Some Thoughts on Full Frame

by ajamess on 8.Nov.10

in Photo Gear,Photographic Musings

So, I took the plunge.  2 days ago, a used 1Ds Mark II arrived on my doorstep in pristine condition, marking my transition to what seems to be a popular thing in photography these days: full frame sensors.  Of course, I could talk of pixel pitch and SNR and the other purported advantages that come with a sensor the size of a piece of 35mm film (anyone else think that is becoming increasingly arbitrary?), but I figured I'd try to give a sense of how full frame compares to crop from the more visceral level.

Human-Camera Interface

I've been shooting crop SLR bodies since August 2006, according to the earliest photo in my Lightroom catalog.  Before that, I played around with various Pentax M42 gear my Dad owned.  One thing I never really appreciated was how damn nice the viewfinders on those Pentax bodies were.  Bright, large, well matted for easy manual focusing…all things that made the act of shooting extremely pleasurable.  Once I got my 30D, though, I kind of lost sight of what it was like to look through the Pentaxes and got used to the cramped and rather dim view afforded by the smaller pentaprism.  A couple years later, I picked up my Mamiya 645 and was simply blown away by the viewfinder…if you've never looked through one, go check out your local camera store and ask to see their medium format film bodies.  It's like sex in a light-proof box.  Of course, then I realized how dismal my 30D really was, not that it bothered me that much.  Now, just a year ago I picked up my 7D, which is really a phenomenal camera ergonomically, and was extremely happy with the wonderfully bright and informative viewfinder it offered.  I didn't really think it could get any better…until I picked up the 1Ds.

It's so BIG!  (That's what she said).  It's actually less magnification than my 7D, but wow, the fact that it's almost half again as large is a real treat.  I really underestimated how big of a deal a nice viewfinder image is to general photographic pleasure.  It's one of those things that you can't really quantify too well in a spec sheet, it's very experiential.  All that said, I wouldn't say it's as nice as a true MF film body, but it's damn close.

Lenses Tell the Truth

I generally shoot landscapes.  As such, lately I've been walking around with my 16-35 more often than any other lens I own, simply because it's the widest I have had for a while.  I did have a Sigma 10-20 for a long time and adored the perspective it provided, but was annoyed by the lack of edge to edge sharpness.  Having gotten rid of the Sigma, I was running about lacking a true UWA for a long time.  I started missing it quite often when I would be in a location that, for one reason or another, didn't lend itself to stitching with a longer focal length, or when running about in the city where the buildings all but tower over you.

The minute I got the FF cam, I threw the 16-35 on it to see what it was like.  Wow.  It's wide.  Really wide.  Probably too wide for a lot of stuff, but it will be a total boon for beach shots.  The 24-70?  Actually usably wide at 24!  70-200?  Eh, not very long any more, but hey, that's what the 7D is for :).  All in all, very happy, and expect now that the 24-70 will spend a lot of time on the FF cam.

Same Perspective Bokeh Advantage

One of the first things I noticed when taking images around the house with an FF camera is the fact that for a given perspective, the camera had oodles more of that creamy subject isolating bokeh for a given aperture.  I always knew this to be the case, but seeing it first hand is a wonderful thing.  One of the annoyances I had with my current lens kit was that I lacked a way of isolating subjects while keeping a generally wide field of view.  Now it seems that even 24mm affords some great opportunities at even modest apertures.

Now, you may ask why FF offers this type of advantage.  We all know Adams and Weston had to stop down to crazy small apertures to get enough DOF for their work, but why?  Well, let's examine the variables: aperture, subject to background distance, focal length, and film diagonal.  For a given focal length, aperture, and subject to background distance, we can expect background blur to be the same no matter the sensor size.  That is to say, if I put a 100mm lens on my 7D and a 100mm lens on my 1Ds Mk II, use f/2.8 on both, and stand the same distance from my subject, I will see exactly the same background blur from both cameras.  The only difference between the two pictures will be the perspective offered by each.  This is because the image circle projected by a lens of a given focal length is always the same size.  In this way, on the FF camera, you will be afforded a wider FOV than on the crop camera, and thus, will be able to blur the background more if you "foot zoomed" such that the perspectives of the two photos were equal.  In this crude illustration, you can see that for a given image circle (ie, lens), a full frame sensor nets a wider field of view with the same background blur:

Sensor Crop Comparison

I'll post some examples of what this looks like in real life shortly.  Until then, enjoy the cat and happy shooting!

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