Extension tube - 6mm? 8mm? 10mm?

Hello all! Ive done a google search and did find this (http://www.4photos.de …on-EF-Extension-Tube.html). But ofcourse I don't have the equipment he has to do what he did. Looked on ebay and came up empty. Does anybody know of a thin (thinnest possible,I have a KENKO 12mm) extension tube? I saw an M-mount 10mm on ebay but Im pretty sure the M-mount wont work on a 5D of 60D.

What say the masses?

I have done Google and Ebay searches as well, and found not a single shorter Canon EF extension tube.
So I disassembled those manual tubes and did some planning - and made the8mm Canon EF extension tube. And later the 6mm thin extension tube you have linked to.

The EF electronics contacs are only a prototype, I do not need those for my manual lenses. I tried it cause some photo tinkering people said such is not possible at all

I just measured an Olympus OM 50mm lens, and from Infinity to 18" the inherent focus mechanism racks out the optics by 8mm from the film plane. Olympus offered a 7mm extension tube for the OM.

One might say that 10-12mm extension tube simply takes the lens from where its own focus mechanism can handle, so a 6-8mm tube length should fall within the focus range already inherent to the lens' own focus mechanism.

Why do you want such a thin extension tube?

Those 8mm focus range (image side) are a bit common for 50mm lenses.
When you want to focus closer than those 8mm helicoid allows, you could take for Canon Ef normaly only a 12mm tube, and now you are much closer than with the lens helicoid.
With shorter lenses like a 35mm lens is is even worse.
On a 24mm you have magnification 1:2 as soon as you use the 12mm tube. With a 6mm extension tube you get 1:4 - much closer to the normal magnification the lens has on minimum object distance.
Near the normal minimum object distance the lens is normaly much better than at 1:2 or such.

Longer lenses like the 85mm/1.2L have correction for close up photography - with a thick extension tube and lens focussing on infinity this correction is gone completely.

Olympus and Nikon offered a quite good lens and accesories programm for close up back then. Olympus with the 7mm extension tube, Nikon even with a 6mm tube.
Today people are told to use a macro lens - but there only few focal lengths exists, and the lenses are normaly relative slow. Or close up lenses or few extension tubes as cheap but not ideal way for beginners.

Perspective is a major thing in photography - only in close up / macro most people forget this / could not use this because there is not much choice.

I use long tele lenses for macro as well assuper wideangle macro - and normal ones too. From f/1.2 (lower at macro setting with tube) to very low f-stop settings.

Wilt wrote in post #17407572
I just measured an Olympus OM 50mm lens, and from Infinity to 18" the inherent focus mechanism racks out the optics by 8mm from the film plane. Olympus offered a 7mm extension tube for the OM.

One might say that 10-12mm extension tube simply takes the lens from where its own focus mechanism can handle, so a 6-8mm tube length should fall within the focus range already inherent to the lens' own focus mechanism.

Why do you want such a thin extension tube?

A lens will have its own internal extension, so even adding a few mm will allow a shorter minimum focus distance.

With a 14mm lens held just a few mm from the camera's mount it'll focus very close (for some freakishly strange effects). Sadly even the shortest commercial tubes are way too long for this len's focal length (you then cannot focus on something in front of the lens), so I'd need to fabricate a DIY alternative to make it practical to use in the field.

Whenever I want to lower the MFD on my M42 lenses I just unscrew the lens a bit from the adapter. Works great.

maverick75 wrote in post #17526954
Whenever I want to lower the MFD on my M42 lenses I just unscrew the lens a bit from the adapter. Works great.

This is one of the advanges of M42 over bajonett mounts. Optimum would be some shims to have the lens parallel and "locked".
For M42 there are short extension tubes too, I think I have a ~5mm thin.

I am bringing this thread back to see if any newer info has arisen to finding a shorter extension tube.

The reason I need one is so that I can stack MKIII teleconverters together, since Canon changed up the design enough that the MKIII 2x doesn't like being stacked with itself or the 1.4x III. A tube in-between should fix this issue, and I want as thin a tube as possible to reduce the "lost infinity focus" effect.

I thinking about trying to make one from a Kenko tube, by shortening the body and putting the mounts back on, without disturbing the ribbon cable, or whatever is there for the electrical connections.

I will try out my 12mm with the 2x on a couple of lenses that don't mount to the TC today, just to see what the impacts are, but I would love an 8mm if there is way to buy one or make one.

Vello makes a 7mm fully manual. Won't work with most newer lenses but it is available.

https://www.bhphotovid​eo.com …l_extension_tub​e_set.html

However I think the outer shell is 7mm. Once you add the mount and focus confirmation ring, I suspect it is still around 21-22mm? This is how I read the product description anyways.

Ok. It is a little confusing. Just found it searching for shorter tubes.

TeamSpeed wrote in post #18492568
However I think the outer shell is 7mm. Once you add the mount and focus confirmation ring, I suspect it is still around 21-22mm? This is how I read the product description anyways.

Exactly!
The 7mm is only the tube, without bajonett front and back. The tube is unusable alone.