If a crop sensor is used, it will look like the focal length is much longer. Photographers that need long telephoto lenses can benefit from this. But instead of using a crop sensor, it is also possible to crop a full frame sensor to have the same field of view. Let's take a look at the differences.
It isn’t really that difficult. A small sensor will record only a part of the projected image of the lens you are using. A bigger sensor will record a larger part of that same projected image. A full frame sensor with the dimensions of 24 x 36 mm will have a larger area compared to a 1.5x crop sensor that measures 23 x 15 mm. But when the recorded image is viewed at the same size on a screen, the image of the crop sensor will result in a magnification of 1.5 times that of the full frame sensor.
This is why a lens on a camera with a sensor that is smaller than a full frame sensor will act as if it has a longer focal length. A 24mm the lens will act like a 36mm lens, a 50mm lens will become a 75mm lens, and a 400mm lens will imitate a 600mm lens. This is when the sensor has a 1.5x crop. If a micro 4/3 sensor is used, with a crop factor of 2x, the focal lengths will be 50mm, 100mm, and 800mm compared to its full frame cousin.
A Canon 1.6x crop camera next to a Panasonic 2x crop camera (MFT).
Use Crop Sensors When You Need a Long Focal Length
If you need long lenses for your photography, a crop sensor seems to be ideal. Because of its smaller sensor, the lenses will appear to be much longer. There are even cameras, like the Nikon Coolpix P1000, with such small sensors that its lens will act like a 3,000mm full frame equivalent. Imagine what a 3,000mm lens on a full frame would look like.
The amazing Nikon Coolpix P1000 with a full frame equivalent lens of 3,000mm
But let up ignore these superzooms with fixed lenses and look at the lens interchangeable cameras like the DSLR and its mirrorless siblings. On a 1.5x crop camera, a 400mm lens will act like a 600mm lens in a 400mm package. Put the lens on a 2x crop camera, like the micro 4/3, and it will be an 800mm lens in a 400mm package. It has a huge benefit due to its size and weight and how easily it can fit into a camera bag.
Using a 800mm lens on a full frame camera. It is not that easy to take with you.
Crop a Full Frame Sensor to Imitate a Long Focal Length
Since a crop sensor only records a part of the projection circle, it is also possible to imitate this by cropping the image of a full frame sensor. You can end up with the same image as from a crop sensor. This way, we can enlarge our subject the same way compared to a crop sensor but in the post-processing part of the workflow.
You could shoot with a full frame and crop afterwards. You could also use a crop camera. Which is the better choice?
Here is the catch. When cropping a full frame image to have a larger magnification, we throw away resolution. We lose pixels. If you want to crop 1.5x to imitate the image from a smaller sensor, you lose between 30% and 40% percent of the resolution. With the high pixel counts of modern sensors, that doesn’t have to be a problem whatsoever. You still end up with enough pixels to make large prints, if necessary.
Is a Crop From a Full Frame Sensor Better Concerning Resolution or Not?
Most crop sensors have resolutions that are somewhere between 18 million and 24 million pixels. Full frame sensors have somewhere between 24 million and 30 million pixels. Newer cameras, both crop and full frame, can have even a higher resolution.
Let’s do a little math. I am going to compare a 20-megapixel Canon EOS 7D Mark II with a 30-megapixel Canon EOS 5D Mark IV as an example. For the Canon EOS 7D Mark II, the surface area is 336 square millimeters. The pixel density is 59,500 pixels per square millimeter. The Canon EOS 5D has a surface area of 864 square millimeters, resulting in a pixel density of 34,800 pixels per square millimeter.
I shot this flying cuckoo with a 100mm lens on a full frame camera and used a heavy crop. Using a 100mm lens on a MFT camera would have the same result.
If we use a 400mm lens on both a Canon EOS 7D Mark II and a Canon EOS 5D Mark IV, and we crop the image of the latter, resulting in the same focal length or subject magnification if you will, the Canon EOS 7D Mark II has a much higher resolution. Therefore, the crop camera would record much more detail compared to the full frame camera with a post-processing crop.
What About Image Quality?
At first sight, you would think a photo from a crop sensor will show much more detail because of the higher pixel count. But there is a major downside to a lot of pixels per square millimeter. It can result in higher noise levels, especially when the ISO level is cranked up. A high noise level will result in a loss in detail.
The noise levels of a Canon EOS 7D mark II at ISO 6,400. Due to the high noise levels, some details are lost.
Which Is the Better Choice?
It all comes down to this question: what is the best thing to do? Should you choose a crop camera to benefit from the gain in focal length, or should you go for the full frame camera and use a post-processing crop?
Before I answer this question, you have to take the high resolution of full frame sensors into account. I took my Canon EOS 5D Mark IV as an example, but if you have a Sony A7R IV or a Nikon Z 7, the number of pixels per square millimeter will reach up to the same levels as the Canon EOS 7D Mark II. On the other hand, the increased resolution of the new Canon EOS 90D balances the differences again. You could calculate the difference yourself if you want.
The Nikon Z 7 is an amazing camera. I loved using it, and it has amazing resolution, allowing a decent crop without losing too much detail.
From that point of view, I would definitely recommend choosing a full frame sensor and cropping the image yourself. It will also give the flexibility of using the large field of view when using wide-angle lenses and the possibility to play with a nice shallow depth of field more easily.
From the other point of view, the smaller sensors will allow smaller cameras and lenses compared with the full frame. The micro 4/3 sensor, like in the Panasonic Lumix DC-G9, makes it so much easier to travel with long focal length lenses. And I guess that can be a real benefit for a lot of photographers. And regarding the increased noise levels compared to full frame sensors, I wouldn’t worry about that too much, unless perhaps when you need the highest ISO levels possible.
Using a 100-400mm lens on a Panasonic Lumix DC-G9 is very user friendly. Its small size makes it easy to carry with you and easy to use. The result at 400mm on this MFT camera is similar to a 800mm lens on a full frame (Photo by Hetwie - www.hetwie.nl).
If you had decided at this moment between a crop sensor or to crop a full frame image, what would you choose and why? I would love to read your experience and opinion on this subject. I think it would also be a great help for those photographers that have to make a choice in the near future.
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ISO depends on the sensor design, not sensor size. You cannot compare it like that.
Aperrture doesn't change - the same amount of light will pass through the lens - it will stay f/4, and concerning the depth of field: it won't look like an f/8 depth of field at all.
Even the focal length won't change. Only the field of view will change. And yes, it will look like a 400mm in that case. But a 400mm with f/4 and ISO800. The noise levels depends on other things than sensor size
I believe you should compare cameras by yourself.
No croping, different focal lengths, different apertures, different isos (and ideally same technology of sensor, yes).
I do compare cameras a lot. I have reviewed an extensive amount of different cameras.
Quite correct. Just to add, the noise level would depend mostly on light and there is also a matter of t-stop when comparing 2 f/4 or similar.
Oh joy! Just go out and buy a camera... any camera.... by lenses... any lenses... Now really learn how to be a photographer by understanding exposure, color management, composition, contrast, and luminosity. Then go look at the images of really good photographers. If you can, go to workshops with really well accomplished photographers. Go back and look at the great photographs that were made before digital was even conceived. Then, go take pictures... edit them... go take more pictures.... edit them.... try to improve.... go take more pictures... edit them.... have fun... make money ..... teach others... be happy....
That's the best advice today.
Well said.
Still, some things are easier to shoot if you choose the right equipment.
They used to tell me that my golf score would improve if I had better clubs; I bought new clubs, yet my golf score stayed the same. I then took lessons from a teaching pro. Then I practiced those lessons. My golf score improved with my new and old set of clubs.
I thought the comparisson would be better if said you would have used a driver only, and discovered you can make the final stroke better with a putter
;)
Ha ha ha ha ha.... some folks said never use a driver; always use a 3-wood because it is more accurate off the Tee. Some said stay away from any irons below 5. Others said use the 7 iron for a bump and run rather than a pitching wedge when you are near the green. The real problem was that I had a terrible swing. When I started to fix my swing, all of the clubs worked at least a little better... fancy that. There are a lot of photographers who don't know which lens to use for what. I'll bet that there are a lot of nature photographers who don't know how to "anticipate" the movement of wild life like a hunter and make the job easier. I went on a trip with noted nature photographer, Adam Jones, and he knew every trick in the book before picking up any camera. We were photographing penguins in Tierra del Fuego. Before we got out of the jeep he kept emphasizing that if you used a long telephoto, there was 6 and 10 chance that you wouldn't get sharp shot because of movement. He made everybody in the workshop get their shutter speeds up to ~800 by increasing the ISO because we were shooting in a 25 MPH wind . I got some really sharp pictures. Without his advice, I would have been trying to hit F11 and would have ended up with junk. It's about knowing the equipment and how to use it. Most of the world tries to solve problems with technology. Remember Osama Bin Laden evaded the U.S. for years by using messengers on motorcycles.
Knowing your equipment is important, but knowing the basics of exposure and the effect of settings on real life is also important. I don't think one prevailes, but it is the combination of knowlegde that is the key to succes. If you don't know how to use your equipment, or have the wrong choice of camera or lens, or you don't know how to enticipate the shooting conditions, your number of succesful shots will decrease.
As a workshop leader I know a lot of photographers know only one of these three things, perhaps two, but they don't make the link between these things.
Ah well. even with the "wrong" lens, or far from ideal setting, the most beautiful images can be made.
At last, someone with a brilliant outlook. I once photographed a wedding and both my camera bodies failed!. I completed the wedding with my mobile phone camera!. If you have vision and a training, you can produce awesome images with whatever gear you have. I gave my brother one of my old cameras. A Nikon D200. And an old lens I never use anymore. A Sigma 28-200. He was bitten by the bug. He took photos of everything!. Most were crap!. (we have all been there!) slowly, but surely, he did this strange thing. He learned from his mistakes!. Learned about exposure. Learned that sometimes, high dynamic range isn't always good and that deep shadows can add to an image to give a more dramatic rendition of the scene. Learned about colour and light. All with his trusty D200.
Nice story.
Thanks for sharing
Well, I'm assuming that everyone here (?) loves photography, improving their skills and is already a great photographer. I might be wrong?
Not everyone is great.... :)
Bite your tongue! (You might get hurt! lol )
Thanks for proposing a 1DXII + 300/2.8, but for my 2 days hike on a 3000m high mountain, I think my Olympus + 40-150/2.8 will do OK ;)
Needs and standards depend on the person and the situation.
It will be a good exercise. After the hike you don't need to go to the gym ;)
Cropping from a FF gives you of course more flexibility afterwards (post processing) than using the full APS-C image. All maintaining more or less the same image quality. ISO performance will only start to kick-in in very low light situations and is still depending on the quality of the sensor and processor. Some FF sensors are actually worse than some APS-C sensors.
What is a difference though is lens compression and depth of field within the same view angle. So using a 50mm focal length on an APS-C sensor will give you a FF equivalent of 75mm view angle, but maintains the compression and DOF of a 50mm. So when you crop a FF image to about the view of the 50mm, you maintain the higher compression and shallower DOF of that 75mm.
Anyway, isn't FF just a crop sensor of Medium Format? I mean, what's a 'crop sensor' anyway when everything is cropped. Let's stop considering cropped sensors as a 'poor man's version' of FF. Every format has its own benefits and draw-backs.
First of all, a FF sensor isn't a crop of a medium format. Sure, you can have a crop that is smaller than 1, but full frame is considered 36x24 nowadays.
Next, the description you mention about dof is not completely right. If you shoot with a 50mm lens on FF and crop, and you crop the FF afterwards, you end up with the same dof.
You should try it, and you will see for yourself.
The only difference in dof occurs, if you change the distance to the subject to have the same angle of view. The reason why the dof will be different in that occasion, is because you changed the distance.
Hi Nando, that's exactly my point. If you use a FF lens of 50mm and you crop afterwards to the view of 75mm, you maintain lens compression and DOF of a 50mm. Now if you use a 35mm on an APS-C (which equals a 50mm in FF in field-of-view) and then crop to a field-of-view of eq. 75mm FF (or 50mm in APS-C) you maintain the compression and DOF of a 35mm. So ending up with the same image in terms of field-of-view, but a different DOF and lens compression between the FF and the APS-C.
PS. assuming you change cameras and lenses, but maintain the same position during exposure and do the cropping in post.
My remark re. FF being a crop-sensor of Medium Format was meant playful. When you look on Wikipedia there are dozens of image formats. Many are extinct, but 10 or so remain to today. All different sizes. MFT was previously called Half Frame and FF was called small format (next to medium format). My point is that crop sensor is often used to indicate something that is inferior to FF. And it's not. It has it's own advantages as does FF and Medium Format.
I am confused. Why would you compare a 50mm on a full frame camera cropped to a 75mm field of view, with a 35mm on a crop camera and cropped to 75mm again?
You use comparable lenses for the two formats and crop them to the same field-of-view (75mm FF eq.). Then you have a similar FOV, but with different compression and DOF.
Or a better example: use a FF lens of 75mm and crop in post to 50mm FOV and compare that with a APS-C image taken with a 35mm (FF eqv of 50mm without cropping in post). You end up with the same FOV, but with different lens compression and DOF. Regardless of IQ...
But this is not what the article is about.
I am talking about using just one focal length (the same lens) on both crop sensor and full frame sensor, and cropping the full frame image to achieve the same angle of view.
If I would use different lenses on the different cameras, it isn't comparable anymore. There are too many variables.
There is one difference: the bokeh. A larger format has a smaller depth of field (DOF) than the smaller format if the same angle of view is used. E.g. FX 200mm compared to DX 125mm.
My D800E 36MP cropped to DX has the same resolution as my D7000 16MP. My D4 got 16MP. I got all three cameras profiled. So the output of the RAW processor is the same. There is only one way to distinguish between the different images besides the minor different distortion of the zoom-level: the bokeh.
Some years ago I shot the same scenery on a tripod with the same ISO, shutter speed and aperture (f/2.8). 4 images I took: 2 with the D800, FX-mode @200mm and DX-mode @125mm - one with the D7000 @125mm and one with the D4 @200mm. D800E/DX-mode @125mm, D800E/FX @200mm scaled down to DX-resolution (16MP), D7000/DX @125mm and D4/FX @200mm. The only difference visible is the bokeh. Most of the time it does not matter much. Certainly not in landscape or architecture photography, not with birds in the air (without visible background) and not with wide angle lenses.
In portrait photography it is a big deal though. I shot photos of kids in a kindergarten just this morning. The weather was bad, we had to stay indoors. There was no usable nice background and the room was not that large and full of ugly furniture blocking the view. Still, it should show where the photos had been taken. I had to shoot wide(st) open to blur the ugly window frame in the back. I arranged some nice background scenery close to the kid so one could still recognize it. The result would not have been that good if I had to shoot with a DX camera and a shorter focal length.
My pro work I only do with FX-cameras. But at any other time, I do not bother much. My D3200 with this fantastic DX 35mm f/1.8 (what a lens!) I do like very much (and the DX 18-55mm f/3.5-4.5 as well): Small, light and cheap.
You talk about bokeh, but that is just the way the unsharp part of the image will look like. Bokeh is something else than depth of field.
The only difference in depth of field you will receive, is when you change your distance to the subject to have the same angle of view. If you don't change your distance to the subject, the dof will be the same. After all, you use the same focal length on both
I know that bokeh is something else than depth of field but:
The depth of field changes with the focal length. The longer the focal length, the narrower the depth of field (with the same aperture). The narrower the depth of field, the more pronounced is the bokeh or to say it in others words, the bigger is the circle of confusion of objects before or behind the subject (that is in focus, thus has an acceptable size of the circle of confusion). (What has nothing do to with the quality of the bokeh of course).
True, in a way the depth of field is changing when you change focal length, But the focal length won't change if you use a lens on a crop sensor camera. Only the field of view is changing.
True as well, certainly! To achieve the same angle of view with DX you have to use a shorter focal length though. Cheers!
Ah, and because of the shorter focal length, the depth of field will change indeed.
But in the discussion we did not talked about changing focal length with a crop camera to achieve the same angle of view, but to crop a full frame to achieve the same angle of view with a crop.
But I guess we are talking about the same thing in different words :)
Interesting conversation. For me, weight of equipment is a big concern (due to health issues) and of course...money! I have yet to see how FF can benefit me more than my current crop sensor.
As already stated...it's about vision.
Now...I just want to upgrade my X-T1 to the new X-T4! 😁
A good reason to choose a camera with a smaller size sensor. :)
Anathore useless ff is the best and we all should buy one article. I rather use my crop camera with crop lenses. The results are more than good enough for prints of 30x40cm, social media and internet use. And it is cheaper, lighter and smaller than ff.
Nando, thank you for a very well-written article. You really took the time to explain things very methodically, and that is appreciated.
I also like the title that you used for the article - not click-baitish at all, and not an absolutist statement. That's great, because those other types of titles make me feel patronized.
As to crop vs. full frame .......
or I suppose that it would be more accurate to say, crop vs. a crop from a full frame .....
At various times over the past 13 years, I have used all 3 of Canon's DSLF sensor formats as my main body. A 1.3 crop from 2007-2008, a full frame from 2008-2010, a 1.6 crop from 2010-2013, a 1.3 crop from 2013-2019, and now a full frame again.
I will say that I definitely prefer the full frame, and that the years I didn't use a full frame was primarily because I didn't have the money for the cameras that I really wanted.
But I am a real believer in doing everything possible to ensure that you are NOT focal length challenged. Use a full frame camera but find a way to get close enough to fill the frame the way you want to, so that you don't have to crop that full frame image.
If you can't get close enough, and you will have to crop, then perhaps it is best to just sit back and enjoy the wildlife and not take photos until you can fill the frame properly.
That's the way I really feel about this topic, as it absolutely kills me to have to crop into an image. Many other wildlife photographers feel differently, but for me, I have the mindset of, "if you can't fill the frame the way you really want, then don't bother taking the shot at all."
Thanks for the comment, Tom. Appreciate it.
All these comparissons are a bit foolish, I think. Although I like to write about it. But in most occasions people have just one camera, and if you learn to use it with the lenses you have it doesn't matter what size the sensor is. The difference becomes only clear when you compare both side by side.
I used the Canon 1,6crop, the 1,3crop and full frame myself, and I could shoot everything with all three sensor sizes.
It is a pity some still believe you have a handicap when not using full frame.
Actually, I know a heck of a lot of wildlife photographers - dozens and dozens of them. And I don't believe that a single one of them has only one camera. All of the wildlife photographers that I know personally have multiple bodies that are all fairly recent and quite capable.
I'm sure that somewhere there is a very casual hobbyist who photographs wildlife and has only one camera, but I have never met such a person in all my years of traversing about the country photographing wildlife.
We wildlife photographers all seem to have an embarrassment of riches when it comes to gear.
I agree totally with your last point...Get close...Use your feet, longer FLs, TCs, Higher-res sensors or whatever...That was one of my main reasons to get a D850 since it does give me more room than a D5 or the crop sensors with the same lens. The thought and maths was fine, but, my mindset remained the same, I still try and fill the frame :)
who cares about size? we care about high iso noise. Simple.
Some people care about size.
What medium format camera do you use?
Boom !
We? You can only speak for yourself, or course ;)
Well you don't know "we".
Well, I don't belong to your "we" ;)
No, Vik, many of us do care very much about sensor size. Sensor size directly affects how much of the projected image we capture, and the angle of view that we include in the frame. This is an extremely important consideration. Anyone who has a lot of experience using various sensor sizes fully realizes the importance of sensor size. Those who have little experience, or who are "armchair quarterbacks" may dismiss sensor size as unimportant, because they are not actually doing any meaningful photography of their own.
I don't believe most professionals care about sensor size that much. They just buy the gear that will do the job. The discussions about these things are mainly by enthousiastic amateurs and people who just care about gear.
use a zoom lens on a full frame
crop-as-you-go
Why not use a zoom lens on a crop camera ;)