When shooting buildings straight on, I have trouble squaring the camera to the building--keeping the film plane parallel to the front of the building. Invariably, I get a slight ski slope at the top and bottom. Any tips you can offer to set me, uh, straight?
Mike
If you happen to own an i-Pod Touch, you could download a program from i-Tunes called Inclinometer for .99. This will allow you to measure the angle very accurately by just leaning the i-Pod against the front and rear standards.Originally Posted by mdd99
That said, you might actually want some foreshortening to avoid a situation where the building looks too wide at the top. This is the visual impression one gets when the sides of a tall building are absolutely parallel. Our visual point of reference causes us to expect the building to be narrower at the top when viewed from ground level. The opposite it true when viewing from a high vantage point. On close ups of sections of buildings, parallel might be desirable because there is no sense of where the ground is so the building assumes more of a 2-dimensional shape anyway and that often looks better when parallel with the edges of the print.
Use a ground glass or plastic overlay with a grid on it, so you can see clearly if everything is square or not.
Incidentally, many buildings actually look more natural with just the tinyest bid of convergence at the top.
Wilhelm (Sarasota)
A level and/or clinometer will get the camera square with the ground and square with itself, but a compass will tell you if the camera is square with the building, presuming you have a flat surface on the building that is itself square with the facade. In practice, this isn't always the case, so a grid overlay is another method of checking that the building is visually square.
I use a Suunto Tandem clinometer-compass to check these things. It will turn any floppy wooden or ultralight camera into a fairly precise instrument.
I have bubbles levels mounted on both front and rear standards and I have a gridded ground glass. I find these pretty much do the trick for me.
Levels, a grid ground glass, and a lot of time making sure you have everything right are the only solutions I've found unless unless you print digitally, in which case you can usually fix the problem you describe in Photoshop. Levels are a big help but they aren't a complete solution because sometimes the building itself isn't perfectly level or parallel.
Brian Ellis
Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
a mile away and you'll have their shoes.
I use a flash shoe level I got at B&H. Orienting it properly while placing it directly on the ground glass, I can be sure that surface is plumb to an accuracy of 1/4 degree or better. Simple calculations show that an error that large would not be detectable as convergence of truly vertical lines without making careful measurements of distances in a print. They certainly wouldn't be detectable to the normal human eye.
On the other hand, there is no way to use a level to avoid convergence of truly horizontal lines. A level on the top of the rear standard can be used to be sure the top and bottom of the frame are horizontal to a high degree of accuracy, but that won't tell you if the camera is square on a building facade. If the facade is aligned perfectly in a known direction, you could in principle use a compass to make sure the lens axis is perpendicular to that direction. I've never tried that, but I have my doubts that you could get the required accuracy.
I have a grid on my ground glass, which was made by Maxwell Precision optics, and I've checked that it is accurate, i..e, with the camera level, the vertical lines are vertical and the horizontal lines are horizontal. I use the grid lines, together with horizontal lines in the subject to check squareness to the subject. (Of course, I also use the vertical grid lines to check verticals.) If you use a magnifier, and you can't see any convergence on the ground glass, then you shouldn't end up seeing any convergence in the print, at least if the film lines up properly with the edges of the standard. The film could be skewed slightly in the film holder, which would rotate the image slightly. But you can compensate for that either when enlarging, by positioning the easel, or when scanning, by adjusting the position of the film in the scanner.
Another way to check parallelism of lines is to use a metric scale to measure the distances between the lines at different parts of the image. You have to be careful that the scale is aligned properly in each case, by using grid lines, for example. But it is hard to read such a scale to much better than 0.5 mm. A convergence that large would in most cases be visible without any measurements, so this shouldn't be used as a primary method.
Of course, it is possible the building is not plumb or that its edges, vertical or horizontal, are not parallel. Builders are usually pretty good about that, particularly for modern buildings, but settling or other issues can upset things. So, if you are sure the camera is perfectly level, and you still get convergence of verticals or horizontals, after carefully making adjustments, consider the possibility that the problem is in the building. In that case, a photo-realistic ethic would suggest just showing it as it is.
I use a small plastic triangle that I picked up at the hardware store for something like $5 that has bubble levels on two sides. It works nicely most of the time for both assuring that the GG and front standard are plumb and for squaring the standards. Plus, it fits nicely into the base plate of the camera, so it's always there.
But, as Brian mentioned, if the building itself is no longer plumb, you still need to make adjustments for the image to look "right".
All good thoughts--thanks. I have an Arca with grid lines on the ground glass, as well as two levels. I do check them closely. Adding to the squaring-up challenge is trying to position the camera in the midpoint of the building.
Here's the problem: After squaring up the camera by checking the top and bottom grid lines, I check the sides. If they're not perfectly vertical (or as in the attachment, the amount of space on either side of the object I'm focusing on isn't equal), I adjust to square them up. But then the horizontals are thrown off. Presumably this means I need to reposition the camera at the midpoint. It ends up being trial and error until I get something close to square all around. I could back the camera up, so the imperfections aren't as noticeable, but I like to shoot tight.
See attachment: The top isn't square, and the space on each side isn't equal (I don't mind the convergence). How would you solve this problem?
Mike
I'm new to this and I could be wrong, but it looks to me that you're not parallel with the building and wall face. Your camera is meeting the vanishing point on the left of the frame. In other words, the the left part of the film plane as you are standing behind your camera is ever so slightly closer to your composition. Having a geared tripod head that allows for three independent movements is not the sole solution but it is helpful in times like this.
However... it's tough to know without also knowing the actual shape of the subject. It's possible that a simple front or rear shift would fix the picture entirely.
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