Topic: The Canon EF--and everything else--spotting scope adapter project

Oh, I spose,  you guys'll tell me somebody in China already MAKES one.

I wanted to do thus:

http://photo.net/sony-minolta-slr-system-forum/00GdBQ

Be able to use my Canon EF mount lenses,  --and anything else--as a spotting scope.   Because I can adapt my favorite lenses to my Canon  EF mount camera   (Adaptall, etc)  this means that an EF mount eyepiece mount would also accomodate any OTHER lenses I have.

I bought  a REALLY  cheap   extension tube set off the 'bay,  intending to junk it just for the lens mount.  Turns out I didn't even have to modify them,  and could still use them.  These are the import variety,  REALLY cheap thread together set  like these:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi … 0244210466

I also bought this  telescope adapter piece:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi … 0073221952

Here's the start of the escapade.   The tube at top is a piece out of an import T adapter setup to mount a camera on a reflector telescope.  I'm thinking I might need it for a barlow.  It screws right onto the ebay piece I just mentioned,  pictured at bottom left of the picture below.   The extension ring set, torn down, is shown at left.   A thick washer  I screwed up on one of the Minolta mirror projects is shown,  as is a cheap  "erector"  mirror:

http://i34.tinypic.com/395cw.jpg

The picture below shows the washer which  I relieved on one side to pilot into the EF lens mount, as shown

http://i38.tinypic.com/2d6sha8.jpg

The picture below shows the washer lying inside one of the extension tube rings.   I relieved the opposite side of the washer to pilot into the minor dia.  of the extension tube, and turned the OD  to fit inside the threaded area.

I had to play with the reliefs somewhat so that the washer would fit inside,  yet the tube ext. ring would fit OVER it, and thread up tight against the shoulder.   When assembled,  the EF mount,  the washer, and one of the tube rings,  screw up tight and hold the washer captive.

http://i36.tinypic.com/x24ec3.jpg

Below,  we have the washer,  with the ID turned to a "convienient dia"   and I just chucked the eyepiece adapter in the lathe and relieved the end to form a small pilot into the washer ID.   Tomorrow,  I'll just drill and tap  3 small holes through the washer/ adapter to hold the two together

http://i36.tinypic.com/1jlogo.jpg

Below we see the washer piloted into the EF mount,  the eyepiece adpapter piloted into the washer.   You next take one of the extension tube rings and screw over the top of the washer,  thus holding the washer in place

http://i33.tinypic.com/3094vg1.jpg

This is what it will look like ready for the lens,  without an "erecting prism"  or "erecting eyepiece."  From what  I've surmized from the www,   my cheap mirror erector won't work, because it "adds length"  between the eyepiece and lens.   I BELIEVE   I've learned that I can cure this,  maybe with a prism instead of a mirror,  and using a barlow.   If not,  perhaps an "erecting eyepiece."     For now,  it should work,  if not inverted!!

http://i38.tinypic.com/npkg1s.jpg

Last edited by 440roadrunner (2008-09-08 04:19:29)

Re: The Canon EF--and everything else--spotting scope adapter project

This sort of thing is very expensive when you can find it. I looked for one a while back.

Might be interesting with a mirror lens.

Did you work out a way for it to be exactly 44mm? Seems like it would be tricky to get the distance right, although with so many screw mounts maybe you can just unscrew a little to fine-tune.

Re: The Canon EF--and everything else--spotting scope adapter project

Actually,  the distance to the eyepiece is a screwey deal,  and I'm no expert.   I started to build one of these some time ago.   It seems that depending on the eyepiece,  you must allow some amount for leeway.  The mirror scopes they fit have plenty of "room"  on the focus rack.     The upshot is, that after posting this last night,  it's apparrent that before I mount this,  I'll have to make the eyepiece mount piece thinner--to allow th short eyepiece to get closer to the lens.   The eyepiece will actually focus--I was out looking at the  moon last night,  but would allow no leeway for inserting an "erecting"  lens.

So far as quality,   the initial results I've gotten look to be a heck of a lot better than looking through the camera.  My goal is to be able to carry a small accessory with me, portable,  without a hugh, heavy,  binoculars or spotting scope.

In no way do I intend this to replace a serious telescope.     "Further testing awaits!!"

Re: The Canon EF--and everything else--spotting scope adapter project

OK,  got the device in a "finished workable"  condition.   If you play with the distance of the eyepiece from the back of the lens,  you can reach a point whereby it's in focus regardless of the zoom setting,  something that may not be important.   This morning I turned about 3/8  off the face of the eyepiece adapter,  in order to allow more intrusion towards the lens.   I believe I'll need this for a erecting prism,  and even THAT may not be enough.   I've seen advertised   "erecting eyepieces"  and may investigate them.  For now,  I have a 25mm Celestron eyepiece,  which by rough estimate is at least 2X  the size image as viewed through my 40D.    I have a Celestron 10mm  which is a lot greater,  but less eye relief, more difficult to use,  and noticeably less quality


All in all, I'd call this a success so far.   Even the wider, (less magnification) eyepiece gives me a MUCH MUCH larger, more defined view than my 7X20    or 7X50 binoculars. 

Mounted on the rear of my 100-400L:

http://i33.tinypic.com/9j29md.jpg

Showing the two 2-56 screws I drilled and tapped for.   (I broke one drill, hence the gobb on one side)

http://i35.tinypic.com/sox0nq.jpg

Re: The Canon EF--and everything else--spotting scope adapter project

thats some beautiful work there

Re: The Canon EF--and everything else--spotting scope adapter project

Hows this thing coming along?

I want to do the same thing wink

Starting afresh with manual lenses ...

Re: The Canon EF--and everything else--spotting scope adapter project

Hi, walhsy.   It's pretty much useable as you see it,  I have done nothing further to attempt an erecting element.   This thing,  other than the inverted image problem,  works great.  The eye image, even with a "short" eyepiece,  is MUCH  larger than the viewfinder image when camera mounted.

Incidently,  I found the focus  issue to be quite easy.   I simply aim the thing at a far object--mountains, etc,   zoom the lens (if a zoom)  out to the long end,  and then focus by "rough"  moving the eyepiece in/out before tightening the thumbscrew.   After that, it's pretty much in focus  at any zoom setting.

One other little glitch,  is that a few of my lenses  would be useable with this device,  but they don't have a tripod mount!!!!   You don't have to have a very long lens!!!!   (over 135mm or so)    to make handholding it a real chore.

Re: The Canon EF--and everything else--spotting scope adapter project

Always a pleasure to see a DIY smile

Re: The Canon EF--and everything else--spotting scope adapter project

I wanted to use my 500/4 and teleconverter for astronomy.

Seems its not as simple as I first thought sad

Just found this site smile

http://www.cita.utoronto.ca/~jank/Photo … index.html

Last edited by walshy (2008-10-27 12:54:11)

Starting afresh with manual lenses ...

Re: The Canon EF--and everything else--spotting scope adapter project

walshy wrote:

I wanted to use my 500/4 and teleconverter for astronomy.

Seems its not as simple as I first thought sad

Just found this site smile

http://www.cita.utoronto.ca/~jank/Photo … index.html

This very website is where my idea was born.  I was actually hoping to find a manufactured item,   the only real issue with my project---and I have not taken the time to research,   is to implement an element to "erect"  the image

Re: The Canon EF--and everything else--spotting scope adapter project

I have since given up and bought a Celestron CPC 800 GPS tongue

I'll post some terrestrial pics soon... 2000mm f/10 is amazing big_smile

This is an interesting blog

http://www.nobell.org/~gjm/photography/efspottingscope/

.
Guy

Starting afresh with manual lenses ...

Re: The Canon EF--and everything else--spotting scope adapter project

walshy wrote:

I have since given up and bought a Celestron CPC 800 GPS tongue

I'll post some terrestrial pics soon... 2000mm f/10 is amazing big_smile

This is an interesting blog

http://www.nobell.org/~gjm/photography/efspottingscope/

.
Guy

OH THANK YOU!!!   This is the info I needed.  Mine works but is inverted.  This project appears to be the finish parts I need to come up with an erect image.