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Edmunds 32mm Military Erfle.

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#1 ngc2289

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Posted 19 January 2013 - 07:24 PM

Well this last Monday I won a Edmund Scientific old 32mm military Erfle. The eyepiece came in today, and right away I could see a problem. Over the years the glass has changed to a dark amber color! The glass is so dark as to be unusable. Now in E-Bays description it states that a used item will be functional. No way this eyepiece could be called functional! Using this eyepiece would be like turning my 6" reflector into a 2.4" or even smaller. Now heres the problem the seller does not accept returns. No where in the ad does the seller state that the glass is very dark nor did they include any picture looking thru the eyepiece. I can see a lot of aggravation in the near future!!!!!! I tried to take a picture thru the eyepiece of some overhead lights. But as you can see the image is very very dark!!! I am very unhappy!!!!!!!!!!!!!!!!! :mad: :mad: :mad: :mad: :mad: :mad: :mad: :mad: :mad: :mad: :( :( :( :( :( :( :( :( :( :(

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#2 Blake Andrews

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Posted 19 January 2013 - 07:35 PM

Four words...
"Pay Pal Buyer Protection".

I've only had to do this twice in 280 transactions.
It worked for me in both cases.

Good luck!
Blake

#3 Mr Magoo

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Posted 19 January 2013 - 09:35 PM

That stinks. Let's say worst case scenario that the seller won't take it back. Looks like some sort of coating degradation. Is is possible for him to remove the coating to bare glass?

#4 ngc2289

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Posted 19 January 2013 - 10:04 PM

Looking at the eyepiece it appears that it is the glass that has darkened.

#5 Blake Andrews

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Posted 19 January 2013 - 10:09 PM

Is the discoloration due to a radioactive glass element?
:question:

#6 ngc2289

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Posted 19 January 2013 - 10:11 PM

:shrug: :question:

#7 DAVIDG

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Posted 19 January 2013 - 10:35 PM

I have a number of old military Erfles include one that looks very similar to yours which also has the amber colored glass. I have tested it for radioactivity and it IS mildly radioactive. It now sits in a thick metal box and I will never use it. The amount of radioactivity coming off of mine is not going to cause me to glow in the dark but if I could I view thru and use it on a regular basis it would increase the odds of me getting cataracts.

- Dave

#8 Blake Andrews

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Posted 19 January 2013 - 11:41 PM

I have a number of old military Erfles include one that looks very similar to yours which also has the amber colored glass. I have tested it for radioactivity and it IS mildly radioactive. It now sets in a thick metal box and I will never use it. The amount of radioactivity coming off of mine is not going to cause me to glow in the dark but if I could I view thru and use it on a regular basis it would increase the odds of me getting cataracts.

- Dave



:dabomb: :ohgeeze: :dabomb:

#9 rathbaster

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Posted 20 January 2013 - 12:04 AM

Have you contacted the seller? If he has a good reputation he might take it back, even if he states a no return policy.

-Joe

#10 John Kuraoka

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Posted 20 January 2013 - 01:00 AM

I've just gotta ask - what was the purpose behind using radioactive glass in an eyepiece?

#11 ngc2289

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Posted 20 January 2013 - 01:15 AM

Yes I have sent an e-mail rathbaster. I am waiting for a reply.

#12 Spectral Joe

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Posted 20 January 2013 - 01:18 AM

In the 1940s it was discovered that adding thorium to optical glass gave it unusual dispersion properties, giving an extra "knob" to turn in tweaking designs. These glasses were also used in aerial camera lenses, I've seen Kodak Aero Ektars and B&L Aero Tessars with radioactive elements, but not all of them. Like with the Erfle in this case they eventually darken from color centers formed by radiation damage. I have a giant Erfle that came off of an M71D telescope, but it uses only normal glass. The thoriated glass seems to date from between the late 40's to the late 50's, the "in-service" tag on my M71D was from 1944.

#13 skullpin

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Posted 20 January 2013 - 05:15 AM

Looks like thoriated glass. Should be safe to use as its radiation is alpha decay which is non-penetrating. This radiation will yellow the glass over time, though this is reversible: leave it in the bright sun or under a UV source for some period of time and it should clear up. Although such "radioactive glass" is safe to handle, proper disposal is another matter.

#14 Blake Andrews

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Posted 20 January 2013 - 10:52 AM

Looks like thoriated glass. Should be safe to use as its radiation is alpha decay which is non-penetrating. This radiation will yellow the glass over time, though this is reversible: leave it in the bright sun or under a UV source for some period of time and it should clear up. Although such "radioactive glass" is safe to handle, proper disposal is another matter.


Very interesting. I did not know that the discoloration could be reversed through UV exposure. Another fun fact!

Thanks!
Blake

#15 John Kuraoka

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Posted 20 January 2013 - 11:10 AM

Cool! So it's post-war atomic tech in an eyepiece! I did a quick search on "thorium glass" and came up with this wiki:
http://camerapedia.w...ioactive_lenses

The wiki says thorium oxide, like fluorite, has properties of high refractivity and low dispersion. The wiki goes on to say that although the radiation level is very low it can pose a danger specifically with eyepieces, where the eye is exposed directly with no skin as a barrier. The wiki also mentions the use of several days of UV sunlight to clear up yellowed or browned glass elements.

Man, if it was an F-mount (which I doubt), I'd totally want one of those radioactive 35mm f/1.4 Nikkors!

#16 DAVIDG

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Posted 20 January 2013 - 12:00 PM

Here is a listing on Ebay for another one. Military Amber Eyepiece :dabomb:

- Dave

#17 ngc2289

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Posted 20 January 2013 - 12:03 PM

Disposal is no problem. This is one of those items you quietly slip into your neighbor's garbage can on pick up day for disposal. Now on a more serious note. I got a reply from the seller. The response stated that her friend who is an expert told her that the coating was dark amber to begin with. I in return told her in return that my "Experts" on CN said it was due to a mildly radioactive element. I left a solution up to her because I did not want to appear to be trying to rip her off.

#18 MRNUTTY

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Posted 20 January 2013 - 05:54 PM

Mike, I would try to leave it I'm the sun to see if it clears up. That is, unless it's just too sour to swallow now.

#19 ngc2289

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Posted 20 January 2013 - 06:11 PM

I just brought the eyepiece in from spending it's first day in the sun. :goodjob:

#20 ngc2289

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Posted 20 January 2013 - 07:01 PM

I didn't mention before that the 32mm is an old eyepiece Edmunds used to advertise back in the 1960's. Edmunds made a 1 1/4" adapter for the eyepiece, and said it had a 65degree AFOV. Here is a picture of the eyepiece in it's adapter.

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#21 rguasto

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Posted 21 January 2013 - 06:56 AM

I have a similar EP. It's a little "cleaner" looking. Supposed to be from an M70 Tank. 1.25 barrel, no field stop that I can appreciate.

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#22 Bart

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Posted 21 January 2013 - 08:31 AM

What does it cost to own an EP like this?

And how about a pic oh how it looks after the sun treatment?

#23 ngc2289

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Posted 21 January 2013 - 09:27 AM

I paid $86 which includes shipping. If the solar exposure works I will provide a picture.

#24 ngc2289

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Posted 21 January 2013 - 04:34 PM

The seller cut me a break, and will let me return the eyepiece. End of story. Thank you all for your responses! :bow: :bow:

#25 John P

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Posted 21 January 2013 - 05:14 PM

These old military eyepieces, especially those from the 50mm anti-aircraft elbow telescopes, were very popular with ATM's making richest field telescopes. It used to be pretty common knowledge that an element of the erfle eyepiece was slightly radioactive and no one paid much attention to it. Guess things were simpler back then.






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