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

[Robert A. Zeichner]

Phil,

I think you are on the right track. I like the idea of the extra panels. I would urge you to consider all four sides being shaded as there are often highly reflective objects below the lens (snow, sand, etc.). You might also consider making one pair of leaves narrower at the front than at the rear end, shaped like a rhombus. This way, if you are using lenses with huge coverage or using lots of movement, you will be able to fold them inward without getting in the way of each other.

[Dan Dozer]

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

The slots were cut with a 1/16" slot cutting router bit. I had both the bit and the garolite left over from building my 8 x 20 film holders. I'm not sure if you can get a slot cutting router bit that is thinner than that. I don't think that going with 1/32" garolite will be of any advantage. The 1/16" seems to work just fine. If you don't have a router, another option could be to sandwich together three thin strips of material with the center strip the same thickness as the fin. Note that I haven't found any type of glue that works with Garolite - I'm sure there is some, but I haven't found it yet.

One bit of advice - the aluminum channel does not like to be bent any more times than once. I cut/filed a 90 degree "v" in the flanges of the channel where the corners are and bent the channel at the web. However, since Aluminum is soft, if you try to rebend the web part, it will likely break in two. You will need to practice to get the V the right size.

If you don't have any garolite and want to try this method, send me a note with your mailing address and I can send you a couple of pieces. I have a little left over that I'll probably never use.

Dan

[phil sweeney]

Phil,

I think you are on the right track. I like the idea of the extra panels. I would urge you to consider all four sides being shaded as there are often highly reflective objects below the lens (snow, sand, etc.). You might also consider making one pair of leaves narrower at the front than at the rear end, shaped like a rhombus. This way, if you are using lenses with huge coverage or using lots of movement, you will be able to fold them inward without getting in the way of each other.

HI Robert,

Thanks for chiming in. I have read your article. I use series IX lens shades and have always know they are a compromise device. I do intent to have a 4 sided device. I am going to try some plastic piano hinge. If that does not work (loose hinge) I'll have to make something with a tighter operating hinge or utilize the dreaded velcro for starters. The article in View Camera: "Camera Flare" described problems I have had quite often.

Can you make any comment on the fourth image where I have illustrated what I believe will be needed when using significant front rise?

thanks

phil

[phil sweeney]

Hi Dan,

I'll probably use an epoxy. If it works on ABS plastic I hope it will work on the garolite (roughed up with sandpaper). I am going to try to epoxy the garolite to the hinge.

Phil

[Robert A. Zeichner]

HI Robert,
Can you make any comment on the fourth image where I have illustrated what I believe will be needed when using significant front rise?

thanks

phil

Phil,

The thing that comes to mind is that you might want to put a slight bend in the doors where they meet the hinge, sort of like the wings of a WWII Corsair fighter. This way there will be clearance enough near the hinge to allow maximum adjustment. I've attached a photo for reference. I think the bend should be where the flocked paper I rubber cemented to the aluminum ends. I hope that is of some help.

[phil sweeney]

Here are some photos of my prototype. The images show the camera with 17" bellows draw. I was focused indoors and camera set with max rise of 3 inches. I was pleased to see the final position of the top and bottom flap resemble what I illustrated in my drawing. At 15" I think the side flaps as adjusted will just encroach on the image.

[GPS]

Phil,
the dimension of the opening doesn't need to change when you change the bellows draw provided you use the same focal length lens. Only if you wanted to change the film format you would need to change the opening dimension too.

[phil sweeney]

I am looking for some very small aluminum or plastic positioning hinges. I am getting a couple samples from ABC plastics but have yet to find anything similiar elsewhere. I would prefer to find something about 1/2" wide and about 1" across entire hinge open. I'd appreciate any advice on sources!

[Robert A. Zeichner]

I am looking for some very small aluminum or plastic positioning hinges. I am getting a couple samples from ABC plastics but have yet to find anything similiar elsewhere. I would prefer to find something about 1/2" wide and about 1" across entire hinge open. I'd appreciate any advice on sources!

The model aircraft guys might have the answer you are looking for. Check out
http://www.hobbypeople.net/gallery/566562.asp

[Dan Dozer]

Hi Phil,

Have you checked your local home center? If brass is OK - I found some brass hinges just about the size you mention at Lowes in the cabinet section.

[phil sweeney]

Hi Dan,

I just picked up a set at Home Depot that will work if I do not find something better. Now I have to figure how to cut a 3" hole in the garolite.

[Dan Dozer]

Phil,

Not sure the best way if you don't have a hole saw. Garolite is somewhat prone to chipping on the back side if you don't have it securly against something like a wood block backing - I learned that when drilling 1/4" holes in it.

You might try a small grinding type of bit in a dremmel working around the outline of the circle and then use a dremmel sanding drum to smooth it out.

Dan

[phil sweeney]

Phil,
the dimension of the opening doesn't need to change when you change the bellows draw provided you use the same focal length lens. Only if you wanted to change the film format you would need to change the opening dimension too.

Hi GPS,

Not sure I follow you on this. I attached a drawing (originally from autocad). The magenta lines show the angle of view to be smaller at 17 inches draw versus 15 inches. I realize the difference is not that much. Is my illustration an incorrect?

phil

[GPS]

Phil,
I'm afraid you mix up concepts here (angle of coverage, angle of view, image circle etc.) The lens angle of view doesn't change with belows draw, even if the image circle does. To make it simple - you don't really need to change the shades dimension when focusing.

[phil sweeney]

GPS,

thanks for your reply

phil

[phil sweeney]

Here is my 250 grams barn door shade. I ended up using 1/32 inch garolite for the panels. I found I can use on my RB67 also. Notice the small front flaps that are needed for the longer lenses.

[GPS]

An interesting way of storing your knifes, Phil (picture # 4). How do they hold on that rack, handles down? Magnets?

[phil sweeney]

Hi GPS,

Yes its a magnet. Made more for a shop than a kitchen, but Little Mama does not mind.

[GPS]

Thanks for the clarification, now I know your knifes attract forks...
Just a small detail, Phil - I don't know if you use the shade for different lens diameters (on your RB, perhaps?) but if not (and only in such a case) you could use just one nylon screw attached to the appropriate ring. Less to screw, of course and even more stable on the lens rim.