Picture size.

[Karl Egressy]

It has probably been discussed several times before.
My questionis; how does actual picture size compare to say taken with a 1.25 crop versus 1.0 crop (full frame) given the fact that both cameras produce equal say 16.2 Mp images.
Is it a misconception that a crop camere produces more "close up" images with the same lengt of lens for example using a 500 mm lens?

Thank you for your answer or link provided.
Karl.

[Jim Neiger]

Karl, if you photograph the same subject from the same distance with both cameras, the subject will appear larger in the crop camera photo. It is likely, however, that the full frame camera will produce a higher quality image that may hold up better when cropped in post processing. The quality advantage may or may not produce a better end result than the crop advantage. It depends on the cameras, the conditions when photos were made, camera settings, and post processing. If you read Arash's 1d4 vs 1Dx review, you will get a clear idea of all that is involved.

[Karl Egressy]

Karl, if you photograph the same subject from the same distance with both cameras, the subject will appear larger in the crop camera photo. It is likely, however, that the full frame camera will produce a higher quality image that may hold up better when cropped in post processing. The quality advantage may or may not produce a better end result than the crop advantage. It depends on the cameras, the conditions when photos were made, camera settings, and post processing. If you read Arash's 1d4 vs 1Dx review, you will get a clear idea of all that is involved.
Thanks, Jim. I will read the article.
I shoot with 1D MIV most of the time and with 7D for the rest of the time.
As the price of the 5D MIII started dropping and the new 7D is going to hit the market relatively soon, I will have to make up my mind as to which direction to move to.
I'll keep the 1D MIV as I just LOVE that camera.

[DickLudwig]

Karl, when comparing 1.3 crop, to a 1.6 crop, to a full frame other than the obvious size differences you need to consider the quality of the sensor. From all reports I've read the 1Dx has a terrific sensor which provides superior image quality compared to older generation Canon sensors. The 5D III appears to have improved quality as well but not quite in the same league as the 1Dx. I would assume that the 7D II will also boast an improved sensor in all likelihood better than the 5 D III although noise (at higher ISO's) while improved may still be somewhat of a problem due to small pixel size (assuming a similar or higher pixel density to the current 7D). Whether Canon can match the latest Sony sensors (as far as DR and noise are concerned) remains to be seen but I wouldn't hold my breath.

[Roger Clark]

There seems to be continual confusion about crop factor.

I agree with Jim that in a crop camera at the same distance and with the same lens, the subject will appear larger in the frame relative to the frame size. That, however, does not necessarily mean you will have more pixels on the subject with the crop camera, and whether or not the image has higher quality in either camera is dependent on several factors. For example, one could have a crop and full frame cameras with the same pixel pitch. In fact just such a case is a full frame Canon 5D mark II and a 1.6x crop Canon 30D: both have a pixel pitch of 6.4 microns and will deliver the same pixels on subject. If the sensors were the same vintage (they are not), the images would have the same image quality.

More on this topic:
http://www.clarkvision.com/articles/cropfactor
Figure 2 shows the situation Jim discusses.

Usually crop cameras have a smaller pixel pitch. Pixels chop up the light in the focal plane to resolve detail on the subject. For a given lens, distance and exposure time, the pixels chop up the image into small pieces to resolve more detail. Smaller pieces (smaller pixels) mean less light per pixel, which means lower signal-to-noise ratio (SNR). Which image (fewer pixels with higher SNR or more pixels on the subject with lower SNR depends on the image, the noise levels and one's tolerance for noise (individual perception). With good SNR, the smaller pixels pretty much always will produce the more detailed and pleasing image. I attach an example of the Moon images made with 4 cameras (1DII, 5DII, 1DIV, and 7D). Which image do you perceive as the highest image quality? For me, it is the 7D. Note the 1DX has 6.9 micron pixel pitch so will fall between the 5DII and 1DII images.

If you have a camera with large pixels, and want the detail that camera with smaller pixels gives, you need more focal length to get the same pixels on subject. For example, to get the same detail on the attached Moon image as in the 7D image, a 1DX would need 1.6 times the focal length. So you spread out the light more and your SNR drops to the same level as that of the camera with smaller pixels. This is a well known concept in optical system design called Etendue ot A-Omega product. There is no free lunch. Larger pixels with lower resolution and higher SNR, versus smaller pixels with more resolution and low SNR. Resolution and pixels are a combination of pixel size and focal length.

Now if you can change your distance to the subject to get closer, or use a larger lens, you gather more light. The full frame sensor has the advantage if one can get closer to fill the frame, or use a larger lens. For example a 1DX + 600 f/4 beats out a 1DIV + 500 f/4 because the 600 f/4 lens has a larger aperture and collects more light. A 1DX with a 500 would also beat out a 1D4+500 if the 1DX moved closer to fill the frame: closer means more light collected from the subject (the 1/squared distance law).

More reading:
http://www.clarkvision.com/articles/telephoto_reach/
http://www.clarkvision.com/articles/telephoto.system.performance/

If one is limited by pixels on subject, buying a camera with larger pixels will not help. In fact, one can combine pixels and reduce noise. So, for example, a 7D with its 4.3 micron pixels: do 2x2 averages and make the equivalent of 8.6-micron pixels with better noise per pixel. That is illustrated here (see figures 6, 7, 8):
http://www.clarkvision.com/articles/pixel.size.and.iso/
But, of course, you lose resolution on the subject.

Now another confusing factor in camera comparisons with different sized pixels is the strength of the blur filter. Two cameras with different pixel sizes and different strength blur filters can be made to look closer or further apart. It seems that Canon has had a tendency to reduce the strength of the blur filters with newer models. The 1DII, for example, had a very strong blur filter, thus making the images softer.

Bottom line in my opinion, the 7D and 1DIV is a great combination. If you are focal length limited with these cameras, moving to camera with larger pixels will not help (it will hurt). However, also consider the reported better AF system in newer cameras like the 1DX. If you can get the pixels on your subject (have enough focal length), but are having issues with AF performance, than an upgrade could help.

Roger

[Karl Egressy]

There seems to be continual confusion about crop factor.

I agree with Jim that in a crop camera at the same distance and with the same lens, the subject will appear larger in the frame relative to the frame size. That, however, does not necessarily mean you will have more pixels on the subject with the crop camera, and whether or not the image has higher quality in either camera is dependent on several factors. For example, one could have a crop and full frame cameras with the same pixel pitch. In fact just such a case is a full frame Canon 5D mark II and a 1.6x crop Canon 30D: both have a pixel pitch of 6.4 microns and will deliver the same pixels on subject. If the sensors were the same vintage (they are not), the images would have the same image quality.

More on this topic:
http://www.clarkvision.com/articles/cropfactor
Figure 2 shows the situation Jim discusses.

Usually crop cameras have a smaller pixel pitch. Pixels chop up the light in the focal plane to resolve detail on the subject. For a given lens, distance and exposure time, the pixels chop up the image into small pieces to resolve more detail. Smaller pieces (smaller pixels) mean less light per pixel, which means lower signal-to-noise ratio (SNR). Which image (fewer pixels with higher SNR or more pixels on the subject with lower SNR depends on the image, the noise levels and one's tolerance for noise (individual perception). With good SNR, the smaller pixels pretty much always will produce the more detailed and pleasing image. I attach an example of the Moon images made with 4 cameras (1DII, 5DII, 1DIV, and 7D). Which image do you perceive as the highest image quality? For me, it is the 7D. Note the 1DX has 6.9 micron pixel pitch so will fall between the 5DII and 1DII images.

If you have a camera with large pixels, and want the detail that camera with smaller pixels gives, you need more focal length to get the same pixels on subject. For example, to get the same detail on the attached Moon image as in the 7D image, a 1DX would need 1.6 times the focal length. So you spread out the light more and your SNR drops to the same level as that of the camera with smaller pixels. This is a well known concept in optical system design called Etendue ot A-Omega product. There is no free lunch. Larger pixels with lower resolution and higher SNR, versus smaller pixels with more resolution and low SNR. Resolution and pixels are a combination of pixel size and focal length.

Now if you can change your distance to the subject to get closer, or use a larger lens, you gather more light. The full frame sensor has the advantage if one can get closer to fill the frame, or use a larger lens. For example a 1DX + 600 f/4 beats out a 1DIV + 500 f/4 because the 600 f/4 lens has a larger aperture and collects more light. A 1DX with a 500 would also beat out a 1D4+500 if the 1DX moved closer to fill the frame: closer means more light collected from the subject (the 1/squared distance law).

More reading:
http://www.clarkvision.com/articles/telephoto_reach/
http://www.clarkvision.com/articles/telephoto.system.performance/

If one is limited by pixels on subject, buying a camera with larger pixels will not help. In fact, one can combine pixels and reduce noise. So, for example, a 7D with its 4.3 micron pixels: do 2x2 averages and make the equivalent of 8.6-micron pixels with better noise per pixel. That is illustrated here (see figures 6, 7, 8):
http://www.clarkvision.com/articles/pixel.size.and.iso/
But, of course, you lose resolution on the subject.

Now another confusing factor in camera comparisons with different sized pixels is the strength of the blur filter. Two cameras with different pixel sizes and different strength blur filters can be made to look closer or further apart. It seems that Canon has had a tendency to reduce the strength of the blur filters with newer models. The 1DII, for example, had a very strong blur filter, thus making the images softer.

Bottom line in my opinion, the 7D and 1DIV is a great combination. If you are focal length limited with these cameras, moving to camera with larger pixels will not help (it will hurt). However, also consider the reported better AF system in newer cameras like the 1DX. If you can get the pixels on your subject (have enough focal length), but are having issues with AF performance, than an upgrade could help.

Roger

Thanks Roger for the informative description and the images. I think I'll wait until the new 7D hits the market and make up my mind based on that.
The only problem with the current 7D I have is that it cannot be used in low light.