The Sweet Spot Scenario

There's still a lot of discussion about sensor size going on, and with it, body size. That's because of the E-M1X and S1/S1R announcements. In both cases, we have Olympus and Panasonic going up-size and up-weight in bodies, and that's being met with varying degrees of push back.

Here's how I look at it:

  1. Sensor size impacts optimal data capture. This is the equivalence debate in a different form. And people don't seem to realize that we had the same equivalence debate in film with similar conclusions. All else equal, bigger capture area is a better choice due to the randomness of photons, among other things.
  2. To buy and use a smaller sensor or bigger sensor, I want a commensurate benefit. The digital ILC era started really started with the Nikon D1, and that was an APS-C sensor. Indeed, the majority of ILC body sales for quite some time were APS-C, because that was the sweet spot for the camera makers in terms of a key component cost. 

Those two things together basically force you to pick a "sweet spot." Let's for a moment assume that the sweet spot for most of us is either APS-C or full frame. To get me to buy an m4/3-based interchangeable lens camera (or Nikon's now discontinued 1" sensor-based ILC), I need a commensurate benefit. My image capture is less optimal with the smaller sensor, so what benefit am I getting from the use of that?

Originally, it was smaller and lighter body, and to a lesser degree increased DOF at my likely shooting apertures. The problem with the E-M1X is that it completely gives up the primary benefit I sought with m4/3, thus it isn't of interest to me. It's not even close to what I'd call my sweet spot.

At the other end, we have Fujifilm with their GF series of cameras and their small medium format sensor (also Hasselblad). With their 50mp count I'm not much above the pixel counts on the top-end full frame cameras. What do I gain from that for the types of photographs I want lots of pixels for? Some dynamic range—though above what I normally require—and some relaxation from captured diffraction impacts.

The problem I have with the GFs is that the camera is becoming more one-dimensional (e.g. not state-of-the-art autofocus), bigger, and I'm not convinced the lenses are fully up to the challenge of providing optimal optics. Not to mention the fact that I'm paying a huge premium for all that.

I've written that the Nikon D850 (DSLR) is the best all around interchangeable lens camera you can buy on the market. That was true when the D850 first appeared, and I believe it's still true today. 

But many, maybe even most, of you tend to have a specialty that you concentrate on in photography. Whether that be landscapes, action, events, street, macro, or something else isn't important in and of itself. What is important is that you analyze what you shoot carefully and make sure that you're picking the right sweet spot product for you. 

I'll give you an example. I shoot landscapes from time to time (a little less so lately, as I've been busy with other things and haven't been able to travel to my favorite places as much). For front-country landscapes, there's no question that my camera of choice that best fills my sweet spot needs is the Nikon Z7 (with the right lenses). The Sony A7Rm3 is very close, though. 

By front-country, I mean drive-to-the-location-and-not-wander-far. 

For back country landscapes, my goto solution has been an E-M1m2 or smaller (with the right lenses). As I get older, hiking many miles with a full set of heavy gear just isn't in the cards any more. My back country "jaunts" can easily run into 16 miles a day. And the majority of the weight I want to carry is going to be water and safety gear, not cameras. Even the E-M1m2 is a bit bigger and heavier than I'd like, though the lens choices are very light. But this is a perfect example where I'm willing to give something up—sensor size—for a clear benefit (weight loss). 

Here's another example from my shooting: I've shot with m4/3 (E-M1m2), APS-C (D7200/D7500/A6300), and full frame (D750, D810, D850, D5) in the Galapagos Islands. There's good news and bad news for all here.

The good news is that you're at the equator and you're only allowed on the visitation sites during daylight hours. The Galapagos is as close to an always Sunny 16 experience as you're going to find. Thus, the smaller sensors generally don't pose a big issue. Sunny 16 gives you 1/1000 a second at ISO 250 at f/8. Not an issue for any of the cameras I mentioned. Indeed, with the right lens, we're still getting near 1/1000 shutter speeds at base ISO even on m4/3 (following image was taken at one of my Galapagos workshops with the E-M1 in a shaded area; it's perfectly fine). 

bythom int ec gal april med hr

So we really don't need the light gathering prowess of the D5 on the islands.

Meanwhile, we're walking on rough ground for long periods of time (though often not long distances), so smaller and lighter gear is just easier to manage in the Galapagos. The m4/3 telephoto lenses are fine, as are the Nikon PF lenses. 

Where I've struggled is with the focus of the m4/3 cameras with BIF (birds in flight) in the Galapagos. On islands like Genovesa, BIF isn't your everyday BIF. It's one thing for your autofocus system to handle a bird that's tens of meters away from you than it is when the bird is at your minimum focus distance moving the same speed. 

bythom int ecuador gal 11-17 d7500 42853

No, I'm not going to give up focus performance for small sensor size here. And the E-M1m2 falls down there (not yet sure about the E-M1X). The above image was from a D7500. 

Now take your gear to Africa and we get a slightly different story, particularly well away from the equator in South Africa or Botswana in their winter months. This image was taken at o-dark-thirty at D5-only ISO levels. Sun not up. No light. Had our vehicle's headlamps lit this hyena I'd have been several stops overexposed:

bythom int africa bots chob med hr


The predators in Africa are generally seeking prey outside the Sunny 16 hours, so you'd better be ready to capture that. The D5 has captured images in Africa that there's simply no chance the smaller sensor cameras I've got would have done any justice to.

So, here's the thing: figure out your sweet spot. There's a right combination of sensor size, size/weight, cost, focus performance, and other factors that is right for the shooting that you do. Make sure you know what that is. 

But here's the overriding criteria you need to always consider: never give up something without getting a commensurate benefit. Make sure you know what you're giving up, and make sure you know what you're gaining and that you need that gain.

I'm always getting messages from site readers about some magnificent gain they see in a product. What I rarely see is an admission of what they might be giving up to get that gain.

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