Part of the lack of real wide angle with APS-C is a matter of the lenses
you had. Judging from spreadsheet the widest was the DA 20-40.
Now I'd prefer all Pentax lenses, but there are ultra wide angle lenses
for APS-C from other manufactures. The Samyang 10mm f2.8 is ultrawide
by any standard, sure it's manual focus but at 10mm DOF pretty much
takes care of focusing even wide open, and there's the Sigma 10-20mm
f3.5 or the older version that's f4.0~5.6. All three have the
reputation of being fine lenses. Then there's the venerable Pentax
12-24. Which isn't really ultrawide. It's not a huge selection, but
there are pretty good options.
Now there are lots of reasons to prefer a K-1 the larger viewfinder is
reason in itself, but I don't think there there's lens wider than 14mm
for K mount that covers FF, and I'm pretty sure that the selection is
just about as limited as for APS-C. You've got the Pentax branded Tamron
design 15-30, a Sigma or two in that range, the old A 15mm f3.5, the
Samyang 14mm there may be others but I can't think of them off the top
of my head. They're not all that thick on the ground.
On 3/27/2017 10:35 AM, Stanley Halpin wrote:
Looking for something totally else, I came across this spreadsheet on my hard
drive: a spreadsheet comparing the field of view of various lenses on each of
these 3 Pentax systems: K-1, APS-C, and 645Z. No new information, nothing that
most of us don’t already know about how various lenses behave in combination
with various sensors, but I found it useful to lay it out this way to be able
to visually compare.
Dropbox link here to a pdf of the single page spreadsheet:
https://www.dropbox.com/s/qn2tzf43nh77n1q/Lens%20FOV%20Comparison.pdf?dl=0
Background: Last summer I spent a lot of time and effort in preparation for a
trip to Alaska. I have traveled to many places, I travel often, but the Alaska
trip was still a big big thing for me. I knew I would be putting myself in
position to capture some memorable photos. No guarantees that the weather would
cooperate, that luggage wouldn’t get lost, that travel wouldn’t be disrupted,
etc. But I wanted to do what I could ahead of time to make be sure that I had
the best possible photo gear to be able to take advantage of whatever photo
opportunities might present themselves. So part of my planning and preparation
was to think through the sort of scenes I might have, and to previsualize THE
shots I would take.
At the time, summer of 2016, I had three camera systems: K-3 APS-C, K-1 full
frame, and 645Z. Plus a variety of lenses for each system. There was no way I
was going to travel with everything, (and there was no way that everything I
did take to Alaska would be with me on every field trip I might take) and so I
spent quite a bit of time thinking about which camera body/lens combination
would work best for various expected situations. As part of that process I
found some resources on the web which calculated the effective field of view
for lenses of a given focal length paired with various sensor sizes. From those
resources I pulled information about lenses I had or might conceivably acquire
and created the linked spreadsheet. Note that the Field of View in degrees
(FOV°) as often used will typically refer to the diagonal dimension of the
sensor - I chose instead to look at the horizontal FOV° because that was more
meaningful for me as I tried to visualize various scenes.
In the end I took all three systems with a subset of the lenses. I convinced my
wife to use the K-3 as her primary camera in lieu of her Leica P&S she usually
uses. So, one less for me to carry, but available as a backup if needed. I used the
K-1 as my primary, with the 645Z along mostly for a few selected landscape shots.
I have since sold all of my APS-C gear and most of the 645Z system (still have
one lens to sell). I think the linked spreadsheet nicely illustrates the major
advantage of the full frame vs the other two systems: availability of lenses.
Neither 645 nor APS-C provides the option of significant wide angle. Yes, I
will grant that the 1.5x crop-factor on the APS-C is nice when trying to
capture wildlife a few hundred yards away, but the DA*400/5.6 on my K-1, with
images cropped in post processing, helped to full that niche. And I will grant
that the size and weight of the K-1 vs. K-3 and other APS-C options can weigh
heavily (pun intended) in favor of the smaller lighter system. But for me I
will put up with the weight and bulk in order to be able to obtain a better
selection of lenses within the FOV range that I prefer to shoot.
stan
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