Takumar vs Pentax-M, thorium vs non-thorium. Which 50mm f1.4 lens is better? (Radioactive lens)
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- Опубликовано: 29 сен 2024
- A quick comparison between two fast 50mm lenses from Pentax. The SMC Takumar (1972 - 1975) contains thorium and thus is radioactive. Does this make the lens better than the later Pentax-M version? I did a quick test to see which lens performed better.
Spoiler: performance is the same, only because of thorium the Takumar is much "warmer"
You can also get rid of the yellowing by leaving the lens to soak up sunlight for a while (or so it's said, haven't had to try it out for myself). Just wrap the other end of the lens in some tin foil so it doesn't start a fire...
Also, before anyone asks, no, the radioactiveness isn't enough to be dangerous. Unless you smash the glass and inhale it, but you wouldn't do that to normal glass either, so...
I'd recommend using a UV lamp. Even the cheap 395nm ones work, but I suppose a 365nm would work even better. I cleaned mine with a 395nm one and it was almost perfect after two or three days.😊
I have the SMC PENTAX lens just like the lens on the right in your video. However when removed from the camera the front elements (stopped down to f 22) have a distinct blue cast while the rear elements consistently show a distinct amber cast. As I understand it, the thoriated lens usually ends up in the rear element group. I have not tested my lens with a geiger counter as of yet but plan to very soon. I also have a MC W ROKKOR-X SI 28mm f2.5 lens with a very distinct amber tone. While Pentax made a long list of lenses using thoriated glass, Minolta only made a couple including the 28mm f2.5.
All those yellowhiing should be corrected with UV lights, then the differences even out
Interesting I have a 7-element and an 8-element version of the 1.4 and cant really tell much if any difference between those 2 lens either
Hi ohjajohh, I'm kind of surprised just how similar the results are, once you've got past the obvious colour shift. Great comparison video, and some nice shots too - love the night time shots across the sea - I could never get tired of seeing that view.
Hi Tim, thanks for watching. I was also surprised to see that apart from the colour difference they really seemed to perform similar.
I live at the Dutch coast, so seeing the sea and ships feels normal to me. :)
Nice. Whats the difference in the price ?
I think on average the Pentax is around $75 bucks and the Takumar usually goes for around $100
Pentax-M more beautiful
Very interesting video. Thanks for sharing. Congrats! I subscribed to the channel!
Quick question, what camera and settings did you use? Thanks.
Sony A7iii and color temperature at 5500. Iso is always at 100 when I'm outdoor. Shutter time varied per scene, but for both lenses I used the exact same shutter speed.
@@ohjajohh Thank you for the prompt reply.