Extension Tubes and how to use them.

So a while back I bought some extenson tubes....without really knowing how/when to use them. I was going through my camera bag just a few minutes ago and I brought them out and started playing with them a bit attached to my 50mm.

My question...does anyone use these? What's they're best application and how do you know which one of the 3 to use? I've got a 36mm, 20mm, and 12 mm that can be used seperately, all together, or any comination of the 3.

They increase magnification by moving the lens further from the sensor, and allowing a closer focus distance. Usually used for macro. You can use any or all, depending on the increase in mag you want. Be advised, they rob light... requiring you to have more, or to compensate in some other way (ie slower shutter speed).

I often use them with my 100mm macro, usually all three at once.

When I was playing with them I noticed the DOF is razor thin. That seems like it'd be a pita to hand hold.

rivas8409 wrote in post #14978342
When I was playing with them I noticed the DOF is razor thin. That seems like it'd be a pita to hand hold.

Takes some getting used to

Back before AF, manual focus lenses focused closer simply by moving all of the optics away from the focal plane, until the MFD limit of the focusing threads was reached. Extension tubes, very simply, moved the lens optics even farther away from the focal plane than the lens' own focus mechanism will allow. That principle was normally applied to 'normal' or 'telephoto' designed optics.

If you now try to do that with 'retrofocus' designed optics (i.e. 'wide angle'), you will often find that you cannot get close enough to the subject...in order to be in focus the subject would need to be 'inside the lens'! So resist the temptation to zoom to the shortest FL, or focus will be impossible to achieve.

And because DOF is so thin, you need to use small apertures. And often, macro shots are best achieved by mounting the camera on a tripod, since your own breathing motion and heartbeat can move your body forward and back!

If you didn't get the tubes with electrical connections you will have to manually set your Ap manually (a PIA). Shooting with tubes you will need to use a smaller Ap to increase the already shrunken DOF.

Try to remember that especially for macro work, more light is mo' betta...

I am guessing you have a Kenko set? If so, I would recommend trying out a lens of choice (zoom with IS for instance) by itself on a fixed subject and then adding on the 12mm tube first and so on until you get used to the idea of ridiculous DOF and the need for longer exposures.

An extension tube of length e increases the magnification by e/F, where F is the focal length. For example, the 135mm f/2 has maximum magnification of 0.19, so would need an extension of 135mm *(0.5/0.19) = 35mm to get to half life size.

You may well see very bad corners with tubes. If the lens were designed to peform decently with that much extension, given how cheap it is to do the maker would probably have put it in the helicoid anyway. Some lenses (a particular medium format portrait lens comes to mind) did, though, perform well on tubes.

Quality of the tubes does matter, a lot. If they wobble or droop, it affects stability and image quality.

If the lens has a floating element it should be set to its close range and a short tube used in preference to a long tube and the lens set to focus farther away.

rivas8409 wrote in post #14978269
...My question...does anyone use these? What's they're best application and how do you know which one of the 3 to use? ...

Yes, I have two pairs of (automatic) Canon EF extension tubes, and some manual extension tubes. I use them with many lenses. Starting from the Zeiss 18mm f/4, Zeiss Distagon 35mm f/1.4, Minolta Rokkor 58mm f/1.2, Meyer Trioplan 100mm f/2.8, Canon FD 100mm f/4 Macro, Kiron 105mm f/4 Macro, Canon FD 300mm f/2.8L and many others up to the long Canon FD 800mm f/5.6.
With the long lenses some extension tubes could even cause vignetting, because of their internal build.

And I use the extension tubes for lenses without focusing helicoid / IF like enlarger lenses or other more special lenses like microscopy lenses. But there I use bellows too.

Wilt wrote in post #14978367
...If you now try to do that with 'retrofocus' designed optics (i.e. 'wide angle'), you will often find that you cannot get close enough to the subject...in order to be in focus the subject would need to be 'inside the lens'! So resist the temptation to zoom to the shortest FL, or focus will be impossible to achieve.

Retrofokus lens designs and extension tubes are not a special problem - you only need short extension tubes for wideangles.

For shorter focal length lenses and lenses with floating elements or internal focus I build a manual 8 mm extension tube. Great for my Minolta Rokkor 58/1.2 or Canon FD 85/1.2L on the EOS 5D.
But I plan to build a even shorter one for the wideangle lenses.

WIth lenses with floating elements or IF you should use as short tube lens as possible at the wanted distance. With too much tube length instead of maximum close up focussing on the lens itself the effect of the image correction with the special IF/floating elements optics design is lost.

ZoneV wrote in post #14980275
And I use the extension tubes for lenses without focusing helicoid / IF like enlarger lenses or other more special lenses like microscopy lenses. But there I use bellows too...


Retrofokus lens designs and extension tubes are not a special problem - you only need short extension tubes for wideangles.

For shorter focal length lenses and lenses with floating elements or internal focus I build a manual 8 mm extension tube. Great for my Minolta Rokkor 58/1.2 or Canon FD 85/1.2L on the EOS 5D.
But I plan to build a even shorter one for the wideangle lenses.

WIth lenses with floating elements or IF you should use as short tube lens as possible at the wanted distance. With too much tube length instead of maximum close up focussing on the lens itself the effect of the image correction with the special IF/floating elements optics design is lost.

OTOH, the FL and the length of extension are directly related to the degree of magnfication achieved on the sensor (extension/FL= magfactor).
So if one had a bellows of 100mm length, one could achieve 1:1 with 100mm lens (which was focused at infinty) while you could also achieve 5:1 with a 20mm macro lens (also focused at infinity). However, using a retrofocus 20mm lens with 8mm extension tube might still allow focus, but only to 2:5 magnification (8/20 = 2/5)...which defeats the purpose of using a short FL with long extension! The Olympus OM mount 20mm f/2 macro lens could achieve 13.6x magnification with the Olympus bellows.

Wilt wrote in post #14981129
... However, using a retrofocus 20mm lens with 8mm extension tube might still allow focus, but only to 2:5 magnification (8/20 = 2/5)...which defeats the purpose of using a short FL with long extension! The Olympus OM mount 20mm f/2 macro lens could achieve 13.6x magnification with the Olympus bellows.

It is sometimes useful to use the wide angle lens with a short extension tube - not to get a maximum magnification, but to get a shorter minimum focus distance with the still wide angle perspective.

Canon FD 20/2.8 (with extended near field capability cause special conversion)

ZoneV wrote in post #14981279
It is sometimes useful to use the wide angle lens with a short extension tube - not to get a maximum magnification, but to get a shorter minimum focus distance with the still wide angle perspective.

Cool shots. I'll have to try that!

BrickR wrote in post #14978552
If you didn't get the tubes with electrical connections you will have to manually set your Ap manually (a PIA). Shooting with tubes you will need to use a smaller Ap to increase the already shrunken DOF.

Try to remember that especially for macro work, more light is mo' betta...

Oh yes.... I did the reverse 50 trick for a couple times.... I wanted to punch myself for doing this. I had the lens attached and set my aperture, I'd hold down the DOF preview button and dismount the lens. It was such a pain....

Now I have kenko extenders and I love them:

IMAGE LINK: http://www.christopher​rhoadsphotography.com …182091&k=Pxg6GT​3&lb=1&s=A

IMAGE LINK: http://www.christopher​rhoadsphotography.com …182261&k=wgHSHD​k&lb=1&s=A

so how much loss of light do you get? 2-3 stops? what does that actually mean for a lens that is fastest at f1.4? Does it essentially make it maybe 2.8 or 3.2?

I'm considering getting the Kenko tubes for my wife who wants to take big pics of earrings and stuff. The only macro lens I have is the 70-300mm which absolutely requires a tripod.. pretty annoying. Will I need quite a bit of light like a lamp shining on the earrings indoors? Or not necessary when your lens is a fast prime?

This or an external flash + softbox...for those of you who have both, which is more essential?

It'd be nice to find someone willing to split a set of 3 tubes somehow

Thanks

hyogen wrote in post #14983184
so how much loss of light do you get? 2-3 stops? what does that actually mean for a lens that is fastest at f1.4? Does it essentially make it maybe 2.8 or 3.2?

Something like that at 1:1. I'm not sure it's much different than with a macro lens though. For instance with the 100mm macro you loose 2 stops of light at 1:1 magnification (without any tubes).

Unfortunately, while you loose the light, I don't think you gain any DOF - it's not like adding an extender.

You usually need extra light becasue even with a fast prime the DOF is so small at you get very little in focus at large apertures. Even focus stacking would be challenging below f4 at 1:1 magnification. For instance Christopher's first shot above says it was shot at f11 and the eye and most of the body are in focus, but not the nose or leg.