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12-13-2016, 11:13 AM   #1
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Ricoh Fast Normals: De-yellowing Needed?

Hello,

Just bought a Sears 50mm f/1.4 MC Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database and a Auto Sears 55mm F1.4 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database which I believe are both Ricoh lenses. Would like to know if these lenses used thorium lens elements and if I have to de-yellow these lenses using the Ikea lamp method.

Sincerely

12-13-2016, 11:55 AM   #2
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If your Auto Sears 55/1.4 is like the one in the review, it is a rebadged Auto Rikenon 55/1.4* and likely has "hot" glass (at least my copy does). Mine responded nicely to the Ikea lamp treatment. Another consideration with that lens is the tendency to produce "hot spot" reflection off the sensor surface under some conditions when adapted to digital cameras. This is not a problem when shooting film.

Edit: Care should be taken if using the Auto Sears 55/1.4 adapted. The auto/manual switch is larger than on most lenses and may interfere with the pentaprism housing on some bodies. This may cause problems when mounting the lens/adapter combo directly to the camera and then attempting to unscrew the lens.

The K-mount Sears 50/1.4 is unlikely to have radioactive glass.


Steve

* Reputably made for Ricoh by Tomioka

Last edited by stevebrot; 12-13-2016 at 12:04 PM.
12-13-2016, 01:21 PM   #3
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QuoteOriginally posted by stevebrot Quote
If your Auto Sears 55/1.4 is like the one in the review, it is a rebadged Auto Rikenon 55/1.4* and likely has "hot" glass (at least my copy does). Mine responded nicely to the Ikea lamp treatment. Another consideration with that lens is the tendency to produce "hot spot" reflection off the sensor surface under some conditions when adapted to digital cameras. This is not a problem when shooting film.

Edit: Care should be taken if using the Auto Sears 55/1.4 adapted. The auto/manual switch is larger than on most lenses and may interfere with the pentaprism housing on some bodies. This may cause problems when mounting the lens/adapter combo directly to the camera and then attempting to unscrew the lens.

The K-mount Sears 50/1.4 is unlikely to have radioactive glass.


Steve

* Reputably made for Ricoh by Tomioka
I am planning to use the Sears 55mm 1.4 with my Mitakon Lens Turbo M42 on a mirrorless so the A/M switch is not really a big problem. But what is "hot spot" reflection and how does it show up on the final image?

I believe the K-mount Sears 50/1.4 is also a Ricoh lens rebranded.
12-13-2016, 05:13 PM   #4
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QuoteOriginally posted by butangmucat Quote
But what is "hot spot" reflection and how does it show up on the final image?
The center bright spot in the image below occurred in the absence of ordinary flare and with no bright light sources hitting the front element.



The phenomenon is relatively rare and first showed up on this site several years ago in the form of floating off-axis green spots in night photography. Prevailing theory is that they are the result of reflection from the sensor onto the back element and back onto the sensor. The Rikenon 55/1.4 has a very wide and rather flat rear element that associated with the anomaly. There is a related problem that crops up with IR digital photography.

Also this thread:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/93388-tamro...ccd-flare.html


Steve


Last edited by stevebrot; 12-13-2016 at 05:25 PM.
12-14-2016, 03:26 AM   #5
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QuoteOriginally posted by stevebrot Quote
The center bright spot in the image below occurred in the absence of ordinary flare and with no bright light sources hitting the front element.



The phenomenon is relatively rare and first showed up on this site several years ago in the form of floating off-axis green spots in night photography. Prevailing theory is that they are the result of reflection from the sensor onto the back element and back onto the sensor. The Rikenon 55/1.4 has a very wide and rather flat rear element that associated with the anomaly. There is a related problem that crops up with IR digital photography.

Also this thread:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/93388-tamro...ccd-flare.html


Steve
Thanks, I guess my Mitakon Lens Turbo should help with this issue.

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