Extension tubes

[timmyquest]

I was thinking instead of buying a new macro lens i could just buy a set of extension tubes.

These are fairly cheap...cheapre then i expected

http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=71515&is=REG

Can you stack the tubes?

How much do they affect focus distance?

[Scottes]

Yes, you can stack them.

They affect focus distance quite a bit, especialy the max focus. A 12mm tube on my 100-400 at 400mm limits my max focus distance to about 35 feet. A 36mm tube brings that down to 11 or 12 feet.

http://photography-on-the.net/forum/showthread.php?t=28037
http://photography-on-the.net/forum/showthread.php?t=28017
http://photography-on-the.net/forum/showthread.php?t=27657

I like tubes with long lens because it gives near macro with plenty of working distance. Butterflies can be done full-frame with 3-7 feet of working distance, depending on the size of the butterfly. Dragonflies from 3-5 feet no problem.

The shorter the lens and the longer the tubes the more magnification, but at a price of working distance. As a note, a 36mm tube on my 70-200 f/2.8 at 70mm meant that I had to take the hood off since I was inches from the subject. Magnification was impressive.

Expect light loss from tubes - a 36mm on my 100-400 f/5.6 often causes hunting, but not so frequently that it's useless. But a tube in low light means manual focus.

[timmyquest]

Light loss, Ok...does that mean a change in F/stop?

[dn7elson]

Light loss, Ok...does that mean a change in F/stop?

Distance from lens elements to sensor is greater so the brightness will be marginally less. Not really a change in f stop, but effectively results in less light reaching the sensor which an f stop change would also do. The amount of reduction is much less than an f stop change would give. It's not anywhere near what you would see with a 1.4X extender.

[CyberDyneSystems]

Yes.. get the Kenko set.

Nothing more to say on it.. just get the Kenko set.

[timmyquest]

Yes.. get the Kenko set.

Nothing more to say on it.. just get the Kenko set.

I think i'll order it after i pay for the 1D (gotta make sure i have enough).

[Roger_Cavanagh]

Other things to note that I don't think have been made clear by the previous posts is that the effect of extension tubes is proportional to the ratio of the length of e-tube and focal length of the lens. As the ratio gets larger (i.e., more e-tubes for the same focal length):

- magnification increases: 50mil of tube on a 50 mm lens gives 1x, which also reduces depth of field

- the working distance decreases to inches and even fractions of an inch

- the effect on light increases, i.e., there is less and less light. With autoexposure, the camera will take care of it, but a 1x mag requires a 2 stop change

Another option to consider is the close-up lens (often called a filter 'cause it screws on the front of a lens like a filter) which can be used with or without extensions tubes. I've more info on the Canon close-up lenses here (http://www.pixelpixel.org/helpinfo/18_500d-1.stm).

Regards,

[MrKickalot]

Yes.. get the Kenko set.

Nothing more to say on it.. just get the Kenko set.

I agree!! I bought a set of these a month ago and have had a lot of fun with them!!

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

I will admit it does affect the f-stop quite a bit but it hasn't really kept me from taking any pictures. I like them because I can put them on my 75-300 4.0-5.6 and take pictures of stuff that won't let me get too close!! Works real will with a 50 f1.8 for the stuff that can't run away!!

Have fun!!

[CyberDyneSystems]

Exactly.. Timmy will be able to turn his pride and joy 70-200mm f/2.8 into a variable zoom macro! :) No ill-effect on the optics... what more can you ask for @ about $100.00 for the set :)

[timmyquest]

Exactly.. Timmy will be able to turn his pride and joy 70-200mm f/2.8 into a variable zoom macro! :) No ill-effect on the optics... what more can you ask for @ about $100.00 for the set :)

I do have two sigma zooms that have macro, i dont intend on keeping htem long, but for the time being what effects would the tubes have on a macro lens?

[CyberDyneSystems]

It'd simply make the minimum focus distance less than it allready is.

[Scottes]

It'd simply make the minimum focus distance less than it allready is.

And magnify the image, even if you don't move the lens any closer, and they'll "magnify" the image a lot if you focus even closer than the lens' inherent minimum focus distance.


A key benefit of tubes is that they'll magnify an image even if you're further than the minimum focus distance.

Again: http://photography-on-the.net/forum/showthread.php?t=28037