[Not a Number]

Ok, it seems the lens release button retracts the drive shaft too. So it might be easier to set to AF and fiddle with the release button while trying to slide the gauge between the pin and drive shaft. The idea is to slide the gauge between the gap of the shaft and pin when the gap is lined up with gap between the body and lens. The gauge will keep the pin from dropping into the shaft hole and you can dismount the lens.

Again this is only going to work if the spring on the shaft is stronger than the spring on the pin.

[pentax360]

Good luck, that's nerve wracking.

[.a.t.]

Hi Botanizer,

I also have a KR mount Sears 60-300 which still has its Ricoh pin. I assume it would stick on my Pentaxes, but it's filled with fungi so I've never used it or even tried to mount it. I've kept it just because I wasn't sure what to do with it. But today it came in handy as a reference for your dilemma.
I can't recommend an easy solution, but I have some observations.

Does this Sears pin have the rounded tip or the flat tip? Should the camera be off or on when I use the auto - manual focus toggle switch?

I don't know if the pin is rounded or not. Usually round pins don't often cause a problem.

It shouldn't matter if the camera is on or not, the screwdrive shaft extends or retracts regardless. The shaft is spring loaded so which ever has the stronger spring wins.

The Ricoh pin on my Sears 60-300 has a rounded tip. But I believe Not a Number has gotten to the crux of the issue.

In past Ricoh pin discussions, I recall people saying they haven't had problems with the pins on Ricoh branded lenses. And, indeed, my pin equipped Rikenon P 50mm f/2 mounts and unmounts easily on my Pentax DSLRs. So I compared the (Samyang made) Sears 60-300's pin to the Rikenon's. The tips look the same - they're both rounded. But in this case, that wasn't the issue. Rather, it was spring strength.

In an attempt to compare spring resistance, I concocted a crude mechanical experiment involving the Sears & Rikenon lenses and my K10D camera. Here's what I found:
The Rikenon 50's pin is softly sprung and the K10D's screwdrive shaft can easily displace it. To fully depress the K10D's shaft into its mount required about triple the pressure needed to fully depress the Rikenon's pin.
But for the Sears, it was the other way around. The Sears pin is very stiffly sprung. The pressure needed for the Sears is double that of K10D.
Thus, the unlucky get their lenses stuck.

Some photos (click on them for larger versions):

Sears 60-300mm KR mount - Ricoh pin and Pentax A contact labelled and the red dot is the top side of the lens (infinity mark). When the aperture ring is moved off the "A" position, the Pentax contact lowers, but the Ricoh pin stays up.



Ricoh pin on my Sears 60-300.



Underside of 60-300 mount. The tab / spring which pushes the Ricoh pin is circled.



Tab / spring unscrewed with Ricoh pin circled.

1. Continue with the feeler gauges that I have, .005 inch and thinner.

2. Get a .005 inch thick saw blade for a dremel and cut the pin.

3. Get a hacksaw and cut the lens tube an inch or so from the camera leaving the lens closest to the camera intact and try to find and pry the flange to release the pin.

4. Send the mess to KEH and pay $300 + shipping...

If you're willing to sacrifice your lens, either by dismantling from the front or by cutting, it appears to me you might be able to loosen the pin without harming your K-1. I used a small mirror to peek under the rim of the mount while it was attached to the lens. As far as I can tell, if the lens were cut in the vicinity of the "Sears Mod. No." ring, you should be able to access the pin's tab / spring well enough to remove the two screws holding the tab / spring in place. Or at least pry up the tab to relieve some pressure on the pin.


Viewing mirror image of Ricoh pin's tab / spring mounted on lens.




Several years ago I had a KR mount Sears 135mm lens stuck on my K10D. After I failed with feeler gauges, I just started wiggling the lens back and forth. After a while, the Ricoh pin simply broke and the lens came off. I'm sure I was wiggling firmly, but it wasn't my intent to break the pin. A small mark was left on my K10D's mount, but there was no functional damage.

I'm not advocating anyone else try brute force as a solution. YMMV and maybe I was just lucky to escape with no damage to my camera. But if I had the same situation again, personally, I wouldn't be afraid to lean on that pin a little if the alternative methods didn't work.

[.a.t.]

HELP...

Any luck?

[Botanizer]

I almost had the aperture ring cut off with the hacksaw, when the lens surrendered and came off. I don't know why, but it did.

---------- Post added 01-04-19 at 07:22 PM ----------

Any luck?

Thanks .a.t., I saw you excellent reply after the hacksaw surgery. The lens is probably functional, but I won't put it back on the camera without removing the pin.

[.a.t.]

I almost had the aperture ring cut off with the hacksaw, when the lens surrendered and came off. I don't know why, but it did...

Thanks .a.t. ...

Ah, what a relief! That's good to know. And you're welcome.

I have a second copy of the Sears 60-300 from which I've removed the Ricoh pin. It's not the sharpest, but the focal range and close focusing make it a versatile lens.

The Samyang made Sears lenses I've used are optically decent and really good values. It's a shame so much grief has been caused by those stiffly sprung Ricoh pins.

[Botanizer]

Some photos of the Sears lens after it came off. After I took the photos, I was going to test the spring strength with a toothpick and felt no resistance. Now the Ricoh pen is inside of the lens. The hacksaw may have broken the spring.

Attached Images

View Picture EXIF

File Date

 

View Picture EXIF

File Date

 

[.a.t.]

Some photos of the Sears lens after it came off. After I took the photos, I was going to test the spring strength with a toothpick and felt no resistance. Now the Ricoh pen is inside of the lens. The hacksaw may have broken the spring.

That's interesting. Thanks for the photos.