making a barn door shade for 7 x 17

[phil sweeney]

Greetings,

I have decided to try and make a "barn-door" lens shade for 7 x 17. I would like some input on my ideas and the materials. I recently made a series IX adapter from a 3" ABS cap and expoxyed in a 82mm to series IX adapter (this is for barrel and med format lenses and is light and works great). The material will be mounted to that device. That is illustrated in the first image. The second image is the proposed device. My idea is to make the shade primarily for a 15" lens. I do not use any shorter lenses. I would like to accommodate a 30" lens if practical or make a second shade. I need input for the three dimensions which are circled on the drawing (second image). I intend to use plastic piano hinges (McMaster Carr 1588A74) and epoxy panels to the hinges. I also need recommendations for panel material. I am leaning towards the materials used in the S&S darkslides which I believe is fiberglass. I think plastic panels would warp. Also notice the idea (question mark on drawing) for an "extra panel" and "cloth as drape" (or small square-ish panel that could be hinged also). Any thoughts would be appreciated.

thanks

phil sweeney

[robert fallis]

that looks ok, I think for panel material. I would use 2mm plywood, painted mat black, but only because I like wood for camera's

bob

[chris_4622]

Phil,

I have been thinking about this recently, though not for a 7x17. I was looking at this page 3529 on Mcmaster's site for the graphite 1/16" thick. The rigid carbon sheets. I haven't looked at the thin metals yet. I would also get some black flocked paper to line the inside of the doors.

I also thought about an extra set of panels. The concern I have is how to control the hinges so the weight doesn't pull them down. There will have to be enough tension to prevent this.

I like your idea about the drape, I think that is a workable solution for the corners.

[phil sweeney]

Hi Chris,

Looks like a good material, a little salty. Maybe a matboard prototype to figure exact dimensions.

[GPS]

I can give you the dimensions calculated for your lens. If interested contact me off the forum.

[phil sweeney]

From image 3, I have concluded dimension 1 could be 6 inches and dimension 3 - 4 inches.

Image 4 allows me to decide on 5 inches for dimension 3. I could use 4 inches but that is too close to the ABS ring size.

If my drawing is accurate the upper and lower doors are shown as needed to be for 5 inches of rise. I probably do not use that much but it does show worst case senario. I hope I am correct on that?

[GPS]

On my side I can only give you the calculated dimensions, according to the efficiency you need/want to have but not the theory behind the calculations.

[Dan Dozer]

I made one last year to work on either the 8 x 10 or 8 x 20 that slips over my Lee filter holder. It's actually only a 3/4 shade (both sides and top). The fins are removable and their angle is adjustable so I could cut fins that have a different angle for other lenses. Materials are aluminum channel, brass end strips, wood side pieces, and the fins are made from 1/16" thick garolite from McMaster Carr. I have 4 more photos that I'll include in a second response.

[Dan Dozer]

Here are the other four photos of my 3/4 barn door unit.

[phil sweeney]

Hi Dan,

Thanks for the photos. How did you cut the slots for the fins?

Do you think the 1/32" garolite would be too thin?

phil