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Last week we talked about how different sized sensors impact your images and the lenses required for different sized sensors. While it was a good primer, I wanted to show why sensor size matters and what some of the visual differences are between using different sized sensors. After all if there was no difference in performance, why would I waste my time writing about it? So I put together a few sample scenarios that show the differences. Of course, at the end of the day your camera gear is only a small part of the equation that goes into making high quality images. So my goal isn't to bash or give unending praise to any camera, just to show the visual differences between different sensor formats.
Background Info
As I explained last week, different sized sensors require different focal length lenses in order to achieve equivalent angles of view. Again it would be so much easier to explain all of this if camera manufacturers marketed and labeled lenses based on angle of view, but that isn't the case so it is my job to explain this. I gathered up an Olympus E-PL1, Nikon D300s, and Nikon D700. The E-PL1 has a micro 4/3rds sensor, the D300s has a "1.5x crop" APS-C sensor, and the D700 has a large full frame sensor inside. So while al of these cameras use different sized sensors, they all share the same 12MP resolution. This made cropping and comparing easier as no resizing was required. In order to maintain a similar angle of view I used the following lenses; Leica 25mm DG f/1.4 on the E-PL1, Nikon 35mm f/1.8G DX on the D300s, and a Nikon 50mm f/1.8D on the D700. For decades the 50mm lens (on 35mm film or full frame DSLRs) has been regarded as a "normal angle of view" so my lens choices for the "non full frame" cameras reflect that line of thought. Here are the results from the test. Please note this is not highly scientific, but the results reflect the obvious differences between the different sized sensors.
Situation 1
I took Nick outside around 4PM when the sun is direct, but setting in the sky. I used a low ISO setting of 200 on every camera and an aperture of f/2.0 across all lenses. I did my best to frame the shots the exact same way as to best show the differences between each format. 100% crops of each image are shown immediately after.
- The E-PL1 shoots in a 4:3 aspect ratio so the images will not totally line up, but they have not been cropped.
- As you can see there is a distinct difference in the depth of field between all of these sensors with their equivalent lenses.
Commentary on Situation 1
As you can see there is clearly less depth of field on the larger sensor. This is evident when shooting at a wide aperture, but I imagine it would be come even more apparent when stopped down a little bit more. There is also some light noise at ISO 200 on the E-PL1, something you don't see as much on the D300s crop, and is barely there on the D700. So right away I can conclude that larger sensors have a better signal to noise ratios, which is a nerdy way of saying that larger sensors perform better at high ISOs. So let's take a look at another situation where a higher ISO is required.
Situation 2
Nick was being a good sport about being put through this boring test, so we decided to go inside and try one more test. Our showroom lights are daylight balanced fluorescent tubes that are fairly bright, but obviously dim compared to direct sunlight. So I set all of the cameras to 1600 ISO. I left the aperture of the lenses at f/2. Just like last time, I included some 100% crops from each image to compare.
- Notice how the 50mm lens obviously compresses space more. I had to move a little bit to try framing these three shots in a similar manner.
- Again its obvious that there is much less depth of field with the longer focal length on the larger sensor. Noise also becomes quite the issue for the smaller sensors here.
Commentary on Situation 2
Again we can reinforce the aspect of depth of field being more shallow on the larger sensor camera. While the depth of field produced by the E-PL1 at f/2 could certainly be considered "shallow" it simply cannot replicate the results of the full frame D700. However "shallow" depth of field here really isn't the issue. The shallowness of the depth of field from the E-PL1 is probably plenty for most shooters. To me the real difference is in the ISO performance of the full frame camera vs the other two smaller sensors. While the noise is visible at ISO 1600 on the D700, it is very noticeable on the D300s, and totally in your face on the E-PL1.
Conclusions
There is a common misconception out there that using a larger sensor camera instantly allows for more shallow depth of field. There is some truth to this line of thought, but it needs to be explained a little bit better. It isn't the actual size of the sensor that equates to more shallow depth of field, but rather the lenses that are required to achieve an equivalent angle of view. The 2x crop factor of the Olympus E-PL1 forces you to use a wide-angle lens such as the Leica 25mm f/1.4 DG lens to achieve a "normal" angle of view. Sure the sensor is only using the center portion of the lens, so you won't get all of the whacky edge distortion that a wide-angle lens would exhibit on a full frame sensor. However you also lose the compression of a longer focal length lens. Compression and depth of field are directly tied to the focal length of your optics. You can see slight effects of this in Nick's face. It is rendered in a much more flattering way at 50mm. This is why portrait photographers use longer lenses! So while the difference in space compression is apparent at 25mm, 35mm, and 50mm, it would become even more obvious when trying to compare lenses that have a more narrow angle of view. Perhaps that is something I will try in the future. Of course you can compensate for this by using a longer lens on a micro four thirds camera, but in order to frame your subject the same way, you will need to dramatically increase your working distance, which isn't always possible. One could make the case that there is a benefit for landscape photographers with the smaller format cameras and I wouldn't argue against that. However there is also a lack in dynamic range with the micro 4/3rds sensor. Newer APS and full frame cameras have about 2 stops advantage in that regard, but I personally believe that can be compensated for by better processing in future m4/3rd cameras. So that is more of a function in technology needing to improve, not an absolute law like compression, depth of field, and ISO performance are. It is very obvious that the larger sensor cameras perform better at high ISO settings. For professionals, this is the key right here. Being able to create cleaner images at higher ISOs opens the door to many new creative possibilities. That is why we have seen the massive migration of professional photographers switching to full frame cameras. Again at the end of the day you can take an amazing shot with any camera. At least 90% of photography is your mind's eye and how you decide to compose an image. All of this techno jargon can be examined way too closely at the cost of losing your creativity. At the same time it is important to know the bullet points on the technical differences between different format cameras. I hope this little test and series of consecutive posts was helpful. If you have a question, please leave a comment here and I will be happy to answer it to the best of my ability. -MZ