my extra equipment (aka crap I horde) to see what I could build and this is what I came up with.

Materials:
-old lens hood
-a couple of crappy filter rings with the filter glass removed/broken out of them
-electrical tape
-the front element (and its housing) of an old or broken lens
-window/door weather seal with one side an adhesive surface (home depot 2$)
-rubber wire housing from some old copper wire laying around or electrical tape can work for this as well
-super glue

I started by disassembling a broken 55-200mm Nikon digital zoom lens. I took the whole front element housing and put away the rest. (NOTE: its important you choose a lens element that equals at or around the (X) magnification you prefer. This 55-200mm front element puts me around 4-5x magnification. The only way I was able to determine this was by comparing it with other crappy loupes of varying magnification I have laying around.


I then wrapped the jagged rear of the element housing with the window/door seal foam leaving just enough of a seal lip sticking out from the element housing so as to provide my focusing eye comfort and safety from the jagged plastic.


Once the seal was applied I then ran a few complete laps around the foam seal with electrical tape to help secure it to the element housing and offer protection for its easily ripped foam surface.


Set the front element assembly aside for now and find your crappy filter rings (for me 52mm rings were needed for the Nikon 55-200mm filter mount). safely remove or just 'break' the glass/plastic element out of the ring. Start with just 1 until you know you will need more after testing the final product.


********can only attach 4 pics per post. continued in pt2 below*********

[Just Josh]

Screw the filter ring onto the front face of the front element assembly.


Again, set the front element assembly aside and find your old lens hood. You will want to use some sort of buffer such as super glue tacked on wire housing or wrapping electrical tape on the front edge of the hood that will contact the gg. This is so as not to scratch the glass while focusing around under the dark cloth.


Now you can attach the hood to the front element assembly at the filter ring and you are ready to test/adjust/fine tune your focusing aid.


********continued in part 3 below**********

[Just Josh]

Mount your LF camera on a tripod and remove the front lens/lens board from the front standard. Point your camera at a bright light source so as to illuminate the ground glass surface. Next place your focus aid against the ground glass.


From underneath a dark cloth you will want to place your focusing eye against the foam eye cup. You are now going to screw/unscrew/remove/or add filter rings as your fine focus adjustment knob on the loupe. You are trying to focus as sharp as possible on the grain of the etched ground glass which is where the image is formed during normal camera operation. The grain is illuminated well by a direct bright light shining in through the front standard.
Once I fiddled and found the sharpest point of the grain I placed an extremely small tack of super glue on the filter ring to hold it in that place. Later my eyes will change and I may break the tack of glue to adjust again for changes to my eyes. It only took me 1 filter ring at a half turn out or so from being tightly screwed on for fine focus.

As an added bonus I used a lens hood with quick release buttons on it. This allows me to pop it off and reverse it onto the front element assembly for compactness and as a hard shell case for travel.


The end result is exactly what I wanted...sharp image focusing all the way to its edges, big bright element, and large viewing area at around 4-5x. I love it so I had to share!

Feel free to ask questions and thanks for reading.

[Just Josh]

******Edit*********

Just to be clear the front element assembly/chassis of the lens actually contains two elements (the large circumference light gathering front element followed by a much thicker and smaller circumference element right behind it) which you do not want to try and remove or you will just end up with a glorified magnifying glass!

[pierre506]

[Randy]

Thanks for sharing Josh. I have several home made loupes Of varying levels of cheapness and usability. My favorite, which really isn't "homemade" is a chimney finder for a Mamiya RB67. It has adjustable ocular for your eye and has a large base that is great for an 8x10 ground glass but is usable on 4x5 as well.