EOS 100/f2.8 macro and Extension tubes

[JAB1]

Help!!!!!! What results will I have when I use my Canon 100 macro lens with extension tubes?....I want to get closer to my subjects and am trying to decide whether to buy Kenko or Canon extension tubes or go with diopters....again, this is with my 100 macro lens....your suggestions, comments and experience will be appreciated...help me spend my money on more magnification....thanks...AB

[Tom W]

Help!!!!!! What results will I have when I use my Canon 100 macro lens with extension tubes?....I want to get closer to my subjects and am trying to decide whether to buy Kenko or Canon extension tubes or go with diopters....again, this is with my 100 macro lens....your suggestions, comments and experience will be appreciated...help me spend my money on more magnification....thanks...AB

I don't have the 100, but I have a Kenko 12 mm tube and I've used it successfully with the 17-40, the 28-105, and the 50 mm lenses. Auto-focus is not always an option with extension tubes, regardless of brand. Best to go manual.

[SteveO]

AB,

A tube is a tube. I've had wonderful results with Kenko tubes and the Canon 100/2.8 macro. For me the use of tubes versus diopters boils down to whether I'm using a fixed length lens (tubes) or a zoom (diopters). When you use tubes with a zoom lens, the focus changes as you zoom in and out.

Steve

[DaveG]

Help!!!!!! What results will I have when I use my Canon 100 macro lens with extension tubes?....I want to get closer to my subjects and am trying to decide whether to buy Kenko or Canon extension tubes or go with diopters....again, this is with my 100 macro lens....your suggestions, comments and experience will be appreciated...help me spend my money on more magnification....thanks...AB

Any tube will let you focus more closely, and with the exception of the dedicated, full of glass "tube" for the Canon 50 mm macro lens, they are just spacer's.

I guess that I'd just wonder what you are photographing. The 100 macro will shoot at 1:1 without a tube. After that you are doing micro, rather than macro work. You'll run into some serious depth of field issues and the slow shutterspeeds that will go along with that.

Still an extention tube is an inexpensive addition to your gear, so buy one and have some fun.

[Jmurman]

This is an interesting question. What is the true photographic difference between a diopter and extension tube?

It would be interesting to see the same shot in each, one with a diopter and one with extension tube.

[DaveG]

This is an interesting question. What is the true photographic difference between a diopter and extension tube?

It would be interesting to see the same shot in each, one with a diopter and one with extension tube.

I assume that by using the word diopter you mean close-up filter.

I'd say the difference is night and day. The close-up filter is going to put a single element of not particularly good glass in front of a lens and this will trick the lens into focusing closer. Think magnifying glass.

The extension tube moves the lens farther away from the sensor or film and creates the close up focusing that way. This doesn't affect the image characteristics of the lens at all except for the improved close focusing. There will be some bellows exposure factor to take into account but if you are using a behind the lens meter you won't even notice it.

The resulting image with the tube will be much sharper - especially at the edges, and the close-up filter images will not even be close to that quality. But close up filters are easily the cheapest way to do macro work and if that's the only way you can afford to do this then it's better than nothing.

[Scottes]

I don't completely agree with DaveG, but close.

I don't think the image is night and day if done right. For instance, I use a 2-element Canon Diopter, the 500D. Very high quality. I'm also on a 10D, so I don't even use the extreme edges of the diopter which is where quality goes down.

I've also got some cheap Tiffen close-up filters - they definitely have an impact on the image.

Tubes reduce light, so if you're on the edge of exposure time that will have more impact on the image (ie; shutter speed dropped, possibly causing camera shake, OR aperture opened, losing DoF). They won't affect the quality of the image at all, but may have side-effects because of light loss.


I've been trying to do a non-scientific study between Diopters & Extension Tubes & TCs on long lenses. I tried to get to it last night, but the extreme close focusing means that I have to work on my lights and platform. When I get around to it I'll certainly post some images on my web site. Probably more like 160 images from the looks of things.

Here's my fist pass: http://www.itsanadventure.com/postimages/500d.html
100-400 IS L with 1.4 TC, 500D, and 1.4TC with 500D. Since I got a set of extension tubes I plan on more comparisons, and I'm going to throw my 70-200 2.8 in there, too. There's a lot of possible combinations planned for the next pass.

[Jmurman]

nice comparisons on the Griffins.

[SteveO]

Here's the skinny on magnification that the griffin shots illustrate so well.
(Taken from John Shaw's indispensible book Closeups in Nature).

The basic formula for magnification with extension tubes is:

Extension used/focal length = magnification.

E.g., 25 mm of extension on a 50 mm lens gives 1/2X magnification.

Now that same 25 mm of extension on a 200 mm lens gives 0.125X. The bottom line is, don't use extension with long lenses if the goal is high magnification. That being said, I do find a use for extension on long lenses: it lets me focus closer than the "native" closest focusing distance of the lens. Note that the formula applies to a lens that has no built-in extension of its own (i.e. a lens that cannot focus and is always set at infinity). Now, no lenses that I aware of are like that. So ... in practice, the tubes will give a little bit more magnification than the formula states.

Diopters, on the other hand, simply change the minimum focusing distance. A Canon 250D (a very fine, two-element diopter) allows ANY lens to focus to a minimum distance of 250 mm when set to infinity. Likewise, the 500D allows focusing to 500 mm (a half meter). Its easy to see that a 100 mm lens focused at 250 mm will give less magnification than a 400 mm lens focused at the same distance. A diopter on a long lens can really crank up the magnification.

Steve