Friday, September 5, 2008

Do You Really Need a Full-Frame Camera? Article by: Miserere

Hi Pentaxian friends.

Aside from writing books for the Pentax line of DSLRs and having this blog site, I surf the internet every night in search of anything Pentax. One of my favorite site and Forum is
www.photo.net I enjoy posting there and reading the posts from all over the world.

Several regular contributors on the forum are particularly well informed. Those regular contributors often bring answers to the entry-level photographers, or display some gorgeous pictures, or post challenging point-of-views, etc. The common quality I find in these contributors is that they never belittle anyone’s opinion. I wrote to a handful of these good “Pentax” souls and invited them to participate in my blog by occasionally writing articles. At the end-of-the-day, I really want this blog site to be everyone’s Pentax blog site.

Today, I am introducing the first article by Miserere. Please shower him with greetings and comments. He already has a follow-up article, “My opinion of whether Pentax should pursue full-frame or not” that will follow soon.

I am excited and honored to have Miserere participating in this blog.
Yvon Bourque
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Do You Really Need a Full-Frame Camera?
by Miserere:

As a child growing up in Europe I watched many American movies and TV series that showcased “the American Way of Life”. To my young eyes it seemed that everything in the United States was bigger, and that made it better. Or at least that was the message I received.

I first visited the US as a teenager and was surprised to see that what I had learnt from the movies was, in most cases, true. Everything was bigger! The cars, the houses, the roads, the burgers… It was great, I would go to McDonald’s and ask for a medium milkshake; what I got was the equivalent to Europe’s large size. And in the US there were still the large and the extra large sizes available!

As I became older, and hopefully wiser, I realised that bigger is not necessarily better. Bigger hamburgers can make you fat quicker. Bigger cars use up more fuel and are more expensive to maintain. Bigger houses, like cars, are not only more expensive to maintain, they also take longer to clean, and I hate cleaning! As for bigger roads, OK, I’ll admit that I do like driving in a wide lane, so let’s keep roads bigger, shall we?

Bigger is better, a mantra repeated down the ages. I’m sure cavemen worked hard to craft the longest spears, the largest bows, and used them to hunt the biggest prey, so it is only natural that in the modern World we should want everything to be BIG.

Should the sensors in our digital cameras also be the biggest they can be…? (See? I am going to talk about cameras, and you’re not on the wrong blog.)

Since the inception of DSLRs using cropped sensors (with the 16x24mm APS-C size being the most common) there has been a yearning amongst digital photographers to shoot with a camera incorporating a full-frame (FF) sensor (24x36mm, the size of 35mm film). Why? Maybe because we always desire what we cannot have, but serious complaints have been put forth by many photographers, and so the belief has endured that in order for DSLRs to come of age they need to evolve towards FF. Oh, because bigger is better, of course.

In the following paragraphs I will list the usual complaints against cropped sensors and attempt to give you a different perspective, one that might lead you to consider whether bigger is indeed better. Let us begin!

We’ve lost the wide angle.
A common complaint at the very beginning of cropped sensor cameras. The truth is camera makers released the new cameras without having a full stable of lenses ready for them, so while the bird photographers were having a ball with the 1.5 “magnification” provided by the crop factor, landscapers were crying out in pain for the loss of their beloved 24mm FoV. But in due course, lenses appeared designed specifically for cropped sensors that addressed this issue, and soon the standard kit lens became some variation of 18-50mm or 18-70mm, which offered the same FoV that the old 28-75mm and 28-105mm lenses had on 35mm film. Nowadays you can even buy the Sigma 10-20mm zoom…do you really need wider than 15mm-equiv.? So why are you complaining then?

The focal lengths are all wrong.
I never understood this one. Focal lengths are a characteristic of the lens, not of the camera. A 50mm lens will always be a 50mm lens, but the FoV it produces will depend on the size of the film/sensor surface you are using. On a 35mm camera, 50mm is considered neither wide nor telephoto, but on medium format film it is wide. On an Olympus 4/3 camera, it is a telephoto lens, while on APS-C it is a short telephoto. I suspect what people wanted to complain about was the fact that their standard zooms (28-75mm and 70-200mm) didn’t produce the same FoVs anymore. Enter Pentax, who decided to produce the new DA line of lenses that would mimic the FoVs of old. They now offer two standard fast zooms, the DA* 16-50mm f/2.8 (24-75mm-equiv.) and the DA* 50-135mm f/2.8 (75-200mm-equiv.), together with a DA 17-70mm f/4 (25-105mm-equiv.), a DA Ltd 35mm macro (53mm-equiv.), and more primes in the pipeline. If you really miss the old FoVs, then sell your old lenses and buy some new ones. Can you imagine a better excuse to feed your inner LBA.

We’ve lost control over the depth of field.
Again, I think photographers are actually complaining about something else, as DoF is still controlled with the size of the aperture. The DoF for a given aperture for a particular subject size on the image plane depends on the size of the film/sensor; the larger the size, the shallower the DoF will be. When they switched to APS-C, some photographers missed the thin DoF they could achieve with their f/1.4 or f/2 lenses. For a given subject size in your frame, and using the same aperture, an APS-C camera will provide about 1.6 times greater DoF than a FF. While it may seem like losing 60% of your DoF is a lot, we should remember that a common gripe amongst photographers, whether using manual or auto focus lenses, is that they missed the focus in a critical shot. Think about it; how many times has this happened to you? Having a larger DoF will only increase your chances of achieving correct focus, and I would think that is a good thing, don’t you? In order to achieve the same DoF as you would have with a FF camera (for the same subject size on frame), you will need to open your aperture up by an extra 1.25 stops approximately. This is feasible in most cases, unless in your film days all you did was shoot at f/1.2.

Cropped sensors have more noise.
This is true! For equal pixel count, a cropped sensor will have smaller pixels than a FF one. But although a FF sensor has twice the area of an APS-C, the individual pixels are not twice as large, but more like 1.5-1.6 times larger. We also need to remember that noise varies with the square root of the pixel area; so going from FF to APS-C increases the per pixel noise by a factor of around 1.26, which is about 2/3 of a stop. If FF pixels were twice the size of APS-C pixels, then the increase in noise would be a factor of 1.4 (1 stop). What this means in practical terms is that ISO200 on a FF camera should look like ISO100 on APS-C; this is assuming both sensors shared the same manufacturing technology and camera software! It bears noting that software has a lot to do with how noisy a particular camera is, possibly a lot more than sensor technology. But even more important than all these technical details is this: How many times do you need to shoot at ultra high ISO? I’m willing to bet that the vast majority of amateur photographs are taken at no more than ISO200, where the differences in noise between a cropped and FF sensor are insignificant. So why complain about noise if we are rarely going to be shooting at high ISO?

Cropped sensors don’t have enough resolution.
This may have been true a few years ago, but not anymore. Pentax released the 14.6MP K20D earlier in the year, while Canon have recently announced their upcoming 15MP 50D. Both use APS-C sensors and offer higher resolution, in linear pixels/inch, than the highest megapixel count FF sensor, the upcoming Sony 24.6MP A900. Furthermore, reports from K20D users suggest that its sensor is challenging their lower quality glass as far as resolution is concerned, so we may have caught up with the resolving power of the available lenses and this may mark the end of the megapixel race (which I would welcome with open arms). Another question I would ask you is “resolution for what?” My parents have a 15x20 photo hanging in their living room that I took with a 6MP P&S, and it looks great! With a 10MP DSLR you can print as large as 20x30 without worries. I believe that’s enough resolution for just about everyone.

Professional photographers use FF.
Professional photographers use whatever it takes to get the job done, period. It used to be that the pros used only medium format cameras, and those using 35mm SLRs were considered amateurs. Time passed, camera technology evolved, 35mm film evolved, and picture quality reached the proverbial “good enough” level. Shouldn’t we learn from the past? Cropped sensors are already being used by professionals, and will continue to be. With every new generation of sensors we find that resolution and IQ increase, while noise and read out times decrease. The only quality that never decreases is our capacity to complain about minutia.

The viewfinder is so small.
Have you actually looked through a digital FF viewfinder? It is not that big, and it is not that bright either. It does not look like the viewfinder you so loved on your ME Super, that I can assure you. If you want to be able to focus manually more easily, buy a replacement split-prism focusing screen for your current APS-C DSLR; it will be a much cheaper and practical upgrade than going FF.

Conclusion

I don’t want to start receiving hate mail telling me I am against FF digital, because I am not. What I am against is hearing and reading photographers complain about how they cannot do this or that because they don’t have a FF camera. Hopefully, I have addressed the major complaints thrown at APS-C sensors and have, if nothing else, made you think twice about what you think FF would really give you that you are not already getting from your current camera right now. FF does have many advantages, but I don’t think it is the Holy Grail that many are making it out to be and not owning one should not be keeping you awake at night.

Now, stop reading, pick up your perfectly capable APS-C Pentax DSLR, attach your oldest lens to it (extra points if it is an M42 Takumar), and go take photos. You see, you need practice, and if when Pentax brings out their FF you are still taking the same pictures you are today, then FF is going to do nothing to improve them and you’ll just be throwing money down the drain.

While you do that, I’ll go across the street and get myself a small strawberry milkshake; because when it is that tasty, small is all I need.
Thank you for reading.
Miserere
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