Ben -- Yes, those markings have a useful purpose, even for UWA lenses! Knowing that an exact spot on the focus ring will bring exact focus at certain distances is often a lifesaver, and certainly a confidence builder.
As you've just found out, even UWA lenses (14-24) obey the laws of optics, and depending your level of magnification when viewing recorded images, the precise plane of focus can still be found even with the lenses stopped down to f/ 5.6 to f/8. In many situations, it seems as thought the focus depth extends almost from our nose to the horizon, but in reality, there is a definite sharp patch. Hit it exactly, and you're a hero. Mis-focus a tiny bit, and you're picture is a zero.
As the lens magnification goes down (wider lens, smaller mm), it gets harder and harder to establish precise focus, because the details are so small even with LV.
Many times for an important twilight cityscape, I need to arrive a the location and set up and establish focus while the sun is still shining, then wait an hour until near sunset to start taking confirming test shots. It's a mad scene if I then need to re-establish focus due to initial error, or budging the lens.
I always try to shoot twilight at the smallest possible aperture, before diffraction really sets in -- just as you said -- to provide an extra cushion of assurance that focus will be acceptable. Usually this is between f/8 and f/10, depending on the lens. Some outdoor "events" can't be re-staged, or weather conditions may not repeat for weeks or months, so the shot has to be gotten if you go through all the trouble of scouting and setting up.
Anyway, congrats on the 14mm lens! My copy is so sharp that I've postponed buying the 17 TS-E for a while, since the 24 TS-E is more useful for me. Eventually I will get it!
Enjoy!
John -- I almost did the same as you, once I worked with the lens for a while. I like the scale like this for my other "run and gun" uses, handheld. It's easy to establish focus, even in between the numbers (I've owned a number of old 120 "folders" with estimated focusing).
I wish they had a focus scale that was adjustable (rotatable) -- maybe loosen a few screws and then turn, and lock again, like the adjustment knobs for elevation and windage on rifle scopes.
So what distances matter? By 10 feet you have infinity. At 7 feet you have at your feet and a fairly decent infinity even at f5.6. If I wanted to use it at f2.8 I would only need to know what gets me infinity at f2.8.
I plan to do some testing today with some well measured targets.
Using 10x live view on a 1DS-mk3. Above 2 feet this is very difficult to read accurately even with a well lighted crisp target and no light on the LCD.
TSE easier to focus because it’s sharper. Shorter focus motion makes it easier to pop.
Some of the error is probably in the camera, all my lenses need micro adjust.
Very good focus would be obtained over a fairly large range at f5.6 or f8.
Tolerance on scale reporting is at least plus/minus one foot especially on Sanyang.
Test done indoors except infinity which is outdoors using a target several miles distant.
If you are going to use focus confirm, micro adjust will impact where MA will light up. However that being said, MA does always seem to have a much larger window (focal range) than Live View 10X with the 5DII. Its not as precise. So its worthwhile calibrating MA for your manual focus lenses too! I use MA with my MF lenses when hand holding the camera and need to quickly grab focus to get the composition I want.
Mike K
Mike K wrote:
If you are going to use focus confirm, micro adjust will impact where MA will light up. However that being said, MA does always seem to have a much larger window (focal range) than Live View 10X with the 5DII. Its not as precise. So its worthwhile calibrating MA for your manual focus lenses too! I use MA with my MF lenses when hand holding the camera and need to quickly grab focus to get the composition I want.
Mike K
I MA my TSE lenses, and my Ziess chipped and adapted 50 f1.4. But the Samyang does not report so it does not work. After my latest test, and lots of bad field experiences, I no longer trust MA on UWA.
I just did a test of both the 14 and 17TSE at the infinity setting at f8. Wish I had done this last year for the 17, would have saved myself a lot of OOF images. Setting them to the infinity mark provided super sharp infinty, way better than focus confirm or live view.
Now for close stuff, all I need to do is focus at the infinity mark and tilt. Or with the Samyang, do one at infinity and one close while using live view and stack.
I also did one at f2.8 on the Samyang. Focus was good but not as sharp as at f5.6 in the center and pretty bad in the edges and corners plus lots of vignetting. But my 35 f1.4 is not so hot wide open either. And its still a lot better than my sorry 17-40.
Knowing that an exact spot on the focus ring will bring exact focus at certain distances is often a lifesaver, and certainly a confidence builder.