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Making scopes out of camera lenses...

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#1 mattyfatz

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Posted 02 January 2014 - 01:48 PM

In this thread we pondered the various ways of making small monocular a and spotting scopes. Low power hand held gadgets. I just found this box of old camera lenses. I'm not a photographer, and I don't know much about the inner workings of these types of lenses. They are all from different makes of cameras.. K-mounts, Oympus, knock off Minolta..et cetera. So I'm throwing out some questions and begging for ideas..

1. How do you disassemble these things? I can't seem to find set screws or obvious places where they lenses are put together?

2. Since they contain a focusing mechanism should I just figure out a way to mount an eyepiece?

3. In these old 35mm lenses is the image correct? :question: the view was through the lens "TTL" right?

4. If anyone out there has tinkered with this idea can you please post some pics, and tell about your experiences/ results..

Thank you in advance! :jump:

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#2 mattyfatz

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Posted 02 January 2014 - 01:52 PM

I should add that these are all manual focus lenses. I know that some people have found ways to attach eyepieces to modern Canon lenses, but I don't think that will work with this old batch. I'm starting from scratch .

#3 ccaissie

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Posted 02 January 2014 - 02:24 PM

You can find adapters for the unique rear mounts.

Then make up a back with a star diagonal or erect image diagonal, and put an eyepiece to it.

You may get a decent low power scope for birdwatching, or low power astro use, and it could be fun.

As far as major astronomy, most scope users would not be very interested.

#4 GlennLeDrew

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Posted 02 January 2014 - 02:37 PM

You cannot take these lenses apart, for they must be left as is in order to deliver a useable image.

The available back focus is typically ~55mm (differing a bit among brands), and so there is little if any room to squeeze in a diagonal.

They are just like basic refractor objectives, in that they produce an inverted image.

Faster lenses should be stopped down via the iris, to no faster than about f/4. Most eyepieces are not corrected to handle light cones much steeper.

The flat field they produce (being designed to image in flattened film) can result in a mismatch with the eyepiece's generally designed-in field curvature (most visual scopes have curved focal surfaces), which would result in off-axis defocus. Another reason to stop down these lenses at least somewhat; a smaller entrance pupil does tend to reduce all aberrations generally.

They should produce a decent enough image down to exit pupils of perhaps 3mm; much less and one is asking for a level of performance not designed for.

Just the first thoughts which spring to mind...

#5 mattyfatz

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Posted 02 January 2014 - 04:17 PM

It's more of an experiment, and just something to satisfy my curiosity. I just want some handheld monoculars a for quick look. I'm not trying to re invent the wheel, and I certainly don't have too high expectations for optical performance. Stopping down is a good idea.. But what about a Barlow? Can I make a Barlow out of these?

#6 mattyfatz

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Posted 02 January 2014 - 04:20 PM

You cannot take these lenses apart, for they must be left as is in order to deliver a useable image.



Why can't I break them down? Why not utilize the components to make a better "scope like" optic? It would seem logical that if you kept the objective portion intact, you'd have a good start..

#7 mattyfatz

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Posted 02 January 2014 - 04:21 PM

You can find adapters for the unique rear mounts.

Then make up a back with a star diagonal or erect image diagonal, and put an eyepiece to it.

You may get a decent low power scope for birdwatching, or low power astro use, and it could be fun.

As far as major astronomy, most scope users would not be very interested.


Who makes these adapter? Where are they found?

#8 m. allan noah

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Posted 02 January 2014 - 06:50 PM

You cannot take these lenses apart, for they must be left as is in order to deliver a useable image.



Why can't I break them down? Why not utilize the components to make a better "scope like" optic? It would seem logical that if you kept the objective portion intact, you'd have a good start..


There is more that a single objective. Even cheap lenses will have a triplet at the front, and a doublet or triplet in the rear, all of which must maintain very precise spacing. I took apart a number of camera lenses to make focusers from, and found that the glass is pretty much useless in anything other than its exact original housing.

allan

#9 Jon Isaacs

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Posted 02 January 2014 - 07:55 PM

The available back focus is typically ~55mm (differing a bit among brands), and so there is little if any room to squeeze in a diagonal.



A typical 1.25 inch diagonal eats up about 70-75mm of backfocus. A possible work around is to use eyepieces like Plossls and either remove the barrel or shorten the barrel and then remove or shorten the eyepiece adapter on the diagonal.

Given the affordability of the ST-80, (80mm F/5 or as a camera lens, 400mm F/5) fooling around with camera lenses has never made much sense to me..

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#10 TONGKW

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Posted 02 January 2014 - 08:42 PM

You can find adapters for the unique rear mounts.
Then make up a back with a star diagonal or erect image diagonal, and put an eyepiece to it.
You may get a decent low power scope for birdwatching, or low power astro use, and it could be fun.
As far as major astronomy, most scope users would not be very interested.

Who makes these adapter? Where are they found?


------

Kenko has adapter to convert camera lens into spotting scopes. This adapter has a fixed eyepiece for straight through viewing.
I have one of their older version shown here turning a Tokina 100-300 mm f4 zoom lens into a 10 x – 30 x spotting scope.
http://www.adorama.c...NKLS10NFSB.html

------

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#11 TONGKW

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Posted 02 January 2014 - 08:48 PM

For using with 1.25” eyepiece, adapters are now available from China to convert camera lens into a spotting scope. It is available to fit the camera lens for Nikon, Canon, Sony, etc.
The end can accept 1.25” eyepiece or T-thread accessories.
http://item.taobao.c...3.AL15El&id=...

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C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST

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#12 TONGKW

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Posted 02 January 2014 - 08:49 PM

I have ordered one such adapter to convert my Tokina 100-300 mm f4 zoom lens intoan a spotting scope or telescope.
With the addition of a Barlow lens, infinity focus can also be reached with a diagonal in place.

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#13 TONGKW

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Posted 02 January 2014 - 08:55 PM

Just to add, adapters are available for camera lens of Nikon, Canon, Pentax, and Sony, etc.
http://www.adorama.c...essory-Adapters

#14 mattyfatz

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Posted 02 January 2014 - 10:29 PM

Thank you. That is very helpful.

My idea is to fiddle with these using crude materials like PVC and duct tape :crazy: :shrug:

I'm hoping to get something 1/2 way usable out of it. The back focus info is very helpful too.

#15 Ravenous

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Posted 03 January 2014 - 05:40 AM

I think it's best to keep the lens elements together - don't try to take their cells apart unless you can do precision machining to get them back in exactly the right place. Positioning and centring is really, absitively crucial for these things.

For one old telephoto lens, I took the lens mount ring off the back - four little long philips screws. I then dismantled and dumped the aperture linkage and other unneeded stuff (it was old Pentax K, like all my lenses). Made an eyepiece holder from rings of 6mm thick plywood, glued together. It screwed back on with the original little screws - they were just long enough. A 1.25" eyepiece holds in by friction.

On mine there isn't clearance for a diagonal (without using a barlow as Tong has said), though if I remove more bits and glue a prism body right on the back it might be possible to get clearance.

(If you really need to get the front lens elements out, sometimes you can lever the labelled faceplate off the front and find either tiny screws or lens spanner holes underneath, apparently.)

#16 ccaissie

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Posted 03 January 2014 - 07:51 AM

http://www.surplussh.../cameras_1.html

#17 Rutilus

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Posted 03 January 2014 - 04:27 PM

I would be very careful taking any old camera lens apart.
Some of them may contain nasty material like radioactive coatings. If you search online you can find that some of the old
Olympus lenses have turned out to be hot.

#18 mattyfatz

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Posted 03 January 2014 - 09:52 PM

Well I started tinkering in the garage today.. Suprisingly I had some success!

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#19 mattyfatz

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Posted 03 January 2014 - 10:00 PM

Sure the images are inverted, but it was very clear and bright! (Daytime of course). The "adapter" is a taped up piece of PVC coupling, and the eyepiece is a 25mm Plossl. Of course no sooner was it complete, that the fog bank rolled in.. :smirk: :smirk: :smirk:
I guess that rule applies to pieced up junk scopes too.
Night time tests will be conducted soon.

More tinkering tomorrow. It was a big box of lenses :grin:

#20 TONGKW

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Posted 03 January 2014 - 10:01 PM

Some of the lens made from the 1940s through the 1970s contain radioactive material used in the glass elements. A Pentax Super Takumar 50 mm f/1.4 lens that I have could be one of them. I believe they are not harmful under normal condition of use.
http://camerapedia.w...ioactive_lenses
http://petapixel.com...d-manual-len...

#21 mattyfatz

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Posted 03 January 2014 - 10:06 PM

Awesome.

#22 evan9162

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Posted 03 January 2014 - 11:56 PM

Sure the images are inverted, but it was very clear and bright! (Daytime of course). The "adapter" is a taped up piece of PVC coupling, and the eyepiece is a 25mm Plossl. Of course no sooner was it complete, that the fog bank rolled in.. :smirk: :smirk: :smirk:
I guess that rule applies to pieced up junk scopes too.
Night time tests will be conducted soon.

More tinkering tomorrow. It was a big box of lenses :grin:


Sorry about the fog. I just had a couple of eyepieces delivered yesterday, and another one that should be here tomorrow. I'm ruining it for everyone in Boise.

On topic, I have a few M42 manual focus lenses that I've thought about doing this with. My plan is to simply machine an M42 female to 1.25" barrel adapter out of some aluminium round stock.

#23 mattyfatz

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Posted 04 January 2014 - 03:25 AM

:ohmy: you should be sorry.:ohmy: ... Getting stuff delivered near a new moon...

At least post some pics in the eyepiece forum.. :grin:

So M42 is the threaded rear cell type? I'm not a lens guru. I actually don't know where or when I acquired this box of lenses. I rummaged around but I couldn't find tubing that matched the diameter, hence the tape job. What do you use to machine threads of that diameter?

#24 evan9162

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Posted 04 January 2014 - 07:56 AM

:ohmy: you should be sorry.:ohmy: ... Getting stuff delivered near a new moon...

At least post some pics in the eyepiece forum.. :grin:

So M42 is the threaded rear cell type? I'm not a lens guru. I actually don't know where or when I acquired this box of lenses. I rummaged around but I couldn't find tubing that matched the diameter, hence the tape job. What do you use to machine threads of that diameter?


The generic threaded rear lens is usually an M42 (42mm x 1.0), also called a Pentax screw mount. It's pretty close to a T-thread, which is 42mm x 0.75.

I haven't made any adapters yet, but if/when I do, I will just be using an old mini-lathe I have. I've cut 1mm threads on it before. They aren't super great quality threads, but I think for this application, they would be fine.

#25 mattyfatz

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Posted 04 January 2014 - 10:06 AM

I couldn't figure out how to mate that screw mount to an adapter. The t-mount available at surplus shed would work, but that kind of defeats my purpose of making these monoculars out of junk and spare parts. I'm sure your finished product will be more elegant than my examples. It's too bad PVC pipe doesn't come in metric.






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