7D2: Considerations for shooting with high pixel density

A couple of years ago when the D800 first came out, many of the same comments were being made about the inherent sharpness of the camera that are now being made by Canon shooters about the 7D Mark II.  Over time those complaints went away as people adjusted to shooting with higher pixel density sensors. Back then I wrote an article in my newsletter to address this.  I've posted that article below.  Hopefully it will be useful to 7D Mark II shooters to better understand what may be causing their concern.  You can basically substitute 7D2 anywhere that it says D800 below.  In fact, 7D2 pixels are even smaller than D800 pixels so it is even more important:

Camera Platform Stability In The Age Of High Megapixel Density Sensors

It is quite often that I hear complaints from people that have upgraded to a D800 (or 7D Mark II) that their pictures aren't as sharp with a D800 as they were with (insert old camera here).  They are sure there is something wrong with the camera.  When I ask them how they are determining this they say that when viewed at 100%, the old camera's pictures are sharper and often they are getting ready to return the camera.  Almost always there is nothing wrong with the camera but it is either the photographer's technique, the lens, or their support system (tripod and head) is not up to the task.

Let's take a look at this with an example.  Suppose you are taking a picture of a single point of light.  Lets also suppose that point of light is 8 microns in diameter when the image is projected onto the sensor.  If I have a pixel size that is 9 microns in width like some of the early full frame cameras, that entire point of light can be contained in a single pixel.  When viewing this at 100%, there is just a single illuminated pixel (ignoring any spill over).  Now let's take that same projected 8 micron point and record it with a camera with just 4.5 micron pixels like some of the highest pixel count DSLRs on the market, it now requires up to 4 pixels to record that same point of light.  When you then look at that image at 100% you see 4 pixels illuminated for a single point of light and we perceive that as being less sharp.  What is really happening in this theoretical exercise is that each of the 4 illuminated pixels is just recording one quarter of the point of light. 

Lets now assume that within that same 8 micron by 8 micron area we have 4 individual points of light, one at each corner of the pixel.  The old camera will record a single dot since all four points of light are fully contained within that single pixel.  The new high megapixel camera can record each point individually thereby recording a finer level of detail than the older camera can.  But for an identical subject, when viewed at the pixel level, small details may be recorded over several pixels while they are recorded in fewer pixels with the old camera and when viewed pixel for pixel may be perceived as being less detailed due to this. 

In a similar vein we can look at lenses.  First, your lenses must be precisely focus adjusted to your camera.  If you haven't done this, you simply will not get the results you expect.  Now, let's say your old camera can resolve 3000 lines per frame and your lens can resolve 3200 lines per frame.  This is a case where the resolution is sensor limited.  In other words, assuming perfect technique, you are recording the maximum detail the camera is capable of but the lens could resolve a bit more detail.  Now let's put that same lens on a camera able to record 5000 lines per frame like a D800E, now you are lens limited and not getting everything out of the sensor that you could if you used a higher resolution lens.  Again, when you look at these two images at 100% on a pixel level, the old camera may look sharper because no pixels were blurred due the lens.  The new camera may have pixels that are blurred to adjacent pixels because the lens limited what the sensor can record.  When normalizing to the same output size, the higher megapixel camera will allow you to create output that resolves everything the lens is capable of where the older one will not. 

Diffraction also plays a role.  Since smaller pixels are more able to record any diffraction from the lens' aperture diaphragm if you compare a lower megapixel (larger pixel size) camera with a higher megapixel (smaller pixel size) you will see more degradation on the newer camera - basically this is the concept as discussed above where the same light spread across more pixels due to the smaller pixel size.

Lastly let's look at technique.  Let's say we have a small detail that projects onto the sensor with a size of 4 microns that we are photographing with a camera with a 9 micron pixel size.  Lets also assume that this point is perfectly centered within a pixel.  You now have leeway of an additional 5 microns of motion (2.5 microns in each direction) before an adjacent pixel will start to record the point of light.  But on the high megapixel camera with 4.5 micron pixel sizes, you only have 0.5 micron of movements (0.25 microns in each direction) before an adjacent pixel will pick up motion and thereby giving you the perception of a less sharp photo when viewed at 100%.  It is therefore imperative that the camera be properly supported and totally steady.  When hand holding we used to say that 1 divided by the focal length is the slowest hand-holdable shutter speed.  That may have been true in the film days or in the days of low megapixel counts.  On a camera like the D800, you should use something more like 1 divided by two or even three times the focal length.  So if you are using a 50mm lens you need a shutter speed of at least 1/100 to 1/150 to even have a chance at a sharp shot.  For most people it's even faster than that.  Stabilized lenses or bodies certainly help in this regard but they are not a fix-all.  When on a tripod and exact shutter timing is not necessary, always use mirror lock-up coupled with shutter delay or mirror lock-up with a cable release.  make sure the camera is mounted steady on a stable tripod with a solid and rigid tripod head.  Do not skimp on camera support or you are wasting the money you spent for all of those pixels.  Use the very best lenses you can afford.

Unfortunately many photographers have spent a lot of money on extreme resolution cameras like the D800 without upgrading their technique, lenses, and support and are getting sub-optimal results.  I am not the first to write that the D800 may be too much camera for the skill set or support equipment of the vast majority of photographers that have purchased it.  I believe that unless you have the best lenses made, a fantastic tripod and head, and superb technique, you may be much better off with a camera like the D600.

Excellent explanation EJ! I am sure that accounts for the majority of complaints with the 7Dmark2. There is a distinct group that finds the camera fine, and another that struggles. I can't believe there are that many "bad" copies out there.

I am sure that accounts for the majority of complaints with the 7Dmark2.

Well, I'm not so sure. I do appreciate the information that EJ provides.  But there are enough experienced photographers reporting focusing problems with the 7D2 that I suspect there is a problem with some batches of the camera.

I assume everyone recalls the focus problems with the 1DIII that Canon finally acknowledged and issued a recall for? I seem to remember that this turned out to be a mirror box issue for a subset of the cameras. I wouldn't be suprised if a similar problem exists for the 7D2.

John

And in a way, the same can be said about the D7100 for the same reasons.

Anthony Medici wrote:And in a way, the same can be said about the D7100 for the same reasons.

You got that right Tony. I am still struggling with the D7100 and my gear and technique is very good. I suspect it is the least forgiving of all DSLRs right now.

John Guastella wrote:

I am sure that accounts for the majority of complaints with the 7Dmark2.

Well, I'm not so sure. I do appreciate the information that EJ provides.  But there are enough experienced photographers reporting focusing problems with the 7D2 that I suspect there is a problem with some batches of the camera.

I assume everyone recalls the focus problems with the 1DIII that Canon finally acknowledged and issued a recall for? I seem to remember that this turned out to be a mirror box issue for a subset of the cameras. I wouldn't be suprised if a similar problem exists for the 7D2.

John

Even VERY experienced photographers were saying the same thing with the D800.  This is the first time that many Canon pros and advanced photographers have had a high pixel density camera.  We tend to slack our technique to the point that is just better than what the sensor can record as it allows us to push the envelope in what we can shoot, what ISO we can use, what shutter speeds we can use, etc.  Pros do that as much, if not more, than amateurs and are also a lot more critical.  While maybe there were a few problem cameras (there always are), two of the so called "bad" ones have now passed through my hands and there is absolutely nothing wrong with them and they perform exactly the same as the other 7 I've tested.

The 7D2 does not, in my opinion have a problem like the 1D3 which was obvious.

The one thing not in the article I started this thread with, is the frame rate of the 7D2 (which isn't an issue with the D800).  When you shoot with the 7D2, the mirror slap and shutter shock, especially as you get to higher frame rates is really significant even with a huge mass like a 600mm lens attached.  If it isn't totally locked down, my testing shows that even at 1/800s you still measure shutter shock at high FPS when comparing it to the silent shutter mode with MLU.

EJ, your analysis makes a lot sense but for one thing, some of the folks complaining are used to the original 7D with its 18mpix sensor (hardly different in pixel density than 20mpix 7DII). Both The Nikon 7100 and Sony 24mpix cameras (as well as the Samsung 28) don't seem to have OOF problems of the 7DII.

John Guastella wrote:

I am sure that accounts for the majority of complaints with the 7Dmark2.

Well, I'm not so sure. I do appreciate the information that EJ provides.  But there are enough experienced photographers reporting focusing problems with the 7D2 that I suspect there is a problem with some batches of the camera.

John

Yeah, but don't forget a few of these "experts" argue they don't need to fine tune the AF to tell that it isn't working correctly. 

Actually most of those complaining, at least that I have read, are comparing them to 1Dx and 1D4 cameras which have much larger pixels.  As for Sony and Nikon, we have been shooting with high density sensors for years and have adapted.  There were complaints about the a7R for the same thing (just like there was for the D800) and yes some percentage of it was due to shutter shock but a lot of it is due to technique.  Finally, Sony shooters and to a much lesser extent, Nikon shooters, tend to shoot with shorter focal lengths where the problem isn't exacerbated.  How many people do you know with the Sony 500mm f/4?  ;)

The mirror/shutter shock of the D7100 and the Sony SLT's (for obvious reasons) is dramatically lower than the 7D2.  

Well you know 1 with the 500 (me).

Yes and you are the only one

What is the 7Dmkii sensor able to record per frame?

Coreyhkh wrote:What is the 7Dmkii sensor able to record per frame?

I'm not sure I understand the question...

I think the experience with D800, 7DII and D7100 in nature photography (understand long focal lengths) will also depend if you come from FF or DX.

Most people that have only a DX body, like a D7000 or 7D, use 300 or 400mm lenses, because they get 450-640mm equivalent field of view. That is enough reach, and enough money spent for most "amateur" nature photog. Upgrading to a 7DII or D7100 is no big change, because the pixel increase is marginal, and the equiv. focal length unchanged.

People that use 1DX/5D3/D4 on a regular basis most probably also own "Big glass", say 500-800mm, initially bought to get enough reach on FF. They buy a 7D2 or D7100 for when even more reach is needed (further animals), and simply put these dense sensors behind their longest lens. The problem is that (1) obtaining a sharp image in these conditions is extremely demanding (a 500 + TC + 7DII would need at least 1/2500s per EJ's rule) and (2) further subject means more atmospheric issues. With the lower performance of dense sensors at high ISO, everything is there to get disappointed by the results, especially when you have high hopes because you are used to FF IQ.

You have to remember that FF in Canon and Nikon with their top of line cameras are low resolution beasts. They can not be cropped for reach as well as the Sony or Nikon high resolution FF which pixel density can not match APS-C. I still shoot with my Sony A900, many years old and still has more resolution and DR than any Canon product. Big glass on Sony's 24mpix APS-C gets sharp pictures with no problem (other than user error) I regularly shoot 3002.8, 70/400, 500f4 and 600f4.

Tim Zurowski wrote:

Anthony Medici wrote:And in a way, the same can be said about the D7100 for the same reasons.

You got that right Tony. I am still struggling with the D7100 and my gear and technique is very good. I suspect it is the least forgiving of all DSLRs right now.

I still think 15MP on DX is the sweet spot for wildlife....which is what you get on a D800/D7000. It's hard enough to get good IQ in average conditions, but getting good IQ with 20/24MP on DX starts to get insanely hard.

Mike in O wrote:EJ, your analysis makes a lot sense but for one thing, some of the folks complaining are used to the original 7D with its 18mpix sensor (hardly different in pixel density than 20mpix 7DII).  Both The Nikon 7100 and Sony 24mpix cameras (as well as the Samsung 28) don't seem to have OOF problems of the 7DII.

Probably because most finicky 7D owners moved to FX. I expect some of them have even tried the 7DII, but quickly gave up when they remembered why they traded up the 7D to begin with...getting optimum results out of high-density sensors in anything less than ideal conditions is HARD. 

Having shot Nikon last waterfowl season, I never had the issues with the D7100 I have with the 7d2. I was Nikon's 200-400 w/1.4x most of the time and AF was fine. When I nailed focus, the camera did it's thing. With the 7d2, nailing the focus is what's causing the problems, I may do my part, but the camera may do it's part. My first 2 definitely did not. 3rd body is better on stills, but jury is still out on moving objects.

Also, it has been mentioned that many of us are comparing 1Dx/1D4s to the 7d2. Exactly what would you expect? Those are the two bodies most, but not all, wildlife photographers shoot if you shoot Canon. There was much ado about the 7d2 being a mini-1Dx by both Canon and their reps as well as there more famous staff. Now we learn it is not. This body was supposed to be a 1D4 killer, but, thus far, in my mind it has not been or the jury's still out.

Technique only goes so far, then the gear has to take over (it works in reverse too). When I leave for my annual waterfowl trip Friday, I will have all three cameras as I have not developed enough trust in the 7d2 to be willing to put my biggest trip of the year in it's hands.

E.J. Peiker wrote:

Coreyhkh wrote:What is the 7Dmkii sensor able to record per frame?

I'm not sure I understand the question...

"Now, let's say your old camera can resolve 3000 lines per frame and your lens can resolve 3200 lines per frame. " 
just wondering with the best lens what the resolving power is of the sensor, I am just wondering out of curiosity. 

Ah OK, I'm pretty sure all of the Canon Mk II lenses out-resolve or at least come very close to outresolving the sensor so you are still sensor and technique limited.