Digital Inclinometer w magnets? accurate w a metal camera?

[photographs42]

http://store.mannyswoodworkersplace.com/6820001.html

These sorts of gadgets look ideal for measuring tilt angles... accurate to 1/10 degree and all that. But would the magnets in their base mess up when used with a metal camera that doesn't have everything in a smooth single plane? (Like a saw blade, which they are intended to be used with.)

Hi Frank,
I have the exact device that you reference. I have not used it with my camera (5x7 Technika) but I see no reason why it wouldn’t work if you have a flat surface to put it against. As someone stated, the magnets just hold it to a metal surface. They have no other function. You set it on a reference surface and zero it to that surface. Then when you tilt it, it reads the angle relative to the reference surface.

If you like, I could try it if you give me a scenario to try out.
Jerome

[Frank Petronio]

I just thought it might be easier to read than a protractor level's dial, and useful for aligning the front and rear standards tilt-wise. Of course any 5x7 Technika will be aligned, it would take a sledgehammer to mis-align it ;-) thanks

[Ron Marshall]

The photo on the package shows it next to a saw blade, so presumably... Truth in advertising aside, if it was designed for use with sawblades it should not be a problem.

[photographs42]

It’s easy to read. The zeroing feature is both good and bad. Good if you want relative readings and not so good if you want absolute level (I think). Maybe it defaults to level, I can’t remember. I’ll play with it tonight and report back.

The lens stage on a Technika is a problem because there is no convenient place to put the device but I’ll check it out tonight.
Jerome

[photographs42]

I just thought it might be easier to read than a protractor level's dial, and useful for aligning the front and rear standards tilt-wise. Of course any 5x7 Technika will be aligned, it would take a sledgehammer to mis-align it ;-) thanks

OK, I played with it and here’s what I found out.
1. It defaults to absolute level when you turn it on and stays that way unless you recalibrate it. That’s good. You can use it like any bubble level.
2. The magnets only hold it to a steel surface. They are on both sides but not on the top or bottom. My Linhof has almost no steel parts, so it sticks to nothing.
3. The readout is in degrees and is accurate to two decimal places. It is easy to read unless the light is pretty dim.
4. I tried to use it to check the front and rear standards to see if they are parallel. For several reasons this didn’t work out so well. The first problem is finding a flat spot on the front stage to hold it against. This is different with each camera but the device is about 2” tall and maybe an inch thick so it doesn’t fit just anywhere. The second problem is that it is almost impossible to adjust the standard while holding the thing against the front or the back (you need more hands). The last problem is the killer. The readout is instant, so if the angle is changing, the readout is constantly changing which makes it hard to read. Even with it stuck to my table saw blade, it is very hard to adjust it in .01 degree increments because .01 degree ain’t much!

All in all, I don’t think it’s the right tool for this task. And BTW, I never use a sledgehammer on my Technika. A ball pin hammer and a Crescent wrench are sufficient.

Jerome

[Jean-Louis Llech]

Frank,
I use an angle indicator that I bought by McMaster-Carr. http://www.mcmaster.com/ - Page 2241. Ref. 20145A41
It is made of cast aluminum alloy, not plastic, an has no magnetic base.
McMaster answered me that overseas air shipping of magnetic products was prohibited (!?!) This model is a bit expensive, but very accurate.

[PViapiano]

I don't understand why you need this...isn't a bubble level sufficient for each standard? Or are you looking to adjust them to other than level, but even?

[Frank Petronio]

Yes, other than level but even.

[Leonard Evens]

I love gadgets and the prospect of being able to measure something to within 1/10 of a degree for a mere $40 is almost too hard to resist. If the economy weren't tanking and my retirement accumulation with it, I would get one for sure, and maybe I will anyway.

But I do have serious doubts about whether or not that degree of precision is useful.

First, I doubt if you can position the standard that accurately just because of mechanical limitations.

Second, and more important, there is usually little need to know the what the tilt angle is. Most people adjust the tilt by what they see on the ground glass. The object is to position the standard so you can't see any shift in focus when you move from one point in the desired subject plane to another. When you've done that, you have the right tilt, and you don't usually care what it is. There are some methods such as Wheeler's Rule which allow you to calculate the tilt angle in advance, but they have inherent inaccuracies, and at best can be used to establish a first guess, which is refined on the basis of what you see on the ground glass. Few people even know that rule and even those that know it, like myself, don't often use it.

PS. Here is the method I use to tilt downward about a horizontal axis, the most common situation. ( I focus by moving the rear standard.) I make an initial guess by moving the top edge of the standard 5-10 mm forward. I choose two points in my desired subject plane, one near and the other far. I focus on the far point and then refocus on the near point. If that requires increasing the distance between the front standards, I increase the tilt. If it requires decreasing the distance between the standards, I decrease the tilt.. I continue until I can't detect any difference, which usually takes two to three iterations. (I think the same rule works if you focus by moving the front standard, but I would have to think it out and try it to be sure.)

PPS. I've done some elaborate calculations which suggest that because of inevitable focusing errors, one is unlikely to be able to set the tilt angle to better than 0.005 radians or about 3/10 of a degree. This is interesting to me as a mathematician, but except in rare circumstances, it is totally useless in practical situations! Still it suggests that accuracy to 1/10 degree in setting the tilt angle is overkill.