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Selective Focus: Yes, Size Matters

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11020374_10204876382127650_1989947298_nSay hello to Lee Shelly — our new resident lensman. Lee is a Philadelphia-based commercial photographer best known for his work in the field of Consumer Electronics product photography, but he’s also a hobbyist who loves to make art with his camera wherever he finds it. You can find him at www.leeshellyphoto.com

In his occasional column here at Part-Time Audiophile, Selective Focus, Lee shares some stuff he gets asked as a pro shooter. In this offering, Lee takes apart some of the more common myths — around size.

Consider it a reference for your next camera.

Camera Choices

–by Lee Shelly

OK, so you’ve done the Selfie thing to death. You’ve filled up your phone’s memory with a million vacation shots. You’ve maxed out your cloud storage with snaps of your cat and your kids. You’ve effectively outgrown your camera phone … but what should you buy next? There are only about a billion options. Here are a few things to consider and maybe help you narrow your choices.

Megawhatxils?

The most often quoted, and among the least important specs, is the resolution. This is expressed in megapixels (mp). A megapixel is a million pixels. A 1mp image is roughly 1200×900 pixels. That’s already a higher resolution than your TV and many computer monitors can display. Billboards have been shot with 6mp cameras. So why do we need 24mp cameras? A few valid reasons. First, you may want to crop in on a smaller portion of the total image and still maintain enough resolution to show it on-screen or have a print made. Second, there are applications where more pixels help, specifically large prints that are meant to be viewed at close distance; photos on your wall, for instance.

So how many megapixels are enough? Well, a rule of thumb is that you’ll want to maintain 150dpi (dots per inch) to get good print quality. Therefore, a file that has 2000 x 3000 pixels (6mp) will print well as large as 13” x 20”, and a file that has 3000 x 4500 (13.5mp) will print beautifully at 20” x 30”. Since just about every current camera will give you 13mp or more, unless you’re looking to print bigger than 20” x 30” or you need to severely crop your images; any camera you’re considering has plenty of resolution.

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To demonstrate the advantage of higher resolution when it comes to cropping, let’s say you would like to crop and print an 8×10 print from the original photo (left). If it were taken with a 12mp camera, to maintain enough resolution, the most you could crop would be shown in the 2nd photo (center). If, on the other hand, you had used a 36mp sensor, you could crop to the 3rd photo and still maintain enough resolution to print an 8×10.

But more is always better, right? Not so much. The sensors for cameras are pretty small already. When you cram more pixels onto the same sensor size, you get more resolution, but you also get more digital noise.

Here are some samples that demonstrate the difference between the noise from a D90, a 12mp APS-C (small DSLR sensor), and a D700, a 12mp full frame sensor. Both were shot at the same ISO.

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Nikon D700 — low noise

 

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Nikon D90 — high noise

 

The same number of pixels, crammed onto a smaller sensor leads to more noise. The bottom line? Megapixels are not all the same and more is not always better.

Does size matter?

It’s an age old question, and despite what we men want to believe, size does matter … at least when it comes to sensor size.

sensors

At 4.89×3.67 mm, the iPhone 6’s camera has a sensor that’s half the size of your pinky fingernail. Cramming 8 million pixel sites onto a sensor that small is going to lead to compromised image quality.

The size of the photo site (aka, a pixel) on the sensor determines the amount of light it can receive in a given amount of exposure time. The smaller the site, the less light it can receive. In order to keep the shutter speeds fast enough, the camera takes the lower amount of light and amplifies it (for you audio nerds, think: “increasing gain”). But that also means it’s amplifying the digital noise and distortion right along with the good information. The more amplification, the more noise you’ll see in your image. Cameras all have “noise reduction” filters that are applied to try to give the impression of a cleaner image, but when you “smooth” the noise, you also soften the picture. That’s why the sharpest images come from the cameras that apply the least gain … the ones with the bigger sensors

So, after your smart phone, buying a nice compact “Point n Shoot” camera is the next logical step, right? That’s a definite … maybe. The popular Nikon Coolpix line, for example, uses a sensor that’s really not much bigger at 6.17 × 4.55mm, but crams as many as 20mp onto it. This leads to many of the same compromises in terms of image quality, but does add other advantages in terms of the lens and the ability to zoom … but we’ll talk about that in a bit.

Where you really start to see a step up in the sensor quality and image quality is when you hit the current crop of “Mirrorless” cameras. These offer you many of the conveniences of a point n shoot, but offer MUCH larger sensors. Bigger sensors mean bigger photo sites (pixels) and better image quality. These also feature the option to swap lenses to get the best lens for the task at hand rather than relying on the built-in lens of a Point n Shoot.

The DSLR (Digital Single Lens Reflex) cameras feature sensors that are at least as large as the mirrorless cameras … and often have larger ones. The best of these feature “Full Frame” sensors that are the same size as traditional 35mm film. Again, repeat after me, bigger is better when it comes to sensors. If you decide you need to have a camera with 24mps … please consider a full frame DLSR if you want the best image quality, because smaller sensors with 24mp are going to lead to compromised images, especially indoors or in low light.

What the heck is “Medium Format”? These are cameras with even larger sensors that can go as high as 80mp and still look fantastic. Who needs that? Professional commercial photographers. I’m just including them here to demonstrate what BIG really is when it comes to sensors.

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What else?

OK, we’ve established bigger is better, but is that the only consideration?

Of course not! If it were, we’d all buy the camera with the biggest sensor we can afford and there would be about 1/4 the number of models on the market. Instead, considerations like size, convenience, flexibility and image quality all need to be weighed. Here are a few of the pros and cons of each category.

Compact “Point n Shoots” (PnS)

These may have the smallest sensors, but what they sacrifice in image quality, they make up for in convenience. Generally equipped with zoom lenses that can bring the action closer, they offer a lot of convenience over your fixed lens cell phone camera. (Oh, and no, that “digital zoom” in your smartphone isn’t really zooming … it’s just cropping. You end up with even less pixels in the end.)

They are also the smallest option. If that means you are more likely to take it with you, then that’s an important consideration. The best camera in the world is useless if you don’t have it with you when inspiration strikes! Prices on these start under $100 and it’s a rare model indeed that exceeds $500.

The Bottom Line: PnS cameras give you the maximum convenience in the smallest package with better image quality than your phone-camera and prices that won’t put too big a dent in your wallet. The PnS category includes the popular Nikon Coolpix, Canon PowerShot and Sony Cyber-Shots as well as many other brands.

Mirrorless Cameras

While the PnS cameras have a zoom lens, they have just that one built-in lens — that is, you can’t swap out the lens for something with more zoom, more width or more whatever. The PnS zooms also tend to have smaller apertures, meaning they let less light in, and this forces you to have slower shutter speeds, and this leads to blurry images in low light or when shooting fast action.

Mirrorless cameras give you most of the size advantages of a PnS, but also give you larger sensors and the ability to switch out the lenses depending on what you need to shoot. There are options for zooms similar to the PnS, but they do add some bulk. Mirrorless cameras might fit nicely into a purse, coat pocket or small camera bag, but not a shirt pocket or the back or your skinny jeans like a PnS will.

You’ll also have to spend a bit more on these. Prices start around $400 with a starter zoom lens and range up to as much as $1500 … and then there are those lenses to buy.

The Bottom Line: The combination of larger sensor and better lenses lead to almost DSLR-like image quality while giving you much of the convenience of a PnS. Among the popular brands in this category are the Olympus Micro 4/3, Sony NEX and Panasonic Lumix.

DSLR

These beasts are not going to win any contests for convenience, but they are going to give you the best performance. They will consistently give you the best image quality, the fastest response (important when you’re trying to catch little Johnny’s soccer action), the longest battery life and the most lens options.

Sounds great … why not get one right away? Because they are also MUCH larger than any of the other categories. Their weight is measured in pounds, not ounces. They aren’t going to fit in ANY of your pockets … that’s why they come with camera straps. They also tend to be the priciest options, with full frame models starting at $1800 and maxing out at $6500 for just the camera body.

Bottom Line: If performance at-any-cost is your primary concern, and you don’t mind the weight and bulk, the DSLR is what you want. Canon EOS, Nikon D-series and Sony A-Series are the best bets in this category.

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Hopefully this takes some of the confusion out of the myriad of choices you’ll face. Or maybe it confused you even more. Feel free to ask questions on the topic in the comments. While I’m not here to make specific brand and model recommendations, I will address general questions.

Get your Occasional now

3 Comments on Selective Focus: Yes, Size Matters

  1. Oh, now we have photography and audio….. At one site. This is going to get intersting, and maybe expensive!

    I just bought a “compact” camera, with a big(ish) sensor that I can take everywhere instead of my EOS7D… The Panasonic Lumix LX100. 4/3 sensor, fast f1.7 lens, 9 blade aperture, metal body, full manual dial controls (nice!)…. Not at the cheap end of compacts, and only for big pockets, but results so far have been very impressive.

    • Scot Hull // March 6, 2015 at 11:06 AM //

      I can’t speak for Lee, but that compact segment has been a life-saver for me. Okay, that’s too strong, but you get the meaning — I can take quality pix without having to lug a big ass bag around, and sometimes (many times), that’s all the difference.

    • Yep…I’m loving the trend toward big sensors in small cameras! I still pull out the D800 for my commercial work, but for my own personal photography, 90% of the time I reach for the Olympus OMD-EM10 or the Fuji X100s. For travel, I can take a camera and 4 lenses in the same bag that barely fits my DSLR and one lens.

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