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Extension rings vs teleconverter?
This may already have been discussed, if so, I beg everyone's indulgence.
I wonder if someone could, please, compare the advantages and disadvantages of extension rings vs teleconverters with regard to close focusing?
For example, if using a 50mm or 24mm lens and wishing to engage in close focus photography (say, up to around 1:1), is there any advantage in using, say, a 25mm extension ring over a 2x teleconverter? Ditto regarding a 50mm Macro lens?
What are their respective advantages/disadvantages?
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I think you want a comparison between extension tubes and close up lenses.
Do an APUG search on extension tubes and you will be reading for an hour or so.
-Fred
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A true macro lens (and not a lens that is merely close focusing) is optimized for high magnification.
An extension tube adds nothing to the optical path, so it's usually a better option than a teleconverter or a close-up lens that screws to the front of the lens like a filter. If you're new to macro photography, get an extension tube, because you can always use it, even if you get a dedicated macro lens later or find another solution.
A teleconverter usually isn't the best solution for macro photography optically, but it will give you more working distance, if you need it for placement of lighting.
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There is a neat Vivitar tele-convertor that has a very flexible close focus capability. Essentially, the Vivitar unit is an adjustable extension tube, with glass, and as such is really handy.
Matt
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The two affect the viewing area in the eyepiece, however, in different ways.
Extension tubes magnify the subject area but knock the DOF down to darn near nothing. Great for macro isolation.
Teleconverters magnify the subject by doubling focal length. DOF is reduced in regards to increased focal length. However you may experience poorer image quality and a slight light fall off.
As to which might be suggested would completely depend upon what you wish to do.
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DOF is affected by magnification and f-stop. So no real difference between tubes and extender there.
Listen to David:
Teleconverters add a mostly not very well corrected assembly of optics to a (hopefully) well corrected lens.
Extension tubes allow the lens to show what it is made of.
I'd chose extension tubes any time.
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Teleconverters will narrow the angle of view, thus making exposure more susceptible to camera shake (tilt).
Extention rings will even broaden the angle of view a little bit.
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 Originally Posted by AgX  Teleconverters will narrow the angle of view, thus making exposure more susceptible to camera shake (tilt).
Extention rings will even broaden the angle of view a little bit. Finally someone clearly spelled it out. There are two different products with two different goals.
Steve
Warning!! Handling a Hasselblad can be harmful to your financial well being! Nothing beats a great piece of glass! I leave the digital work for the urologists and proctologists.
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OK, I have read your responses (thanks  ) ) and I also have done some homework reading and the message I get is that:
You lose some light with both.
Both give a "magnified" image, though there may be some image degradation with a teleconverter -depending on its quality.
Extension tubes result in a reduction of "working distance", whereas a teleconverter retains the lens' original "working distance". (This could be good with live subjects and from the point of perspective and lighting.)
Is there anything else?
With regard to the "light loss": is this "automatically" compensated for by TTL metering for both tube and converter?
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