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07-10-2017, 04:40 AM   #1
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Atomic power by Pentax?

I don't know where else to put this, and it DOES relate directly to Pentax (or at least Asahi Optical Co Takumar) glass, so enjoy it for what it's worth.



07-10-2017, 09:09 AM - 2 Likes   #2
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What fun! Work is being done by the emissions from that rear element


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07-10-2017, 11:34 AM   #3
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he sure is giggly today.
07-10-2017, 11:57 AM - 1 Like   #4
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QuoteOriginally posted by stevebrot Quote
What fun! Work is being done by the emissions from that rear element
All of his hairs fell off immediately after using a Takumar 50 f1.4 wide open.

07-10-2017, 12:23 PM - 2 Likes   #5
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Has he switched from a tin-foil hat to a lead-foil hat?
07-10-2017, 01:11 PM - 1 Like   #6
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This is hogwash.

Don't believe it - there is not enough energy from the lens to power much of anything.

He calls his other bobbler the control, but he did not do the simplest control: take away the lens from the "lens powered" bobbler. There may have been enough charge stored in its battery, or enough random light from his flashlight to energize it. He should also have wrapped or covered the photocell of the bobbler photocell so that NO light could possibly have reached it. The beta and gamma radiation would have penetrated the wrapping.

This is a completely uncontrolled experiment as described and not valid. (Of course, the whole thing could also be an attention-getting intentional fraud.)

Take a look at this paper: http://nvlpubs.nist.gov/nistpubs/jres/64A/jresv64An4p297_A1b.pdf

by somebody who actually knows what they are doing and has sophisticated measuring equipment as well as STRONG sources of radiation.

In figure 3, using a Cobalt 60 source (roentgens per minute) - WAY stronger than any lens!! see below - he gets currents of a few tens of nano-amps (billionths of an amp). That's not enough to do anything.

For instance, reported here: Thorium coated camera lens, what kind of danger is there from using it? (x-post from /r/photography) : askscience ,

the rate from the back end of some lens was "measured the dose rate at the surface of the camera lens to be 0.48 mrad/h". (I think that should be mrem - millirem; a rem is comparable to a roentgen) That is a couple thousand time weaker than the source in the above NIST paper.

Last edited by AstroDave; 07-10-2017 at 03:04 PM. Reason: Make clear "rem" and roentgen" are about the same
07-10-2017, 02:24 PM - 2 Likes   #7
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Terrible looking video, too - he must have been using a Pentax.

07-10-2017, 04:17 PM - 1 Like   #8
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QuoteOriginally posted by pathdoc Quote
I don't know where else to put this, and it DOES relate directly to Pentax (or at least Asahi Optical Co Takumar) glass, so enjoy it for what it's worth.
Please, for the love of all things Pentax, stop posting this guy's rubbish.

07-10-2017, 04:42 PM   #9
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QuoteOriginally posted by AstroDave Quote
There may have been enough charge stored in its battery, or enough random light from his flashlight to energize it.
Good question. I have some experience with photo-powered bobbers and the ones I have played with stop fairly quickly when they don't have light. I am not sure, but I believe the motor is powered from a capacitor that accumumates charge from the photovoltaic cell. As you note, a well-designed experiment would have shielded the photocell completely from light, though doing so should not require taping over the detector face. I have a few "hot" lenses and should simply try to replicate.

QuoteOriginally posted by AstroDave Quote
For instance, reported here: Thorium coated camera lens, what kind of danger is there from using it? (x-post from /r/photography) : askscience ,
I'm gonna have to remember that thread the next time I field a question on thorium-coated lenses. Hint: When someone finds a thorium-coated lens, let me know. All that I am aware of have the thorium as part of the glass mixture.


Steve

Last edited by stevebrot; 07-10-2017 at 04:51 PM.
07-11-2017, 03:35 AM   #10
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QuoteOriginally posted by MarkJerling Quote
Please, for the love of all things Pentax, stop posting this guy's rubbish.
Oh for the love of Takumar, I put it up as a bit of a laugh. See it as that.
07-11-2017, 03:38 AM   #11
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QuoteOriginally posted by pathdoc Quote
Oh for the love of Takumar, I put it up as a bit of a laugh. See it as that.
If that was your intent, then I missed it. Apologies.
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