Canon 10-18 and DOF button

For many of my landscape photos when I want to focus to infinity I select the furthest point I want in focus, go to 10x view on the screen, hold in the DOF preview button and manually focus until it is sharp.

Why doesn't this method work on my Canon 10-18 (just got the lens tonight)? It seems to manually focus okay in live view but as soon as I hold the DOF button the manual focus ring no longer works.

shane_c wrote in post #18537412
For many of my landscape photos when I want to focus to infinity I select the furthest point I want in focus, go to 10x view on the screen, hold in the DOF preview button and manually focus until it is sharp.

Why doesn't this method work on my Canon 10-18 (just got the lens tonight)? It seems to manually focus okay in live view but as soon as I hold the DOF button the manual focus ring no longer works.

My guess is that STM is interfering with your process. STM lenses are 'focus-by-wire'; AF is only active while you are focusing. Holding the DOF button down must take you out of AF mode.

FWIW, you are using a UWA lens improperly, in my opinion. Focusing at infinity is almost never a good idea; it wastes DOF. For the deepest DOF you can get, dial in the aperture you want first. If it is f/8 or so, focus on something/anything about 4 to 8 feet from the camera (less at 10mm, more at 18mm), then LEAVE THE FOCUS ALONE. Release the shutter. This will get you the deepest DOF available. Google the term 'hyperfocal distance' for more information.

^

For example,

• with APS-C camera and Canon 10-18mm set to 12mm and f/8,
  if the 8x10 print is viewed at 'standard distance' (12"), the viewer with 20/20 visual acuity will see a DOF zone that extends from 4.5' to Infinity when the lens is focused at 9'.
  
• with APS-C camera and Canon 10-18mm set to 12mm and f/4,
  if the 8x10 print is viewed at 'standard distance' (12"), the viewer with 20/20 visual acuity will see a DOF zone that extends from 9' to Infinity when the lens is focused at 18'.
  

Wilt wrote in post #18537581
^

For example,

• with APS-C camera and Canon 10-18mm set to 12mm and f/8,
  if the 8x10 print is viewed at 'standard distance' (12"), the viewer with 20/20 visual acuity will see a DOF zone that extends from 4.5' to Infinity when the lens is focused at 9'.
  
• with APS-C camera and Canon 10-18mm set to 12mm and f/4,
  if the 8x10 print is viewed at 'standard distance' (12"), the viewer with 20/20 visual acuity will see a DOF zone that extends from 9' to Infinity when the lens is focused at 18'.
  

IOW, the DOF Preview even in Live View with an UWA is a bit of an unnecessary feature!

Thanks for the numbers, Wilt. Sometimes real life tells a more compelling story.

A few years back, I bought a Rokinon 14mm f/2.8 lens. A buddy berated it for not having AF, or even a confirmation light activator. To counter his argument, I told him I could shoot ANYTHING with this lens and NEVER have a focus issue. I mounted that lens on whatever full frame camera I was using at the time, and spent an entire day on a college campus. I put the lens on f/8, focused at 3' (IIRC, maybe 4'), and left it there. I shot well over 100 photos. Subjects included flowers up close (2' ?) and long shots down the 'green' (maybe 1500 yards). Everything, in every photo, was acceptably in focus.

AF on UWA is redundant at best, and actually gets in the way more than it is useful.

Thanks! It's my first UWA lens. I've heard that DOF isn't an issue with UWA lenses but was curious why it wasn't working. The method I mentioned above has served me well with both my 17-50 and 70-200 when shooting landscapes. I'll give your suggestions a try today. Thanks again.

Instead of trying something completely different when your method has worked for you, how about doing what you are doing, then just back off from infinity a tad. Then using DOF preview check that both infinity and the nearest subject are as sharp as you expect.

DOF is always potentially an issue. But I guess it depends how you shoot or how picky you are because plenty of people don't seem to have an issue. I have examples of shooting a fisheye at f22 and still having the background blurred. Also, 'within DOF' is not necessary 'acceptably' or 'optimally' sharp enough for everyone.

For landscapes I would very much advise going with a focusing method that you work out for your style of shooting. There are a bunch of different methods that work well for different people and mine actually depends slightly on the lens I'm using, because they all have slightly different characteristics.

Good to know about STM lenses though.

Had the chance to take some pictures yesterday with the lens. I'm not very impressed with it. It's not overly sharp and the DOF doesn't seem very deep even at F8-10 when shooting landscapes. I miss not being able to focus as I normally do.

I was going to return it yesterday only to find out that I am past the 15 day return period, despite me just getting it in the mail 5 days ago (ordered it online 19 days ago). The store told me to call today and talk to the manager. I'll try a few more test shots today since the light will be better as yesterday was gray.

shane_c wrote in post #18541210
Had the chance to take some pictures yesterday with the lens. I'm not very impressed with it. It's not overly sharp and the DOF doesn't seem very deep even at F8-10 when shooting landscapes. I miss not being able to focus as I normally do.

I was going to return it yesterday only to find out that I am past the 15 day return period, despite me just getting it in the mail 5 days ago (ordered it online 19 days ago). The store told me to call today and talk to the manager. I'll try a few more test shots today since the light will be better as yesterday was gray.

Very odd post, IMHO. You mentioned infinity focus at the beginning of this thread. You can't maximize DOF by focusing at infinity. Using HYPERFOCAL DISTANCE will get you the most DOF possible.

DOF is NOT lens specific. It depends on your focal length and aperture, ONLY. Wider lenses at narrower apertures give HUGE DOF. If you dial in f/8 @ 14mm, and focus at 5', EVERYTHING from 2.5' to infinity will be in focus. Dial in f/8 @ 18mm, and focus at 8', EVERYTHING from 4' to infinity will be in focus. At f/11 @ 10mm, focus at 3' and EVERYTHING from 1' to infinity will be in focus. Data obtained here: http://www.dofmaster.c​om/dofjs.html

Autofocus, especially on a lens this slow, just gets in the way of taking landscape photos. Set your camera to f/8, focus at 5', AND SHUT OFF THE AUTOFOCUS. Zoom all you want, nearly everything you point your camera at will be in focus. You can shoot all day like this and NEVER have to re-focus your lens.

There is a learning curve to effectively using UWA lenses. Hyperfocal distance is your friend.

Bassat wrote in post #18541216
Very odd post, IMHO. You mentioned infinity focus at the beginning of this thread. You can't maximize DOF by focusing at infinity. Using HYPERFOCAL DISTANCE will get you the most DOF possible.

Thanks for your reply. I’m not sure how my post was odd. Maybe I was calling it the wrong thing. Perhaps the method I mentioned in my first post is setting the hyperfocal distance, either way I can’t focus the same way with this lens as I’m used to. Even on a lens that has the distance marks I know you can’t just put it to the infinity mark.

DOF is NOT lens specific. It depends on your focal length and aperture, ONLY. Wider lenses at narrower apertures give HUGE DOF. If you dial in f/8 @ 14mm, and focus at 5', EVERYTHING from 2.5' to infinity will be in focus. Dial in f/8 @ 18mm, and focus at 8', EVERYTHING from 4' to infinity will be in focus. At f/11 @ 10mm, focus at 3' and EVERYTHING from 1' to infinity will be in focus. Data obtained here: http://www.dofmaster.c​om/dofjs.html

I realize that wide lenses have a larger DOF. But what I was saying is that even though I was stopping down and focusing at something a few feet away I did not find that the rest of the image was adequately sharp (i.e. a shallower DOF than what I would have expected), compared to doing the method I mentioned in my first post with my 17-50 or 70-200.

shane_c wrote in post #18537412
For many of my landscape photos when I want to focus to infinity I select the furthest point I want in focus
...

There is NEVER a good reason to focus an UWA lens at infinity. Less than never if you are after DOF.

shane_c wrote in post #18541233
Thanks for your reply. I’m not sure how my post was odd. Maybe I was calling it the wrong thing. Perhaps the method I mentioned in my first post is setting the hyperfocal distance, either way I can’t focus the same way with this lens as I’m used to. Even on a lens that has the distance marks I know you can’t just put it to the infinity mark.


I realize that wide lenses have a larger DOF. But what I was saying is that even though I was stopping down and focusing at something a few feet away I did not find that the rest of the image was adequately sharp (i.e. a shallower DOF than what I would have expected), compared to doing the method I mentioned in my first post with my 17-50 or 70-200.

There is NEVER a good reason to focus an UWA lens at infinity. Less than never if you are after DOF.
Focus method has nothing to do with DOF. So your old method doesn't work. Big deal. Isn't it RESULTS you are after?
DOF too shallow? If you can use this lens to get EVERYTHING from 2' to infinity in focus, I can't figure out what 'too shallow' even means.

Example below. 6D @ 12mm & f/8. It is HARDER to get deep DOF on FF than it is on crop. I focused on the solid blue hat sitting on the aisle. The red-dot blue hat is 3-4' from my camera. The Irving Park Apartment building (tallest, center field) is over a mile from my camera. Both are in focus. Period. Not 'adequate', not 'good enough'; they are IN FOCUS.

I had the 10-18. It isn't this wide, but it is more than capable of this shot.

That's the problem. I CAN'T. Even when I stop down and focus on something a few feet away, as mentioned by you and others, the amount that is actually in focus seems quite limited IMO.

I'll try a few more shots today since the light is a lot better than yesterday.

Bassat wrote in post #18541268
There is NEVER a good reason to focus an UWA lens at infinity. Less than never if you are after DOF.

i think it works well when you're taking pictures of stars...


op post some pictures...with exif intact, they help more than anything...and then of course there's the old question on if you have a filter on the lens

I concede. I don't do stars.

shane_c wrote in post #18541297
That's the problem. I CAN'T. Even when I stop down and focus on something a few feet away, as mentioned by you and others, the amount that is actually in focus seems quite limited IMO.

A few feet away is too close. Try 10 ft away.

Post a shot that you think is too narrow dof.