Depth Gage for the M42 lens

This is a precise Depth Gage for SIGMA-SD, 3D curved from an aluminum block. There are various kinds of M42 lenses and depending on the focal length some lenses have their back glass moving towards behind. If these lenses are carelessly used with the SD camera, it may hurt or sometimes destroy the dust protector of the camera. This depth gage has a depth of 9.4mm, which is exactly the same allowance as SIGMA SD. We strongly recommend you to check all your M42 lenses with this Depth Gage before the actual use. Set the focal length of a lens short and mount the Depth Gage. If it cannot be mounted properly, obviously the lens cannot be used. Move the focal length to infinite and If you can turn it until it reaches infinite, then that lens can be used with the SD camera. If it stops before it reaches infinite, it cannot be used because the back glass of it will certainly interfere the dust protector of the SD camera.

The lens is not included.