Originally posted by yeatzee
for me....
reversing lenses on tubes > macro lens

And that's another point -- I didn't mention it above because 1) I'd written about it on other threads and 2) I got lazy. Yes, all camera lenses (that aren't utter trash) gain flatfield sharpness when reversed. The PRO: All that sharpness, for no extra money! The CON: Working distance for primes is around 4.5cm, under two inches. That's OK for studio shooting, but kinda cramped for field work. Bother.
But wait! There's more! Reversed zooms act a bit differently. I diddled-around the other day with my lowly A35-80, arguably one of the crappiest lenses Pentax ever sold. I reversed it, using a simple 49mm-PK mount-reversal ring. At 35mm it reaches 2:1 magnification at about 5cm distance. At 75-80mm it focuses out past infinity, and reaches 1:2 down at about 15cm distance. And it is quite sharp, reversed! A bit of fringing at extreme high-contrast edges, but otherwise pretty decent.
And that's with a crap lens. Better zooms should give better results. So I tried my Promaster-Tamron 28-70 (FF-AF) on a 58mm-PK reversal ring plus 52-58mm step ring. It didn't reach infinity focus at 70mm -- that step ring adds enough extension to pull far focus down to about 27cm -- but I don't see any fringing! I also tried a couple older push-pull zooms, but they are sloppier to use than more modern zooms with separate zoom rings. Just make sure your zoom has an aperture ring, and it'll make a dandy macro lens! As with any lens, more extension gives more magnification.
NOTE: You can use CIF (catch in focus) with mount-reversal rings. Don't try the metal tape trick. The tape adds enough thickness to jam the adapter on the camera mount. Instead, scrape or file away the adapter's black paint in the appropriate location, to safely short the contact pins on the camera mount. And where is that location? Just opposite the red dot (index mark). Looking at an adapter: With the red dot at 12-o'clock, remove paint between 5-6-o'clock.
Last edited by RioRico; 04-23-2011 at 01:32 AM.