[Leica] IMG: Takumar 50/1.4

[Jim Nichols]

Thanks, Steve, you are correct.  I have two of these lenses, a SMC 
1:1.8/55 Product # 37108, and a Super-Multi-Coated 1:1.4/50 Product 
#37902.  Both are listed on the internet as being radioactive, the 1.4 a 
little more so than the 1.8.  The 1.8 lens is almost clear, while the 
1.4 lens is yellowed.

 From research reported on-line, the yellowing is in the glass of the 
rear three elements due to thoriumdioxide added to the glass. It can be 
reduced by exposing these elements to blacklight for about a week.

Jim Nichols
Tullahoma, TN USA

On 3/13/2017 4:23 PM, Steve Barbour wrote:
> I recall the yellowing has something to do with a radioactive element in the glass.
>
>> Lluis,
>>
>> After your comment, I took the lens and looked through it toward a cloudy sky, and it does have a warm color.  Whether it was made that way, or darkened with age, I can't really say.  I seem to recall that, at one time, I placed it in bright sunlight for a few days, to reduce the yellowing.  The color is not really objectionable to me, but could be to some viewers.
>>
>> Jim Nichols
>> Tullahoma, TN USA
>>
>> On 3/13/2017 2:48 PM, lluisripollphotography wrote:
>>> This lens performs very well, as you know I like the rendering of the old lenses. These ones look to me warmer than others with modern lenses. Isn’t it?
>>> Lluis
>>>
>>>> El 12 març 2017, a les 22:07, Jim Nichols <jhnichols at lighttube.net> va escriure:
>>>>
>>>> I have always been impressed by the results I got from the old Pentax Super-Multi-Coated Takumar 50/1.4 lens.  While watching softball on TV, I shot a few images from my recliner, not worrying about being square with the subject.  I played with Exposure Adjustment to try to get somewhere near the correct light.
>>>>
>>>> I was impressed, once more, by how the lens performed on the X-T2.
>>>>
>>>> My son, giving me the latest news from his iPhone 7:
>>>> http://www.gallery.leica-users.org/v/OldNick/20170312-DSCF0918.JPG.html
>>>>
>>>> Sharpness, from a crop of details above the fireplace, shot at an angle, with distortion corrected:
>>>> http://www.gallery.leica-users.org/v/OldNick/20170312-DSCF0909-1.jpg.html
>>>>
>>>> Comments and critiques welcomed and appreciated.
>>>>
>>>> -- 
>>>> Jim Nichols
>>>> Tullahoma, TN USA
>>>>
>>>>
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