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Helpusing 21mm tube


New Member
hello, big question - i don't want to lock up my camera or lens .
which do I mount frist. do i mount the tube to the camera body frist or do i mount the tube to the lens frist then mount the combined tube and lens to the camera. then how do i dismount the tube and lens. help- i don't want to lock up the body?
Hi, George: It is best to first mount the tube to the body, then the lens to the tube. Dismount them in reverse order: first the lens from the tube, then the tube from the body.

If you remove the tube with the lens mounted , never try to remove the lens from the tube now . This will kill the shutter . (happened to me once)
If you have removed lens and tube as "one piece" , put them back on again , and then remove the lens first and then the tube , As Scott discribed above .

No, never put the combination back on again!
If you do, and the thing fires while doing so, you will have to partly dismantle the camera to clear up the mess.

The camera 'anchors' the mechanism. Put the tube on the camera, so its mechanism is held secure. Then add the next tube, or (finally) the lens.
Removing the stuff, work the other way round, making sure you only remove the single, outermost bit, working towards the 'anchor' i.e. the camera.

If you have removed a comination of tube and lens, put a coin in the slotted axle of the tube, and hold it to prevent it rotating.
Then press the lens release catch and take the lens off the tube.
You need three hands to do that, so unless you happen to have that many, better not let it come so far that you need them all.

I have done so many times and never encountered a problem . Of course , you can only do that , after the camera body is "cocked" . Why should the thing fire when doing so ? ? ?


Because not very much (a tiny lever, barely in contact with the thing it is holding) is preventing the thingies from doing so, while a couple of springs are trying to.

You seem to have peculiar luck: good with this thingy, bad with your CFV.
Anyhow: do not remount a tube-lens combination on the camera. You may be lucky enough, enough of the time, yes.
But there's no need to, and you could end up with a bigger mess than just a lens on a tube off-camera.
So just don't!

Here I have (in front of me) a MACRO PLANAR CF 5,6/135 and a vaiable extension tube .
These 2 things were put together as follows : Attach the tube to the camera , then attach the lens . Perfect . Variable extension ring and lens now build one unit . (here it does not matter if it is a 10mm ring or that variable ring) . Ring and lens build one unit . Right ? ?
Now , I can take that unit off and put back on again , and that is exactly as if I take a lens off and put back on again .
When I want to separate the two again , I attach the the "unit" back to the camera and then remove the lens first and then in step 2 the variable extension ring . And thats it .
It works . Although , I must admit , it says in the extension tubes users guide : Never remove the lens and tubes together . It does not say why . And I know from experience , that not all comments in the users guides , are correct .
Oh, but they are. Not all of the time, maybe. But they do not put that in because it is nonsense...
George, putting mechanics aside for a moment, let me add that I hope you have a 150mm lens to mate with the 21mm tube. The combination provides gorgeous portraits with the eyes brilliant and the background a pleasing blur.