EF-S 10-22mm - filters and vignetting

[neuroanatomist]

<p class="MsoNormal"]<span>Hi All,<o></o>
<p class="MsoNormal"]<span><o>Spurred by a [url="/forums/t/3496.aspx]question in this thread[/url], I performed some
admittedly non-quantitative testing (not up to Bryan&rsquo;s standards, I&rsquo;m sure) of the
effects of B+W MRC UV filters on mechanical vignetting on a UWA lens (the EF-S
10-22mm f/3.5-4.5 USM).</o>
<div>


All tests were performed with my 7D and EF-S 10-22mm, using
various combinations of stacked B+W MRC UV filters.<span> The F-Pro mount is the standard filter mount, and the XS-Pro
mount is the new-ish slim mount that retains front threads (for stacking
another filter or mounting the standard Canon lens cap).<span> The relevant thicknesses are:
</div>
[list][*]Slim mount - 3 mm[*]XS-Pro mount - 3.4 mm[*]F-Pro mount - 5 mm[*]Slim CPL - 5 mm[*]Standard CPL - 8 mm[/list]


[quote=Brian Kreitman]Is the slimmer XS-PRO[i]required[/i]to avoid vignetting for the EF-S 10-22mm?[/quote]
<div>


The short answer is no, the F-Pro mount is fine.
</div>
<p class="MsoNormal"]<span><o>I don&rsquo;t have a fancy studio setup with strong continuous lighting,
so all images were taken with ambient light in my office today.<span> The center AF point was used, and the focus
target was a brain on the wall of my office (hey - my handle is neuroanatomist - what else do you think
I&rsquo;d use as a focus target?!?)<span>[:P]</o>
<p class="MsoNormal"]<span><o>I didn&rsquo;t have my tripod, so please forgive the slight variance in camera to wall distance - I was approximately 12&rdquo; from the wall, and the variance
was less than 1&rdquo;.<span></o>
<p class="MsoNormal"]<span><o>All shots are at 10mm. In the composite image below, all images are crops of the upper
left quadrant (to reduce the size of the final composite image).<span> For each filter combination, I took
three exposures - f/3.5 with peripheral illumination correction enabled (+PIC),
f/3.5 with peripheral illumination correction disabled (&ndash;PIC), and f/8 with peripheral
illumination correction disabled.<span>
All images are straight-from-the-camera JPGs.</o>
<p class="MsoNormal"]
<p class="MsoNormal"]<span>First, it&rsquo;s apparent that peripheral illumination correction
does a pretty good job on in-camera JPGs (and the same correction is applied on
RAW images processed with DPP, but not with Lightroom, Aperture, etc.).<span> Second, and surprisingly, not only is
the XS-Pro mount not required at 10mm (16mm on FF, despite B+W&rsquo;s
statement that vignetting is likely with an F-Pro mount at FF focal lengths
wider than 24mm), it appears possible to stack an XS-Pro and an F-Pro mount filter, or an XS-Pro and a Slim CPL, without mechanical vignetting.<span>One caveat is that I didn't have any of my F-Pro ND filters with my today, and the 2 XS-Pro + 1 F-pro is 1.8 mm thicker than 2 F-Pro filters stacked. But, that difference is too close for my personal comfort.<o></o>



In summary, an F-Pro MRC UV will not cause mechanical vignetting on an EF-S 10-22mm lens. However, if you stack a standard CPL onto the UV filter, even with an XS-Pro UV filter it will vignette;if you want to stack a Slim CPL or an F-Pro ND/grad ND/etc. onto your UV filter, an XS-Pro UV filter is recommended.


Hope this helps anyone considering a filter purchase for a UWA lens.


--John

[btaylor]

Great stuff John. The in-camera P.I.C looks to work pretty well there. Some good info in there - I might actually get around to putting a UV filter on my 10-22mm as well (no particular reason why I haven't, all my other lenses have them).


Cheers mate, Ben.

[Brian Kreitman]

I really appreciate all the time and effort that you put into answering my question. The comprehensive answer will serve as a valuable reference for all.


It makes my purchasing decision that much easier.


Thank you again for your efforts.