Over - Under -shot not in focus?

fiend

EOS T7i
Mar 17, 2012
68
0
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?
 

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J.R.

EOR R
Jan 13, 2013
1,749
0
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?
 

fiend

EOS T7i
Mar 17, 2012
68
0
J.R. said:
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.

EOR R
Jan 13, 2013
1,749
0
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?
 

Kernuak

EOS 6D MK II
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
 

fiend

EOS T7i
Mar 17, 2012
68
0
Kernuak said:
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

EOR R
Nov 23, 2011
1,667
0
Lala land
www.aaronbaff.com
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.
 

fiend

EOS T7i
Mar 17, 2012
68
0
Drizzt321 said:
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

EOR R
Nov 23, 2011
1,667
0
Lala land
www.aaronbaff.com
fiend said:
Drizzt321 said:
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
 

fiend

EOS T7i
Mar 17, 2012
68
0
Drizzt321 said:
fiend said:
Drizzt321 said:
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 :/
 

eml58

1Dx
Aug 26, 2012
1,939
0
Singapore
fiend said:
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.
 

fiend

EOS T7i
Mar 17, 2012
68
0
privatebydesign said:
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.
 

fiend

EOS T7i
Mar 17, 2012
68
0
eml58 said:
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.
You can't focus on something in the water then?
Manual focus.. so what should I focus on? Then I have to manually focus before I put the lens into the housing but then I can only use the setup for under/over-shots and not for general underwater shots aswell?

I use back button focusing so I don't have to think about the camera "refocusing" when I'm shooting the shots.

Rain X Glass? You can't use just some soap or something that repells the water or makes it more "slick" ? :)
Don't know if Rain X Glass is a product that is available in Sweden where I live.
 

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
7,790
883
119
fiend said:
privatebydesign said:
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.
Is the tube part number "#5510.11 port body"?
 

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
7,790
883
119
fiend said:
privatebydesign said:
fiend said:
privatebydesign said:
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.
Is the tube part number "#5510.11 port body"?
Yes :)
OK, you have the correct port extension, but you should still have some vignetting on the ff 5D MkIII. Anyway, as a start f4.5 is way inadequate, as eml58 says try f16 and I suspect your problems will be gone.

If not it will take some fiddling, put lens in manual focus and focus on the overwater section, take the housing out of the water dry off the port and take it off to see where you focus is, make a note, then do the same thing with the underwater part. You will end up with two figures, make sure you use dof/aperture value that comfortably encompasses both figures. Done.
 

fiend

EOS T7i
Mar 17, 2012
68
0
privatebydesign said:
OK, you have the correct port extension, but you should still have some vignetting on the ff 5D MkIII. Anyway, as a start f4.5 is way inadequate, as eml58 says try f16 and I suspect your problems will be gone.

If not it will take some fiddling, put lens in manual focus and focus on the overwater section, take the housing out of the water dry off the port and take it off to see where you focus is, make a note, then do the same thing with the underwater part. You will end up with two figures, make sure you use dof/aperture value that comfortably encompasses both figures. Done.
If you look at the full res picture you can see that there is no vinjetting or at least as far as I can see :)
Might be a little darker in the corners but that's not bad.
I will try f16 and see if it will be better when I try to shoot with a smaller aperture.

Then I have to be at the correct distance to the object before I put it in the housing? Since I can't manually focus when it is in the dome.

Lets see if I understand it right.
I focus on the object that I want in focus ABOVE the water.. check the reading.. like 1m
Then I put it down in the water and to the same and check the reading.. and I get like 0.3m
Then what? :)

I've attached a picture of the lens with the focus set on 0.5m (focused under the water).
How can I know the aperture/focusdistance to the "over"-object with this? :)
 

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