Super-telephoto Folding Lens Hood
and a different lens cap




Folding hood and new lens cap
for a Canon 500mm f/4L IS
     Yep...this is another project to make something for my 500mm lens. Actually it's two somethings... a folding lens hood, and a protective lens cap (more about the lens cap in a bit). The idea of a collapsible folding lens hood was not mine...well, what I mean is, I didn't think of it first. There is the "TravelHood" made by LensCoat, and AquaTech makes their "Soft Hood" product. I wasn't aware of either product until I heard about the "TravelHood" on a photography forum and checked it out. It is actually a good idea.... a hood that will fold flat and save space. And for $110-$150 either product is a much cheaper alternative to replacing a damaged or lost Canon 500mm hood than getting another Canon hood for well over $500.

Mounted to the lens is the original
Canon hard hood with my DIY camo cover.
Next to it is my new DIY folding hood
 
Original Canon 500mm hard hood in
shooting position next to my DIY lens cap
from an earlier lens cover project

 
Original Canon 500mm hard hood
reversed with my DIY lens cap from
an earlier lens cover project
 
     Though my hood did not need replacing, I had for some time been hoping to find a way to more easily fit my 500mm lens into my Bataflae 32L backpack. If I didn't have to carry it with that huge hood, it would fit much better. A folding hood sounded like an ideal solution. But once again, I ran up against that wall that separates my wants from my wallet. Am I REALLY going to pay $110-$150 for something I can easily make with less than $10 worth of fabric and a sewing machine? Yeah, well, you already know the answer to that question. Heck, you could buy the material AND a brand new basic sewing machine for less than $150. Let's get real, folks.

     The general concept is very simple - flat slats sewn between an outer camo material and an inner non-reflective black material, which then wraps around the lens to form a hood. The slats must be stiff, yet flexible while being strong and unbreakable, and completely waterproof. The LensCoat "TravelHood" uses velcro straps to hold it into shape, while the AquaTech "Soft Hood" uses buckled straps. Frankly, the buckled straps appeared to be overkill (and awkward) for a lightweight hood, and the LensCoat hood's huge velcro straps gave it an unfinished, "slapped together" apperance. I had a better and cleaner-looking idea in mind for attaching my folding hood. Both products appear to be made from nylon or polyester Cordura type fabric that is water repellant and sturdy. I already had some remnants of 600 denier polyester Cordura camo fabric on hand, the same as I've used for so many of my other projects. All I had to do was figure out what to use for the slats.

The first assembly - pockets with
the vinyl slats inserted


     With a bit of head-scratching, I finallly remembered some vinyl strips I had in the garage. I had recently put vinyl leaf guards on my rain gutters, but the guards were a little wide for my gutters. So I trimmed 1-1/2 inches off one edge on all of the leaf guard sections to fit better. It turned out those leftover strips, just under 1/16 inch thick, were exactly what I needed - waterproof, very flexible, yet stiff enough in 9-inch lengths to spring right back into shape when bent. It would work perfectly for the slats. The width (1-1/2 inches) was just right as is. I cut 13 pieces about 8-1/2 inches long and smoothed any rough edges. Your project may take different lengths or a different number of slats, but for my 500mm I calculated that 13 x 1-1/2 inches would do the trick.

First Assembly - Hood Stats:
     After taking measurements of my lens and the original hard hood, I cut some Cordura camo and black ripstop nylon material 25-inches by 9-1/2 inches for the new folding hood (yours doesn't have to be camo). Both measurements are oversized to allow for hems and flaps for velcro (particularly on both ends where it wraps around into a cylinder). I sewed the Cordura camo face to face onto the ripstop nylon around three edges (one long side and both short sides). Then I turned it right side out so the camo is facing out (which hides the 1/8-inch hems inside).

 
Styrofoam strip butts to
lens ring for alignment
 
3/16 inch thickness and 3/4 inch width
is sufficient for styrofoam strip
 
         Examples of the shiny "plastic"
type styrofoam to use
Shelf liner used on alignment strips
     Next I marked lines 1-9/16 inches apart on the black ripstop side to show where the stitching goes to form the pockets for the slats. Be sure to leave extra material on both short ends for overlapping where the velcro will hold the ends together into a cylinder. Your measurements will be different than mine, depending upon the lens you're making it for. Then I slipped the 13 slats into the pockets I just stitched. This first assembly is shown in this photo. It's important the pocket width is sized so the slats just slip in snuggly.

Second Assembly - Alignment Strip:
     The alignment strip fits around the lens ring and holds the hood in place and properly aligned on the lens. I started with a piece of black ripstop nylon long enough to wrap around the lens ring, and wide enough to form two channels - one for the styrofoam and one for gray foam strips, plus flaps on both long sides to attach it to the hood slats assembly. I found some "plastic" type styrofoam (used for packing in a box of something I'd bought recently). Be sure you do NOT use the brittle type made for arranging artificial flowers (won't work so well). The styrofoam I found was 3/16-inch thick (just right for my lens), so I cut 3 pieces 3/4-inch wide by 7 inches long. End to end they would wrap around nicely. This will be used to butt against the lens ring where the hard hood hooks on. If you don't have this type of styrofoam, use something that is firm so it will butt against the lens ring and hold it's shape, yet it must be flexible to wrap around. If it's not so flexible, you can cut notches in it on the inner face so it can wrap around the lens easily.

     Also needed is some dense gray foam (which I salvaged from equipment box packing) to serve as the padded fitting on the alignment strip to hold the hood onto the lens. I also added a 2-inch wide strip of black shelf liner (like I used in my lens sleeve project) over the foam strip to provide some grip to the hood when it's strapped onto the lens.

     While working on this project I discovered that it can get tricky when working with circumferences. Inner and outer circumference measurements will throw you off quickly. When the padded alignment strip piece was wrapped onto the lens and butted end to end, it fit just right. But when laid flat against the hood slats piece, it came out about 3/4-inch short of where the ends should have been on the slats piece. I was surprised, since the slats are less than 1/16-inch thick. I did not expect that much difference in the outer circumference. Now I understand why the LensCoat and AquaTech products were all curled up. It has to me made that way because of the difference between the inner and outer circumferences. So, I had to build that curl into my DIY folding lens hood.

Finished alignment strip with
shelf liner installed

How the alignment strip fits
onto the lens ring
Alignment strip ready to attach
to hood slats assembly
Alignment strip has velcro flap added and
is attached with circumference adjustments
Pinning and sewing channel for
styrofoam insert inserts
Marking and sewing channel
for foam inserts
Fitting It Together:
     The necessary curl was built into the unit by stitching the alignment strip assembly onto the hood stats assembly with the slats puckered up about 3/16 inch at each stitching point, as shown in this photo. Your adjustment amount may be different, and will take a little calculation. My alignment strip fit was about 3/4 to 1 inch short of where it should line up on the ends of the hood slats assembly. I divided that by the number of sewing attachments points (the gap between every other slat), which in my case was six. That came out to about 3/16 inch per attachment point. With my slats spacing at about 3-1/8 inch per 2 slats, I placed sewing marks on the alignment strip assemby every 2-15/16 inch. This forced the slats to accordion a little to make the sewing marks align with the gaps between slats, providing the adjustment I needed. I realize it's difficult to explain here, but looking at the photos should help make it clearer.

     Note that the ends of the alignment strip are not sewn down. On one end of the alignment strip I added velcro loops, and the other end I added a flap with velcro hooks. This velcro holds the ends of the alignment strip together on the lens and makes the hood fit snug, hold tightly and align properly. With velcro added to the end flaps of the hood slats assembly, it holds the wrap-around overlap of the slats in position. This completely hides all indications of any kind of mounting straps, making for a very neat and professional-looking hood.

Pull alignment strip ends close together
and connect velcro flap
Alignment strip velcro flap is
closed, holding hood firmly
Next, fold over hood flaps connecting
velcro strips on hood
Alignment strip is completely hidden,
as are the hood's velcro strips

LensCoat TravelHood AquaTech Soft Hood
Original Canon hard hood with camo cover.
The new DIY folding hood
     The new DIY folding hood has no cumbersome straps and buckles, or unsightly velcro strips on the outside like the LensCoat and AquaTech products shown at left. In the photos at right, compare the original Canon hard hood with the new DIY folding hood. The DIY folding hood really looks much neater and sleeker than the commercial alternatives. The folding hood does extend backward over the lens about an inch farther, making it appear slightly longer. But the folding hood extends in front of the lens the same distance as the original hood. It is also the same diameter.

     Not only does this hood look better, it weighs only 7.9 oz. The AquaTech Soft Hood for a 500mm lens weighs 12.9 oz., while the LensCoat small TravelHood for a 500mm lens weighs 7.2 oz. (just 1/2 oz. less than the homemade version).

     I was very pleased with how this project turned out. But it looks so good, I'm afraid I'll forget it's not the original hard hood and try to stand the lens on end on the hood. That's the one caveat with these folding hoods, although AquaTech does claim you can do that with their hood. It's something to consider.



So, What About The Lens Cap?
left: Lens cap for hard hood
right: Lens cap for lens
Inside view of lens cap Outside view of lens cap

     Yeah, there is that issue of a lens cap, now that you realize the one you used over the hard hood won't work over the bare lens. The whole idea here was to be able to pack the 500mm without the hard hood, but that's not a good idea without a lens cap. DIY to the rescue once more. After having previously made my own lens cap for the hard hood, it wasn't that hard to make one for the lens itself.



New lens cap and folding hood combo

     I found a lid from a large plastic coffee can that fit the lens diameter nicely. I also had a plastic lid from some sugar cookies that came in a plastic bowl. The two lids nestled together perfectly to form a base. Then with a coping saw I cut three disks from 3/32-inch plywood and sanded the edges nice and smooth. Two of the disks were slightly smaller than the inside diameter of the lens. These were glued together with wood glue and covered with ripstop nylon. They just fit inside to insure centering of the cap. The third disk was cut to the outside diameter of the lens. Along with the plastic lids cupping the outside of the lens, it insures the cap cannot get pushed into the lens. With the the lids sandwiched between the plywood disks, I have an extremely strong and lightweight protective cap. Next I covered the lens cap outside with a bit of foam padding and some Cordura camo fabric to give it a professional look. The final touch was to use 1/8-inch bungee cord and a cord lock to snug up the cap on the lens. It's small, light, and very strong, which makes packing the lens in my backpack case so much simpler and easier.