Grub screw size for front section of 28 ASPH Summicron

[wlaidlaw]

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My 28mm ASPH Summicron, has the unfortunate but common fault with these lenses of a loose front section. This is usually caused by owners grasping the lens by the original large rectangular lens hood to mount and unmount. If you have larger fingers, it is difficult to get behind this hood to grasp the lens on the knurling designed for mounting and un-mounting. The damage was unfortunately already done when I acquired the lens and replaced the large original hood with a far neater Contax GG1 hood. The front section/front optical group of the lens is prevented from unscrewing by three tiny grub screws. When I looked at tightening the screws, I could see that they had suffered from previous ham-fisted attention, using I suspect inappropriate or cheap screwdrivers and cannot be further tightened. I can probably get these screws out but I will almost certainly destroy them further in the process. I would not want to start this process unless I have replacements to hand. I would intend to use decent hex-socket screws rather than cheese/slot-head as Leica used

My question therefore is: Before I start down this path, does anyone know the thread diameter of these grub screws. Normally I would say they would be either M2 or M1.6 but Leica have in the past, been known to use non-standard M1.75 screws. I cannot find anyone listing M1.75 grub screws, whereas M1.6 or M2 are easy and I can either buy these in blued steel hardened or stainless steel. 

Wilson

[wattsy]

Maybe you'll need to sacrifice one of the grub screws to determine the thread size, Wilson? If the screws are nonstandard and hard to obtain you could always consider making your own or re-tapping the hole to accommodate the easier to obtain variety?

As a sidenote, I have mixed feelings about this lens (which I owned for more than a decade). With film, I think it is a fabulous lens but I was never quite so taken with it when used on a digital body. I also think its reputation for dodgy build quality is well founded. My long term copy didn't suffer the grub screw problem (I'm always quite careful with lenses when mounting or dismounting from the camera body) but it did start to fall apart from the rear. For years it worked perfectly fine and then, for no apparent reason, it developed a considerable amount of play at the rear of the lens and I suspect, left to its devices, it would have fallen apart. Leica, to their credit, repaired it for free even though it was long out of warranty. I suspect this lens, introduced in (I think) 2000, was a bit of a transitional design for Leica. Optically superb in an ambitiously compact size but built presumably to a price at a time when Leica was heading into troubled financial waters.

[wlaidlaw]

Ian, 

I suspect you are correct. Looking at the horrible state of the screws, getting them out is going to be a real mission. I may have to re-tap them to say M2.2 x 0.25 or M2.5 x 0.35 fine. Alternatively, I may send it to Malcolm Taylor who is now working again part time, after his recent illness. He already has my 250FF and motor drive IIIa for repair/CLA, as he is the only person who has parts and repair knowledge of these odd devices. He was telling me that when he was at Hove Cameras, at one point, he had 16 Reporter 250's in for repair at the same time. 

Interestingly, I have just bought a 7 Artisans 28/f1.4 from Hamish Gill at 35MMC at the exorbitant price of £405 or less than 10% of what Leica charges for a 28 Summilux. Now I am not expecting it to be as good as a Summilux but I bet it is better than 10% as good. I am with you on the 28 Summicron and I mostly use it on my M7 or M4-P, both of which are currently with Alan Starkie for repair for the M7 and CLA for the M4-P, whose slower speeds were getting increasingly off. Quite a few people seem to think the 28 Elmarit is better on digital than the 28 Summicron. I bought an 18mmTL in the USA at the back end of last year and I have to say I am not wild with enthusiasm over that either. I don't think it is as good as the 28mm length on the excellent, if rather large 11-23 TL Zoom. I bought the 18 to use on my CL to have a digital camera that I could put in a pocket, my wife having stolen my C112, when her ancient V-Lux 20 died. 

Wilson