Why 16 Megapixels, When I Could Have 50?

If there was a 100 MP DSLR announced tomorrow, I would pre-order it, then spend many sleepless nights waiting for it to arrive. I’d suffer nightmares where Imatest monsters would kick Zeiss Otus’s around and laugh at their feeble attempts at keeping up with my high resolution camera. It would get even worse when I put a second mortgage on my house so I could afford the new supercomputer to crunch those images. I’d pace the halls of my house, past my favorite matted and framed 24”x36” lens chart prints, while wondering if I needed a car with a bigger trunk that could carry enough CF cards for a day’s shooting.

But it doesn’t need to be that way. Even if they plopped the Lincoln Monument in the middle of Yosemite Valley I could take the architecture in the grand landscape shot with only a 12-16 MP camera and never know the difference between it and my 100 MP dream machine. How can I say this?

Here’s proof. I took these nearly identical images of these trees on Nasim’s recent fall color workshop. One was shot on the full frame 36 MP Nikon D810 with Zeiss Distagon T* 35mm f/2 ZF.2 – a match made in Mansurov Heaven. The other was the duo from hell – the discontinued 16 MP DX Nikon D7000 sinfully saddled with a Nikkor 18-300mm superzoom, Photography Life’s worst reviewed lens ever. I set up my tripod, framed the shots as equally as I could (zooming to 35mm equivalent on the loser lens), then snapped two frames. When I loaded them into Lightroom, the superzoom shot looked horrid – oops, I forgot to remove the split ND filter. Oh well, I dodged it back into decency then exported both files using Photography Life’s recommended web resolution. I then put the images up side-by-side on my laptop monitor (MacBook Pro Retina) and asked Nasim to tell me which was which. After much squinting and head scratching he pointed to one and said “That’s probably the Zeiss”. He was wrong – it was the superzoom.

“That’s not fair,” Nasim groused, “I need to see these at 100 percent.”

And there’s the rub. You don’t need to see images at 100% because that’s not the way final output is viewed. When you look at a Herb Ritts print in a gallery are you obsessing over seeing a 1:1 cropped scan of the original negative to make sure it’s a good photo? Of course not. All that counts in the end is how good the final output looks.

So my 16 MP shot fooled Nasim at final output (2048×1638 pixels) and it looks just fine on the web. But what about 16 MP vs 36 MP for gallery prints or magazine work? Again 16 MP is just fine because even printed at 300 PPI, for the cover of an 8.5”x11” magazine the file only needs to be 8.4 MP. Oooh, but what about a two-page spread? That would take 16.8 MP at 300 PPI. I hate to break it to you, but 16 MP is still enough as the human eye (assuming perfect 20/20 vision) when viewing a magazine just short of arm’s length can only resolve about 150-220 PPI depending on who’s figure you use for the resolution of the human eye (0.6 to 1 arc-second). That is why Apple calls their laptop display a “Retina” display because we view laptops at the same distance as we read magazines and the Retina display has a resolution of 220 PPI (for us geeks out there the new Mac 5K display is 217 PPI which unless you view it at laptop distance is overkill).

Here’s a recent shot of mine as it appeared in the table of contents in February’s Arizona Highways. It was shot with the 16 MP Nikon D4s and cropped to about 9.5 MP and looks tack sharp (I crunched the dimensions and got 218 PPI as final resolution as published). All those two-page spreads that impressed us five years ago were probably shot with 8-12 MP cameras. They look just as good as those today.

The key to this all of this is the concept of “normal viewing distance”. We view shots on our phones closer than we view magazine pages. We view huge gallery prints from across a room, not tucked in a narrow hallway (my lens chart pin-ups excepted). We view billboards from a block away.

The further away your final output is viewed, the less PPI it needs to be printed at. This is why billboards are printed at ~10 PPI. From half-a-block away you can’t tell the difference between 10 PPI or 1000 PPI. A 16 MP image printed at 10 PPI will be 41 feet wide. I’ve only had one photo published on a billboard and it was taken with an 8 MP point-and-shoot and looked fine at 30 mph.

Even though camera resolution has grown rapidly in the last decade, the resolution of the human eye has remained the same. Unless you’re a cropoholic, a forensic specialist, or working for over-demanding clients, anything more than a 16 MP camera is overkill. With the exception of one of the first two shots (I can’t tell which), all of these were shot on 16 MP DSLR bodies.

I hope I’ve saved you a load of money with this article. When it comes to sharp photos, you don’t need to invest in a high-resolution camera or matching state-of-the-art lenses because your eye will never know the difference. Go ahead and laugh at those fools with their 50 MP cameras and 5K displays. Then you can take all that money you just saved and go over to my website and buy some delicious gallery prints. Goodness knows I could use the money. How else will I be able to pay back for my Nikon D810?

All Content © John Sherman

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