I'm again tinkering

[moribundman]

Originally Posted By: IndyIan
Well that's cool, what's the modification?

As I have explained previously, I made internal dust shields that fit over the binocular's internals and under its external clamshell cover. The dust shields cover the four prisms and they also seal the objective lenses' focusing mechanism. See the posts with all the images for a better explanation. In those pictures the prisms and lenses have been stripped. Once I get around to finishing the project I will post a couple more pictures that will hopefully show more clearly the function of those dust shields.

 

[jldcol]

Hardcore DIY, really HARDCORE. If only you could grind lenses and prisms, coat them, and had a optical bench to align them. Truely a rare bird.

 

[moribundman]

There's no need to manufacture and to coat lenses and prism. The parts exist already and they are coated. I know someone who has a collimator, so alignment is no issue.

 

[moribundman]

Two weeks ago, after retrofitting a few more of these binocs with dust shields for some other people, I was about to finish my own. As it usually happens when I am about to finish a project, a thought crossed my mind. I began wondering why, if I already had spent that much time on this project, I shouldn't add a military spec reticle to my own binoculars. My 7x50 Steiner binocs have a reticle, which I find very useful, but the Steiner binocs are not pocketable due to size and weight. I decided to add a reticle to my small 7x20 Nikon binoculars. Some Nikon engineers are probably rolling their eyes now.

I sourced the M-22 reticle from M24 military binoculars (7x28). The reticle is on a small plane parallel piece ("filter") of coated optical glass.

The penny is for size comparison. I had to make a mount for the reticle. I used Delrin, brass, and urethane resin. This picture was taken with the penny and the reticle placed on a light table, so everything is backlit:

The reticle must be installed in the left eyepiece, because the right eyepiece has the diopter adjustment. The diopter is adjusted by turning the eyepiece, which means the reticle would also turn if it were mounted in the adjustable eyepiece.

I removed and took apart the left eyepiece. Red numbers denote original parts, green numbers denote modified, fabricated, or additional parts:

1: Rubber eyecup

2: Knurled eyecup mount

3: Threaded tube that contains lens elements 5 and 7, with spacer 7 between these two elements

4: Threaded adaptor ring that screws on one end to tube 3 and on the other end to the binoculars

5, 7: ocular lens elements

8: Retainer that screws into threaded tube 3 (holds lens 7 in place). This part had to be modified (shortened) to become part 8A.

9: This ring is used to bring the reticle into focus. I cut this brass ring from a brass tube. I then cut the ring open, and it was nice and springy. I widened the diameter with a ring mandrel so the ring would slip over tube 3 and make for a tight fit.

10: The reticle was mounted in another brass tube that fit precisely over tube 3.

A closer look at the spacer 9 and the reticle in its mount:

The width of this spacer is critical for proper focus. The proper width was obtained by lapping spacer on a flat diamond hone and by checking focus visually (required complete assembly of eyepiece):

Here you can see the reticle with its mount (tall brass tube) attached to tube 3. You can also see the ("focusing") spacer already described. Another function of the brass mount is that it allows turning the reticle so it will be properly aligned (plumb) once the eyepiece is screwed into the binoculars. Once the reticle is aligned, the brass tube and the spacer are secured with a piece of tape. That way the assembly can't move, but is still removable (for adjustment and servicing). All the brass parts will be painted with ultra fine matte black pigment camera enamel before final assembly. The eyecup mount and the eyecup have also been attached:

The adaptor ring 4 is screwed onto tube 3:

The eyepiece is now fully assembled and the reticle is in focus. The eyepiece can now be attached to the binoculars:

This how the reticle looks. It can be used to calculate the distance of objects or the size and height of objects.

The so called "constant factor" will need to be determined (easy to do empirically). The formula for calculating the distance of an object is then easily determined: Distance = constant factor x (object size : reticle units). Object size is calculated accordingly, if the distance is known.

Yeah, so now it's all done right? Well, having a compass display under the reticle might be useful. I think I'm about to stroke out.

 

[Shannow]

You've got WAY too much time on your hands mori.

What about a set of poro/roof prism hybrids manufactured to an Alsatian patent, and available on ebay for a pittance ?

 

[moribundman]

Well, modifying the eyepiece with the reticle was about three hours worth of tinkering. All done between 2 and 4 am over the course of a couple nights.

The most difficult part is yet to come: keeping dust out during the final assembly. Especially the reticle must be absolutely clean, because the tiniest spec of dust will be magnified to a huge size in the eyepiece. I'm not looking forward to assembling that sucker! I'll probably have to use my ionizing (Pollonium 210 -- alpha particles) Staticmaster negative brush.

 

[duaneb9729]

Mori could you use a modified small sand blasting cabinet for the final assembly ?

cut holes in the top and install a merv 15 filter, perhaps even two of them, then use a bath fan to pull air through the cabinet?

just sort of thinking out loud here

 

[moribundman]

Unless I can stick my head in the cabinet, no, it's not going to work. I have to get very close with a watchmaker's headband magnifier and inspect every glass element under various angles for dust particles. The best bet for removing dust is the ionizing brush. Just holding the brush close to the dust will make any particles pop right off the surface. Another option involves using the type cleaning kit that is used to clean the imaging sensor of digital cameras. I'll do this on a humid day when the air is relatively clean.

 

[JHZR2]

how much for all this great modification?

 

[moribundman]

I know, I know, the project is totally nuts. That's the way I like it! Actually, the project cost me nothing but time, and I made actually money off it. Which is how I prefer my hobby projects to turn out.

I knew one guy who wanted his old (from mid to late '80s) Nikon Travelite binocs sealed. He made me an offer I couldn't refuse. He was willing to pay what I charged for mold making and casting dust shields. I did not charge him for designing and creating the dust shields, because I was going to make more than one set in an effort to diffuse the cost (labor, time). The price would have likely killed the project. I designed and fabricated the dust shields, and I cast quite a few pieces. My customer was happy with the result.

With the proceeds from the project I then bought five of the same model Nikon binoculars for next to nothing. Four of them I cleaned (1 hour job each), installed the dust shields (20 minute job each), and sold them.

The fifth Nikon was new old stock, still in the box, made in 1986, with the 25 year warranty expiring in 2011.

I kept that one for myself. That's the one that now sports the reticle (and which has lost its warranty due to my "tampering"). Sourcing the reticle was surprisingly easy. A friend of mine has access to military surplus gear. He got the reticle out of M24 binocs. Don't ask -- I surely didn't.

I also sealed those binocs even more thoroughly than the previous ones. I'll explain later!

 

[Shannow]

sweet

 

[moribundman]

Oh, I forgot to mention I did have to buy dampening grease. 100 ml cost $30.

 

[moribundman]

All right, let's see how the dust shields were installed and how everything was sealed.

The dust shields are press fit and match the cutouts (Curse you, Nikon!) in the binoc's internal frame perfectly. The gaps between the dust shields and the frame were further sealed with aluminum duct tape, which is thin and which conforms to odd shapes if it is burnished. There are a few tiny spots where tape can't be used because it interferes with the outer plastic clam shell covers. On my own binocs, I used Plasti Dip to seal those minute gaps. I applied the Plasti Dip with a toothpick. A small amount of Plasti Dip will dry very quickly. It sticks well enough to seal, but it can also be easily peeled off the dust shields and off the metal frame. Since I have so much Plasti Dip left, I dipped a bunch of my tools and even the brake levers of my bike!

Here you can see the frame of the binocs, with the optics and the dust shields installed. The silver tape is what seals the gaps between the frame and the dust shields:

I colored the dust shields so you can better see where they are. You are looking at the objective lenses in the front, with the binocs upside down. During focusing, the objective lenses slide in greased guides (The arrow denotes direction of motion). Dampening grease is used to achieve a smooth focusing action. Note the yellow dots: they show where grease forms a seal. Dampening grease is very tacky and doesn't get runny (for a couple decades). This is important, because the grease forms a dust seal between the objective lens tubes and those dust shields.

There is more to come, but not today. I have to prep the pictures, but now I'm pooped.

 

[moribundman]

Here is a picture of some of the tools and supplies that I used.

Clockwise, from left:
- Swiss Champ XL (scissors and screwdriver were used)
- blower (Where does all that dust come from?)
- Plasti Dip (in ketchup bottle with Yorker tip)
- resin coloring agent
- fine pigmented flat black camera lacquer (to touch up scuff marks and to paint brass tube and spacer)
- tube cutter (for cutting a brass tube and a brass spacer)
- tube of dampening grease
- aluminum duct tape (for sealing)
- spanner wrench (for taking lens assemblies apart)


Center, bottom to top:
- screwdriver
- scalpel (to cut aluminum)
- pencil
- pen
- steel straight edge ruler (measuring and cutting aid)
- Rodico gum (to remove dust and smudges)


I also used sanding sticks and sandpaper, toothpicks, Q-tips, paper napkins, lens tissue, denatured alcohol (for cleaning), Simple Green (for degreasing -- all the old grease was removed), a diamond hone (for lapping the tube I cut) and files (for deburring and chamfering). I'm sure I'm forgetting stuff. Yes, I forgot my calipers which I used to measure the tube and spacer that I made.

 

[moribundman]

I used 5 minute epoxy to glue the reticle into the brass tube that I made. The resin was dyed with the coloring agent I showed in the above picture. The same coloring agent was also added to the liquid casting urethane that I used to make the dust shields.

 

[JHZR2]

awesome write-up so far, with great pics!

 

[moribundman]

Since my projects tend to take a fair amount of time, I might over the course of weeks or months forget what, why, and how exactly I did it. That's why I always document my projects for later use. What I post here is essentially a rough draft. Once I have all the required information gathered, I edit it, print it out, and put together a folder, a manual if you will.

 

[moribundman]

I finally got around to putting the last images together.

The upper casing halves have been attached. The front covers and bottom casing halves snap into place:

Completely assembled binocs:

Size comparison with my 7x50 Steiner, which also have a reticle. Note the 25 cent coin for scale:

I had to figure out how to use the reticle. There is a relationship between the binocular's magnification and the reticle units (used for measuring angles). Here is what I did:

Constant Factor = (Distance x Reticle Units) : Object Size

I used Google Earth to measure the distance between two distinct spots at a familiar location. I measured 132 meters. I then went to this location. There I made a white chalk mark on a wall and walked 132 meter away. I looked through the binoculars and had a helper mark the wall with chalk exactly one half reticle unit from the first mark. I did this by directing my helper ("Two more centimeters to the right!"). The distance between the two marks turned out to be 83 cm.

With the distance (132 m), the object size (0.83 m), and the corresponding reticle units (0.5) calculating the required Constant Factor was easy:

Constant Factor = (132 x 0.5) : 0.83 = 79.51
For practical purposes I rounded that figure to 80. The Constant Factor is 80.

Calculating distance or object size is now easy. You either have to know or guess the object size or the object distance:

Distance = (80 x Object Size) : Reticle Units
Object Size = (Distance x Reticle Units) : 80

Done!

*'Lost' boom sound*

 

[Julian]

Originally Posted By: moribundman
Done!
Awww!

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[GROUCHO MARX]

Let the voyeurism begin!