DX smackdown

Someone on flickr decided to engage in a smackdown of the APS-C format.

The problem with these is that they often parrot experts who don’t really remember their history. I’m sure when these experts were young pups, they defended their 35mm film cameras against the old codgers doing medium or full-frame photography. They miss the reality that they’ve become the old codgers themselves.

I’m not claiming that they don’t have a valid argument. I’m just claiming they’re a guilty of hypocrisy: They diss another format as being the “one true format” implicitly exposing own bias in their own format as the “one true format.”

Here is an example pulled in full from the thread:

“DX myth”

“The DX myth is the belief that the DX format is inherently superior for digital cameras than the full frame format. What makes this myth so appealing is a lot of people want to believe the myth with their whole heart. Why???… Because, believing the myth justifies saving a lot of money over investing in a full frame sensor.

“To buy into the DX myth, I would have to believe that all vignetting problems are insurmountable. Specifically, I would have to throw out Huygen’s principle and I would have to believe that it’s impossible to build a retrofocus lens to cover a full frame sensor. I would also have to believe that pixel vignetting cannot be mitigated via simple gain compensation or micro-lenses. Now, we know Huygen’s principle has worked to explain the wave nature of light in 3-space since 1678. Retrofocus lenses have been a standard design for the 35mm format since the SLR flip-up mirror and pixel vignetting is easily calculated and compensated via a fairly simple gain compensation algorithm within the constraints of Poisson statistics.

“It’s easy to contrive tests that favor the DX format over the Full Frame Sensor and vise-versa. However, format size has been and is going to be a dominant factor in image quality for a long time.

“If format size doesn’t matter, why did Ansel Adams and Hy Peskin use large format camera’s… they didn’t even resort to retrofocus lenses to solve the severe vignetting problems associated with large format photography… they had to understand large format camera technology a little deeper to solve vignetting problems.

“Bob Atkins has fairly balanced review of the full frame sensor vs the APS-C sensor.

“The same points that Bob addresses for the Canon EOS 5D vs EOS 20D comparision, apply to the Full Frame vs DX format. We have to be very careful to control the right variables when comparing apples to oranges…Bob Atkins does a pretty good job of keeping things straight.

“PS: I think Bob’s test method #4 is the fairest way to evaluate the DX vs full frame format.”

Arguing from physics

Ignoring the absolutely pointless digression into Huygen’s principle, his arguments about adding a retrofocus group and digital compensation of vignetting are valid. (Though compensation in the microlenses themselves is more than a little far-fetched; you have to realize you need to have a pretty extensive set of lens model, focal length and focusing distance data to correctly compensate for vignetting using gain compensation; and any such gain compensation will correct for contrast/sharpness issues only at the expense of increased noise.)

The problem is that you may take the same or similar facts and draw completely wrong conclusions. The facts in this case don’t support the conclusion.

Here, let me show you:

My response

The “full-frame” myth is the belief that the 35mm format is inherently superior for all photography than any other format. What makes this myth so appealing is a lot of people want to believe the myth with their whole heart. Why? Because, believing the myth justifies spending twice as much for half the quality body.

To buy into the “full-frame” myth, I would have to believe that 35mm is inherently a “magic” format size. Specifically, I would have to throw out the simple principle of volume and weight as going as the cube of the linear dimension. I would also have to believe that a $2500 1.6 Kg lens can be carried and used in every situation that a $750 .6kg lens can. Now, we know that lenses designed for film bodies never needed to consider the case of light reflecting off a sensor or the angle of incidence of the primary rays. Such problems are a recent issue that can be easily calculated and compensated for in a new lens design such as every DX lens ever made and only one very expensive 35mm prime lens.

It’s easy to contrive tests that favor the 35mm format over the APS-C sensors and vice-versa. However, format size has been and is going to be a dominant factor in weight, size, and cost for a long time.

If format size doesn’t matter, why did Galen Rowell and John Shaw use 35mm film cameras instead of medium or large format ones? They didn’t even resort to carrying a wooden tripod at all or carrying primes for all shooting situations. They had to understand that film chemistry and lens coatings had improved to the point where grain issues on large prints became acceptable and the contrast issues of multiple element zooms were mitigated, despite the inherent quality advantage of a prime lens on the larger-sized film format in medium and large-format photography.

Bob Atkins has fairly biased of the 35mm sensor vs the APS-C sensor. That’s understandable. He made his bed with Canon a long time ago.

The same points that Bob addresses for the Canon EOS 5D vs EOS 20D comparision, don’t apply to the APS-C vs full-frame format. We have to be very careful to remember that until recently, Canon treated APS-C as a second class citizen. Bob Atkins has a lot of trouble keeping straight that APS-C is an entirely new format with different pros and cons and insists on comparing it to 35mm photography.

P.S. I think Bob’s test method #4 shows his clear belief for 35mm as a “one true” format. The fairest way to evaluate a DX vs. full frame format is to compare a similar cost, size, and weight DX lens designed for a DX camera and a full-frame lens designed for a full-framed camera. Oh wait. Such a thing doesn’t exist does it?

My conclusion

My argument is simple. If the quality of a given format is all that matters in photography, why did most photographers leave large-format for medium, leave medium for 35mm film, and are leaving film for APS-C digital? If quality over cost is so important, go buy a medium format digital camera.

My conclusion is also simple. Neither format is inherently better than the other. Diffraction effects and distortions are a huge problem in the case of the smaller formats. Cost, bulk and weight are a huge problem in the case of the larger formats.

I am not claiming APS-C is better than 35mm, but unlike Bob Atkins and other Canon-biased champions, I’m not claiming 35mm is better than APS-C. I’m claiming they’re different. I am claiming that there is no such thing as a “fair” comparison between 35mm and APS-C—the testing criteria will determine the outcome before the test is actually performed.

And to all you old codgers out there defending “full frame,” Get over it already.

Canon did.

Published by

tychay

light writing, word loving, ❤ coding

7 thoughts on “DX smackdown”

  1. Quite right that DX has advantages in its own right. Those advantages, however, are generally more suited toward your shooting style than mine. Neither will die out for some time, nor should they, but DX is naturally going to be more popular among birders than in available-light portraiture. But it’s nice to have options. Even with 35mm, sometimes you wanted an F5, sometimes you wanted a Leica.

  2. Ryan,

    I think a case can be made for using APS-C or 4/3 for even some of your photography. Besides the obvious argument of price, there are other things as distance to the subject, frame rate, and bulk/utility concerns: you take a photo with the lens you have on, not the lens you liked to have on. In the last example, a swivel camera such as a Sony Cybershot or the old Nikon Coolpix’s are going to take pretty amazing candids that are impossible to get with any TTL camera.

    Having said that, yes, I believe in areas such as wedding photography and photojournalism/documentary photography, the less depth of field is an advantage. Though I might argue that medium format cameras do significantly better than 35mm in that regard, but they’ve all but disappeared from the field.

Leave a Reply

Your email address will not be published. Required fields are marked *