Review Kenko Extension Tubes with 10D *Lg Pics*

[mjordan]

I recently bought a set of Kenko extension tubes and had a chance to try them out yesterday. I used my 85mm 1.8 lens and the smallest tube, 12mm, to take a few pictures of my mom's last couple of hibiscus flowers. The following image was taken with my 10D, 85mm 1.8, ISO 400 (I should have changed it to 100), 1/250th at f16 on a tripod.

http://www.sitnprettyphoto.com/display/hibiscus3151.jpg

The following picture is of the remains of one of her other flowers:

http://www.sitnprettyphoto.com/display/flower3159.jpg

With the compression, the images lose a little and I was using late morning sunlight that was a bit harsh, but I still think the tube did real well with this lens. The hibiscus is full frame and the other is cropped a bit.

They are cheaper than the Canon tubes and cheaper than a macro lens, so for people that only occassionally need macro, they should do real well. I have played with them a little on my 70-200 2.8 and 100-400 4.5/5.6 lenses but not on a tripod of specific items. It is interesting how close you can focus with these though. :lol:

Mike

[MrKickalot]

I praise this set every chance I get. Put the whole stack on your 70-200!! I use the whole stack with my 75-300 f4.0-5.6 (which we know isn't that great of a lens) and get awesome pictures!! It allows you to stay far enough away from bugs and spiders but not scare them!! Here is my favorite macro pic yet... (no cropping, about 3-5 feet away)

http://www.fotop.net/allmanphoto/Insects/IMG_5940

There are more examples of here:

http://www.fotop.net/allmanphoto/Macro

Have fun!!

[Jay Todd]

Do you retain AF when using these, unlike the Canons'?

[Ed Rotberg]

Do you retain AF when using these, unlike the Canons'?

Yes, you retain AF with these as you would with the Canon set. There is no reason for the tubes to inerfere with AF. What you lose is the bility to focus at infinity (and depending upon how manymm of tubes you are using, focusing at longer distances). You also lose some light, which can be a problem with Macro photography where you typically have to stop down to get decent DOF.

They also work well with tele's whenyou need to get closer than the minimum focusing distance. Here is a photo taken with my 400mm f/5.6L lens and some tubes allowing me to "fill the frame" with an Anna's Hummingbird. The 400 f/5.6 has a notoriously long minimum focusing distance.

http://www.edrotberg.org/images/Annas%203_5-15.jpg

= Ed =[/img]

[stuartf287]

I just bought a set of Kenko tubes and I'm wondering how you achieve autofocus using the tubes with a 400 F5.6 lens. The tubes should reduce the effective maximum aperture below 5.6 and therefore also should eliminate autofocus capability. The effect is similar to using a teleconverter. Does anyone have the formula for computing the F-stop effect of adding extension tubes of various lengths?

[Ed Rotberg]

I just bought a set of Kenko tubes and I'm wondering how you achieve autofocus using the tubes with a 400 F5.6 lens. The tubes should reduce the effective maximum aperture below 5.6 and therefore also should eliminate autofocus capability. The effect is similar to using a teleconverter. Does anyone have the formula for computing the F-stop effect of adding extension tubes of various lengths?

The tubes reduce the amount of light coming in - not the minimum aperture. There is no indication sent to the lens that the aperture has changed, which it has not. It's actually more akin to using an ND filter, or just shooting in lower light situations.

= Ed =

[Jon]

It's not the effective f/ stop so much as it is the reported f/ stop. And unless you have a substantial extension, you're not going to make an apreciable differnece in the f/ stop any way. With a teleconverter, you double the focal length without changing the maximum aperture opening. With 12 + 25 mm extension tubes on a 400 mm lens you change focal length by less than 10%.

[timmyquest]

This will probably be overkill but...

The only reason i've kept my sigma 70-300 is because it has a macro mode and somehow magically gets fairly sharp when used as a macro lens. I've also got a tiftan (SP?) 1x macro filter and i intend on getting these tubes some day.

Will that be "too much"...is that possible? :twisted:

The only thing i figure is that there wont be enough room between my subject and my lens to get it into focus, any merrit to this concern?

[stuartf287]

I see what you mean -- relatively small extension tubes used with relatively long focal length lenses have little effect on the maximum aperture.

The following discussion taken from a Macro website is the kind of thing I was looking for (and thinking of) when I last posted:



"When you increase the distance between the film and the optical center of the lens (as is the case when you are using extension tubes or the soon-to-be-discussed bellows units), you also reduce the amount of light transmitted to the film, because the diameter of the lens aperture is smaller relative to the overall focal length of the lens/extension combination. Fortunately, your camera's built-in through-the-lens exposure meter will automatically compensate for this loss of light. But if you use a hand-held meter, you must remember to compensate for the loss of light caused by using the extension tube(s) or bellows. The formula to do this is fairly simple: f = FL/A, where f is the effective f-number of the lens/extension-tube combination, FL is the effective focal length of the combination and A is the diameter of the lens aperture. Here's an example: If you're using a 50mm extension tube with a 50mm camera lens set at f/8, FL = 100mm (50mm lens plus 50mm tube), and A = 6.25mm (50mm lens divided by the set f number of f/8). Therefore, f = 16 (100 divided by 6.25). This means that, when the 50mm lens is set at f/8 and attached to a 50mm extension tube, the effective f-stop of the combination if f/16—two stops smaller than f/8. So you must give the shot two stops of additional exposure to compensate for the light lost due to the extension. Aren't you glad that 35mm SLRs come with built-in TTL meters that compensate for this light loss automatically?"



So if I use a 12mm extension tube with a 400mm F5.6 lens, the effective maximum aperture becomes 412/(400/5.6) = 5.768. Not much change at all, as you indicated. The combination should still admit sufficient light for a 10D to autofocus (since my Bigma autofocuses at 500mm and an actual maximum aperture of 6.3). Even 50mm of extension would reduce the effective aperture to only 6.3. That may be the autofocus limit, however.

Thanks, your explanations were helpful.

[Ed Rotberg]

As I stated before, the camera will continue to try and auto-focus. The camera still believes the lens is f/5.6 so it amounts to the same thing as using an ND filter or just shooting with less light. It's doesn't affect the aperture per se, and particularly what is reported to the camera. As long as there is sufficient contrast and light, the camera will autofocus just fine. I have done this with my 400 f/5.6L and 56mm of extension. The 10D autofocused just fine.

Further, the tubes will have absolutely no effect on the exposure metering of the camera. If you have sufficient light and need to reduce the minimum focusing distance, they are a win-win. You also get a bit of magnification boost as a bonus.

= Ed =

[Shakespeare]

Any changes to any of this if you're using a 300D?

Also, what lenses can these be used with?

S

[mjordan]

McKick, yes, I have stacked them on my 70-200 and 100-400 and I can get so close I can't focus. :lol: And those are some great bugs and flowers you have. I think you can get too close to bugs though. Boy are they ugly. :lol:

Also, to to add to what's been said, I've not lost autofocus when I've used them stacked on any of my lenses either.

Ed, that's a beautiful shot of the Hummingbird. It's because of some of the macro images I've seen on here and other sites that I've wanted to get at least the tubes. I did a lot of looking at the different macro lenses but I didn't really need another lens in any of those focal lenghts so the tubes were a good comprimise.

Mike

[Adam Hicks]

Forgive the ignorance, but I've never seen these before. Just looked them up on B&H. Would you typically use them with Macro lenses or does it matter either way? I think they might be cool to use with my USM 100mm 2.8 Canon Macro lens on the 20D.

I see that you stack them on the body of the camera, but what does the 15mm, 25mm signify? The depth of the extension tube? Is the purpose simply to allow you magnification at more of a distance or? A quick explanation will take care of me!

Thanks!
Adam

[tofuboy]

I too didn't really know what these were, until this post and decided to look them up on b&h... I'm really tempted to buy the Kenko set, as it's not all that much and I think it would be fun to play around with. Well, time to wait for b&h to re-open... I've been bitten by the buying bug x_x;; I've heard some good things about the Kenko tubes, is there any reason to buy the Canon ones over these?

[mjordan]

Adam, the 12mm, 20mm and 36mm size of the tubes is how much space they put between the lens and the camera body. The further from the body the lens is, the closer you have to be to the object to be able to focus, which increases the size of the object. Many people use the 1:1 macro lenses so the object is life size. With longer tubes (or any combination of the 3 put together) you can create images of small bugs and have them fill the image and be much bigger than life size. This is great for things like jewerly and plants, but tiny ugly bugs look even uglier when they are shown bigger. :lol:

The one thing about the Kenko tubes is that they have no glass in them to get dirty or degrade the image. All they do is increase the distance between the lens and camera body. So there isn't a lot to go wrong with them.

Also, you can put these on any lens although different lenses work better than others. The longer focal lenght lenses work a bit better because you don't have to get so close to the subject. This gives you room to compose. I like the 85mm 1.8 because it's long enough to give me good working room but is also an excellent quality lens. With some lenses you just have to play with it and see how it works out with the subject you are trying to photograph.

Mike

[Persian-Rice]

Forgive the ignorance, but I've never seen these before. Just looked them up on B&H. Would you typically use them with Macro lenses or does it matter either way? I think they might be cool to use with my USM 100mm 2.8 Canon Macro lens on the 20D.

Adam

Just to slightly clarify, extension tubes just create some space between the lens element and sensor, which help in focusing etc etc.

You can pretty much create a "macro" type lens from a normal lens which will be able to focus very close. Think of it as a solid bellows.

These is a mjordan explanation in a short and Persian-rice stupid kinda way lol.

BTW these are great quality images *adds Kenko tubes to wishlist*

[Hatem Eldoronki]

This will probably be overkill but...

The only reason i've kept my sigma 70-300 is because it has a macro mode and somehow magically gets fairly sharp when used as a macro lens...

Strange! My 75-300mm acts the same way! I was going to sell it, because it sucks when used to shoot far away subjects, but for macros, it is gold!!! (Well, almost :)

[Shakespeare]

BUMP the question about whether any of this info changes on a 300D

Also, can you use an extender and extension tube at the same time?

S

[Jon]

None of it changes on the 300D.

You can use both an extension tube and a teleconverter at the same time. For best close-up results, apply the extension tube to the lens, then the teleconverter to the combination. That way you're extending the shorter lens, for maximum close-up effect, and magnifying the result. Applying the TC to the lens and putting an extension tube on the result, you're applying the extension tube to a longer lens, and it will have less effect.

[Lesmac]

I agree with the comments regarding kenko tubes, they are excellent for the price.
I use them frequently with my 10D and 100mm macro.
Some examples in my gallery under 'odds and sods'

http://lesmclean.photoblink.com/

Regards
Les

[mjordan]

Excellent pictures, Les, and not just the macro ones.

Mike