I wrote this post in the tech cam image thread and thought it warranted further discussion on its own. Here is the original post for reference:
Here are some more examples and info (hopefully) explaining the value LV played with my tech cam.
The first was the "ah-ha" image that brought it home. It's not a great image, but I was wanting to try closer focus technique with my 40 and see how it performed. 1/4 sec at f11:
I seriously shot about a dozen images tweaking focus trying to get the rim of frost on this cattail in focus. Doug told me to try live view, so I did. "Wow" was the first expression out of my mouth -- the reason I could not get the frost perfect is the DoF of even the R40 HR at f11 was so shallow that a fractional turn of the focus helical on my Arca, meaning about half a full number, went in front or behind the frost rim almost immediately. With live view, I could tweak half a hash-mark and register the sharpest plane right where I wanted it. (On the Arca, 1/10th a whole number is just slightly over 1 degree or 1/360th of a full turn on the focus helical.) Keep in mind these are still relatively longish morning light exposures and cattails move with a breeze. Here's the crop of the cattail I working with in live view, imagine my surprise when I could see the FM light up on the frost and the actual structure of the frost crystals in 100% review:
Next example. I was at a stream later in the day, and wanted specifically to "practice" using LV to focus with large degrees of tilt. So I set this shot up. It is another long exposure, 2sec at f11 with the R70mm HR lens. My goal was to get the close rock moss and the far stream bank both in focus. The difference here is there was no infinity, and focus distances were much closer -- the lower rock is against my tripod leg, the moss maybe 20cm away from the camera and the far bank about 3 meters distant. Moreover, the camera is only about 0.5m off the ground. (Camera height affects final tilt angle.) Additionally, I had compounded my set-up by adding 15mm fall to get the perspective on the close rock I wanted. So I focused mid stream and wanted to see how many frames using Focus Mask plus 100% reviews while tweaking tilt and focus it would take to nail it. Seriously, I gave up after about 2 dozen frames -- I simply could not get anything in critical focus no matter what I tried!
Here is the full frame:
So I went into LV and while it still took about 3 or 4 minutes of iterative tilt and focus movements, I finally got it -- turned out because I had so much fall and pretty extreme tilt, I had originally estimated I'd need 3º, I actually needed to move my focus to almost infinity to get the extreme plane I was after sharp!!! In the end, I added even more tilt to 4º, then had focus probably around my 20 meter mark and got this result.
Here is a crop of the moss on the near rock -- again remember this has 15mm fall, so the rock is quite a ways from center IC:
And here is a crop of the far bank of the stream. Note this portion of the frame is near the center of the IC:
Try to get this range of DoF without tilt! I did the online calculator (http://www.dofmaster.com/dofjs.html) using a 2-pixel average diagonal CoC of 12u, an aperture of 64 (smallest it goes) and even assuming zero diffraction, if I focused on the moss at 0.3m my total DoF extended from .29 to .31m! If I focussed at 2.1m, the far bank at 3m was my far DoF and I got my close DoF at 1.59m. At f11, the DoF at 3m was still only 0.5m -- totally explains why I could not get this nailed without using live view!
In conclusion. When I first received my IQ back, I tested LV and almost immediately dismissed it as a viable or practical field shooting tool. The image is noisy, the refresh rate is painfully slow and I felt it more a gimmick than a serious tool. Well, that opinion changed last week. My new opinion is simple: If you are going to use tilts and want to have anything less than an exercise in frustration getting your camera set up, you'll want to use some form of "live" view. This can be live viewing of a ground-glass of course. But if you have an IQ back, do not assume the LV feature isn't valuable -- it is a valuable feature.