The Difference Between Full Frame and Crop Sensor Cameras – FX and DX

The difference between a Full Frame and a Crop Sensor camera is the difference in the size of the sensor that records the image.

For the purpose of this post I will use the Nikon terminology of FX for ‘full frame’ and DX for ‘crop sensor’. Each manufacturer uses different names – for example Canon use ‘Full Frame’ and ‘APS-C’ for their crop sensor version. And each manufacturer’s ‘conversion factor’ differs slightly. I will use a conversion factor of 1.5 times for simplicity. I cover ‘conversion factor’ below.

Full Frame cameras originate from the 35mm film camera days when the size of the negative was 35mm. Full frame sensors are made to the same size.

The question really is “Why do we have two sizes? Surely this just creates confusion”


Why We Have Full Frame and Crop Sensor Cameras

It all comes down to economics – dollars!

When digital photography was first introduced the obvious size for a sensor was to stay with something equal to what we were all used to – and that was the 35mm film camera size.

It is this 35mm size that equates to doday’s Full Frame sensor.

However, developing a sensor of that size proved to be very expensive.

If my memory serves me right (and one can confirm this on Google) the first digital camera with this size sensor came out with 1.6 or 1.8 megapixels and cost an astronomical +/- US$20,000.00!

An image of a fistful of dollar notes depicting the difference in costs of a full frame or crop sensor camera

Holy smokes that was probably at the higher end of the annual salary scale and clearly put such a purchase out of reach of the average consumer.

Imagine coming home to your significant other and declaring “Hi love – I bought a camera for $20K to cover our camping holiday”.

Had I done that the camera would have been shoved up a very dark place never to see the light of day again – the camping trip might have been canceled too!

Clearly digital photography was not going to be a consumer product at those prices so a solution needed to be found.

That solution was to be found in reducing the size of the sensor quite substantially and hence the crop sensor was born.

Creating a smaller sensor reduced costs dramatically and yet image quality did not suffer much.

With the introduction of a smaller crop sensor digital photography became more accessible to the average household but was still relatively expensive – and still is today.

The solution to this particular dilemma is to offer a range of cameras with different capabilities (features and menus, pixels, shutter speeds, ISO options, bracketing, HDR, frames per second and a bunch of other features too numerous to discuss in detail in this post).

And so we have entry level, mid-range and top-end cameras in the cropped sensor range – everyone’s budget is catered for and camping holidays can resume!

Rightly or wrongly full frame cameras retain the status of being the “go-to” standard for professional photographers.

As with cropped sensors, full frame options abound with features designed specifically for sports, low light, portraits, landscapes and all round categories.

You can still pay a high price for a full frame camera but nowhere near as much as originally and you will most certainly get a camera with more benefits and features – 50 megapixels is not unusual these days.

Who knows where we will end up?

This post is for us mortals with just enough money to waste without being extreme so let’s press on.

Full Frame vs Crop Sensor Quality

With a reduction in sensor size comes a reduction in image quality. True or false?

The bad news is it is true but the good news is that the smaller sensors produce amazingly sharp, clear, well rendered images of a standard that it is so high that it makes little difference to 99.9999% of us.

I don’t want to go into too much technical detail here as that could take pages and pages of writing boring stuff that makes no sense to all but the really analytical among us.

There is plenty of information on the internet and probably the best place to start is with a specific search on Google for whatever   interests you.

I want to cover the more practical side of the difference between a full frame and a crop sensor.

Quality wise the average consumer, and most professionals, are more than happy with the crop sensor’s capabilities.

Obviously a full frame sensor being bigger, and therefore able to have more dots-per-inch, will produce greater detail. If that detail is important to you, as it is to say landscape photographers, then full frame is the way to go.

Another important aspect to consider is that the full frame camera will produce a greater depth of field than the crop sensor version with the same lens. The reason for this is fairly technical involving the crop factor, hyper focal length, macro range and aperture.

To end the chapter let me just say that a competent photographer will take a better photo with a full frame camera than he will with a crop sensor when using the exact same lens, set-up and subject.

Is that enough for you to spend the extra dollars on an expensive body, much more expensive lenses and embark on a steep learning curve? Only you know the answer to that.

The Conversion Factor ... also known as the crop factor

As humans we feel a need to compare apples with apples and the introduction of smaller sensors required some explaining to the average photographer.

Unfortunately knowing this semi-technical stuff, while confusing to many (me included initially), is essential, if you are to avoid expensive mistakes as explained under the ‘Crop Sensor vs Full Framed Lenses’ section below.

Crop factors have since become even more complicated with the introduction of mirrorless cameras, phone cameras and the like but for DSLR cameras where I am talking about the difference between full frame and crop sensors the conversion factor is roughly 1.5 times.

The easiest way to explain this is to say that with a crop sensor camera you will see 1.5 times more of what is in front of the camera than you will with a full frame camera with the same lens attached.

With a 50mm lens on a crop sensor camera you will see the equivalent of a 75mm lens on a full frame body.

You get more “zoom for your buck” without even asking for it!

Useful information to know when you ask someone what lens did you use (because we want to produce as good a photo – right?). If they are using a full frame camera and you have a crop sensor you need to use a different lens to achieve the same result.

And then you aren’t always going to get it right because 50mm divided by 1.5 equates to 33.33mm and there is no such animal. You will have to round up to a 35mm to get a similar result.

Crop Sensor vs Full Frame Lenses

The most important thing to remember about using lenses on the different sized bodies is that you can run into problems if you aren’t careful.

These could turn out to be very expensive problems.

  • Not all lenses are compatible between models – some lenses are designed specifically for DX (crop sensor) bodies.
  • At best if you use a crop sensor lens on a full sensor body you will get an image that has a big black circle around it – as if you were looking through a tunnel. The reason being that the lens is designed to cover an area 1.5 times smaller than the large format sensor.
  • Conversely, using a lens designed for a full frame camera will result in only the center portion of the glass being utilized but this is a wonderful thing because lenses are designed to be sharpest in the center. This is a BIG PLUS and one of the reasons I always advocate buying full frame lenses if you can afford them. Two more reasons are that good quality lenses retain their value and buying full frame now puts you in a good position to upgrade later if you decide to go that route.
  • Canon users beware of fitting a crop sensor lens on a full-frame body. They don’t fit! Pressing the shutter could damage the mirror. Just don’t take the risk.
  • Canon (and other manufacturers) have different shaped dots (or squares) on their lenses, these are used to line up your lens with your camera body. The shapes and colors are different for a reason – take the trouble to find out what those reasons are. To avoid the disaster mentioned here do not fit a Canon lens that has a white square on it to any full frame body!
  • It is quite safe to use lenses designed for full frame bodies on any crop sensor body as far as I am aware (but please check first – I would hate to think I had anything to do with you making a mistake).
  • Full frame lenses are generally of a higher quality and, while priced accordingly, are well worth the money. Buying good quality glass is a relatively easy way to improve your images on a crop sensor body; its also a good investment. New bodies continually come on the market and as soon as they do the older modelss drop in price – not so with lenses.

My Choice Between Full Frame or Crop Sensor ... a tough decision

Oooh … this is hard man.

I’d probably have to make it harder too by considering a mirrorless.

So many choices and not enough $!

But assuming the $ weren’t an issue I will take the plunge and say it would be a full frame camera – now mirrorless or DSLR?
I think I need to make a cup of tea before I do something silly.

Whilst the kettle is boiling tell me your thoughts below.

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5 thoughts on “The Difference Between Full Frame and Crop Sensor Cameras – FX and DX”

  1. I hope you got your cup of tea and didn’t do anything too silly 🙂
    I really enjoyed your post here. For you this might be second nature, but for me, this is all information that is new. I am part of the 99.9999% that wouldn’t be able to tell the difference between sensor sizes.
    Your post reminds me of some thoughts I had the other day. My husband and I got married in 2001, and one of our dearest friends bought us a camera as a wedding gift. He was a keen photographer himself. From memory, the camera was 1 megapixel, and we were so delighted! And now, our smartphones take some really impressive pictures (well to me they are impressive!)
    Anyway thanks for your post. I can tell how much you love what you do.

    • Hi Melissa. Where do I start?

      Let me start with thanking for your delightful comment. Your sincerity shines through.

      I love it when photography jogs memories even if the memory is prompted by a comment as opposed to an actual photo. Tell me did the 1 megapixel cost your friend $20K? 🙂
      And yes smartphones take amazing photos. I call it “sweet and sour” – sweet that we (the world) now take more photos than ever but sour that we only get to see them fleetingly on Facebook or other social media before they get swamped and sink.

      A quick rant – if I may. Before posting photos on FaceBook I wish people would either learn to use their flash or exposure compensation to avoid those photos where the subjects face is completely dark and the background is perfectly lit! End of rant.

      I still love printed matter.

      As you well know there are two things you have left over after a wedding – one is photos and the other is a husband, its imperative that both are excellent! 😉

      Thanks one again for commenting.

    • Hi Marisa,
      Thanks for you lovely compliment. Its always nice to know that passing on what little knowledge one has benefits someone else.
      I am continually learning new stuff every day and also realising that there is so much that I don’t know.
      Photography truly is a never-ending learning curve.
      I know you have just bought a ‘new’ Sony a7R 11 so can say with confidence that you are going to have a lot of fun with it.
      All the best


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