Establishing Parallel Standards On Drop-Beds

[jhogan]

This is a question for those familiar with drop-bed issues:



Can anyone illustrate/describe a practical and reliable process for assuring the front standard/lensboard is parallel to the groundglass when using the bed in a dropped position?



I know that some practice the “eyeballing technique” but in my experience its accuracy is suspect- especially in windy or cold conditions.



Some details: I’m using a MT2K with an SS80XL on a recessed board. It’s a tidy little package- I mount the camera on the tripod, snap it open, adjust the required rise, focus by scale and I’m ready to shoot (after attaching the CF and NDs, if needed).



The work involves architectural elements so parallel standards are crucial. And, since I’m often working in public spaces, speed is of the essence.



On many monorail cameras, there are scales marked for quickly establishing the relationship between standards- ideally I’d be able to fabricate/install/rig something similar … unless, of course, there’s an expensive little gadget to BUY. Any suggestions?



Thanks in advance for the advice.

[Ralph Barker]

I use a little 4" plastic triangle that has two bubble level vials on the sides. That makes it easy to ensure that both standards are plumb. ($5 or so at the local hardware store) The triangle is also handy for leveling the base, or making sure the back is at right angles to the base.

[Dan Jolicoeur]

Well, If your front standard and rear are less than 6" than i would suggest a digital 6" caliper. They can be bought at Harborfreight.com for about $16 on sale for a chinese model. I used one to measure the dmax focus spread to calculate my f/stop. I focus far zero focus near find the spread and move 1/2 the distance. inch and metric mode. Very fast and accurate. You could do the same thing by measuring the top and bottom of the front to rear to make sure they are the same distance to within .001", again top front to back, then bottom front to back, repeat for both sides.

[Dan Jolicoeur]

Sorry, I got booted off before I finished to explain. I am making a prototype at the moment to mount to this to my Shen Hao. I have ground off the front of the calipers and part of the rear. This will be used as an accurate but cheap digital linear scale for focusing. I will post pictures when I have all the mounting hardware complete, and designed so it will not be in the way and can be taken off, and on quick if wanted.

Dan

[Gem Singer]

Hi J,

A small, horizontally mounted, bubble (spirit) level on both the front and rear standards is the simplest method of solving the problem. I realize that they are not precision instruments, but they seem to do the job.

[Kirk Keyes]

I thought with the Technikas that if you drop the bed to the first stop, and then tilted the top of the lens back to it's maximum movement, then the front and rear standards would then automatically be parallel. Is that what you are looking for?

[jhogan]

I wish it were that simple, Kirk. The board moves 30 degrees, in order to allow the for the lowest dropped position... I need reliable way to make sure it stops at 15 degrees- the "mid" position, or first drop...

[Ernest Purdum]

I use a gadget called an "Angle Finder". It is more versatile than a spirit level because it measures angles other than vertical or horizontal. It consists of a 360 degree dial with a weighted needle. If you have a tilted subject, you can use it to set up parallel to the sub ject. It is available from many sources that supply carpenters. There are obviously several different makers and some are a lot more expensive than others. Mine is one of the cheap ones. I got it from Harbor Freight (www.harborfreightusa.com).

[David A. Goldfarb]

A small level works for me. I make sure the back is level and the front standard is level, and they should both be parallel.

Is the issue that you are dropping the bed to avoid vignetting or to get some front fall?

If you need the front fall, I find it just as easy to mount my Tech V upside down as right side up, if I'm not using the rangefinder. I just leave the accessory shoe in my bag when I work this way.

If you need to drop the bed to avoid vignetting with verticals, then another option is to turn the camera vertically and rotate the back accordingly, but this requires an oversized tripod head.

[jhogan]

I use the bed dropped for two reasons David: avoiding vignetting is one, but also because the Lee grads need a little extra room below the lens...