Extension tubes: 8mm v 10mm

The 10 mm together with the 21 and 55 mm were introduced in the fifties. These are the first generation extension tubes for the 500 series cameras. Both the 10 mm and the 21 mm will not go with the 2000 series cameras that were introduced in 1977.

In the eighties a second generation was introduced, 8/16/32/56 mm tubes that are suitable for the 2000 series cameras except the 8 mm. The smallest size is designed to go with the 80 mm lenses that have an extension of 9 mm with their focusing mount.

The new range makes 8/16/24/32/40/48/56/64 mm and longer extensions possible. From 64 mm a bellows can take over.

The choice for 21mm was made because of the 150 mm and 250 mm C lenses that have 21 mm extension with their focusing mount.

Finally the 10 mm can not be used with later cameras like the 501 CM that have a larger release button.

"The choice for 21mm was made because of the 150 mm and 250 mm C lenses that have 21 mm extension with their focusing mount."

Only the 150 mm. The 250 mm comes with a good deal more, about 32 mm, just like the newer tube. ;-)

Q.G.

Thanks for correcting me. It seems like a clear case of needing new glasses!