# Making It Longer...



## tmjjk (Jun 5, 2012)

Figured if I had a catchy title I might get some attention 
I am trying to understand extension tubes... but I have no idea where to begin.  I have watched a few videos and read a few articles, but I am at a loss for even the basic info regarding these.  Are there different tubes for different lenses or are they specific to your camera body? Can you add tubes together? Is this the same equipment used to reverse mount a lens? Or is that another thread entirely... thanks for your patience with me


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## tmjjk (Jun 5, 2012)

ok.. from what i can see, it looks like extension tubes are specific to your camera lens mount...ef, efs and what not.  These seem fairly inexpensive... is there a difference in quality? Recommendations? Thanks again


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## Overread (Jun 5, 2012)

Extension tubes come in three basic sorts:

1) Ultra cheap. These are basically lightly built tubes which have no internal electronic connections. They give you the exact same effect as the other tubes, but they remove your ability to control the lenses aperture blades and focusing. You can use them if you have a lens that has a manual aperture control on the lens itself (nikon can do this with some lenses) and Canon has a work around that lets you close the blades constantly, but its slow and fiddly to use. These work but are not recommended.

2) Good price good quality - Kenko are the market favourite ,but there are a few others. These are well built, quality extension tubes with the metal contacts so that you retain all controls of the lens.

3) Manufacture own brand - these are overpriced in general. For the same price as a single tube you can get a set of 3 Kenko (which is basically all you'll ever need). Quality of build is also on par with the kenko so you gain no advantage when using these.


The rough math when using extension tubes is:

(length of the extension tubes in mm -- divided by the focal length of the lens) + base magnification of the lens itself = magnification : 1

where:
Magnification = size of the subject as reflected on the sensor by the lens
1 = size of the subject in real life.


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## tmjjk (Jun 5, 2012)

Awesome info... thank you


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## sm4him (Jun 5, 2012)

I have a set of the Kenko extension tubes--I *think* that either those or the Zeikos tubes are the most often recommended. DON'T get the really cheap ones, because...well, because they're really cheap. They just don't produce decent, sharp results.

I found it REALLY hard to get decent focus with the extension tubes, but once I got a macro lens, and learned some of what I was doing wrong, I think I could also get better results with my tubes now. I need to take them out and try them again.

I bought the 3-tube set, 12mm, 20mm and 36mm. You can use one, or all three or some combination thereof.  I found when I tried using all 3, I just about had to be INSIDE the object I was shooting before I got focus.  They get you REALLY close...they also give you REALLY small DOF.


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## Overread (Jun 5, 2012)

sm4him said:


> DON'T get the really cheap ones, because...well, because they're really cheap. They just don't produce decent, sharp results.



The extension tubes contain no lens optics - each option, from the cheapest to the most expensive will give exactly the same image quality (provided that the tube is built well enough not to allow light leaks into the lens from the side of course). The difference is, as said above, that the cheap ones lose you lens control and thus aperture adjustments are impossible or difficult (which can mean you're forced shooting wide open for every shot which means razor thing depths of field).


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## sm4him (Jun 5, 2012)

Overread said:


> sm4him said:
> 
> 
> > DON'T get the really cheap ones, because...well, because they're really cheap. They just don't produce decent, sharp results.
> ...



Right. I remember that now.   I just remembered I'd been told not to get the cheapo ones.

OP, I was about to edit my post anyway and say that I got called away by my boss while I was typing, and so in the meantime Overread responded...seriously, listen to HIM, not me.   Anything I know is just what little I've learned by trial and error anyway...plus, I've already FORGOTTEN more than some people ever learn in their lifetime.  No, seriously, I was just trying to relay my own experience with the tubes, because I really don't know much about them. Which is part of the reason I still struggle to get good results with them.

Overread: that information about the rough math for using extension tubes rocked! Thank you, that really clears some things up for me, too!


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