J R's Images & Ideas
home    images    ideas    words    websites    contact    resume    links    meta    prices   DallasArtsRevue

My New Camera - Day 2

A Steep Curve Learning Experience
involving f-stops & tinker's dams

<yesterday    Index    email J R    tomorrow>

Friday February 24: I woke up obsessing on comparing f-stops and tinker's dams. I know what an f-stop is — a fraction expressed as the focal length of a lens divided by the diameter of its aperture. Focal length = distance in inches from the optical center (not always on or in the lens itself, thus confusing this definition immensely) of a lens to its in-focus projected image when focused on infinity.

Lens apertures or f-stops are usually created by a series of blades arranged inside a circle so that they create a more or less rounded hole of various diameters. Before that photographers may have used actual holes placed in the path of an oncoming image much as a tinker's dam is a piece of metal placed over a hole in your bucket so it doesn't leak, although I have a camera from the early 1900s that uses just such a movable blade diaphragm, so maybe f-stop holes preceded that. If they ever existed.

feather

slightly sharpened full view of Feather-Sun with much more informative 100% crop from near center
1/5 @ f/5.6 - ISO 100

LESSONS: either my tripod is not sturdy enough or my depth of field at this setting isn't deep enough to render everything sharp in this extreme close-up (near the close focus limit of the 180mm f/2.8 lens. So I learned how to set the self-timer. This shot is soft. I want sparkling details. Guess I'll have to wait for sunlight. The lens was focused on the feather.

feather 100%

Photography is several centuries old, and cameras (camera obscura) were once darkened rooms with lensless window apertures (windows are still refereed to as apertures, as are any opening in an otherwise opaque obstruction) projecting natural color images upside-down on a wall (before film). Artists used them to render images "photographically." A neat trick many of them kept secret.

If you know about pinhole cameras, which can be as simple as a round oatmeal box with a piece of film or light sensitive paper stuck in the flat bottom and a pinhole stuck near the center of the removable top, then you begin to appreciate apertures.

Because of their tiny apertures, pinhole cameras approximate f/45, f/64 or f/90, which renders almost everything in the resulting image in sharp focus, although exposures tend to be long to make up for the small amount of light that makes its way through the hole/aperture.

The reason I was vagueing on about apertures this morning is that the trend seems to be away from large ones.

When I was getting into photography in the 1960s, I was astounded to learn that Canon had a normal (more about normal, as in lenses, in a bit) lens with a maximum aperture (lenses are generally classified by their maximum aperture) of f/.95, which means it theoretically admitted more light than actually hit its glass. It wasn't a great lens, except for photogs who shoot in extremely low light, and now I read on Björn of a 50 mm f/0.75 Rodenstock TV-Heligon that he awards a 1 (out of 5) for sharpness.

I still have a 35mm (a wide angle when projected on 35mm film's 24x36mm image size, now having a 35mm [the continuing photographic standard] 52.5mm equivalency). It used to be a mild wide-angle lens. Now it's a normal lens, meaning it renders an image with roughly the same angle of view as we see with our own eyes.

top

I once used that lens exclusively for one full year just to prove that I could. I had to engage the foot zoom method often, but I did it, and I'm glad I no longer feel the need for such silliness.* Foot zoom means walking right up close or walking back to fill the frame with your subject.

My 35mm lens has a maximum aperture of f/1.4. Which by today's standards, is amazing. That's just at six times faster than the heavy-weight favorite above. It's not a zoom, so I'd have to use my feet — or my brain — to correctly frame subjects.

Now most lenses are zooms. One of the problems of making zooms is that, because the focal length, angle of view and ratio of focal length to effective aperture changes so radically during zooming, the effective (the hole stays the same size, just its ratio to the focal length keeps changing) maximum aperture becomes smaller while zooming toward telephoto.

That's why most of the lenses in my wish list [above] have mutiple-number maximum apertures. I.e., f/3.5-5.6, which is a significant range of hole-size. Bigger apertures (the smaller numbers; remember, it's the bottom end of a fraction) make it easier to hand-hold while maintaining a shutter speed fast-enough not to blur the image with my own motion.

More images are ruined by moving the camera during exposure than any other cause, and smaller maximum apertures that let in less light do not help. The trend toward higher usable ISOs helps. But it's always a trade-off. Higher ISOs show more digital noise.

In my heyday, I could hand-hold a short telephoto (my trusty 105mm f/2.5) lens down to 1/8 of a second or longer and still get sharp images (Wide angles are easier to hold long, because they magnify the image less.) Sometimes I still can. But VR would help considerably. Nikon claims as much as a 4-stop advantage with their VR lenses. Being able to use higher ISOs helps, some.

So I am stymied by the choice of a longer zoom versus a wider max aperture. Size matters. Heavier cameras are easier to hold still, maybe, but heavy equipment hurts. Longer zooms are more versatile and heavier. So far, only longer zooms have VR, though eventually VR will be available in DX primes (non-zoom) and short zooms, too.

My trusty old Sony F707 had a much-ballyhooed Carl Zeiss 5:1 zoom (about 35mm to 200mm in 35mm-speak) with a maximum aperture of f/2 at wide angle and only down to f/2.5 at the far end of telephoto. I miss that already. Nikon has nothing that even comes close.

Hefalump Watch Glass 2006 by J R Compton. All Rights Reserved.

Hefalump Clock Glass in my front window

I just surprised myself by daring to plug my D200 directly into my Cube. It worked. I assumed it wouldn't since I'm still running good old OS9, and thought I'd need a special plug-in that I probably couldn't get anymore. But it works fine sans software assistance. I loaded my first batch of images onto my OSX laptop, thinking that I couldn't load them onto the computer I actually used. Wrong again.

In fact, loading images to my puter from the new Nikon is exactly like loading from my old Sony. That's a relief! Sifts right into my standard operating procedure.

Today's shots are all tripodal units shot on this sun-free day of drizzling rain and ubiquitous gray. Great low-contrast day that sparkles color (A lot of people think bright sunlight is needed to show colors, but dull, cloudy days actually do that much better, because there's less less distracting color contrast), but limits my aperture and shutter-speed combinations. I had the AC on in my car last week in brilliant sunshine, but I didn't have my 200. Now that I do, skies is gray.

I've promised myself I'd throw out all the mediocre and bad images on the new cam, since I wasted so much disk (hard drive, CD and DVD) space on my old F707 losers. But I need to keep these few around awhile, so I can learn from the mistakes I can glean from them.

top

I have to re-read Björn's review of this 180mm lens I have decided to keep stuck to the front of my new cam for at least the first several days [See silliness above.], although its focus is so slow at this near-limit distance, I might be better off with "shorter" manual focus lenses.

He says the 180 is great wide open and 5.6 is amazing, then quality falls off after f/16. He probably has a better tripod and real sunlight.

I've been thinking about other cameras I've owned, back to the 4x5-inch (film size) Speed Graphic with ground glass back and the 2-1/4x3-1/4 inch Crown Graphics with roll-film back I loaned to my friend Dwayne Carter for about five years, so he could shoot film poses, get those shots printed, then be able to render skin-tones with that wonderful high-resolution sheen. I'm hoping for some of that, too, with my new hi-res dSLR.

As a kid I shot snapshots on a Kodak Brownie, but my first professional camera (and I was a professional photographer before I was an amateur) was a 4x5 Speed Graphic with a Polaroid back. The first film I shot with it was then-new 3,000 speed film.

Graphlex Speed Graphic camera

I remember my first shot with that camera upstairs at the University of Dallas' then main classroom building. I knew that to shoot a camera indoors, one needed to use flash, so I did. When I peeled back the print, all I saw was white. It took awhile to figure out I'd blown the smithereens out of that fast (very sensitive) film. Learning photography was pretty quick with 3,000-speed instant print materials. I learned quickly, and I still am.

One of the things I learned was that when I carried that big clunk of a camera, they'd always let me in free, anywhere I went. I looked professional with that big, old camera, and I carted it places I never even intended to shoot pictures at, simply for the glory factor and free entry.

JPEG Images from my Sony usually load in at 1.8 to nearly 4 megabytes (depending upon the level of fine detail — JPEG is a horizontal compression scheme that increases file size with vertical detail. Vertical striped JPEG images make larger file sizes than horizontally striped JPEGs do. Plain backgrounds help keep file sizes small.)

I'm sticking with JPEG format images while I learn the new cam, because I understand them. One steep trail up the learning curve will be figuring out and using RAW format, which will render larger but more versatile files. D200 images load at from 2.5 to almost 6 meg JPEGs. RAWs will be larger.


[All shots taken with the Nikon 180mm 2.8 AF lens.]

top