Fast, Expensive and Equivalent APS-C Zooms and why they may not make sense (or even be equivalent)

Started 10 months ago | Discussions thread
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SeanTXK Regular Member • Posts: 330
Fast, Expensive and Equivalent APS-C Zooms and why they may not make sense (or even be equivalent)

The problem with first-party (read expensive) APS-C fast zooms (and for that matter, highest-end APS-C bodies) is two fold. First, the price point gets too close to full frame for most APS-C buyers to jump in. Second, the performance per dollar is questionable when true equivalence is taken into account.

First, let’s look at price in the abstract. While it is true that not every APS-C buyer is buying on price alone, I think it is true that most APS-C buyers are. Get away from forums and into the real world of APS-C buyers, you find very few buy more than the basic body plus one or two lens kit, and of those that do buy extra lenses, few are buying lenses like gear/hobby forum enthusiasts. They have other hobbies that demand money, bills to pay, and spouses to keep happy. Once they get past the Dunning-Kruger curve (if they get that far) most APS-C owners know that their skills have limits they may never surpass, and keeping a realistic cap on cost is something they’re going to try to do. So, first party fast zooms, which will be expensive (this is Sony) will probably be purchased by very few APS-C buyers in the larger market. As an example of price, I tend to think about the excellently reviewed Fuji 16-55 f/2.8 (aka “the Brick”) and their 50-135 f/2.8 lens (alias unknown) which are priced at $1,200 and $1,600 respectively. How many APS-C buyers are actually ready to spend that amount of money for any APS-C lens? Not many I’m afraid, and covering the R&D cost, tooling marketing and production is going to be an uphill battle for a first party camera maker with a dual format (APS-C and FF) lens mount, as producing such a lens for exactly one line of their cameras, aimed at the most cost-sensitive segment, will likely price the lens out of the market for most of the target buyers.

Then we get into performance per dollar, and for this question, we need to think of true equivalence, or more specifically, what are we really equivalating to. Most everyone on these forums know there’s a 1.5X crop for Sony APS-C, and that a 16-50mm crop lens is meant to reproduce the 24-70-ish focal length used with 35mm full frame film. The classic fast lenses we tend to lust over, made famous by every wedding photographer and their mothers, are the good old 24-70 f/2.8 and the 70-200 f/2.8. Ok, great. So just bring us an APS-C 16-50 and 50-140 f/2.8 already right?

Well, not so fast.

An APS-C 16-50 f/2.8 does NOT actually equal a full frame. 24-70-ish f/2.8.

An APS-C 50-140mm f/2.8 does not equal a 70-200-ish f/2.8 either.

Figuring the 1.5X crop factor to both field of view and DOF, a 16-50 f/2.8 on APS-C is actually reproducing a 24-75mm f/4.2, so the longer 50-140 f/2.8 for APS-C is giving a full frame equivalent DOF of f/4.2 as well.

f/4.2 not 2.8.

Now I can already hear the objection that while FOV & DOF are effected by crop factor, exposure is not. Ok, fair point, but let’s not forget that for any given generation of sensors, full frame is giving you about an extra stop of ISO performance, meaning you can push ISO up a bit to match the shutter speed and get the same exposure without the penalty of noise.

I can also hear the objection that not everyone wants a faster zoom for APS-C just for shallower DOF. Ok, that’s fair too, but for a big percentage, shallower DOF is one of the biggest motivating factors for the fast zoom lust.

Oh, and what about the issue of size/weight. Surely an APS-C lens would be smaller and lighter, right? Well, funny that. When you look at the size of an APS-C 2.8 zoom and it’s FF f/4 real equivalent, you sometimes find the FF a little larger, like the 70-200 f/4 for example, and actually sometimes the FF lens is actually a little smaller, like the 24-70 f/4. And as far as width and weight, let’s not forget that not only focal length but aperture size are the best predictors, and f/2.8 vs. f/4 comes into play here. For example, the Brick is actually 54% heavier and 14% thicker than the Sony 24-70 f/4. Often though, truly equivalent APS-C zoom lenses are practically the same size as their equal FF counterparts.

This then brings us back around to performance per dollar spent, and whether at the much higher price point of first-party fast zooms, you’re really getting what you’ve paid for. If the Fuji lenses are a likely pricing benchmark for Sony (and I’d bet they are) what are you getting for your money?

Paired with a $600 more expensive FF body (assuming you don’t go last generation A7ii at the same price as an A6500) a Sony 24-70 f/4 lens, which costs $1,100, is coming in $100 cheaper than the likely $1,200 price of a 16-50 f/2.8 for APS-C, and is giving you a slightly shallower DOF at f/4 vs. f/4.2.

Likewise, a 70-200 f/4 on a full frame body costs $1,400 from Sony, and is giving you the same slightly shallower DOF than a 50-140 f/2.8 for APS-C at $200 less cost. (Fuji’s price is $1600)

Things can be different with primes, but again, not always so when you look at truly equivalent lenses.

The classic full frame 50mm f/1.8 prime can be roughly reproduced by a 33mm f/1.2 lens on APS-C. No one makes a 33 f/1.2 that I’m aware of, but again using Fuji’s excellent lineup as a benchmark, we could look at their 35mm f/1.4. Yes, the DOF of a 50 f/1.8 is actually shallower on a full frame body, but at least the 35 f/1.4 is cheaper and massively smaller right?


Nope and not so much.

The 35 f/1.4 is $600, and the Sony FE 50 f/1.8 is $200. That’s $400 more for an APS-C lens that isn’t even quite equivalent, and the size difference is nearly indistinguishable.

What about the classic full frame 85 f/1.8? All you would need is to release a 56mm f/1.2 for APS-C. Sony doesn’t have one, but again Fuji does.

FE 85mm f/1.8 is $600
Fuji 56mm f/1.2 is $1,000.

$400 cheaper for FF, and again, nearly indistinguishable in size.

Let me be clear about what I’m getting at, and what I’m NOT getting at.

I’m a happy APS-C owner. I seriously doubt I’ll ever move to FF. Likewise, I’m a bit of a gear head, and would probably be one of the few to purchase a fast zoom for APS-C if Sony or a third party produced one. I’m not saying fast, expensive first-party APS-C zooms and more equivalent primes shouldn’t be produced, or that no one would purchase them. I’m simply skeptical of the business viability of first party manufacturers doing so when they have a dual-format mount and lenses, and the long term value for consumers when you figure that the real cost is pushing dangerously close, and sometimes over the cost of just going full frame.

In my view, the sweet spot for APS-C is in smaller, cheaper, NON equivalent lenses, giving excellent performance per dollar and slotting in at a decidedly lower price bracket than full frame. A product where I can get the performance I’m looking for without slipping into the price bracket for the next rung on the ladder. Buying a kit full of truly equivalent APS-C lenses at prices that clearly push into the full frame bracket seems like a strategy of questionable value, leaving me asking why I didn’t just go full frame in the first place.

For a third party manufacturer like Sigma or Tamron this idea may make more sense, as the same fast APS-C zoom can be made with slightly different mounts and sold to buyers of multiple systems (or in Sigma’s case, can also be sold to the dozens of Sigma camera owners) but for expensive first party companies, this isn’t a very good idea. As a side note, this is the likely real reason Fuji went from APS-C to medium format, skipping full frame altogether. If Fuji had started making full frame X-Mount bodies and lenses, current X-Mount APS-C buyers would likely abandon the smaller sensor bodies and lenses since their FF equivalents would likely be the same size, cost and weight. Well, that and the fact Fuji medium format creates a high-end company halo, but I digress.

Anyway, those are my thoughts for what they’re worth. I’m open to disagreement, and maybe Sony or other dual format camera makers will prove me wrong.

Until then, and as long as I can keep my gear lust in check, I’ll be (mostly) happy with my smaller, less expensive and totally non-equivalent APS-C bodies and lenses.

I have no idea why let’s me attach Fuji lenses to Sony bodies, but I’m glad they do. Hopefully, these links work.,777.393,ha,t,777.392,ha,t,777.639,ha,t,777.580,ha,t

 SeanTXK's gear list:SeanTXK's gear list
Sony a6000 Sony E 50mm F1.8 OSS Sony E 55-210mm F4.5-6.3 OSS Sony E 16-50mm F3.5-5.6 PZ OSS Sony E PZ 18-105mm F4 G OSS +2 more
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