Points in Focus Photography

Clouds as Art

Over the past couple of days I’ve been chasing a Spot-breasted Oriole thought he neighborhood in an epic game of telephoto cat and mouse. Mostly with the mouse, er bird, winning. In the mean time I’ve also been working on continuing the two open series, A Brief History of Focusing and Photographing Flowers as well as starting work on a 3rd series investigating the design of camera UIs.

The Bully
The Bully

I hate reading the rumors and rumor sites, they’re like a train wreck, horrible but so very hard to to look away from.

The rumor mill seems pretty consistent on the perspective that the next EOS 1D will be an APS-H camera, and why not Canon’s own Chuck Westfall mentioned that Canon is committed to the APS-H format sometime ago in a Tech Tips. Further, apparently sports and journalistic photographers have put their backing behind the continued existence of this third class format as well.

I think there are compelling reasons to move on at this point. APS-H may have made sense when it saved some money compared to the larger full frame sensor, and sensors were clearly exotic and expensive to make. That would be what 5 years ago? The EOS 5D, EOS 5D Mark 2, Nikon D700 and Sony Alpha 900 have shown that a full frame sensor can be packaged in a body that costs less than the 1D. Clearly if a full frame sensor can be made inexpensively enough to put in a mid-tier camera at acceptable profit levels, the same should be true with a top-tier camera. Sensor cost certainly shouldn’t be an issue, nor do I think it ever was, in the ~$4000 price tag on an EOS 1D body.

What’s worse, APS-H buys us nothing over a full frame sensor and costs us wide-angle. No where in the idea of a sports or low light camera does it say it needs to be crop too. But wait, crop gives us free telephoto, you say. Oh no, not when the pixel density doesn’t increase as well. The only way to make your sensor size act as a free teleconverter, relative to a crop from the larger camera, is to make the pixels in the smaller sensor smaller.

Camera Native Resolution
(in MP)
Native Crop Factor Resolution if Full Frame Resolution cropped to 1.3x
(in MP)
Resolution if Cropped to 1.6x
(in MP)
TC Factor for a 10.1MP image
1D 10.1 1.3 17 10.1 6.7 1.3
1Ds/5D-II 21.1 1 21.1 12.4 8.2 ~1.44
40D 10.1 1.6 25.9 n/a 10.1 1.6
Native crop factor is relative to a full frame image equivelent to a 135 format film frame.
The TC factor is the field of view equivalent crop factor compared to a full frame image when cropping to a fixed resolution.

So long as the APS-H sensor’s pixel density continues to remain behind that of it’s full frame cousins, as it should to keep those high ISO capabilities where they should be, it never will get as much “reach” as they do. In fact, if it wasn’t for the 50% drop in frame rate (which is almost certainly due to the 2x increase in data that needs to be processed) you’re be better off shooting with a EOS 1Ds Mark 3 and cropping to if reach alone was your objective.

For all that non-gain in reach, we really do lose wide angle. What makes it even worse, is that by sharing the full frame mirror box of the 1Ds, there is no specialized ultra-wide but crop glass. Even if Canon made a 12mm ultra-wide, let alone a 12-20something mm ultra-wide zoom, it will always be wider on the 1Ds or 5D than on the 1D. Of course this doesn’t mean that the 1D is useless for anything but sports but it is limited in a way that the Nikon D700 and D3 aren’t.

I just don’t see any advantage to keeping the APS-H format at this point. For a long time I felt that Canon’s APS-C bodies were the second class citizens in the Canon lineup. When compared to Nikon’s DX bodies, they certainly are. However the APS-H 1D is almost certainly the 3rd class citizen. It’s a cropped sensor with less “reach” than the current full frame ones and no access to crop specific glass to give it really wide angle coverage that the APS-C bodies have.

I was working on a new series about the history of focusing and focus aids when I looked outside and saw this the sky was turning simply amazing colors. Unfortunately, it was too late to go find a foreground worth including, but I wasn’t about to pass up the shot at the colors.

South Florida Sunset Color

South Florida Sunset Color

I’m in the process of writing a rather long essay on the evolution of focusing and focusing aids from ground glass to contrast detection, and everything in between. It’s probably going to be a while before I get that finished and this was interesting enough that I thought it warranted an aside.

Nikon has filed for a patent on a mechanism to embed what amounts to auto focus pixels in the imaging sensor itself. This would in affect solve the performance issues contrast detection autofocus poses.

A bit of background, contrast detection AF systems suffer from a number of limitations that prevent them from matching the speed of the simpler phase detection systems. There are three main problems that contrast detection systems need to overcome. First is pixel sensitivity, because the camera is using information from the imaging pixels, it’s not possible to tune the the autofocus pixels to be more sensitive to light. This means that the camera makes more of a trade off in autofocus speed as light levels drop.

The second issue is it’s nearly impossible to tell which direction the image should be shifted without performing very complicated image analysis on other parts of the image, and even then there’s no guarantee that will be right. This is because to the imaging pixels a front or back focused lens simply produces a diffuse blob.

The contrast detection problem, which way do you shift the focus? Both examples are out of focus, but to the sensor they simply appear as diffuse blobs.

The final problem is the required processing power. In a contrast detection AF system the camera’s processor is actually trying to quantitatively find the point where to pixels have the highest different in brightness. A phase detection system simply compares the brightnesses of each pixel in two different rows of pixels. In an in-focus image they two rows of pixels will be the same, in an out of focus image they won’t line up.

What it appears Nikon is doing is miniaturizing the optical path of prisms and lenses that feed our current phase detection sensors and embedding them in the actual imaging sensor in place of imaging pixels where they want the auto focus point to be. This givens a camera using this system all the speed and efficiency benefits of phase detection without requiring a mirror or other beam splitter to direct some light away from the sensor.

None of these problems apply to a phase detection system. Because of the way the prisms bend light the direction that the lens needs to be focused is already known (except in the case of a severe defocus situation). In addition the specialize pixels used in the AF array can be tuned to be sensitive at much lower light levels while maintaining a good signal to noise ratio so they can be read quickly. Finally, processing is almost a non-issue thanks to the limited number of pixels the actual operation being performed on them.

The only possible problem is that the camera has to interpolate image data to cover up the holes the autofocus pixels leave. But truthfully that’s probably not much of a problem at all. Cameras current map out defective pixels and replace their measured values with interpolated values from the surrounding pixels. Even the basic Bayer layout of the sensor requires interpolation to turn the RAW data coming out of the sensor into something we can understand as a picture.

What it ultimately boils down to is this could give a point and shoot the same AF performance SLRs have. Of course if you pair this with another Nikon patent for what looks like an interchangeable lens camera in the Olympus E-P1 style, you might be able to start putting together an image of what Nikon has in store for us in the future. One thing that’s clear this patent has the potential to close the performance gap between Point and Shoots and SLRs, and pave the way for a mirror free/prism free SLR that can maintain current autofocus performance levels.

The patent in question is number 2009016727.

Clouds

I’ve always liked clouds, not normal clouds but big cumulonimbus clouds. Especially when they’re back-lit in the morning or late afternoon. Abstract in nature, often with interesting lighting and tonalities and always impressive in scale. On that note, I shot these of a brewing storm a couple of weeks ago.

The setting sun lights riseing cumulonimbus clouds.

Faint crepuscular rays form though riseing cumulonimbus clouds.

Focus Today concluded round 2 of serious focus testing. What’s different this time from the last? A new target, a new alignment strategy, and some new results. Last time I looked at autofocus, I had enough problems focusing fast lenses that I was growing concerned that there was either a systematic design flaw or similar error in phase detection AF systems. I was seeing behavior with fast lenses on both Canon and Nikon bodies that would inconsistently focus depending on a verity of situations.

The good news, the new target dramatically improved auto focus consistency on both platforms and the new alignment strategy shortened setup time and aided accuracy. The not so good news is that I’ve determined that there is definitely a problem with my EF 50mm f/1.8 II and it may in fact be a much wider issue; though I guess you could say, what do you expect from a $100 lens.

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I just finished up helping a fellow photographer and friend setup and calibrate his new Dell 2407WFP LCD display and yet again I am reminded how much I really hate dealing with color and color profiling.

What settings should you use to calibrate your display?

In Michael Reichmann’s From Camera to Print, Jeff Schewe comments that instead of specifying the traditional D65 white point and gamma-2.2 you should simply profile your display at the native white point and gamma. The argument being that because the video processing chain (i.e the OS, video card, and monitors) are 8-bit the extra translation step forcing D65 and a specific gamma requires can actually create or increase errors in color.

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Syl Arena, over at www.pixsylated.com recently put up a Canon Speedlite Wishlist. Syl gives us 17 points to chew on that he thinks would make Canon’s Speedlite system better; most of which I agree with, some I think are silly, and some I think are a bad idea in the larger scheme of things. However, in that spirit here are my thoughts, however little they may count, and my Canon Speedlite Wishlist.

My Wish-list

  1. Replace the power switch and slave mode button with a single multi-position power switch (off, solo, master, slave)
  2. Get rid of ratios for wireless groups, use straight exposure compensation for all of the 3 groups.
  3. Insure that every flash has proper EMI shielding
  4. More zoom, so long as it doesn’t make the flash bigger
  5. Replace the ST-E2 with something that exposes the full functionality of the system
  6. Replace the MR-14 and MT-24 with something more flexible and modular
  7. Open or license the TTL protocol to the wireless remote manufacturers

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