Tuesday, July 27, 2010

Nikon D300 focusing system flaw?

After working with my camera for the last 4 days I have to ask; does the Nikon D300's AF system have a focusing flaw? If I shoot my Nikon 50mm f1.4D from f1.4 to f2.0 (one and a half stops) it will consistently focus ahead of the point of aim (POA for shorthand). At 2.2 it's reasonably sharp for its very shallow depth of field (DOF). From f2.5 and on up, it's fantastic! Now that I have the AF system placing the point of focus and POA together at the sensor plane I can finally see some terrific results at wider apetures. Prior to my readjustment, f5 or f5.6 was the minimum I could use on my big Sigma 70-200mm f2.8 lens. Forget about f2.8-f3.5... they don't exist! Now, however, even f3.2 is on the mark, though just a tad soft. I was practicing in the middle of the day. In low light I'm sure f3.2 would be fine.

But this leads me to the great "focus shift" or "aperture shift" question... Is the D300 flawed? I get the same behavior with two high-quality, wide-apeture lenses. One is just a D lens, but it's a well-respected, tack-sharp lens. The other is expensive because it's got big glass elements inside and zooms to 200mm. In my book, both should be useable all the way to their minimum apetures. Through the viewfinder, the images look sharp when focused (don't forget this is with the lens wide open) but when exposed, what you get at the imager varies wildly with changes in the f-stop. If you adjust the camera so that f1.4-2.0 is useable on the 50mm D lens, then the AF is massively pushed too far back at f5.6-f8. I've been doing this for four long days now, in the CA desert heat, confirming results on my laptop, and as sure as a bear craps in the woods, I can reproduce this one hundred percent of the time. I even know exactly how far to turn the AF mirror stop to make the point of focus walk closer or farther.

Now my "kit lens" an 18-55mm f3.5-5.6 lens will do just a little bit of this, but it's wide open values aren't as great as the f2.8 of the Sigma or the massive f1.4 of the Nikon D prime. The only other lens I have to try is a Tokina 12-24mm f4 which has to be "pushed" +20 in the AF Fine Tune setting even AFTER the AF system's been adjusted! It clearly has an issue which will probably require going in for service. Truthfully, I use this lens for precisely two photos with ever car photo shoot. I'm not going to miss it very much while it's away having its tiny electronic brain fiddled with. Besides, it does actually work at +20 and f4, and I gain a ton of depth of field at f8 to f11, so it's not really troubling me. It's the 50mm and the big Sigma I use ninety percent of the time.

So why does the D300 do this? I originally bought a 50mm f1.8 for this body back in 2008, and sold it in 2009 because it had this same trait. I thought it was just a flaw with that Chinese-made plasticky-cheap Nikon lens. Has anyone else noticed this with their D300 or D700 (which uses the same AF system)?

You don't know what you've got 'til it's gone!

File this under Camera Gripes v3.0: Eye-start auto-focusing... Not something you really think about if you don't have it. The camera starts focusing when you squeeze the shutter button down, right? Well, have you ever thought about the motion this induces into the camera body? Probably not. I hadn't, until I was trying to reset my Nikon D300's AF system, and was shooting a ton of photo each day with my big, heavy Sigma 70-200mm f2.8 lens attached. That's quite a handful on the already-stout D300 body! Squeezing down on the shutter with tired fingers, by the third day I was noticing a dramatic amount of camera shake. That's when it dawned on me, Minolta knew this years ago! My 700si film body has it. My Konica-Minolta 7D digital camera had it. I just didn't think it was something I'd really miss all that much. Guess what? I do. I really do miss it. I'm tired of my hands hurting from gripping this heavy body while squeezing a shutter button at a wierd angle (it's the right angle for fingers, but the wrong angle for camera shake) or having to squeeze the AF-ON button on the back of the camera. Eye-start was bloody brilliant!

And there's STILL no word from Sony about a replacement for the A700. Yes I've seen the photos and vids of the camera from the PMAs. It looks nice, but a bit underwhelming. For once it would be fantastic if Sony produced that body for the "pro-sumer APS-C" crowd, and unleased a full-frame-with-pop-up-flash body for the pros who'd like to use the Minolta wireless flash system. That Minolta system DOES work better than the Nikon variant, I must say honestly. More range, more control, easier activation, no hidden menus in each flash unit. I can see advantages to both systems though.

Am I going to be stuck buying a Sony A900 when my taxes come in next February? 24MP is enticing, but unnecessary compared to a light- and color-sensitive FF sensor like the D700 has. Doesn't Sony want to be in that market or do they have some sort of "exclusive" deal with Nikon for a sensor that they themselves produce?

Thursday, July 22, 2010

Life's little irritations!

Politics: Get off GW Bush's back, everyone. He had a Dem Congress since 2006 (currently the lowest approval rating of any Congress ever!), and all of this country's fiscal problems can be traced directly to Democrat-enacted laws and policies. Democrats control the bankrupt states, and bankrupt cities and yet, somehow Obama got elected by promising "Change". He has totally failed to deliver "Change" from the crap which has gotten us into the hole we're in. He promised no new taxes, budget cuts, pay-as-you-go, pre-bill-signing "sunlight" periods, and has reneged on all of these promise so far. Obama fans, how long will you continue carrying the water for this embarrassment of a President?

Sony: Get off your conceited butts and deliver a full-frame replacement for the A700 already! Geez! The KM 7D was a brilliant camera which was released about two years too late to save Konica-Minolta. You are continuing that disastrous trend. The A750 needs to be released TODAY in order to compete with the Nikon D700 and whatever Canon makes in the cheap full-frame market. Oh wait, neither Canon nor Nikon make a "cheap" full frame camera anymore, unless the Nikon F6 can be counted.

On focusing: Why is it so difficult to have a camera which focuses properly 100% of the time. With tiny viewfinders and no cross-prism focusing aids, it's impossible to hand-focus a DSLR. AF systems need to recognize this fact and step up the game!