EF 25 Extension on tele?

[clicky]

Simple question, does anyone know if the EF 25 extension-tube has a "weight limit"? What about the combination 1D mk II / EF 25 / EF 70-200 f/2.8. Has anyone tried this, with any bad experiences?

[gasrocks]

Think of it as the extension tube is really going to hold up the weight of the camera. You do have the tripod collar, and tripod on the lens? Many people use a short ext tube (I'm thinking 12mm here,) on long lenses just for closer focusing. Only limit I can think of on (how long, how many) extension tubes is how much light can you afford to lose.

[willg]

the ef 12 i have seems very solid

[Tom W]

The EF extension tubes are most likely as sturdy as Canon's teleconverters. And that is pretty sturdy.

[CyberDyneSystems]

Absolutely this combo will work.. it even works with the cheezy Kenko tubes.. the Canon unit is MUCH more solid :)

[Tom W]

Absolutely this combo will work.. it even works with the cheezy Kenko tubes.. the Canon unit is MUCH more solid :)

Funny that you mention the kenkos - I stacked a 25 mm Kenko, 12 mm Kenko, and the 2X Canon teleconverter on the 300/4 (don't ask why) and it became the flexible flyer. I actually had a small amount of play where I could move the lens up and down a bit. I would hope that the Canon TC's would be a little tighter.

[CyberDyneSystems]

Sounds like a very pricey "lens baby" :lol:

[musthavemuzk]

i have a question about the extension pieces.

who much closer can you focus with one?

i have a nifty right now and am planning a 85/1.8, 70-200/2.8 soon. so i am curious as to the real benefits of the extensions?

i keep reading they are a cheap way to macro shooting and that intrigues me.

thanx

Monty

[robertwgross]

who much closer can you focus with one?

It depends on the focal length.

I have used the EF25 on a Canon 100-400 lens, but the weight of the lens is irrelevant. The weight of the camera body is what is hanging on the EF25, since the tripod supports the center of gravity of the whole works, which is out on the lens.

---Bob Gross---

[gasrocks]

Actually the extension tubes don't let you get closer (closer isn't always a good thing either.) They actually change the optics of the lens - you wind-up a little further away with a bigger image.

[CyberDyneSystems]

Actually the extension tubes don't let you get closer (closer isn't always a good thing either.) They actually change the optics of the lens - you wind-up a little further away with a bigger image.

You are mistaken on both counts.

"Extension tubes" contain no optics at all.. they are hollow tubes that fit between lens and camera that change the focal point of a lens to allow you to focus closer. The size of the image is not magnified through optics (there are none) it is increased solely because they allow you to be closer to the subject. You will lose infinity focus.

What you are referring too I have to assume is a "Teleconverter" or "Tele-extender" (the latter term a bad one that one manufacture seems to insist on using) I won't go into a huge amount of detail on these as there is an excellent sticky thread on there properties directly above this thread, here's the link;
http://photography-on-the.net/forum/showthread.php?t=41922

However,. tele-converters DO contain optics,... but they DO NOT change focus distance.. either longer or shorter. Focus distance remains exactly the same as it would with the lens alone.

[gasrocks]

I didn't say that ext tubes have optics - only that they changed the optics of the lens mounted on them. When I add extension to a lens and try to see what "power" I now have (compared to w/o the ext,) and close focus, I am a bit further away than with the lens w/o the ext. A bigger image from a bit further away is nice though there is a loss of light.

[Tom W]

did a little experimenting with the 85 mm lens, 25 mm extension tube, and my most picturesque Cleveland Browns figure with some batteries hanging around for scale and cool bokeh.

The first image is with the 85 mm lens alone at its closest focus distance, approximately 2 1/2 feet (0.85 meters):

http://www.pbase.com/photosbytom/image/43418381/original.jpg

Then I left the tripod in the same position and added the 25 mm extension tube between the 85 and the camera. This was the best focus I could achieve at 2 1/2 feet:

http://www.pbase.com/photosbytom/image/43418382/original.jpg

Finally, I moved the camera towards the figure until I got about as close as I could with the extension tube and still maintain good focus. The distance from the lens to the figure was about 10 inches at this point. Here's the result:

http://www.pbase.com/photosbytom/image/43418383/original.jpg

I realize that with different lenses and different tubes, there will be more overlap in the working distances (especially longer lenses with shorter tubes), but the generalization is that the basic extension tube allows you to move in tighter than you could otherwise do with the bare lens. With this lens and tube combination, there was no overlap - the tube wouldn't focus at the lenses' "untubed" minimum focus distance and required moving closer.

Somewhere between 2 1/2 feet and 10 inches, the lens with tube would have achieved focus at infinity, but I didn't test where that would happen.

[musthavemuzk]

thanx a ton Tom. now that is what i was really wanting to see. real world examples.
i am assuming this was with AF or was it MF?

Monty

[Tom W]

Monty, I used AF in the first and third shots, but manual in the second shot since it was out of the range of the lens. The best focus I could achieve (which wasn't near being in focus) was at infinity so that's where I shot it.

[Jon]

I didn't say that ext tubes have optics - only that they changed the optics of the lens mounted on them. When I add extension to a lens and try to see what "power" I now have (compared to w/o the ext,) and close focus, I am a bit further away than with the lens w/o the ext. A bigger image from a bit further away is nice though there is a loss of light.

I think that you're not understanding what you're seeing. All an extension tube will change is the distance from the nodal point of the lens to the sensor plane, which is what the focussing helical does internally on a lens. As an example, a 50 mm lens is at infinity. If you put a 25 mm extension tube on it, you will have effectively racked the focussing helical out 25 mm. At that extension, it will be focussed on a subject 150 mm from the lens' nodal point, and will give you a magnification of 1:2, or 1/2 life size. The focussing index will be set at infinity, however. Similar changes will apply throughout the focussing range. But the extension tube does not change the focal length of the lens.

It's possible that you're using a lens that changes the focal length as you focus it. In that case, if you focus it without the extension tube, the lens elements will be adjusted for one focal length and will give you one magnification, but when you add an extension tube and focus to achieve the same magnification, the lens elements are actually giving you a longer focal length, because the lens is at its infinity setting rather than focussed closer. This is more likely (but far from a given) on zoom lenses than on primes, although it's reported behaviour on the 100 f/2.8 macro.