Thanks for the quick response, OG.:)
I have heard that some photographers use a mixture of both tubes and teleconverter in the one exposure.
Has anyone here done that, and do they have any comments as to the advantages/disadvantages of such a technique?
I have a comment: it's a bad technique that cannot be discouraged enough.
What it does is either enlarge the faults the lens itself may show more when used at close range, and add the poor correction or the extender.
Or enlarge the poor correction of the extender and what that thing makes of the perhaps somewhat lesser performance of the lens that's on it.
In short: having the extra glass somewhere between subject and film is still not a good idea.
Any reason you can't use bellows? That would be the best bet.
Bosaiya, at this stage, I'm only interested in "close focus", as opposed to actual "Macro", so bellows would be overkill for me at this stage.
It would seem that some practitioners are not overly fussy about their choice of equipment (close focus lenses, tubes or tele-extenders) and some mix them and match them at will. See the attached link (once open, make sure to go on to "part three":
They are two different birds built to acheive two different aims.
A teleconverter magnifies the image, but actually reduces close focusing ability. They are used to decrease the angle of view; usually of a lens that is already at least a medium-long lens. They are not made for close-up photography. They contain optics. Infinity focus is maintained.
Extension tubes increase close focusing ability at the expense of far focusing ability. They do not contain any optics. They are made for close-up photography. They simply move the glass farther from the film so you can focus on closer objects. Infinity focus is not maintained.
A bellows unit is the same basic idea as an extension tube, but lets you vary the length of the extension as needed. It is more versatile, but also less portable, of course.
Diopers are accessory lenses that are mounted in filter rings. They screw into your filter threads and increase the close focusing ability. Though these are the worst option for optical quality, there are good ones out there that give fine results, and they can certainly give "special" effects if that is what you want!
TCs, extension tubes, and bellows units all cut light by making it travel farther from the glass to the film. A 2x TC doubles FL, but the physical aperture of the lens remains the same, therefore you only transmit 1/4 as much light at a given f stop (or 1/2 as much with a 1.4x TC). I have only screwed around with diopters; never taken a pic with them, so I am not sure if they cut light to a notable degree or not, but I don't think that they do.