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Author Topic: Shooting square to a flat plane (surface)  (Read 9640 times)
dwdallam
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« on: July 17, 2012, 11:21:50 PM »
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How do you go about getting dead on square to a flat plane so that the lens is at an exactly 90 degree angle as the plane or surface you are shooting?

If I were shooting a vertical wall I can use he bubble level on my camera or tripod, as long as the wall is vertically level, but what about horizontally?

I'm thinking a protractor with a string attached to it, where the protractor is set on the lens, and then the line ran to the wall?

 I haven't been posting much becsaue my work has taken me to modeling stuff, but I'm getting the urge to do other stuff again.
Thanks much.
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marcmccalmont
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« Reply #1 on: July 18, 2012, 01:29:29 AM »
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How about a yardstick at the base of your tripod and a tape measure to make sure the yardstick is parallel
once you have your tripod set the rest should be easy to eyeball
Marc
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Marc McCalmont
dwdallam
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« Reply #2 on: July 18, 2012, 01:54:01 AM »
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Not really sure I understand what you are saying, Marc.

You can't eyeball this because if you have horizontal lines (or vertical) in the picture, and you are even 1 degree off horizontally, the line in the picture will not be horizontal because of the relative perspective of the camera to the wall, like looking down a railroad where the lines eventually converge. Even a small degree can ruin the picture, or at least make it a snapshot, not a professional image.

I'll post an example.
« Last Edit: July 18, 2012, 02:13:32 AM by dwdallam » Logged

FredBGG
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« Reply #3 on: July 18, 2012, 02:28:22 AM »
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Very simple. Put a flat mirror on the flat plane you want to square off the camera.

When you see the reflection of the camera centered in the viewfinder you are squared off.
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dwdallam
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« Reply #4 on: July 18, 2012, 02:55:06 AM »
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Can you give an example?
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Robert Roaldi
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« Reply #5 on: July 18, 2012, 06:46:35 AM »
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Very simple. Put a flat mirror on the flat plane you want to square off the camera.

When you see the reflection of the camera centered in the viewfinder you are squared off.

Conceptually simple, but in the real world not always the case. I occasionally photograph my wife's art work and the one wall in our house big enough is not exactly flat. (In fact, none of them are.) But then, neither are the canvas subframes, so that when I place one against the wall, anything can happen depending on its size and where it touches the wall. I tried the mirror trick, but getting a mirror to stay flat on a flexible canvas surface is difficult, and so getting it parallel with the plane of the painting is impossible in my hokey set-up. Also, the entire set-up has to be torn down/rebuilt every time, because we use this room for other purposes. I'm kind of stumped. So far, I've only done this for her web site use, so good enough is relatively easy to achieve, but geez, getting it right is not easy.
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theguywitha645d
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« Reply #6 on: July 18, 2012, 08:43:56 AM »
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I think you are over thinking this problem. I would use the mirror and not worry about perfection beyond that point.
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marcmccalmont
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« Reply #7 on: July 18, 2012, 10:23:51 AM »
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Not really sure I understand what you are saying, Marc.

You can't eyeball this because if you have horizontal lines (or vertical) in the picture, and you are even 1 degree off horizontally, the line in the picture will not be horizontal because of the relative perspective of the camera to the wall, like looking down a railroad where the lines eventually converge. Even a small degree can ruin the picture, or at least make it a snapshot, not a professional image.

I'll post an example.

Ok set your tripod up one leg forward 2 legs back, if the distance from the rear legs to the wall is equal the tripod is parallel to the wall. I have a A/S cube so it is easy to look down on the head and square it with the tripod but a straight edge against the rear display should be good enough to look down and square it off. Or one could with some help put a yardstick against the rear screen and make sure both ends are the same distance to the wall.
Marc
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Marc McCalmont
EricWHiss
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« Reply #8 on: July 18, 2012, 01:10:03 PM »
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There are a number of alignment tools for this purpose... zigalign and versalabs both make them. 
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Ellis Vener
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« Reply #9 on: July 18, 2012, 02:48:26 PM »
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I use the zigalign mirror.
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dwdallam
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« Reply #10 on: July 18, 2012, 03:50:36 PM »
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Ok set your tripod up one leg forward 2 legs back, if the distance from the rear legs to the wall is equal the tripod is parallel to the wall. I have a A/S cube so it is easy to look down on the head and square it with the tripod but a straight edge against the rear display should be good enough to look down and square it off. Or one could with some help put a yardstick against the rear screen and make sure both ends are the same distance to the wall.
Marc

Marc, thank you. this makes sense now. I can use the bubble level that comes on my RSS ball head, and then use the rear tripod legs to equal the distance to the wall. Of course if the isn't square, then it's impossible.

To others, thank you for the information. I will check on the zigalign mirror too.

Please feel free to continue suggestions. This is a helpful thread.
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dwdallam
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« Reply #11 on: July 18, 2012, 04:14:37 PM »
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After looking at versalabs and zigalign, I don't think they will work for my needs. I don't use a view camera, for one, and I am not using an enlarger for film, and the Ring Module seems like it might work, but would be almost impossible to your outside of a studio, for example, if you need to photograph a wall at 30 feet or more. Am I missing something?
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BartvanderWolf
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« Reply #12 on: July 18, 2012, 05:05:55 PM »
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I don't use a view camera, for one, and I am not using an enlarger for film, and the Ring Module seems like it might work, but would be almost impossible to your outside of a studio, for example, if you need to photograph a wall at 30 feet or more.

Hi, that's a bit of a different scenario than e.g. reproducing a painting. In the case of a more distant wall, I would use a Laser Distance Finder that allows to measure almost realtime distance, e.g. a Leica Disto. It is accurate to 1 millimetre and when I slowly swing it horizontally it will continuously update the distance, and when the distance is at its minimum it is perpendicular to the wall for the rotation you used. Tweak for the vertical distance in a likewise fashion, and you have found the spot on which to center your optical axis.

The older Disto A5 I use has a tripod mount (I have to assume more recent models also do) so you can also align your tripod head very accurately, assuming you have a well squared camera mounting system. You'll find out if the sensor in your camera is well aligned soon enough ...

Cheers,
Bart
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dwdallam
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« Reply #13 on: July 18, 2012, 05:12:13 PM »
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Hi, that's a bit of a different scenario than e.g. reproducing a painting. In the case of a more distant wall, I would use a Laser Distance Finder that allows to measure almost realtime distance, e.g. a Leica Disto. It is accurate to 1 millimetre and when I slowly swing it horizontally it will continuously update the distance, and when the distance is at its minimum it is perpendicular to the wall for the rotation you used. Tweak for the vertical distance in a likewise fashion, and you have found the spot on which to center your optical axis.

The older Disto A5 I use has a tripod mount (I have to assume more recent models also do) so you can also align your tripod head very accurately, assuming you have a well squared camera mounting system. You'll find out if the sensor in your camera is well aligned soon enough ...

Cheers,
Bart

That sounds more like what I need. It would be nice if they had a mount for the camera. However I am using a RRS heavy ball head with the RSS "L" bracket.
« Last Edit: July 18, 2012, 11:24:01 PM by dwdallam » Logged

marcmccalmont
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« Reply #14 on: July 18, 2012, 06:05:38 PM »
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how often do you need to do this?
Marc
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Marc McCalmont
dwdallam
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« Reply #15 on: July 18, 2012, 11:24:21 PM »
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Interesting question. Why do you ask?
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marcmccalmont
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« Reply #16 on: July 19, 2012, 12:52:15 AM »
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I was thinking if you are doing it a lot then investing some $ is worth it
I was thinking a RRS 28" bar to clamp on your ball head ($150), 2 carpenters distance measurer's (laser or ultrasonic, 2x $100) mounted on each end and squared off and a 2 axis spirit level ($5) mounted in the center.
you could mount this in the clamp to square and level the head to the wall quickly and I would think accurately?
Marc
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Marc McCalmont
dwdallam
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« Reply #17 on: July 19, 2012, 01:06:09 AM »
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You'd have to have some way to square the distance tools with the bar itself, and also with each other. But I see what you're getting at. The Leica measuring tool could be used alone, too.
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marcmccalmont
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« Reply #18 on: July 19, 2012, 02:34:08 AM »
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I restored a Lotus 7 many years ago when setting up the suspension I manually set the ride height, caster, camber and toe in. All I used was 2 people, a tape measure and an angle gauge with a bubble level. Several years later I was curious so I took it to a professional with all the automated equipment. It was spot on no adjustments to make. It's amazing how accurate your eye and a tape measure can be!
Marc
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Marc McCalmont
BartvanderWolf
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« Reply #19 on: July 19, 2012, 03:59:53 AM »
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You'd have to have some way to square the distance tools with the bar itself, and also with each other. But I see what you're getting at. The Leica measuring tool could be used alone, too.

Like Marc, I'm thinking of some of the following RRS or similar components.

Stuff that can be used for horizontal alignment/squaring:
  • 1. MPR-73: 73mm Multi-purpose rail (with 1/4" camera screw), for mounting under the Leica Disto. It has an anti-twist flange that can be mounted to square the rear of the Disto. I had a Wimberley P30 lens plate laying around which functions just as well, maybe it's cheaper.
  • 2. B2-FAB/mAS Mini-Clamp Package, for mounting the MPR-73 on a horizontal bar at a right angle.
  • 3. A horizontal (CB-18 and/or CB-28) Bar, for sliding the miniclamp package with Disto along to check for identical distance at both ends (or average along the width of the bar if the wall is not even). For increased accuracy, the bar itself can also slide in the clamp that holds the bar, so you can achieve a measuring base of allmost twice the bar length.

Then you replace the bar by your camera with camera plate.

Following this horizontal parallel bar/wall calibration, you can calibrate the vertical parallel by minimizing the measured distance when you vary the pitch angle. It helps to use a geared head or a geared leveling plate for such precision alignment.

BTW, using a bar parallel to the surface automatically compensates for any minute non-square mounting of the Disto to the bar. Whatever slight angle there may be, the distance is measured at that same angle in the left and right measuring position.

To give an idea of the accuracy. A 1 mm difference over a 800 mm measuring base (like with a single CB-18) represents 0.072 degrees, and a 1 mm difference over a 1300 mm measuring base (like with a single CB-28) represents 0.044 degrees of accuracy.

'RRS' also sell a slightly cheaper package which combines the dual clamps with a bar (items 2 and 3 of the above list), in case you have don't have one or the other yet and would have to purchase both.

Cheers,
Bart
« Last Edit: July 19, 2012, 06:36:23 AM by BartvanderWolf » Logged
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