The Cathedral Parish of St Patrick is one of my favorite churches and I previously shared an image of its ceiling captured at 12mm.
While I liked that one a lot, I wanted to see what the same scene looked like captured at 11mm.
Can a 1mm difference in focal length make a significant difference in an image? Absolutely. While a 1mm difference is meaningless at 400mm, it is substantial at extreme wide angles and the difference between 11mm and 12mm is very noticeable. Of course, wider is not always better and sometimes 12mm is a better choice than 11mm. If you must decide between these two focal lengths, keep in mind that an 11mm image can be cropped to 12mm framing. Cropping of course results in reduced resolution, but going the other direction requires panorama capture and that becomes especially complicated when mixed with an HDR technique as was required by this image.
While it seems that going into a church and photographing straight up would be easy, this image was very challenging to capture. Getting the camera alignment (nearly) perfect was the big part of the challenge. The camera had to be perfectly centered in the scene, directed straight upward and aligned square with the architecture. Any misalignment meant that certain aspects in the scene would not match throughout the image, such as the bottom of the arches being equally aligned with the designs painted on the ceiling.
A slight misalignment makes it appear that you didn't do your job correctly. Intentionally framing the scene so that it is not close to square saves a lot of effort. Challenges are fun, but those not wanting to make that effort should consider the latter.
If you don't have the very-fun 11mm focal length covered in your kit, the Irix 11mm f/4 Firefly Lens is an inexpensive option that performs very well.