where to focus for sharp water reflections

[travelfinn]

A few weeks ago attended a shooting at night course and stayed at one location with another guy to try and take some pictures of this old renovated picnic hut. It was late and dark so we used my car lights to illuminate the hut about 220 meters away. We couldn’t get the car to the shoreline and there were lots of trees so could not get a shadow free illumination. You can see the tree shadow on the right side of the picture.
Put my Nikon 800E on my Gitzo explorer tripod with the Manfrotto three way gear head and as lens Nikon 70-200 2.8 with TC-1.7 connected my Camranger to the Ipad and set iso 100 f8 and 30s. and started hunting for the hut in liveview found the hut or saw only the traffic sign and its reflection.. Took the first picture had to correct focus and straighten the picture, next one picture straight but not in focus and 105mm too wide. Then 165mm and not correct then 180 looked ok and focused on the traffic sign it was the only thing I could see. Saw that the sign was blowing out and a lot of blown shadows. But took three shots more and the last one at f5.6. The other guy had already called it enough and also looking at my jpg on screen said it’s also for me.
Back home processed the raw files and was surprised how good they look.
Was wondering why the reflection of the hut is different thought first wind but then discovered had refocused for the last shot. you notice it on the branches in the left corner..
So question number one is where one should focus for the best reflections in water. To get it right is very difficult with AF lenses with a small throw in manual mode.
The camera was low about knee height would higher be better regarding reflections.
Would the picture be better with a light in the hut and or car lights some ware behind the hut.
Blown shadows corrected with still longer exposure and merged in Photoshop which I don’t have. Have only Nikon viewnx2
The photos are in camera jpg it’s what I see on the Ipad. Then two converted files with different reflections and a 100% crop all different frames.
Really should have a notebook with me and download the shots process the raw files and then retake. Nothing really changes during the night hours.
Planning on a retake with a second car but the foliage will be different.

[Mike Buckley]

It seems to me that your issue has nothing to do with the reflection and instead has to do with trying to use auto focus when the scene has so little contrast that auto focus doesn't always "find" the same focus point. If I was in that situation, I would use Live View and manual focus. I would enlarge the Live View to ensure that the absolute most important part of the scene was tack sharp. If I was concerned about the most desirable depth of field perhaps not being achieved, I would make several exposures using different aperture settings knowing that in each capture the area of the scene that had to be sharp would indeed be sharp. Once I had returned to my computer, I would decide which depth of field was preferable.

[chauncey]

From your description of your gear and the shoot itself, it would appear that the problem dwells
in the photographer and his lack of skills in using that superior gear.

Mike's suggestions are a good starting point, heed them. But you need to understand why they
are necessary. That gear will cough out superior images...if you can do your part.

Learn to use manual modes in difficult scenarios and quit with the, cooked-in, jpeg results.

[ajohnw]

Reflections change the distance to the subject they show making it longer. Easiest way to explain is to imaging you are standing 2m in front of a mirror and want to take a photo of yourself taking the shot etc. The focus distance will be twice the distance to the mirror. Your AF in this case will also focus to twice the distance. The mirror is effectively working as an optical element and transferring the image back to the camera. In this case if some one focuses on the wall behind the mirror and then views the mirror at the same setting all that will be seen clearly is the mirror not the reflected image. Focus again but on the mirror and the reflection will be focused.

Going on to the OP's shot imagine a line running from the nearest point of the reflection to the same point on the object causing it - the length of that is the focus distance for that point. Then imagine another line running from the furthest point on the reflection to the corresponding point on the object. That is it's focal distance. These distances will be different - usually longer - than the distance to the object causing the reflection especially the nearest point of the reflection.

The answer to the question really is to focus and use an aperture that accounts for these various depths of field just like any other situation. The only complication is if there are ripples or leaves or what ever floating in the water - the distance to those is as it appears. Only the reflections are "further away".

John
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In the OP's situation I would manually focus via the viewfinder and set an aperture to suit based on experience. Some would set the aperture via a hyperfocal distance calculator. Some might carry a laser range finder for distance measurement and a theodolite to measure reflection angles and calculator to work out these distances to but really this it not a critical situation if a suitable aperture is selected as the object is some distance away.

If I used live view and the situation was not really bright enough I would also set live view boost to make the view brighter but the OP's camera may not have that facility.

John
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[travelfinn]

Sorry this a double post as a novice without the pictures. The other thread with the same name is the correct one.
Ilmari