Image sharpness and pixel density - Canon EOS 7D

[Filippo]

Hallo. This is my first post here and I hope it will be helpfull for the community.


Let me briefly introduce myself: My name is Filippo, I live in Italy (Piemonte, northern Italy, very close the Alps, on a lake called "Maggiore"). My gear is EOS 5D MkII and now a 7D with some nice lenses...


I bought the EOS 7D essentially to use it with a 100-400 L lens and a 300 lens from Canon, to take pictures of animals and birds. The images of this camera appears defenitely soft. I notice that to get right images in good sharpness I have to increase considerebly the shutter speed. This is for two essential reasons: first is the "crop factor", second is the too high pixel density of the sensor that amplifly the camera shaking, and results as Micro-shaking that delivers as a consequence a not sharp image.


As a rule of thumb I currently use as a minima, the double of the current lens focal lenght as basic shutter speed (not considering Image stabilizers or similar devices). For istance, if you are using a 300mm lens, I use 1/600sec as a start. Normally even higher if I use the camera to follow an animal. This unfortunately force me to increase the ISO and, as a consequence the noise.


Tell me if you are having similar experience with this Camera, that could be perfect if Canon didn't push too much the pixel count. Having more resolution is nice, but it becomes very hard in the "field use".


Cheers


Filippo

[SteveR]

I noticed this shake susceptibility when I changed from a 30D to a 50D. I am not that impressed with the noise levels that ensue, anything over 200 ASA is unusable at 100% crop for landscapes with any grey in them. However, I suppose that on the flipside you are forced to use a tripod, which of course I should be doing anyway.....

[alexniedra]

Welcome to the forum! []


Thanks for sharing your experience with us - I am sure many in the forum will find this information very helpful. Unfortunately, I do not have hands-on experience with the 7D, so I cannot comment on the high-ISO performance of the 7D in real world use.


I really think your "on the safe side" approach to shutter speeds is very good and will increase your keeper rate when you are shooting wildlife. I think that using a shutter speed denominator equivalent to double the focal length is a great rule of thumb, especially when shooting fast-moving wildlife. I too can be very unsteady when tracking fast-moving subjects. Out of curiousity, which 300mm lens are you using? The 300mm f/4L IS? 300mm f/2.8L IS?

[Filippo]

I have the 300 f4, but I'm planning to get the 2,8 next month. Anyway I'll keep the f4 because is very old and I'll not get too much money if I sell. Furthermore is a joy when I travel because is very compact and light, and for close-ups (focusing distance better than 2,8). But the 300 f 2,8 "IS" THE 300

[EdN]

I just picked up my 7D just a few weeks ago and I'm still going up the learning curve. On my first batch of shots, I thought I noticed softness compared the 5D MkII but that was using a 300 F4L IS with a 1.4X Extender shooting at a moving target about 50 ft away while trying to pan at F/5.6 and 1/1600 sec. Lighting conditions were not that great.


Since then, I 've shot in good lighting conditions with the 24-105F4 IS and shots are just as sharp as anything from the 5D MkII. ISO setting was limited to 400. On another shoot, when pixel peeping, I thought at 1-1, the 7D had a more granular texture than the 5D MkII. Lighting conditions were good and the shots were well exposed.


What I can conclude so far is that in good lighting conditions up to ISO 400 so far, there is not that much difference in the image quality of either camera. I think what the issue on softness is the 7D is more susceptible to camera shake when hand held because of the high density of pixels. You really have to hold the camera still to get good shots. What you suggested in doubling the inverse of the focal length in setting a shutter speed helps butmore effective is to be able tobetter hand hold very still when using a long lens.


Another thing I have noticed is the noticeable improvement in the 7D's AF system. It's not perfect but it nails the focus more often and quicker than the 5D MkII.


So, for the 7D, it has better performing AF but this is off set by more sensitivity to camera shake, especially when using long lenses. The 5D MkII has better image quality and high-ISO performance but its AF isn't that quick when looking for birds and animals. This spring, I'll try to give both a good work out and get a better idea of their strengths. For now, the 7D is great for birds in flight because of the AF and 1.6X extra reach.

[Filippo]

This is true, but usually I use the 5D Mark II for landscapes. And anyway I prefer to use a tripod for landscapes. I bought a Benro Travel angel in carbon fiber. Light, compact, steady. It's not a Gitzo, but is very good, I do suggest it. It's useless in my opinion to have a tripod which resist a tornado but weights too much. It will be always at home...

[Filippo]

Yes, I'm doing the same learning curve as you told. Anyway switching from a FF camera to an APS one, everytime you have to "reset" your aperture/shutter speeds. And sometime I forget....


Comparing the 50D files to the 7D the latest produces better files, and the "native" raw file I found with less noise than the 50D. This also deactivating all the "bells and whistle" like NR, ecc ecc. I'm just talking about Raw file.


Let's see if we can improve the IQ discovering better this wonderful DSLR

[Daniel Browning]

Welcome! Great first post.

As a rule of thumb I currently use as a minima, the double of the current lens focal lenght as basic shutter speed (not considering Image stabilizers or similar devices). For istance, if you are using a 300mm lens, I use 1/600sec as a start.

I agree - that is a great rule of thumb. The old "one over focal length" rule of thumb only worked for full frame film and typical print sizes (8x10 or less). Now it's common to examine images at 100% crop, which is equivalent to a print that is 6 feet wide. On top of that is the smaller sensor, which increases reproduction magnification.

[...] that could be perfect if Canon didn't push too much the pixel count. Having more resolution is nice, but it becomes very hard in the "field use".

I disagree. There is no downside at all to the increased resolution. For example, if you downsize your 7D pictures from 18 MP to 10 MP, you will find that the shutter speed needed for sharp images at 100% crop view is the exact same. You only have to increase your shutter speed if you want to take full advantage of the additional resolution. If Canon had left the pixel count at 10 MP, then *everyone* would be limited to that, even those who are shooting still subjects. This way, if you want additional resolution, you can have it. But even if you don't, then you can still get sharp 10 MP shots.

[Filippo]

[] Hi again. I link this interesting articles about this topic found in the infobank of the Canon Professional Network.


Filippo.


http://cpn.canon-europe.com/content/education/infobank/capturing_the_image/pixels_and_image_size.do

[Daniel Browning]

I link this interesting articles about this topic

Here is the portion that is relevant to your post:
<p style="padding-left: 30px;"]Even after making these changes, images from more recent EOS
professional digital cameras can still look softer than those from
earlier models. This is because recent models have more pixels, which
means that pixel size is smaller (11.5&micro;m on the EOS-1D; 7.2&micro;m on the
EOS-1Ds Mark II). Smaller pixels are more sensitive to camera shake, as
a smaller movement will cause the image to move across more pixels. You
need to hold the camera steadier - ideally on a tripod.


The above is only correct when one assumes display size/resolution is scaled with sensor resolution, which is a context that is very commonly misunderstood. It is more informative to understand the effect of pixel size within the context of diminishing returns.


Under ideal circumstances, smaller pixels increase resolution by 100% of the expected amount. That is a full return. But if the motion blur is bad, it will reduce the improvement to, say, 50%. If it's really bad, the return will be 0%: the smaller pixels will only be the same, and not any better. In no circumstance will the smaller pixels ever be worse ("look softer") due to motion blur. It is the same with many other causes of diminishing returns: missed focus, lens aberrations, diffraction, etc.
<p style="padding-left: 30px;"]For
the same reason, sports photographers also need to re-think their
shutter speeds, as blur from subject movement will be more apparent on
cameras with more pixels. Where possible, consider increasing the
shutter speed, even if this requires an increase in ISO speed.


This is good advice if you want the full return (not diminished by motion blur).