Extensions Tubes

[acparsons]

Thinking about getting some extension tubes. I know they make lenses focus closer. What would happen if I pop it on a wide angle lens?

 

[Overread]

Exactly the same thing.

No matter the focal length of the lens an extension tube will reduce the lenses maximum and minimum focusing distances. Note that its possible to reduce the focusing distances to the extend that the maximum and minimum move within the lens itself. This basically means the lens can never focus. In addition you can end up with a focusing distance so short that your lens is touching or very close to touching the subject, which typically makes it impractical to work with.

Once you're starting to use wide angle and ultra-wide angle you really won't get away with much tube addition before you'll encounter these problems. By all means give it a go, but don't be surprised if your lens can't focus or will only focus at impractical distances.

 

[480sparky]

Reversing a wide- or ultrawide-angle lens on the tubes can also greatly increase magnification. But as mentioned, it comes at a price.

 

[CameraClicker]

Hummm... Inquiring minds want to know. And, I have never tried tubes with anything shorter than 50 mm. So:

This is 10 mm on a T2i, focused as close as I could get with focus lock.


Then I put on a 12 mm tube, and discovered I could not focus. So, I cranked the zoom ring to 20 mm and took this:

The edge of the lens was touching the keyboard and I tipped the camera so window light could get between lens and keyboard


And, finally, I took the tube off, put the lens back on at 20 mm and took this:


Once again focused about as close as possible.

 

[pthrift]

The tubes really make a difference. Wow. That's a pretty neat comparison.

 

[limr]

Yeah, you need a lot less tube than you think you do to get that close. And you'll often get a crazy shallow dof. Sometimes you have to be so close to focus that you block the light. Plus, the tube increases the amount of light you'd need anyway, so it can be problematic.

This was with a 50mm lens and the two shortest tubes stacked: (excuse the dust spots - I haven't done any kind of processing on this yet)



It can be fun to play with sometimes, but in practice the shortest tube is often good enough to get a less drastic but still interesting effect.

 

[Derrel]

In the past, Nikon made some ultra-short K-series extension tubes, for use with short focal length lenses. IMMSMC, the shortest was a 3mm tube.

 

[Overread]

Hmm I wonder if modern lens mounts could do 3mm? Canon side at least they've all got a "clip" function so that might physically limit what you can make (as the 3mm tube would still need a locking mechanism and a release lever). I suspect in the days of screw-mount lenses it was likely easy to make a 3mm mount - just a rare and front mount and a small bit of space between them.

 

[Derrel]

In the past, Nikon made some ultra-short K-series extension tubes, for use with short focal length lenses. IMMSMC, the shortest was a 3mm tube.

Bad memory..... 5.0 mm was the shortest tube in the K-ring set. Nikon F and F2 Extension Tubes

 

[D-B-J]

Or you could use an 85mm. Here's my 85mm on FX with a 20mm and 36mm tubes. I don't even think this was closest focus.

I Was Bored by f_one_eight, on Flickr

 

[dennybeall]

Is there a particular lens, or class of lens, that is BEST suited for an extension tube?

 

[480sparky]

Is there a particular lens, or class of lens, that is BEST suited for an extension tube?

Macro (or, as Nikon likes to say, Micro).

 

[CameraClicker]

Is there a particular lens, or class of lens, that is BEST suited for an extension tube?

Well, it worked at 20 mm, and when I wanted to shoot live grasshoppers which were determined to keep me at a distance I used a 2X teleconverter, stack of extension tubes and Canon 100-400 lens at 400 mm to frame just the grasshopper from about 4 feet. It works great with a 100 or 150 mm macro lens.

I don't think the lens matters as much as the subject. Keys on my keyboard are an easy subject, they are in front of me, are not poisonous and don't attempt to leave if I get too close. Flies, grasshoppers, spiders and such all like their space. Longer lenses let you have the space to explore those subjects even with extension tubes.