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01-13-2010, 06:04 AM   #1
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What's the difference between a teleconverter and extension tubes?

I don't have a macro prime yet, so I will be using this on my Tamron 28-300. I don't know if I should spend the money for a teleconverter, or just get a set of extension tubes. I honestly don't know the difference between the two. any thoughts or suggestions would be great! Thanks in advance.

01-13-2010, 06:42 AM   #2
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Either one will work but with loss of light to the sensor. The teleconverter used lenses inside it whereas the extension tubes just move the lens away from the camera. Don"t like them myself...either of them
01-13-2010, 06:56 AM   #3
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Extension tubes just move the lens farther from the camera. The attendant increase in magnification is:

Magnification Change = extension/focal length

so a 50mm extension tube could give you a maximum magnification of 50/28 ~ 1.6X (if the lens doesn't get in the way). Since there's no extra glass, the image will be as good as the original lens can do. You'll likely lose all automatic features of your lens/camera system with a low cost set of tubes.

A 2X TC will give a magnification of twice what you can get without it; probably something like 1/2X.

A good solution for your situation is a Raynox DCR 150 ($50) that clips onto the front of your 28-300 zoom and will give a large, continuous range of magnifications (about 2X max) at a good working distance (about 8") while preserving all the automatic features of the lens/camera. Plus it is easy to carry & snap on & off.
01-13-2010, 08:30 AM   #4
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You should also know that extension tubes dont really magnify, but instead just changes the range at which u can focus. So with a 50mm a focusing like 5cm to 10cm but this all depends on the size of the tube and the lens. There a great way to start with macro photography but you'll want a prime lens which you can manually change the aperture or you'll get frustrated fairly quickly
I dont have any experience with tele convertors though so cant help you there

01-13-2010, 09:49 AM   #5
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Teleconverters and extension tubes werve 2 different purposes. A converter has glass and "extends" the focal length of you lens so your zoom would be a 56-600 with a 2x converter. Also with a 2x converter, you loose 2 stops of aperture effectively. A 1.4x works the same, just multiply the focal length by 1.4.
Extension tubes move the lens away from the sensor and allow you to focus very close. They are just hollow tubes. They usually come in a set of three. They enable you to turn your lens into a "macro" of sorts. I use my ext. tubes with my older Takumar primes in manual mode. I have heard some griping that there are no extension tubes available that allow for auto focusing and auto exposure for Pentax so some people buy a cheap TC with the auto contacts and remove the glass to make it an auto extension tube. If someone knows of an auto extension tube set, I'm sure they will mention it.
01-13-2010, 12:03 PM - 1 Like   #6
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Plain english answer:

A teleconverter lets you stand in the same spot and things will look bigger than they did without it. Image quality suffers, though.

Extension tubes don't make anything bigger at all - they just allow you to move closer to the objects you are photographing. They do not degrade IQ at all.

So teleconverters are a way of getting bigger but worse pictures of things far away when you don't have a long enough lens. Extension tunes are a way of getting bigger pictures of things right in front of your face, simply by allowing you to focus from a few inches away instead of a foot or two.
01-13-2010, 06:25 PM   #7
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THANKS! Looks like extension tubes are the way to go. Now I just need to find a set!
01-13-2010, 06:52 PM   #8
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you may also wish to put a close up lens in front of your lens. they are scaled in dipoters.

the way they work is as follows, a dipoter is 1/focal lenght of the small lens, in meters

when you put this lens in front of your main lens it changes the focusing of the lens, such that the maximum distance (from front of the lens to subject) is the focal length of the macro lens.

as a result,, with a 1 dtiopter lens you can focus from 1 meter down to about .25 meters, with a 2 diopter lens you can focus from, .5 meters down to about .1 meters and so on.

like extension tubes they allow you to focus closer, and as a result get a clear larger image, Extension tubes however offer slightly better image quality because every peice of glass you put in the optical path will degrade the image a little.

the advantage of close up lenses is that they allow all the automatic functions of yoour camera and lens, where as most extension tubes limit you to manual focus and manual exposure.

In the end both work, at least well enough to see the kinds of results you can get, and convince you to get a true macro lens.

The main advantage of a true macro lens is that the lens is capable of focusing from infinity to very very close, without any attachments. Adding either extension tubes or close up lenses allows the lens to focus only over a resticted subject to lens distance , making setup a little more difficult, because part of focusing becomes physically moving the camera towards or away from the subject, as opposed to just turning the focusing ring

01-14-2010, 03:40 PM   #9
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Another reason to go with a good quaility closeup lens (like the Raynox ones, or any other advertised as a "achromatic" lens) rather than extension tubes: tubes are more effective the shorter the focal length; closeup lenses are more effective the longer the focal length. With extension tubes, you'd only get closeup at the short end of your zoom, and you'd have to be just an inch or two from your subject to achieve that. A closeup lens would achieve the same apparent magnification at the long end of your and alow you to still shoot from more like half a foot to a foot away.
01-14-2010, 11:07 PM   #10
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Supplementary Lenses

I'm surprised that it took so long for these to get a mention.

Yet another consideration is that when you use a supplementary lense you do not lose any relative aperture i.e. if you set f/16, say, the effective aperture stays f/16. With a converter the effective aperture is reduced according to how much the converter increases the focal length e.g a 2x converter would change f/16 to effective f/32. An extension tube or, more precisely, focussing travel reduces the effective f stop. Any focussing travel at all theoretically reduces the effective aperture but for general photography the reduction is so small that it is always disregarded by practical photographers. Not so for macro photography. I can't give you the mathematical formula off hand. If memory serves, for a 1:1 image the exposure needs to be prolonged 4 times. Don't take my word for it, though, as my memory is unreliable but consult a reference work.

Supplementary lenses shorten the focal length to enable the focussing travel provided for in the mount to suffice for a closer approach to your subject. You do have to get closer to your subject than with a teleconverter. Sorry.

Last edited by Kendrick; 01-14-2010 at 11:10 PM. Reason: typo
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