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Offline johndiver

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focus on reflection
« on: 23/09/2005 13:57:09 »
I would like to photograph a young lady standing on the other side of a bird bath, such that I would focus on her reflection in the water to get a shimmering image of her face.
Question, do I first focus on her head, then swing the camera to the water, or should I focus on the water instead. Any ideas? [?]


 

Offline johndiver

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Re: focus on reflection
« Reply #1 on: 27/09/2005 03:59:05 »
A gentleman from a photography forum suggested I focus on the water, then set the depth of focus to include the subject, thereby ensuring a clear picture either way.
 

Offline neilep

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Re: focus on reflection
« Reply #2 on: 27/09/2005 04:06:30 »
can you try it both ways and let us know which turned out better ?

I'm just trying to think this through....does it make any difference whether you focus on the girls face or the reflection ?...I mean, doesn't the reflection in the water equate to the distance the girls face is at.....do you understand what I mean ?.....

we need Tweener to answer this, he's an avid photographer and I suspect this may be down Gsmollins avenue too, hopefully they'll post a response..in the mean time...good luck.

Men are the same as women.... just inside out !!
 

Offline ukmicky

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Re: focus on reflection
« Reply #3 on: 27/09/2005 04:11:59 »
You have to focus on the reflection because thats what your taking the picture of.

and in order to get the best result you would need to experiment with extra lighting .

Michael                                      
« Last Edit: 28/09/2005 01:11:25 by ukmicky »
 

Offline Solvay_1927

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Re: focus on reflection
« Reply #4 on: 27/09/2005 19:57:08 »
I'm sure this is a simple problem in optical physics, but I can't remember the techniques/formulae you would use (to determine focal lengths, etc.) - and, well, I'm just to lazy to look it up. :)

But I would guess it would be logical to focus on the water, as that's where the light is coming from before it reaches your camera.

Consider a situation where you want to photograph the reflection of a person in a mirror, and the person is standing 1 metre from you but the mirror is, say, 20 metres away.  Logically, you'd want to focus on the image in the mirror.  If you focussed on the person first and then used that setting when pointing at the mirror, the image would obviously be blurred and unfocused.

But this situation is analogous to that of the bird bath - the distances involved may be very different, but the same principles must apply, mustn't they?

Not that I understand WHY you want to photograph a young lady standing beside a bird bath.  (Personally I'd rather take pictures of young ladies taking a bath ... hmm, maybe I'd better stop there.)
 

Offline johndiver

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Re: focus on reflection
« Reply #5 on: 29/09/2005 02:49:26 »
realistically, the distance from lens to lady is about the same as distance from lens to water, and so a small aperture would erase any difference in focus between the two. However, if it were otherwise ... that is, if there were a noticeable difference between the focus points, would the reflected image be in focus at the distance of the water's surface, or at the distance to the subject?
BTW ... Another photographer suggested a more semantic approach take 2 or 3 photos and keep the best one.
 

Offline tweener

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Re: focus on reflection
« Reply #6 on: 29/09/2005 04:44:54 »
If the distance from the lens to the lady and the lens to the water are about the same, you are right that you can stop the lens down a little and get both of them in focus at the same time.  Compositionally, you might try it both ways - having both in focus, and also having the water image in focus and the actual subject slightly out and vice versa.  It depends on your creative impulse.

If there is a difference in the distance between the two "subjects" then you will have to have a very small aperture (large f number) on your lens to have any hope of getting them both.  Then it will depend on the focal length of the lens and how close they actually are.  With a telephoto lens you will have much less depth of field than for a wide angle lens, and the closer you are the less depth of field you will have for a given lens.  So if you have a telephoto that is focusing fairly close (like four or five feet) you will have at best a few inches of depth to work with.  If you use a fairly wide lens (like 28mm) then you migh have everything from three feet to infinity in sharp focus.  

If the camera you are using has a depth of field preview, you can check this in the viewfinder.  Or, if you are shooting digital, you can take a shot and check it on the LCD.  If you are shooting film and don't have depth of field preview, then the only advice is to take lots of shots and hope one comes out the way you want.

On a more esoteric note, if you were to use a view camera for this, you could achieve a very shallow depth of field and also keep both of your desired points in focus.  This is achieved by tilting or swinging the lens relative to the back, which changes the focal plane in the image to be somewhere not parallel to the film plane.  This is called the Scheimpflug Principle and can do some really amazing things for a photo.

I agree with the suggesting above - take several with different settings and compositions and choose the one you like best.  Often the LCD on a digital is not sufficient (at least for me) to determine how the photo really looks.  So, even with digital I take several and decide later which ones are keepers.  Sometimes it takes several months to figure out whether I like a shot.

Good luck and keep us posted.  I'd love to see the shot you come up with.  You can e-mail me if you have any questions.  I love to talk photography (if you can't tell).

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John - The Eternal Pessimist.
 

Offline neilep

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Re: focus on reflection
« Reply #7 on: 29/09/2005 13:24:31 »
Dear Mr Tweener Sir,

Is one of those Throw-away cameras suitable for my nieces wedding ?

..I have been appointed chief photgrapher and have seen a bulk-buy  offer of 30 of these cameras for 10. The cameras are only five years past their use by date but I figure it should be ok. I gather the only special equipment I need is a big bag to carry the cameras in and some loose change for when I pop down the photo processing booth.

I'm sure my niece and her new hubby will be very happy with their once-in-a-lifetime photos...what do you think Mr Tweener Sir ?

Men are the same as women.... just inside out !!
 

Offline gsmollin

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Re: focus on reflection
« Reply #8 on: 30/09/2005 02:33:13 »
quote:
Originally posted by johndiver

I would like to photograph a young lady standing on the other side of a bird bath, such that I would focus on her reflection in the water to get a shimmering image of her face.
Question, do I first focus on her head, then swing the camera to the water, or should I focus on the water instead. Any ideas? [?]



You focus on the lady, if you are taking a picture of the lady. You focus on the reflection of the lady, if you are taking a picture of the reflection of the lady. You focus on the water, if you are taking a picture of the water. It is all pretty obvious, and all three are at different distances from the lens. Ray tracing will show you.

"F = ma, E = mc^2, and you can't push a string."
 

Offline neilep

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Re: focus on reflection
« Reply #9 on: 30/09/2005 03:18:03 »
Have you ever had one of those moments when the penny drops and clarity hits you right in the face ?...the answer above by Gsmollin does it for me .

Men are the same as women.... just inside out !!
 

Offline johndiver

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Re: focus on reflection
« Reply #10 on: 01/10/2005 14:20:45 »
Neil: re: cheap 1-time cameras.
We gave each table at the reception one of those cameras. Good idea, as it allowed each person to take a candid photo of what they thought was funny or relevant. The cameras were collected at the end of the night and the photos were developed and placed into an album for humorous viewing.
 

Offline daveshorts

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Re: focus on reflection
« Reply #11 on: 01/10/2005 18:36:41 »
The problem with focussing on the water is that the ripples in the water will make the camera focus on the water not the reflection of the face.

What you could do is get a cheap mirror lay it on the bird bath focus on the lady in the mirror and then remove the mirror. The focus will then be right to catch the lady in the ripples.
 

Offline ukmicky

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Re: focus on reflection
« Reply #12 on: 01/10/2005 19:08:59 »
originally posted by daveshorts
 
The problem with focussing on the water is that the ripples in the water will make the camera focus on the water not the reflection of the face.

What you could do is get a cheap mirror lay it on the bird bath focus on the lady in the mirror and then remove the mirror. The focus will then be right to catch the lady in the ripples.

___________________________________________________________
Dave

I must be missing something (it happens):)

Ripples in the water? why would anybody what to put bars of chocolate in a bird bath.:D


Seriously though, he could always take his shots when their's was no wind,to disturb the surface.

I'm good at this problem solving:D

Michael                                      
« Last Edit: 01/10/2005 19:19:26 by ukmicky »
 

Offline johndiver

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Re: focus on reflection
« Reply #13 on: 02/10/2005 23:38:00 »
enough talk!
I took my camera, tripod, and mirror outside today, layed the mirror on a table so I could see a reflection of a tall tree at the end of the yard. I focused on the mirror surface, then the table surface, and finally swung the camera up to focus on the tree then held the focus while I aimed the lens at the mirror again. Camera was Canon Powershot A75 set to Aperture and f2.8.
Results? The focus on the mirror's surface gave a sharp picture of the table and a semi-sharp picture of the tree. Focus on the table resulted in more blur of the tree's reflection. Finally, focus held on the tree but aiming at the mirror gave a blurred mirror and sharp tree.
Conclusion? If I want all to be in focus, I'll take two photos, then layer and merge them in PhotoShop. Otherwise, change the aperture to keep both reflected image and reflecting surface in focus, or choose one of the two.
 

Offline ukmicky

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Re: focus on reflection
« Reply #14 on: 02/10/2005 23:54:54 »
Hi John,More talk :)

So maybe you should focus on the mirror but move in closer or try changing the angle of the mirror in respect to the tree or the angle of the camera in respect to the mirror or both.:)


Michael                                      
« Last Edit: 03/10/2005 00:37:19 by ukmicky »
 

Offline neilep

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Re: focus on reflection
« Reply #15 on: 03/10/2005 02:42:22 »
quote:
Originally posted by johndiver

Neil: re: cheap 1-time cameras.
We gave each table at the reception one of those cameras. Good idea, as it allowed each person to take a candid photo of what they thought was funny or relevant. The cameras were collected at the end of the night and the photos were developed and placed into an album for humorous viewing.



What a great Idea :D...ok...carry on with the thread.

Men are the same as women.... just inside out !!
 

Offline anthony

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Re: focus on reflection
« Reply #16 on: 03/10/2005 13:01:31 »
A focus is a focus, if you have an SLR it's easy, It's also easy if your autofocus sees a bright image of the girl. Your photographers first suggestion is good because it focuses on the girl and the ripples, which will give you the best looking picture. Otherwise you need to focus on the girl, with an autofocus camera you'd just point at her focus then move the camera to point at the water. If the angle to the water is close to grazing this should be alright. If you've focused on both the girl and the ripples you see a girl's reflection on rippled water, if you just focus on the girl you see the distorted image of the girl. The reason being there will always be additional information, the image of the rippled water, which will be lost if this is not in focus.
 

Offline tweener

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Re: focus on reflection
« Reply #17 on: 03/10/2005 19:13:54 »
quote:
Originally posted by neilep

Dear Mr Tweener Sir,

Is one of those Throw-away cameras suitable for my nieces wedding ?

..I have been appointed chief photgrapher and have seen a bulk-buy  offer of 30 of these cameras for 10. The cameras are only five years past their use by date but I figure it should be ok. I gather the only special equipment I need is a big bag to carry the cameras in and some loose change for when I pop down the photo processing booth.

I'm sure my niece and her new hubby will be very happy with their once-in-a-lifetime photos...what do you think Mr Tweener Sir ?

Men are the same as women.... just inside out !!



Neil,
Good plan as long as you don't want to be an uncle (or a sibling to her parent) anymore.  It's amazing how fast one can shed friends and even relatives when photographing a wedding.  And the pictures don't even have to be bad to do it! LOL


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John - The Eternal Pessimist.
 

Offline AlphBravo

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Re: focus on reflection
« Reply #18 on: 04/10/2005 01:15:49 »
Being an avid camera bug, for an SLR you can get one of those like filters that like those bifocal glasses that will let you focus on two objects, but I guess Tweenie has put it best take a few shots and wait for the results, though I have been mainly using a digi camera lately which preclues filters and such, the best thing is the near instant review!
 

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Re: focus on reflection
« Reply #18 on: 04/10/2005 01:15:49 »

 

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