Created: 2016.08.20
When are APS-C cameras better than full sensor sized cameras (and at the same time cell phones)?
When I first wrote about APS-C, I think it was in 2004, it was a really big surprising, and at time irritating, deal. I had bought my first APS-C Camera, a Canon 20D. All my previous digital cameras - of which I had several Fuji and several Nikon had a 'normal' sized sensor. Through the years I've come to like both and use them where they are best suited. Of course it helps that one of the companies I own is a photographic company, and to run profitably, I need several cameras that are all 'active' in the same time frame - something the average person obviously doesn't have.
This article is mostly about where APS-C is better than 'full sized sensor' cameras - and at the same time cell phones. There are many obvious reasons why, at times, any 'real' digital camera is better than a cell phone (and many obvious reasons why cell phone cameras, at times, are better than any 'real' digital) - but that will be an article for a different day. For now I want to focus specifically on the advantages that the sensor size itself gives you.
It is a film or sensor size.
If I may, first I'm going to give you an overview of film sizes to put it in perspective.
Without getting too technical. There have always been different sizes of film. Some of the more common ones historically have been:
When digital cameras came out, the most popular where the ones that had a sensor the size of 35mm film and the best ones used modified 35mm cameras, like Nikons, to create digital cameras. The biggest reason was probably because of all the lenses people could get - so they would be happy to buy a Nikon based (Fuji or Nikon) digital camera that they could use all their Nikon lenses on.
Then companies started creating sensors that were smaller than that and putting them into 35mm cameras. Again, using at least the design of 35mm cameras so that the lenses could be used. I suspect there was some technical reason why it was easier to build the smaller sensor, perhaps the angle of light, perhaps heat, perhaps die size. I don't know - but Google probably does if you care.
So now, why the -C on APS-C?
The C means 'Classic'. So a Digital camera company is telling you "The sensor size is about the same size as the classic APS film".
And of course, professional photographers, who were happy using their Full sized sensor (meaning the same size as 35mm film) loved the fact that the APS-C were Amateur...sized sensors. It gave us the ability to laugh at non-professionals with their 'Amateur' sized sensor. Now I was not one of the ones who laughed, but when I bought my 20D - I can tell you that at least one other 'professional' photographer laughed at me and said -"Really? You are trying to use an AMATEUR photo system sized sensor? That's not a real camera."
Funny thing, as I write this in 2018, I still use that 20D for professional work - 14 years later! And the photographer that laughed at me has retired from photography.
While I understand that, as a tool, different tools have different qualities, and some tools are not useful to professionals for a variety of reasons, I do not think that this is the case for cameras that have an APS-C sized - or really any sized - sensor.
And if so ... are any of those advantages over cell phone - really really tiny sensors?
I hope I'm not surprising you by saying - yes.
The most common advantage is that:
APS-C makes all your lenses 'longer'.On Zoom lenses, this is most useful at the end with the biggest number.
If you are trying to get pictures of wildlife for example, if the full sized sensor and the APS-C sensor have the same MegaPixels, the APS-C sensor will let you get a more detailed close up picture of the wildlife than the full sized sensor will.
Did you catch the caveat there? If you have a full sensor, for example, that has 30MP and an APS-C that has 12MP as an example, you'll be able to crop the full sensor 30MP image to get more detailed closeup than the 12MP APS-C. But if both are 12MP - then the APS-C, with the same lens, will be able to 'zoom in' closer.
Another caveat, you may have heard of the 1/mm rule for hand-holding. It is a general rule of thumb not an absolute number. But as a working comparison it is very accurate. If you have an APS-C with a 1.6x multiplier, then your 100mm lens becomes a 160mm lens, and that means even though it says it is a 100mm lens which means the rule of thumb of 1/100th second as the slowest picture, you'll need to use 1/160th second when using that same lens on an APS-C camera - because the APS-C camera turns it into a 160mm lens. This is particularly a problem as the numbers get bigger and you now need a 1/460th second (1/500th realistically) for your 300mm that only required 1/300 on a full frame.
But if you are going to crop your full frame sensor, you have exactly the same problem, so this is more a word of warning, not really taking away from the advantage.
APS-C has less distortion when using full sized sensor lenses, basically "lenses that worked with 35mm film".
Stepping back a bit to explain 2 things.
First step back: I've had someone tell me "my lens is better because it is the same as yours but it has a D added to it". Well, the D stands for 'Digital' - and the 'D' means "it doesn't put enough light to use on a full sized sensor". So while it may be 'better' because it costs less, and it may be 'better' because it weighs less, it doesn't mean that it does a better job generally. It is mostly a warning "D - this lens Does not work on a full sensor, you have to use an APS-C or smaller sensor with this lens'.
Second step back: No lens is perfect! And all lenses are less perfect the closer you get to the edges. So if you use a lens that is made for a full sized sensor on an APS-C sensor, and you use use the same manufacturer, same basic lens but a 'D' version - you will almost always find that the full sized sensor lens has less distortion, because if you use the full sized sensor lens on an APS-C sensor, you are copping out the worst of the distortion every single time! There are lots of articles talking about 'pincushion', 'mustache' and 'barrel' distortion as well as other distortion, so I'm going to skip going into that in detail.
The result is this though:
Combine this with, if you are buying second hand lenses, you are much more likely to find a bargain on a full sized sensor lens than a 'D' lens, partly because the average person assumes that D means it is BETTER! But now you know better, and partly because people who used to shoot 35mm are more and more abandoning their 35mm equipment and just using their cell phone, and partly just because a lot more of them were made and sold and continue to be made and sold.
The biggest disadvantage is it is impossible to get wide angle lenses for APS-C that are as wide angle as for Full sized sensors or the 'normal' for most cell phones.
Then, if you don't need the advantages, and you are using a lens that works for full size sensors - you are carrying extra weight (and spending extra money) for a lens that gives you no benefits - 50% of the lens is doing nothing for you. It's just dead weight.