Wednesday, 30 June 2010

Home made stand off ring

A stand off extension ring is a ring for attachment to the filter threads of a lens, and allows for mounting something further away from the lens. It has the same diameter threads on the outside as on the inside.

This kind of ring has many uses. One can be to offset an attachment to the Panasonic Lumix 20mm f/1.7 pancake lens. Mounting a step up ring to the Lumix 20mm is not advisable, since it will cause the lens to jam when powering down. The front lens assembly is withdrawn into the chassis when powering down, which will cause anything wider than a normal filter to jam. But using a stand off ring between the lens and step up ring solves this problem.

Stand off rings are uncommon, and can even be pretty expensive. What's far more common and inexpensive, though, are UV protection filters. These can be bought from various auction sites at a small cost. You can remove the glass from these, and what remains is a stand off ring.

Here is an example UV protection filter:

Let's break the glass off it:

Be sure to use eye protection, and gloves. I used gloves then breaking the glass, but not in this illustration photo. Note that I put the ring into a plastic cup, to avoid having the shattered glass flying all over.

Breaking the glass takes a surprising amount of force. The round shape of the glass makes it extra strong. This is the reason why airplane windows are rounded: A rectangular shape is much weaker, especially in the corners. Hitting the glass towards one side may be an easier way to break it.

Once broken, remove the shattered remains:


It turns out that the glass was held in place with a threaded locking ring. Unscrewing this ring would have released the glass, without having to break it! Anyway, this was a cheap filter, so no harm done.

What I have now is a stand off ring, used to mount front lens accessories at an offset from the lens.

Here is an application of a stand off extension ring. A 52mm screw in hood is attached to the Lumix 20mm f/1.7 Pancake lens. As the lens has 46mm front filter threads, a step up ring is needed. However, connecting a step up ring directly to the lens is a bad idea due to the jamming risk discussed above. Using a stand off ring between them solves this problem.

Of course, attaching all this stuff to the moving front assembly of the lens is not a good idea. If you want a hood, it is better to use a light, low profile one.

1 comment:

  1. Good tip this, followed your advice and works fine - thanks.

    ReplyDelete