Originally posted by Nick Siebers I went out to try a little reversing, and I would withdraw that from consideration - too much magnification, too little working distance. But fun! (M 50/1.7 on a Tamron 70-150/3.5)
Fun indeed! And too close, indeed! A couple of the rules of camera optics are:
1) A non-reversed single lens can never focus closer than its focal length.
2) A reversed lens (single or stacked) works at the lens' register distance.
(1) tells us that a single 100mm lens can't focus closer than 100mm. I often use a 162mm enlarger lens on bellows for a working distance over 6 inches. And (2) tells us that the working distance of a reversed Pentax lens, whether singly on tubes and/or bellows, or stacked onto another lens, is 45.46mm, under two inches.
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Cheapest good macro: One or two sets of PK tubes (~US$7 each) under a manual 135mm lens, for ~5.5 inches working distance.
Cheapest quick-and-dirty macro: A set of +dioptre ('close-up') filter-lenses (~US$10-20). IQ suffers, mostly around the edges. Oy.
Cheapest flexible macro: A M42 or PK bellows (usually under US$50), a cheap safe flanged M42-PK adapter (US$5), a cheaper M39-M42 adapter ring (US$2), and a choice of enlarger lenses (most EL's are M39 thread). I bought three EL's this week for ~US$5 each, and I missed an EL-Nikkor for US$7. EL's are generally VERY sharp. EL's longer than 80mm can usually focus to infinity on bellows, for non-macro shoots.
Easiest pseudo-macro: A Raynox DCR-250 (~US$60) snapped onto any mounted lens. If the host lens is A-type, you can use flash or ringlite easily.