Friday, June 24, 2011
So, here’s a ladybug. I used my Tamron 90mm macro lens that I picked up used at Glazer’s a year or two ago. The more I use it, the more I’m convinced that it doesn’t result in quite as nice of images as my Minolta-mount Kiron 105 that I got on Ebay. But, it’s a heck of a lot easier to use. That’s because it’s actually a modern, electronic lens that is designed for working with a Canon body, as opposed to an old, physically actuated lens that was designed for a mount that I’m not even sure they make anymore. The reason that makes a difference in usability primarily comes down to the aperture. With modern lenses, the aperture is held wide open as you’re focusing and composing, then it’s closed down to the desired size when you hit the shutter button. The minolta-mount lens has the same idea, but it’s done physically – meaning there’s a little spring-loaded rod in the mount that, when moved to the side, holds open the aperture. When you hit the shutter button on a camera that uses that mount, it then moves something out of the way that was previously holding that rod in place, thus the spring that I mentioned then closes down the aperture. But obviously, a modern Canon-mount camera doesn’t support that.
So, the upshot of all that is that when you’re using the Kiron lens, you have to close down the aperture before taking the shot. Which means that you’re restricting the amount of light that you have to focus with, sometimes severely so. And, to make matters worse, you’re enlarging your depth of field at the same time. So it becomes extremely difficult to tell if you’re focused on just the spot you want, particularly so when you’re taking macro shots, where being off by a millimeter or less can ruin the shot. Yeah, it’s hard. So, that’s what I mean when I say the Tamron is easier to use, because you can use the wide open aperture to focus, and it’ll automatically step down when you take the shot. But the images aren’t as nice. So it goes.
Notes: Canon EOS Rebel T1i, Tamron 90mm macro lens with Opteka extension tube and Phoenix macro ring flash. 1/160s, f/16, ISO 100.