what do you folks use to measure Hot lenses/thorium

[Paul A]

i am in Canada. i am having an extremely difficult time trying to ward off legacy glass desire.
what instrument(s) do you folks use to measure radiation levels of the lenses and how/where would i find one of these instruments?
yes, i've read a number of threads suggesting the levels of a, b, and/or, Gamma these lenses put out is negligible. i have no reason/evidence to dispute this advice. nonetheless, I just can't kick the bad vibe i get when thinking about the issue and the vibe (right or wrong) is holding me back from using/acquiring more legacy glass. call me a fool as it very well could be accurate.
what gets me is this...i have read threads about numerous lenses that state "it" (any particular lens i am researching) is not a Thorium doped lens and is not radio active yet i will find threads pertaining to the same year/make lens that state that it does emit a, b, an/or gamma.
so i can't just "try" and stick to this or that copy/year of certain lenses to simply avoid the issue entirely.
So, in theory, if i have my own metering device i will be a happy camper(collector).

Thanks,
Paul

[visualopsins]

I don't worry too much about it. There is an iPhone App, of all things. The thread about it is here: http://forum.mflenses.com/measure-radioactive-lenses-using-your-phone-t50144.html

[s58y]

There are two main types of radiation detectors that I use:

1) Geiger counter. The advantage here is that they are relatively inexpensive. One disadvantage is that they will respond best to beta rays, and maybe alpha (depending on how the geiger tube is made). This will make the lenses look more radioactive than they really are, compared to the natural background radiation (mostly gamma rays and other things). Measured with a geiger counter, some lenses may look 1000x more radioactive than the natural background, when you press the probe up to the front or back of the lens.

2) Gamma Scintillation detector. These are more expensive, and also you can get widely varying readings, depending on the High Voltage and Threshold (low-level discriminator) Voltage you set on the meter. The big advantage here is that these are much more sensitive to gamma rays, so natural background is much higher (perhaps 100x higher in CPM) than with a geiger counter. You can get a more accurate picture of how radioactive lenses really are. Lenses can be up to 100x (instead of 1000x) more radioactive than the background, measured at the front or back of the lens. A meter away from the lens, you can see that the reading is only slightly above natural background.

A good place to get Geiger counters or Scintillation detectors is Ebay. The most sensitive geiger counters are have "pancake probes" and are sensitive to alpha.

[Paul A]

[tanheis]

I bought russian Radex 1706.
Seems to be easy to use and compact size.
It has 2 geiger tubes and should be more sensitive than some with just one.

Works with 2pcs of AAA batteries and works just with one also. Second is just for extra battery life so if there would be an emergency one is enough. Clever thinking

I have measured my SMC Takumar 50/1.4 with that and it shows around 100x background radiation if holding VERY close to rear element (the one doped with thorium)
If that radiation level is accurate I would not even think about danger because there is normal areas in the world where background radiation is higher because of natural radioactive elements on the ground and people get that kind of a dose all the time when going out (whole body)

Using the lens radiation in your fingertips when holding the lens will drop to around 25% from the rear element so that is low.
Everyone can decide their maximum radiation and even say no to x-ray if wanted in hospital or dentist.
Well if you take one you get a lot of it quick.

I think short time of strong radiation is a lot worse than long dose of weak.
At least I saw studies from places around world with high background radiations there is no cancers skyrocketing.
Well even the background radiation in those places are high you cannot compare it to nuclear disaster areas. It's just emitting from natural soil from the ground.
That I have seen it can be dangerous if you make a mine and start digging it and getting that precious radioactive and or other stuff and play around with that radioactive stuff. Seems to be quite harmless if left like it is but human beings do play dirty games as we all know.
That I know powerful radiation is always VERY dangerous and even short time can make bad things.

From ebay the Radex is like this:
http://www.ebay.co.uk/itm/NEW-Detector-Geiger-Counter-High-Quality-Radiation-Monitor-RADEX-RD-1706-/221064319915?pt=BI_Security_Fire_Protection&hash=item337875d3ab

Remember thorium is dangerous if you have it as a pure metal and you break it (get the dust on your body or even more inside your body)
I think same doesn't apply with lens well if you use some kind of sanding machine to make some sort of glass powder which has thorium and play with it

Well this is going wrong direction but hahah. Someone might be so dumb to actually do that