Crop sensor - extra reach?

Steve

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I've tried to search for this but can't seem to find a definitive answer.

I've seen several posts saying a crop sensor is better in some situations such as sport and wildlife photography for the extra reach given.

I understand this. But my confusion is that surely the larger sensor of the full frame would enable the picture to be cropped more to replicate the extra reach of the crop sensor?

So in my mind there is no difference...the extra reach of the crop is replicated by the extra ability to crop in a full frame. So the end result is the same?

Or have I missed something or being too simplistic?
 
I'll try and explain my understanding (I'm not great at this type of explanation) ...

Pixel density has a role to play - if both cameras have the same Mp rating, e.g. a D300 and a D3 both are 12 MP - then the D300 will put more pixels on the object for a given focal length than the D3, so if you were to crop the D3 to the DX size the D3 crop will have less pixels.

If you were to take a D7000 and a D800 though and do the same exercise then then end product would be virtually the same as the D800 in DX crop is around 15.5MP and the D7000 is 16MP.

I think that if the MP are the same or similar then the crop will have the advantage of putting more pixels on the target than the FF will.
 
Paul has pretty much nailed it, pixels on target.

My 5D3, when cropped to the same area as the 7D it replaced, produces an 8ish MP image whereas my 7D was 18mp.

HOWEVER there is a caveat. While you might get more aparrent detail from a high pixel density crop camera, the level of detail recorded by a full frame sensor is really quite remarkable.

Printed up to A4 - and even above - I'm not sure I would want the task to telling the two shots apart.
 
Steve said:
I've tried to search for this but can't seem to find a definitive answer.

I've seen several posts saying a crop sensor is better in some situations such as sport and wildlife photography for the extra reach given.

I understand this. But my confusion is that surely the larger sensor of the full frame would enable the picture to be cropped more to replicate the extra reach of the crop sensor?

So in my mind there is no difference...the extra reach of the crop is replicated by the extra ability to crop in a full frame. So the end result is the same?

Or have I missed something or being too simplistic?
Click to expand...

Steve, I think I understand your question, i can see what you meant.

Before digital camera and their crop sensors. In the days of film cameras. After printing the photograph, sometimes the photographer (or editor) would say: "Too much background around the subject. Let's crop in closer." so they go back to the darkroom and used the enlarger to zoom in closer.

So with digital cameras, yes, if you have a full frame camera like the Nikon D4, of course, you can upload the picture to a computer, look at it, and say: "Too much background around the subject. Let's crop in closer." So you used crop tools to outline a box around the subject, and crop in, then print the photo.

But that is not what they are talking about when using crop sensor's extra reach to get in closer to the subject. They are talking about taking advantage of the crop sensor's ability to turn a lens into a longer lens.

For example: A 300mm lens on a full frame sensor like the D4 would be a 300mm lens. But a 200mm lens on a crop sensor camera like the D1 would turn the 200mm into a 300mm because of the 1.5x crop factor. 200 x 1.5 = 300. So a 300mm on a crop sensor acts like a 450mm lens, a 500mm on a crop sensor acts like a 750mm lens. That is the crop they are talking about that they find useful for close in on action and wildlife because of the extra reach.

It's like if you put a 200mm on a full frame camera and took a photo of a bird or any other wildlife, then print the photo, you may look at it and say: "Too much background, let's crop in closer." But...

If you put the same 200mm on a crop sensor, then take the photo and print it, you may find that you seems to have got zoomed in much closer. So there is no need for 'darkroom cropping' because the 200mm on a crop sensor acted like a 300mm.

Either way, if you use a full frame or a crop sensor, and took a photo of a subject far away, of course there would still be some unwanted stuff that shows up around the subject, like a foot at the edge of the photo because someone just about walked into your view, so you used the computer to crop that part off, like you would with darkroom work. Full frame or crop sensor, either way, we would still use crop off unwanted parts and refreame the photo on computer.

That crop that gives the extra reach, is really all about taking advantage of the crop's turning the lens into longer one.

Hope that gives you answers?
 
As Paul said, you can end up with a lot less pixels depending on the cameras you're comparing. A Nikon D3 has 12mp and a D300 has 12mp, if you crop the D3 image to get the same as what came out of the D300 you're left with 5mp. And if you're trying to match an image that was cropped a little more while editing, you'd have even less pixels to play with.

A D800 starts with 36mp, but leaves you with 16mp when in DX/cropped mode. Still loads of pixels, and comparable to a D7000, but the D7100 has 24mp, so you're losing 8mp in that comparison.

You also get the benefit on DX/cropped camera of the subject filling the viewfinder, whereas in cropped mode on an FX/full frame camera, you have to keep your subject in a small central section of the frame.

You get a benefit for distant subjects with a cropped sensor camera, but lose out on wide angles. :shrug: Swings and roundabouts.
 
Thanks for the replies.

Yes...that now makes sense to me :)
 
I do remember the days when I had film camera but did not have the money to buy anything longer than 300mm, I only had the 70-210mm zoom, and when I took photos, I find there is too much background surrounding the subject, so I used darkroom enlarger to crop in closer.

Had I used a digital camera with a crop sensor, my 210mm would have became (unless my maths is rusty) 320mm, then I would have found my photo to look like it is framed much closer on the subject, making me feel like there is no need to use 'darkroom enlarger' to crop in closer.

But of course, either way, there may still be something on the side of the picture that seems to keep catching the eye, which needs to be cropped off, so...

In darkroom, I would use the enlarger to zoom in closer on the subject and crop off unwanted items.

With crop sensor photos on computer, of course I would still use the crop tool to crop off unwanted items even if it still feels closer in.

So of course, for some with crop sensor cameras, they will still do some cropping on the computer. So there's still no different.
 
IMHO far too much is made of this cropped sensor issue, for a given pixel density all that changes is the bit of the image that is recorded. Every thing else is the same.
 
there are some great answers here. i use a crop camera and see the diference as a narrower field of view. i was shooting the same subject at the weekend with a friend who was using a full frame D800 compared to my crop D7100, both using the same 300mm lens. the difference was the amount of space around the subject,i had frame filling bear images whilst he had a bear in its environment. to get the same image composition as him i had to use a zoom lens at 200mm.

to compare the two it all depends on the amount of pixels for the field of view/area of the image. the distance the subject is away from you matters too, sometimes a subject can just be to close for a crop camera or too far away for a full frame camera.
 
paulminus273 said:
IMHO far too much is made of this cropped sensor issue, for a given pixel density all that changes is the bit of the image that is recorded. Every thing else is the same.
Click to expand...

It's pretty rare to do a direct comparison between a crop body and a full frame with the same pixel density so that slightly simplistic view doesn't work in real life comparisons. You're more likely to compare crop to full frame sensors that are both of similar resolutions, in which case it can make a huge difference.

Just a very quick mention with regard to Major Eazy's post. The focal length of a lens never changes, a 200mm lens on a crop sensor is still a 200mm lens, what changes is the field of view to give the effect of a longer lens. :)
 
There's one key point missing from the above.

When an image is cropped, by whatever means, it requires a greater degree of enlargement for a given print/ouput size. This demands higher resolution from the lens, and when resolution goes up, so image contrast goes down. This is basic optical physics, and contrast generally contributes more to perceived sharpness than sheer resolution, ie if the detail is so feint that you can't see it, it's not much use.

This is the main reason why full-frame cameras deliver higher image quality than croppers - they simply allow the lens to perform better.
 
PMN said:
Just a very quick mention with regard to Major Eazy's post. The focal length of a lens never changes, a 200mm lens on a crop sensor is still a 200mm lens, what changes is the field of view to give the effect of a longer lens. :)
Click to expand...

This.
The back of a lens will project the same image into the camera regardless of whether it's attatched to a full or crop sensor camera. As the crop sensor is smaller it will not pick up as much of the projected image. This is the same as taking the output from the full frame camera and cropping the sides. There is no change of focal length. The cropping by the sensor only changes the field of view.
This takes us back to the original question.
Simple answer, if the full frame camera has a high enough resolution to crop and leave you with the same resolution as the crop camera then it's pretty much the same thing.
At the top end of crop cameras (for Canon,) is the 7D at 18Mp which costs ~£1000 new. Considering the crop factor, this would leave you looking for a full frame camera with 46Mp*. At the top end of full frame cameras you'd be looking at the 5Diii at 23Mp which doesn't come close and costs ~£2300. I expect other makes to be similar.
For the more complete answer, there are other factors involved which are covered above.
I would add that full frame has the advantage with cleaner higher iso settings allowing faster shutter speeds without the high iso noise.
(EFA. I forgot to square the crop factor for the increase in area 18Mp * 1.6 * 1.6 = 46Mp.)
 
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Andy_S said:
This.
The back of a lens will project the same image into the camera regardless of whether it's attatched to a full or crop sensor camera. As the crop sensor is smaller it will not pick up as much of the projected image. This is the same as taking the output from the full frame camera and cropping the sides. There is no change of focal length. The cropping by the sensor only changes the field of view.
This takes us back to the original question.
Simple answer, if the full frame camera has a high enough resolution to crop and leave you with the same resolution as the crop camera then it's pretty much the same thing.
At the top end of crop cameras (for Canon,) is the 7D at 18Mp which costs ~£1000 new. Considering the crop factor, this would leave you looking for a full frame camera with 28Mp. The closest would be the 5Diii at 23Mp but that costs ~£2300. I expect other makes to be similar.
For the more complete answer, there are other factors involved which are covered above.
I would add that full frame has the advantage with cleaner higher iso settings allowing faster shutter speeds without the high iso noise.
Click to expand...

It's much higher than that. Full frame is more than double the image area of APS-C. Difference in pixel count is crop factor squared, 1.6x1.6=2.56, so 7D's 18mp x 2.56 = 46mp equivalent on full frame.

This illustrates just how much harder lenses have to work on smaller sensor formats to deliver the same standard of sharpness, and they just can't do it. Bigger is always better for sharpness, and within reason, pixel count hardly comes into it. Also, because more than double the amount of light is collected on full frame, ISO performance is better too.
 
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We can throw in lots more red herrings :-
Circles of confusion
Viewing distance of out put
Type of out put
Lens design
Type of glass used in the lens
Sensor design
Camera firmware
Ect
But my statement still holds true
 
paulminus273 said:
IMHO far too much is made of this cropped sensor issue, for a given pixel density all that changes is the bit of the image that is recorded. Every thing else is the same.
Click to expand...

paulminus273 said:
We can throw in lots more red herrings :-
Circles of confusion
Viewing distance of out put
Type of out put
Lens design
Type of glass used in the lens
Sensor design
Camera firmware
Ect
But my statement still holds true
Click to expand...

So what was previously your opinion is now fact?

And all those folks shooting full frame have wasted a lot of money.
 
“far too much is made of this cropped sensor issue” is still my opinion

Without making proportional investments in the other areas such as good quality lenses suitable output yes folks have wasted a lot of money on full frame
Also not all full frame is expensive 6mp fx cameras can be obtained for less than a modern dx the results may not be better than a state of the art dx but are still fx


edit

As an addition good photographers can produce better images than me with c**r equipment however my knowledge of optics is founded in many years of design and development in the field
 
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paulminus273 said:
Without making proportional investments in the other areas such as good quality lenses suitable output yes folks have wasted a lot of money on full frame
Click to expand...

If that's your opinion then I'd guess you've never spent serious time shooting with a full frame camera. ;)

paulminus273 said:
As an addition good photographers can produce better images than me with c**r equipment however my knowledge of optics is founded in many years of design and development in the field
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Who's talking about optics? :thinking:
 
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PMN said:
If that's your opinion then I'd guess you've never spent serious time shooting with a full frame camera. ;)



Who's talking about optics? :thinking:
Click to expand...

I have used fx and mf kit enough, I currently use a d7000 with a 24-70 2.8, take a modern fx put c**p glass on it and see which has the better IQ or take a 6mp old dx and put the 24-70 on it and see which has the better IQ.


Hoppyuk talked about optics

However my statement still holds true all the rest of the debate muddies the water as to understanding the lack of difference made to things like focal length, angels of convergence and DOF
 
paulminus273 said:
IMHO far too much is made of this cropped sensor issue, for a given pixel density all that changes is the bit of the image that is recorded. Every thing else is the same.
Click to expand...

Paul, this is untrue and it's unhelpful to claim otherwise.

Take say a Nikon D300 and D700, same pixel count and same generation technology, but different formats, and shoot them side by side. The superior full frame image quality stands out a mile. Or take a Canon 7D and 5D2, also very similar, and you'll get the same.

Format size matters, it's fundamental, and if it was just down to pixel count we'd all be shooting with compacts.

On the other hand, if you were to say that crop format DSLRs are perfectly 'good enough' for most things, even quite critical work, then you'd have a better argument.
 
paulminus273 said:
take a modern fx put c**p glass on it and see which has the better IQ or take a 6mp old dx and put the 24-70 on it and see which has the better IQ.
Click to expand...

Or take the same lens and put it on two newer bodies so we at least have the basis of a fair comparison. ;)

HoppyUK said:
Or take a Canon 7D and 5D2, also very similar, and you'll get the same..
Click to expand...

Exactly, a decent standard lens will probably give sharper results on my 5D2 than any of my L series lenses will on my 7D if we're looking at straight out of the camera 100% crops.
 
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You make my point dx is not an automatic improvement
Also my statement still hold true
 
Will an old 6mp dx will C**p glass outperform your APS-C with good glass if not sensor size dose not automatically improve IQ
 
paulminus273 said:
Will an old 6mp dx will C**p glass outperform your APS-C with good glass if not sensor size dose not automatically improve IQ
Click to expand...

Maybe, maybe not. It's such a massively vague question I don't really see how I can answer it but you're missing the point. The question should be will the same lens perform better on a full frame DSLR than a crop one and the answer will almost always be yes, my point of a lesser lens on the full frame and a high end lens on the crop was merely intended to highlight how big a difference it is between the two.
 
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The question was about the difference in reach between fx and dx and the answer is none it only the crop that is changed
 
paulminus273 said:
the op question:bang:
Click to expand...

I know what the original question was, I was just trying to decode your writing.

The original post was regarding the difference in reach but the discussion shifted slightly when you started saying silly things like this:

paulminus273 said:
Without making proportional investments in the other areas such as good quality lenses suitable output yes folks have wasted a lot of money on full frame
Click to expand...
 
Thanks for the replies all.

I thought I understood this, but am now a bit confused.

Was hoping someone could help with a practical example. Say I want to take a telephoto picture of a bird a distance away. I have one 200mm lens that works on both my D300 and D700, both of which have same pixel count

By using it on the D300 I get extra reach so the bird fills the frame and no cropping is needed. By using the D700 I have to crop PS to get the bird to fill the frame.

Put these 2 pictures side by side and is one better than the other or are they the same?
 
If you need the reach then the crop camera is probably the better of the two, I do a lot of aviation photography and the crop factor of my 7D can definitely work for me sometimes in getting me a bit closer. :)
 
Steve said:
Thanks for the replies all.

I thought I understood this, but am now a bit confused.

Was hoping someone could help with a practical example. Say I want to take a telephoto picture of a bird a distance away. I have one 200mm lens that works on both my D300 and D700, both of which have same pixel count

By using it on the D300 I get extra reach so the bird fills the frame and no cropping is needed. By using the D700 I have to crop PS to get the bird to fill the frame.

Put these 2 pictures side by side and is one better than the other or are they the same?
Click to expand...
The DX crop from a D700 is around 5MP iirc. The D300 has a higher pixel density. The focal length doesn't change, but the field of view does.
 
Steve said:
Thanks for the replies all.

I thought I understood this, but am now a bit confused.

Was hoping someone could help with a practical example. Say I want to take a telephoto picture of a bird a distance away. I have one 200mm lens that works on both my D300 and D700, both of which have same pixel count

By using it on the D300 I get extra reach so the bird fills the frame and no cropping is needed. By using the D700 I have to crop PS to get the bird to fill the frame.

Put these 2 pictures side by side and is one better than the other or are they the same?
Click to expand...

In this case, the D300 shot should be better, because the lens is working exactly the same in both images, but the D300 puts more pixels over the bird (assuming the lens has enough resolution to make use of them). That's pixel-reach.

However, if you have a 200mm lens on the D300 and a 300mm lens on the D700, you will have the same framing and the same number of pixels but the D700 image requires less enlargement to make the same print/output size, so the lens will be working at a higher contrast level and that means a sharper image.

This is basic Modulation Transfer Function theory, simply this - when resolution demands go up (ie higher pixel density) then image contrast goes down. That's why larger formats are always better (all other things being equal) because they allow the lens to work better.

Generally, if you need more reach, then the best option is to get a longer lens. If that's not possible, then a teleconverter might do the trick, both options deliver optical-reach. Then if all else fails, try cropping (pixel-reach).
 
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PMN said:
I know what the original question was, I was just trying to decode your writing.

The original post was regarding the difference in reach but the discussion shifted slightly when you started saying silly things like this:
Click to expand...

It is only silly if you believe that an pro level camera will produce great IQ with any rubbish lens
 
This subject has confused me before...:bang:

After reading through everything I can safely say I know very little about technology and think I need to :bonk: as now even more confused :cuckoo:

So...for my simple brain..
Say a 200 EF lens on my crop sensor giving an image that would be equal to a 320mmEF-S lens, am I right there?
If so how would an image on a full frame using a 100-400 EF lens set at 320mm be better quality than my crop sensor using a 200 EF lens?
I'm sure the answer is already here somewhere but I just can't work it out :bang: :bang:
 
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paulminus273 said:
It is only silly if you believe that an pro level camera will produce great IQ with any rubbish lens
Click to expand...

At this point I genuinely can't work out whether you're still honestly missing the point of what's being discussed here or whether you're trolling. Who said they believed a pro camera will give great IQ with any rubbish lens?

This is getting very, very stupid.
 
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HoppyUK said:
...However, if you have a 200mm lens on the D300 and a 300mm lens on the D700, you will have the same framing and the same number of pixels but the D700 image requires less enlargement to make the same print/output size, so the lens will be working at a higher contrast level and that means a sharper image....
Click to expand...
Richard can you explain this for me please? I don't understand the less enlargement bit, are you talking output here?
 
HoppyUK said:
Paul, this is untrue and it's unhelpful to claim otherwise.

Take say a Nikon D300 and D700, same pixel count and same generation technology, but different formats, and shoot them side by side. The superior full frame image quality stands out a mile. Or take a Canon 7D and 5D2, also very similar, and you'll get the same.

Format size matters, it's fundamental, and if it was just down to pixel count we'd all be shooting with compacts.

On the other hand, if you were to say that crop format DSLRs are perfectly 'good enough' for most things, even quite critical work, then you'd have a better argument.
Click to expand...
My point is pixel density,
Ie 10mp Nikon dx and a 24mp Nikon fx of the same generation ( if that is possible) with the same lens
Crop the fx image down to the same size and place as the dx, the images would be identical.

If you use the same pixel count but a 200mm on dx and 300mm on fx there would be a number of differences in the image, DOF converging angels in fact a noticeable difference in look
 
Martyn D said:
This subject has confused me before...:bang:

After reading through everything I can safely say I know very little about technology and think I need to :bonk: as now even more confused :cuckoo:

So...for my simple brain..
Say a 200 EF lens on my crop sensor giving an image that would be equal to a 320mmEF-S lens, am I right there?
If so how would an image on a full frame using a 100-400 EF lens set at 320mm be better quality than my crop sensor.
I'm sure the answer is already here somewhere but I just can't work it out :bang: :bang:
Click to expand...

Try this analogy: a fast car might accellerate from 0-60 in 6 seconds, but it won't accellerate from 0-120 in 12 seconds, more like 20 seconds, because the faster you go, the harder it gets.

Lenses are the same, and the more resolution you ask them to deliver, the less contrast they produce, ie the detail may be there, but it's so feint you can't see it.

A crop format camera's sensor is a bit less than half the area of full frame (the difference is the crop factor squared) so if it has the same number of pixels as full frame, they're half the size and packed in twice as tight. This puts much greater demands on the lens and is the main reason why full frame produces better image quality.
 
Martyn D said:
This subject has confused me before...:bang:

After reading through everything I can safely say I know very little about technology and think I need to :bonk: as now even more confused :cuckoo:

So...for my simple brain..
Say a 200 EF lens on my crop sensor giving an image that would be equal to a 320mmEF-S lens, am I right there?
If so how would an image on a full frame using a 100-400 EF lens set at 320mm be better quality than my crop sensor using a 200 EF lens?
I'm sure the answer is already here somewhere but I just can't work it out :bang: :bang:
Click to expand...

If we pretend that the pixel count is the same, and the lenses are of equal quality, the ff image will be better because its being enlarged less for the final output size.

In reality, the pixel size will favour the ff camera too. Obviously all other things being equal the smaller pixels require greater amplification so will produce more noise.

However, if both lenses were designed for ff, the crop camera is using only the central portion of the lens, **** is likely to be sharper, definition reduces towards the edges.

You see how there's no such thing as a generalisation, but there sort of is anyway:thinking:
 
Guys, you're not getting this lens Modulation Transfer Function thing. Those squiggly graphs lens manufacturers produce show MTF - that is sharpness, eg here http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_300mm_f_4l_is_usm

Sharpness has two components - resolution (the fineness of detail) and contrast (how clearly those details are shown). It's no good having one without the other and sheer resolution (call that high pixel density) is no use if the detail is so feint (low contrast) that it's hard to see. Actually, contrast contributes more to perceived sharpness than resolution.

A fact of optical physics is that when resolution goes up, so contrast goes down. Check out that graph linked above (or any MTF graph). Don't worry about the detail of it, but note how clearly there are two groups of lines, one above the other. The top group is lens contrast at 10 line-per-mm, and the one below is at 30 lpmm, ie image contrast has dropped and sharpness is reduced.

You can't go throwing more and more pixels on to a sensor, getting ever smaller and smaller, and expect the lens to render them all the same. It can't happen.
 
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