April 17, 2014, 12:28:42 PM

Author Topic: Over - Under -shot not in focus?  (Read 3959 times)

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Over - Under -shot not in focus?
« on: September 24, 2013, 08:41:31 AM »
Hi!

I've tried out my underwaterhousing today at the indoor swimmingpool :)
It worked out great!

But when I tried to do some Over/Under-shots all the over-part was WAY out of focus. Is it supposed to be like that? Aperture was 4.5 and I guess that with f22 it would be more in focus but almost all the things under water was in focus.

Any ideas?

canon rumors FORUM

Over - Under -shot not in focus?
« on: September 24, 2013, 08:41:31 AM »

J.R.

  • 1D X
  • *******
  • Posts: 1429
  • A Speedlight Junkie!
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #1 on: September 24, 2013, 08:57:20 AM »
My guess is that refraction from the water is altering the plane of focus which would explain why the area underwater is sharp. Did you shoot at any other angle? 
Light is language!

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #2 on: September 24, 2013, 08:58:47 AM »
My guess is that refraction from the water is altering the plane of focus which would explain why the area underwater is sharp. Did you shoot at any other angle?

Any other angle, what do you mean?
Horisontal/Vertical etc?

I shot some split shots but only towards that "corner" of the pool. Didn't want to offend or disturb any other people swimming in the other sections :)

J.R.

  • 1D X
  • *******
  • Posts: 1429
  • A Speedlight Junkie!
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #3 on: September 24, 2013, 09:03:23 AM »
Ok. By shooting at another angle I meant if the camera was tilted slightly upward or downward. How and where did you focus while taking the shot?
Light is language!

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #4 on: September 24, 2013, 09:08:35 AM »
Ok. By shooting at another angle I meant if the camera was tilted slightly upward or downward. How and where did you focus while taking the shot?

se attached pictures :)

J.R.

  • 1D X
  • *******
  • Posts: 1429
  • A Speedlight Junkie!
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #5 on: September 24, 2013, 09:13:38 AM »
I feel it is refraction ... the experts will chime in I'm sure ...  :)
Light is language!

Kernuak

  • 1D X
  • *******
  • Posts: 1108
    • View Profile
    • Avalon Light Photoart
Re: Over - Under -shot not in focus?
« Reply #6 on: September 24, 2013, 05:57:21 PM »
Water and air have a different refractive index (different liquids will too, it is how oil is used for microscopy, to refract light enough at high magnification to allow focusing). Most shots I've seen along this idea have been with a fisheye, where the DoF is much greater and where the subject is closer. One in particular is of a lily above and below, although I have also seen one of spawning salmon with a landscapes in the background, but the landscape wasn't completely sharp from memory, it was more of a suggestion of the surrounding environment, just sharp enough. Also, a fish aquarium was used to place the camera in, instead of a housing.
Just found that Laurie has his salmon shot uploaded now.

http://www.lauriecampbell.com/recentwork.htm
« Last Edit: September 24, 2013, 06:00:53 PM by Kernuak »
Canon 5D MkIII, 7D, 300mm L IS f/2.8 and a few other L's

canon rumors FORUM

Re: Over - Under -shot not in focus?
« Reply #6 on: September 24, 2013, 05:57:21 PM »

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #7 on: September 24, 2013, 06:02:35 PM »
Water and air have a different refractive index (different liquids will too, it is how oil is used for microscopy, to refract light enough at high magnification to allow focusing). Most shots I've seen along this idea have been with a fisheye, where the DoF is much greater and where the subject is closer. One in particular is of a lily above and below, although I have also seen one of spawning salmon with a landscapes in the background, but the landscape wasn't completely sharp from memory, it was more of a suggestion of the surrounding environment, just sharp enough.

Is there any way around this perhaps?
I'm using a 8" dome and a 15mm fisheye. Underneath the water everything looked like it was in focus with only aperture f4.5 in this picture.

Perhaps where you focus can have an inpact. Prefocus on a point a third into the picture?

Drizzt321

  • 1D X
  • *******
  • Posts: 1645
    • View Profile
    • Aaron Baff Photography
Re: Over - Under -shot not in focus?
« Reply #8 on: September 24, 2013, 07:06:22 PM »
Were you using Auto-Focus? At a guess it chose the underwater portion of the frame and since the refractive index of water is quite a bit different than air, and you were using f/4.5, the air part of the frame was OOF.

That's my guess, never had an underwater housing...I'd like to have one though.
5D mark 2, 5D mark 3, EF 17-40mm f/4L,  EF 24-105mm f/4L IS USM, EF 135mm f/2L, EF 85mm f/1.8
Film Cameras: Mamiya RB67, RB-50, RB-180-C, RB-90-C, RB-50, Perkeo I folder, Mamiya Six Folder (Pre-WWII model)
http://www.aaronbaff.com

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #9 on: September 24, 2013, 07:09:04 PM »
Were you using Auto-Focus? At a guess it chose the underwater portion of the frame and since the refractive index of water is quite a bit different than air, and you were using f/4.5, the air part of the frame was OOF.

That's my guess, never had an underwater housing...I'd like to have one though.

Yes, I was using the cameras autofocus when I was shooting these pictures :)
So the thing should be to either try to fix the difference in the refraction-issue-thing or use a better focus point underneath the water.. aswell as a smaller aperture? Like f14-f22 ?

Drizzt321

  • 1D X
  • *******
  • Posts: 1645
    • View Profile
    • Aaron Baff Photography
Re: Over - Under -shot not in focus?
« Reply #10 on: September 24, 2013, 07:10:19 PM »
Were you using Auto-Focus? At a guess it chose the underwater portion of the frame and since the refractive index of water is quite a bit different than air, and you were using f/4.5, the air part of the frame was OOF.

That's my guess, never had an underwater housing...I'd like to have one though.

Yes, I was using the cameras autofocus when I was shooting these pictures :)
So the thing should be to either try to fix the difference in the refraction-issue-thing or use a better focus point underneath the water.. aswell as a smaller aperture? Like f14-f22 ?

Could be a combination of those. Take a whole bunch at different settings, pop out of the pool and take a close look. It's not like you have to wait a day or two to get them developed and printed :P
5D mark 2, 5D mark 3, EF 17-40mm f/4L,  EF 24-105mm f/4L IS USM, EF 135mm f/2L, EF 85mm f/1.8
Film Cameras: Mamiya RB67, RB-50, RB-180-C, RB-90-C, RB-50, Perkeo I folder, Mamiya Six Folder (Pre-WWII model)
http://www.aaronbaff.com

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #11 on: September 24, 2013, 07:11:27 PM »
Were you using Auto-Focus? At a guess it chose the underwater portion of the frame and since the refractive index of water is quite a bit different than air, and you were using f/4.5, the air part of the frame was OOF.

That's my guess, never had an underwater housing...I'd like to have one though.

Yes, I was using the cameras autofocus when I was shooting these pictures :)
So the thing should be to either try to fix the difference in the refraction-issue-thing or use a better focus point underneath the water.. aswell as a smaller aperture? Like f14-f22 ?

Could be a combination of those. Take a whole bunch at different settings, pop out of the pool and take a close look. It's not like you have to wait a day or two to get them developed and printed :P

The thing is that I'm heading abroad on friday (in 1.5 days now).. so I don't have all that much time over to get into the pool again to shoot more and do some tests :/

privatebydesign

  • 1D X
  • *******
  • Posts: 1585
  • Ermintrude says "moo"
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #12 on: September 24, 2013, 07:35:09 PM »
What lens, port, housing, tube etc?
Is Christmas really coming? I suppose it is..............

canon rumors FORUM

Re: Over - Under -shot not in focus?
« Reply #12 on: September 24, 2013, 07:35:09 PM »

eml58

  • 1D X
  • *******
  • Posts: 1226
  • 1Dx
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #13 on: September 24, 2013, 07:35:36 PM »

Is there any way around this perhaps?
I'm using a 8" dome and a 15mm fisheye. Underneath the water everything looked like it was in focus with only aperture f4.5 in this picture.

Perhaps where you focus can have an inpact. Prefocus on a point a third into the picture?

Manual Focus, only way.

If you Auto Focus your Focus Point will pick up what ever it's locked onto, underwater area/above water area, you have to Manual Focus for the best compromise between the Underwater section & Above water section.

Another trick is to wipe your Dome (The Housing Dome, not your other dome), with "Rain X Glass", helps make the water droplets not stick to the Dome and becoming a problem with blurry spots in the Image.

Over/Under shots done well are a bit of a suck & sea, lots of practise, but always with Manual Focus, f/16.

I use a Seacam Housing with a 5DMKIII + 8-15f/4 or 24f/1.4, 8-15 @ 15 & f/16, the 24 @ f/16.

Have a look at some of "Lemmyshowyou"s Images on the 1Dx site, maybe PM him and I'm sure he will gladly give you some more advise.
The only thing necessary for the triumph of evil is for good men to do nothing

fiend

  • Canon AE-1
  • ***
  • Posts: 64
    • View Profile
Re: Over - Under -shot not in focus?
« Reply #14 on: September 24, 2013, 07:40:32 PM »
What lens, port, housing, tube etc?

Canon 5D mk3
Sigma 15mm/2.8 Fisheye
IKELITE housing
IKELITE dome 8" + wide angle adaptor/tube so no vinjetting.

canon rumors FORUM

Re: Over - Under -shot not in focus?
« Reply #14 on: September 24, 2013, 07:40:32 PM »