Remember when I mentioned baking my Super-Takumar 50mm f/1.4 lens in the back yard? As weather permitted, the experiment continued. I spent a couple of days shifting the lens like the head of a sunflower, always pointing it towards the sun. The main goal, of course, was to remove the yellow tint created on the rear lens element from the decaying Thorium. The end result should be better clarity in the raw image.
I will admit to being somewhat skeptical. There was not much harm in trying. The images this lens has produced for me have an amazing clarity when I nail the focus. Getting rid of the yellow-tint would add to the quality. It is my duty to revive this lens and give it a second life. Okay, okay. Not actually my duty. But it would certainly be fun!
I took a series of images of the lens and through the lens so that I could monitor the change. Above, you can see what the tinting of the lens before I exposed it to direct sunlight. It may be hard to tell, especially if you are using an uncalibrated device. Look closely and you will see that the faint yellow coloration in the center of the lens.
In the second image, most of the yellow is gone. This is after about 24 hours total, spread over several days. The yellow is barely noticeable in the viewfinder, to the point that I’m not entirely convinced that I’m seeing things. I will do another shoot or two and see how it fares.
The image in the header of this article is a composite to help demonstrate the difference with a bit more clarity. Don’t mind the dust and specks. It is a fifty-year old lens. It has a few miles and has seen better days. My hope is that now, having bathed in the glorious sunlight, it will see many more miles in the future.