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Film Pentacon Six TL
- Thread starter yohan
- Start date
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- Tags
- film film photography
thanks. I was looking at that lens. will have to see how finances look! certainly good to have some real world opinion of it. thanks.
- Location
- Switzerland
- Name
- Matt
I have this camera as well and love shooting it; the Biometar is a very nice lens - small, yet capable. Unfortunately, mine's quite radioactive - uncomfortably so, front (clearly) heavier than rear. Only the zebra'd ones are affected, btw. (see below) My Flektogon's rear lens is radioactive as well, but no radiation is detectable outside the body or the lens barrel, so I'm basically fine with carrying it around all day. The Biometar - less so. The original (Thorium-related) alpha radiation isn't that much of a risk as long as you don't swallow any glass fragments - but among the daughter products are gamma emitters as well, and my lens is old enough to contain some of them in detectable quantities. The amount of radiation isn't critical for occasional use in principle - just a bit high for extended and regular use. Just a heads-up, and remember: Only original zebra'd (lenses with polished strips of metal on both the focus and aperture ring) are affected.
M.
M.
Wow! Love those clean lines. The craftsmanship on cameras from that era was impressive.
- Location
- Switzerland
- Name
- Matt
- Location
- Switzerland
- Name
- Matt
Now for the bad (well, a little worse) news: I looked into the "hot lens" issue a bit deeper - and discovered that the rear element of my Flektogon 50mm f/4 is blazing:
For reference: 0.2 microsievert per hour is the average background world-wide; in my flat, it's actually 0.16 usv/h. This means that the radiation directly on the rear element is 27 times the usual radiation level. That said, it's not quite as bad as it looks; firstly, it's a contained and very limited source, and it's directional - the outside of the lens is completely safe, as is the front element. Secondly, the body shields the radiation from the lens *completely* (I get *no* extra radition once the lens is mounted) - which means that there's probably hardly any high-energy gamma radiation around. Alpha radiation will be stopped by every surface anyway (i.e. the mirror will absorb it), and beta also doesn't make it out of the body, not even through the focus screen (I looked ...).
What I didn't take an image of is the situation with the zebra'd Biometar 80mm f/2.8; radition is not that high, but it's enveloping the lens (it's strongest right at the elements, but measurably higher than background all around), and it's *not* contained by the body once mounted - so there's gamma radition involved, probably from Radon, a daughter element of Thorium. Now, outside readings are far from dangerous, absolutely fine for casual use, but solidly twice as high as the average. Carrying the camera in a bag will probably shield your body from getting exposed, but you'll get a little extra exposure when using the camera. You'll get loads more from a common X-ray and at least twice this amount *as a full body dose* when flying - so while using the lens is potentially not without risk, it's actually very remote.
M.
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For reference: 0.2 microsievert per hour is the average background world-wide; in my flat, it's actually 0.16 usv/h. This means that the radiation directly on the rear element is 27 times the usual radiation level. That said, it's not quite as bad as it looks; firstly, it's a contained and very limited source, and it's directional - the outside of the lens is completely safe, as is the front element. Secondly, the body shields the radiation from the lens *completely* (I get *no* extra radition once the lens is mounted) - which means that there's probably hardly any high-energy gamma radiation around. Alpha radiation will be stopped by every surface anyway (i.e. the mirror will absorb it), and beta also doesn't make it out of the body, not even through the focus screen (I looked ...).
What I didn't take an image of is the situation with the zebra'd Biometar 80mm f/2.8; radition is not that high, but it's enveloping the lens (it's strongest right at the elements, but measurably higher than background all around), and it's *not* contained by the body once mounted - so there's gamma radition involved, probably from Radon, a daughter element of Thorium. Now, outside readings are far from dangerous, absolutely fine for casual use, but solidly twice as high as the average. Carrying the camera in a bag will probably shield your body from getting exposed, but you'll get a little extra exposure when using the camera. You'll get loads more from a common X-ray and at least twice this amount *as a full body dose* when flying - so while using the lens is potentially not without risk, it's actually very remote.
M.
