visual acuity

21 February, 2006

1) I went to Baltimore on Sunday for a photowalk with some flickrites. Now I own me three lenses, strictly speaking: the Rebel’s kit 18-55 EF-S, the Canon 50mm f/1.8, and a lensbaby (the “strictly speaking” :). Basically from the minute I got the camera, the 50 has been on (with occasional lensbaby fun); I do a lot in low light and I avoid built-in flashes generally and it’s perfect for those things. One of my favorite shots with my new camera is still one I took that first night:

1,2,3,4

After using my A85, having control of depth of field and the ability to pull off low light without stabilizing the camera on something was a treat. I love how that picture’s focus is the hands holding the camera (not even the camera itself). That DOF (with the implicit knowledge that I had to have had a camera to MY face at the time too) achieves the creative goal of the picture for me.

But that’s a digression. I mention this because I figured that in Baltimore for a true “out and about” day, a zoom would be a good idea, 18-55 is a good range, it duplicates my 50 anyway, and it was so damn bright the lens’ slowish speed shouldn’t matter. But you know what? Not only is cheap glass usually cheap for a reason (which I had already heard about the 18-55, to be fair) but you don’t need to be doing this all that long or be all that picky a human being to be able to see the difference. I was surprised how soft everything was when I dl’d the day and started culling.

I think I’d been analogizing photography to aural-based hobbies (audiophilia, cars); it is often difficult for me to hear things that audiophiles/gearheads can easily hear, and I figured it’d take time for me to learn to see and judge lenses in the same way as more experienced people. Not so much. (I’ll grant you that you would be hard pressed to find a pair of lenses with a wider quality difference at their focal lengths, and that the 50mm is optically exceptional generally. Still: today I went around with a 17-40 f/4L, and I STILL NOTICE a sharpness difference.)

2) My hobbies — baseball, and now photography — are easier to do with contact lenses than glasses, so I went and got an exam today. All was well until the sun went down, and now I am seeing something I never saw before: in my right eye only, lights like stoplights and streetlights have a halo, which vanishes only as the source gets closer. Ah, I must have slightly the wrong prescription, thought I, and indeed the optometrist covered her bets by giving me two sizes for each eye to try out. But this is a new one on me after wearing contacts for 15 years. After just one year of wearing only glasses, I have a new appreciation for their better quality (for me at least, and when clean).

…And this is why I blog, because only as I was writing did I see the connection here. Glasses are at a fixed position and permit the eyes completely normal function and you get better acuity (or I do anyway), but they are cumbersome and only a small part of your visual field is covered by them. Contacts provide complete coverage and eliminate gadgetry that gets in the way of normal life, but at the cost of being in your eye’s personal space screwing up their function, even when they are working perfectly and not perceived by the wearer.

Hmm. Convenience vs quality. Contacts vs glasses. Zooms versus primes. Digital vs film. Blockbuster vs. local video store. Macy’s vs Marshall Fields/Hecht’s. It’s a theme in this blog, isn’t it?

3) Walking around today with an L lens on Rita (I picked a name for my camera, did I tell youse?) is totally a retread of my first week with Rita and how uncomfortable I was with such a big piece of equipment that nevertheless represented a lot of value in a small, non-palmable, non-pocketable package. I got over that right quick with the 50mm on, but this lens is 3 or so times bigger. And I have to remember that not everyone knows what a red stripe means. 🙂

4) I keep trying to push my glasses up my nose when my vision blurs. And then I feel like a dork.

5) I almost bought a 40-year-old, 150-page book about depth of field today. It was a bit more than I wanted to spend but I am attracted to the optic theory behind photographic lenses and this book had diagrams a gogo (I love diagrams!). (The bookstore also had 2 of the 3 Ansel Adams Photography books, of course not the one most relevant to digital photographers, the first one.) It’s a very me thing to do to study like that and use that very book-based knowledge to further my own empirical understanding. On the way back from NYC for example, we were discussing a lens f1.4 had tried out on his full-frame 5D at B&H, a softball-sized lens that was, IIRC, an 85mm f/1.2. Discussing how fricking WIDE the thing is, I thought: yeah, it makes sense, 1.2 is a ratio of the aperture to the focal length and if you need a 7cm aperture, that will necessitate a pretty damn wide lens opening. I was the least experienced person there but I think I was the only person to think along those lines, so clearly this kind of thinking has nothing to do with skill. It’s just there to make me the girl with all the annoying questions. 🙂

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