Leveling a field camera

[Kevin Kehler]

So I set up the tripod and 3-way tripod head, both of which are rated more than enough to hold the camera. I leveled the tripod and head using my trusty spirit level I keep in the camera bag. I then attached the camera to the tripod head and and re-leveled the tripod, placing the spirit level on the block under the bellows. I put the ground glass on and ensured all adjustments are neutral (no tilts, swings or shifts). However, the building directly in front of me does not line up with the etchings on the ground glass: one of the walls starts 1-2mm on the left of one line and ends up 1mm to the right of the line but if I adjust the tripod, I can straighten it all out where the wall runs parallel to the line (I think I can assume the etched lines are straight as it is a professionally made ground glass). However, the spirit level under the block now reads a non-level with a tilt to one side.

Which reading do I take as accurate? My initial reaction was if the camera is leveled properly, then use that. However, I also considered that what-you-see-is-what-you-get and if the building is not straight on the ground glass, why would it be straight on the film? Is it possible my adjustments were not truly neutral which caused the problem?

Thanks in advance.

[TimFox]

I have found it necessary to put a level directly on the ground glass, or on the ground-glass frame nearby, to ensure that the film plane is vertical.
This is what governs the convergence you see.
However, I have sometimes pulled my head out from the dark cloth and found that the building was tilting in reality.

[degruyl]

I also considered that what-you-see-is-what-you-get and if the building is not straight on the ground glass, why would it be straight on the film?

If you want the building to be straight in the photograph, it has to appear straight on the ground glass. This is why lenses with movements are called perspective correction lenses in the small format world.

If you want the camera to be level, it has to be level (actually, the film plane and lens have to be plumb). Those two things are separate.

Maybe I'm missing something, but the base plate of a field camera has very little (none) impact on the image, so leveling that is only in aid of squaring off the front and rear standards.

[Leigh B]

Did you level the damera side-to-side?
One of the levers on your tripod head should allow movement on this axis.

Bubble levels come in all different accuracies and resolutions. It's possible yours is not well-suited to the task.

BTW, levels are self-calibrating.
Find a flat surface like a counter top (need not be perfectly level), and tape a shoebox onto it.
Put your level in one corner of the shoebox, up against the side, and note the reading.
Turn the level around 180° and repeat. Compare the two readings.
They should be identical. If they're not, the level is inaccurate.

The previous comments about the ground glass are important.
The GG is the final arbiter of what will be on the film, regardless of what your levels say.
Use a level that measures on two planes, and put the vertical one against the GG. Adjust the back so the GG is vertical.

That still does not evaluate camera tilt side-to-side, as discussed above. Adjust the camera as needed.
If necessary, adjust the camera tilt so the building vertical lines up with grid on the GG.

- Leigh

[David A. Goldfarb]

I've had a level on the tripod legs, another on the platform of the tripod head, and another on the camera, that don't agree. I trust the one on the camera usually most of all, but you still have to confirm on the groundglass, presuming that the groundglass is installed straight in the back and the back is straight on the camera, which may not be the case. Then buildings sometimes lean...

[Leigh B]

Measurements on the camera itself are the only ones that actually matter.

Having the platform/head level may be desirable if you want to change axial position front/back or side-to-side.

Setting the GG and the lensboard parallel (vertically) can rely on readings from the same level, even if the level
itself is inaccurate, as long as the same end is up for both measurements.

- Leigh

[David A. Goldfarb]

It's relatively unusual not to have to pan the camera a bit, so I like having a level platform to pan from, although one can always make a final adjustment after panning.

[Leigh B]

...I like having a level platform to pan from, although one can always make a final adjustment after panning.

I agree. I do the same thing, for the same reason.

My comment was addressing the question of disagreement among level readings at different points in the system.

- Leigh

[ic-racer]

My initial reaction was if the camera is leveled properly, then use that.

To get vertical lines of the building straight you have to have the back perfectly plumb. In fact it only needs to be leveled by eyeball approximation because you can correct for not being level when printing by rotating the easel one way or the other.

[cliveh]

So I set up the tripod and 3-way tripod head, both of which are rated more than enough to hold the camera. I leveled the tripod and head using my trusty spirit level I keep in the camera bag. I then attached the camera to the tripod head and and re-leveled the tripod, placing the spirit level on the block under the bellows. I put the ground glass on and ensured all adjustments are neutral (no tilts, swings or shifts). However, the building directly in front of me does not line up with the etchings on the ground glass: one of the walls starts 1-2mm on the left of one line and ends up 1mm to the right of the line but if I adjust the tripod, I can straighten it all out where the wall runs parallel to the line (I think I can assume the etched lines are straight as it is a professionally made ground glass). However, the spirit level under the block now reads a non-level with a tilt to one side.

Which reading do I take as accurate? My initial reaction was if the camera is leveled properly, then use that. However, I also considered that what-you-see-is-what-you-get and if the building is not straight on the ground glass, why would it be straight on the film? Is it possible my adjustments were not truly neutral which caused the problem?

Thanks in advance.

Levelling a field camera - I don’t understand this concept, as surely image making is not about levelling. The photographer decides on the composition, which may mean putting the horizon or whatever, horizontal, or at an angle. The eye determines this, not a spirit level. How can you let science dictate the aesthetic?