Originally posted by MadMathMind If you want to do macro photography, I'd look into the legacy lenses. For one, macro shots are invariably best done in manual focus mode anyway, so getting a macro lens that doesn't have AF is not much of a loss. When you look in this direction, you no longer care about A-type tubes and can get some without electrical contacts entirely. It's a good way to get into this sort of thing while saving a boatload of money.
The A-type tubes aren't for the autofocus - at least not for screw drive lenses. The recommendation to get A-type tubes was so that a newer DA style lens, without an aperture ring, could be stopped down.
Even if the lens has an aperture ring, if you have an A-type tube, you can put the lens in A mode and use auto exposure modes. I've got a set of Kenko A-type tubes. They don't support auto-focus, but they do support auto-exposure. At least, that's what I remember. I don't use them since I now have an 100 DFA WR macro lens.
Originally posted by MadMathMind It's really quite good and can be obtained relatively inexpensively. Because it's M-series, it works great with extension tubes. f/4 may seem slow, but in macro mode, DoF is soooo small that f/4 is more than enough. Going to 2.8 will reduce your DoF to tiny fractions of inches (think 0.10" or smaller) when you focus closely. A major advantage of this lens is that you can shoot it wide open, so actually, you don't even need to do stop-down metering or worry about much else.
The advantage of an F 2.8 macro lens is the brighter view you get in the viewfinder. I can attest to that because I went from the M series F4 macro to the DFA F 2.8. It's not a huge difference, but every little bit helps when you're loosing light due to magnification.
But in my case, the lens earns its keep. The M series lens was falling apart and repair would have probably cost 1/2 the price of the brand new lens, so I could justify the upgrade.
---------- Post added 02-21-2014 at 04:06 PM ----------
Originally posted by filoxophy What I would emphasize is how extreme 1:1 magnification is. On a 100mm lens, your subject will be about a foot from the focal plane (near the back of the camera), and most of that foot is taken up by your camera and lens! So although I have a Sigma 105mm f2.8 autofocus macro, in all honesty my personal closeup needs would probably be just as well served by an older manual focus 1:2 macro, such as the Pentax M series 100mm f4.
I'll agree with that. When I was shooting film with the M series 100 F4 macro lens ( 1:2 magnification ), I would very occasionally add the narrowest extension tube to get the desired framing on a small subject. Once I went digital, the crop factor of the sensor made this unnecessary. And even if I needed additional cropping, it's easy to crop the digital image, and probably preferable to adding extension. I eventually
upgraded to the WR that goes 1:1, but I rarely come close to using that level of magnification.
Cheers