Now with Stabilization
11 April, 2008
Sometimes, the inevitability of a working life gets in the way. Unfortunately, this week is the final week of the dreaded “tax season” here in the good old U-S-of-A, and the outlook of a worthwhile Friday post looked “hazy” according to my magic 8-ball, and finally passed to “Get real.”
However, I do bring you hope. I have finally (thanks to the glory of credit card rewards) purchased both the Tamron 17-50mm f/2.8 and the Canon 55-250mm f/4-5.6 IS lenses that I talked about in my previous post.
My initial thoughts on both are fairly positive, though oddly moreso with the Tamron. I understand that the Canon 55-250mm is, for all intents and purposes, a budget lens. For that budget, there is a terrific optical quality - but the autofocus speed leaves much to be desired. Shots lagged for more than a second while the AF hunted for its target in lower light. This isn’t really the issue I make of it for most people, as you wouldn’t be shooting a very long lens whose maximum aperture is 4.0 in low-light situations often. Its outdoor daytime speed is much snappier - I just felt it should be mentioned exactly where the “budget” starts to show.
The Tamron 17-50mm, on the other hand, I could not be happier with. The lens used to be plagued with AF low-light problems, but at least on my copy it acts responsive and finds targets quickly even at wide apertures and low light. In a side benefit, I find the viewfinder to be much brighter with this lens than with the old kit lens - a side benefit of the wide max aperture. The Canon 350D-400D series is plagued with a notably dim viewfinder, so this makes a world of difference.
I hope to get out on Sunday and take some good shots with each lens for illustration, as well as to test Canon’s remarkably bold statement of four whole stops of gain from the IS.
In fact, let’s go into a little bit of what the real gain is for Image Stabilization (IS on Canon lenses, VR on Nikon). Many people seem to expect it to “fix” the blur in a bad image, and in a way that’s true, but that blur can only be from the camera end - not the target.
Normally, you must use a shutter speed of about 1/focal length to prevent ‘hand shake’, or the minute movements of your hand from shaking the camera during exposure. So, if you’re shooting at 55mm on your lens, you need about 1/55 (1/60) shutter speed to assuredly prevent blur. The longer the lens, the faster that shutter has to be.
But when you get out to 200-250mm as many telephoto lenses do, that means you need a shutter speed of 1/250th just to eliminate the shake - which is a pretty fast picture. Coupled with the fact that telephoto lenses naturally have a more narrow aperture (most are around f/5.6 at that range), you are already not letting in a lot of light. Since your shutter speed must be 250 or faster, you only have two options - crank the ISO up to 800-1600 (maybe higher), or miss the shot.
See, shutter speed and ISO, unbeknown to many amateurs, are both also measured in “stops.” This helps make the relationship and the give and take of the big three in photography - ISO, Shutter and Aperture. If you shrink your aperture by one full “stop” (f/4 to f/5.6, for example), you are subtracting one stop of light (roughly illustrated by the light meter as -1 if your image was properly exposed). To bring it back up to 0 (proper), you can either increase your ISO by one stop (go from 400 to 800), or increase your shutter speed by a stop (250 to 125). Conveniently, though aperture uses weird decimals for its stop values, shutter and ISO are just halved or doubled roughly.
So, when you go out to that 200mm and your aperture shrinks to f/5.6, you may find yourself suddenly needing to go to a shutter speed of 1/125th - the address of Hand Shake City.
IS/VR allows you to avoid this - at a small caveat. Canon’s boast of four full stops on the lens means that I can take a photo with a shutter speed of 1/30th at the full 250mm and not blur. The lens does this by voodoo magic or by decoupling the focusing element from parts of the lens construction…I’m not sure which, but my bet is on voodoo.
The trick is, it only works for shake at the camera end. This means tiny tripod bumps, hand shake, and mirror vibrations. It will not fix an image where the subject is moving.
Let’s say that together: IS/VR will not prevent blur of a moving subject.
Good. With that, I’m off to do some taxes and hopefully take some pictures this sunday. Tuesday’s post may be a bit delayed, but rest assured it will appear - even if it has to be Wednesday morning.
Topics: Equipment, Musings | 1 Comment »
Rural Decay Photo Shoot
08 April, 2008
This last Sunday was my latest opportunity for a photo shoot, and it was a pretty great trip. Being as I live out in the middle of rural Northeast Ohio, I took the opportunity to go explore some of the neighboring towns.
The photo shoot that followed can really be summed up by one term: “Rural Decay.” You can check out all the shots in the gallery.
It really is a sad state of affairs, and I’m afraid that (as one who is affected by it greatly) it will probably be a fairly regular topic for me. A drive through the back country fields and forests shows plot after plot of dilapidated barns, overgrown fields and lowlands that are flooded from the incredibly unusual seasonal patterns as of late.
This, my friends, is the true rural America.
I still have quite a lot to uncover through a lens on this subject, but I have already posted a few of the shots that I took from this particular trip. As spring comes and the fields green up, it just gets more beautiful and I can’t wait to go take another afternoon drive.
In the meantime, what I did want to talk about is black and white shooting. I’m a bit of a novice at this, usually much preferring color for my shots. However, I think that the black and white (and mild HDR to “wash out” some of the other shots that were left in color) helps to set the mood of some of these pictures.
The biggest challenge I had with framing what should be black and white shots is the sky - a bright white sky (which all of the images were as of the start of processing) is not nearly as open and empty as I would want - instead, it just makes you feel as if you are in an old photograph - a nice effect, but not what I was looking for.
My purpose in going black and white wasn’t to age the picture, but rather to deeply enhance the contrast - to show every dying vine, flaking paint chip and cracked board. To help that contrast with a white barn, a dark sky was needed.
This is where Adobe Lightroom becomes nearly vital. The software’s “Grayscale” conversion method (under the Develop module) is fantastic. When you switch to grayscale, your image will convert as if you made a conversion in Photoshop - nothing too special. However, if you move down the sidebar of the development functions, you’ll see that there are still Hue alterations that you can do. This actually sets the “black value” for the conversion of each of the major colors, even including whites and neutrals.
If you have a mostly blue sky and want it to go dark in the image (adding contrast to the clouds), slide the blue slider all the way to the left - it will make the blue sky go very dark. You can tweak the cyan to help catch the fringes around the clouds.
Still not dark enough? Go up to the exposure section and pump up the ‘Recover’ feature, which is designed to save blown highlights. It doubles as a reflected light remover in grayscale mode, and sliding it back and forth will help you find a good balance where the sky grades evenly. Be careful though - too little or too much of this value can create a bit of wash-out or a lot of film grain.
While you’re playing with levels, try messing around with the colors for grass and brush. You’d be surprised at how much you can control the contrast of individual elements - and for once it’s more powerful (when ease of use is considered, at least) in Lightroom than it is in Photoshop.
I hope that this will help you get the look you want with your black and white conversions. Skies in black and white are one of the hardest things to get the way you want them, but that doesn’t mean you have to settle.
Topics: Photo Shoot, Post Processing, Technique | No Comments »
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