tkoutdoor wrote in post #7669730
For some things you may find a Tilt/shift would have some depth of field advantages. Canon has 3 ranging from 24mm - 90mm. They aren't cheap, but they are one of the known ways to get what you're after.
F8 is not likely to make all the rivets on a bridge be in focus. F16 to f22 has a better chance at that. Beyond f/11 isn't going to be the sharpest part of the lens, but it's a wide enough aperture that it has a better chance at having things in focus from front to back. You have another factor with corner softness etc. that has to be fought more on the non-L lenses as well. You may set the right aperture, but through no fault of the aperture and due to the softness of the lens in general you may still find the rivets out of focus. If having all the rivets in a bridge in focus is that important to you then it's possible that you may have to raise the lens quality a bit. You could rent something before you buy it to see if it indeed offers what you're after. I'm not saying it's impossible to do with less than an L lens or a tilt/shift, but you've set the standard high enough that I think you would be doing yourself a disservice if you didn't evaluate what they will offer you.
One has to consider other factors like chromatic aberration as well. It's easy to lose considerable detail at the high contrast edges of dark/light. L lenses are designed to combat this at a high level. Non-L's struggle with this aspect significantly. Choosing a smaller aperture helps to fight against it, but an L lens has much more to offer in this area. Using graduated neutral density filters and/or flash to balance the dark and light areas can help overcome CA as well. It doesn't all have to be up to the lens. Many times CA is spot specific around lighting etc. though so the lens plays a huge role.
Some excellent advice here.
I'd like to add a few comments. Don't expect to see everything sharp or in the greatest detail with a WA or UWA from foreground to background. The resolution just isn't there. Any small object that isn't really covered by a group of pixels, just doesn't show detail, and with a WA or UWA the number of pixels available for background detail diminishes rather exponentially towards the background. This isn't just limited to digital, BTW, with film this is even worse.
I also thought of a TS-E immediately, but another option might be a 17-40L, maybe a good, used one. Stop it down to F/8, F/11, or maybe even F/16 on a FF body, and you should be able to get quite far in what you want.
The 20 F/2.8 is not a bad lens at all, but it is a fairly old design, and the corners only get comparable to the centre at F/8 and F/11. On FF the 17-40L is a better lens, IMO, and you can go wider too. And a used 17-40L is not all that more expensive than a new 20 F/2.8.
Kind regards, Wim