View Full Version : Lens Index Screw?

Bill Smith
2-Aug-2001, 15:24
I don't know if this has ever been asked, so here goes.

I just received a new Schneider lens. There is a small screw that sticks out fro m the silver ring that sits against the lensboard. This screw does not allow my lens to sit flush to the lensboard.

I looked at my other lenses (all mounted by the dealer) and none of them have th e screw. It appears that the screw has been removed.

Is this an index screw for a special lensboard? Should I remove it to fit a sta ndard Wista board?


paul owen
2-Aug-2001, 15:28
Bill, IMHO...throw it!! I understand that they are used as extra insurance against the lens assembly becoming loose. I don't know of anyone who uses them as you need to drill out a hole on the lens board for the said screw to slot into. Paul

Bill Smith
2-Aug-2001, 15:38
Thanks for the info. I just removed the screw and the lens now mounts easily and snugly.

Thanks, Bill

2-Aug-2001, 17:26
Don't throw the screw away. Put it in a plastic bag and keep it with the lens box, so the next owner can use it or not, as he desires.

2-Aug-2001, 18:35
I'm glad you said it. Save the screw. You will need it when you want to mount this lens into a focus mount. Maybe next owner needs it. Cheers!

Walter Glover
2-Aug-2001, 19:11

Don't throw it AND don't stow it. As stated earlier in the thread, the screw is there to eliminate the possibility of the lens rotating on the board. All Copal shutters have the hole for the screw but to my knowledge only Schneider actually supply it in situ.

This is particularly useful with lenses of large diameter (e.g.: Super Angulons) when fitting filters and accessories to the front screw mount where the leverage of the 95mm diameter exerts a lot of force on the smaller diameter Copal 0 capstan.

I have retained the screw on all my lenses and it is no great problem modifying the boards to accept it. With Copal 3 a small hole must be drilled at a distance away from the shutter hole whereas for Copal 1 & 0 a small groove is filled into the edge of the shutter hole. (Your comments on not sitting flat indicate to me that you're probably looking at a 1 or 0.)

Why do this? It means less pressure is required on the capstan (or jam nut) to secure the lens and shutter in place. The fabrication of the shutter housing is extremely light weight metal, to minimise weight, and excess pressure through over tightening increases the risk of 'crushing' internal mechanisms.

Like Centre-Filters and other paraphenalia there will be a myriad of folk say that they get away without worrying about this - good luck to them. The screw is there, it's free and only requires a little effort to fit ... why not use it and err on the side of safety?

One possible exception to this is the fitting of a Copal 3 for fitting to a Linhof MT. The shutter needs to be mounted forward of the lens panel to clear the front standard and so the spacer ring supplied will sit the shutter too far forward to reach the panel. In this case don't use it and certainly don't drill!.

Cheers Walter

paul owen
2-Aug-2001, 20:16
Bill, Save it if you must!! But IMHO there is NO POINT!! Shutters are more than capable of being fitted to the lens board without crushing their mechanisms. I think that they exist as a "throwback" to the days when lens boards were wooden. Never had a problem without using one!!

Bill Smith
2-Aug-2001, 20:28
I called Schneider. They said that the little screws are provided as a convenience item and is there if needed. They said not to worry, additional screws are always available upon request.


Steve Grimes.
3-Aug-2001, 16:55
Some photographers prefer to use the locating screw as a security against the shutter loosening on the lensboard and that's an OK use. It is extremely rare to see shutters with this properly installed. In actual practice this screw causes a great deal of harm since it's usually ignored and tightened against the board causing the shutter to be tilted and not able to tighten onto the board. The usual practice is to continue to overtighten the retainer and or the front element into the shutter/board until it stops wobbling or until the shutter casting breaks. For this reason its no longer supplied with new shutters so, if you actually want to use it for whatever good reason you have then you need to specifically ask for its installation. If not mentioned I routinely remove and discard that screw since the other later damage is caused by another phogographer breaking the shutter mechanism by trying to unscrew it from the board unaware that there is such a then hidden screw.

The actual throwback reason for the screw is where "timing" (clockwise orientation) of a shutter is critical, such as installation of a shutter in a folding rollfilm camera or installation on a lensboard with a flash solenoid or remote cable release fitting.

An advantage of throwing away the screw is that you don't have to worry about finding it later.


Warren Weckesser
20-Jun-2005, 15:09
Just a quick "thanks" to everyone who answered Bill's question almost four years ago. I just encountered the same problem, and it was nice to find the answers already in the forum.