Disassembly of 50mm RB lens

[andrew chalsma]

Hi,

Anyone have instructions for disassembly of the 50mm RB lens? I have one that needs internal cleaning. I have

done other lenses before, but at the front element does not come out like I think it should after taking the trim

ring off.

 

Thanks

[Ed_Ingold]

Do you plan to insert a piece of paper with someone's initials or poem. That's becoming very popular for paper weights these days :-)

[andrew chalsma]

Thanks for the sarcasm. Very helpful. Given it is a paper weight now, a little careful exploration is entirely appropriate.

 

Does anyone who has a clue have an idea about my original question?

[norman_valentine]

Try Kyphoto.com there are lots of people there who might be able to give sensible suggestions.

[paul ron]

The 50mm is not like the other lenses. It has a floating element encased inside a helix that lives just under teh front element. You'd have to disengage the control arm of it via the side of the barrel inorder to unscrew the entire from cell off it's shutter mount. To do this you'd have to remove the thumb grips. Under them are acceess hole which allow you to unscrew the barrel halves, disengage the floating element mechanism. Once that has been done, take out the name ring on the front of the lens and the entire front cell unscrews like a light bulb. Word of caution when reinstalling everything... you'll have to reset the floating element to it's infinity setting again and that takes some practice since it will be totaly out of focus now that you have moved it.

 

So how far are looking to clean inside this lens? There is a simple way of accessing the rear of the front cell by removing the rear cell which simply unscrews without taking the barrel halves appart.

 

Open the shutter using the T setting. Then carefully clean the rear of the front cell but do not hit the iris or shutter blade edges as this may dislodge em and cause damage to the shutter which would definately force you to dissasemble the entire lens.

[andrew chalsma]

Thanks Paul. I will work on it and see what happens. After posting I figured that it was the floating element that was different and the issue.

[andrew chalsma]

Good news. I actually didn't have to remove the floating element. There is a trim ring that screws off the front element after removing the nameplate ring. It simply unscrews. The element that needed cleaning was the center of the front group which is a cemented element. Rear of it hand some fog. Cleaned right up. Lens good as new.