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Prescription Glasses, DA vs. XL/AL models, Lens Plates, OptiLoupe, Quasar LED Light, and Diopters vs. Magnification ...
on June 10, 2016
Donegan vs. MagnifyLabs vs. Bausch & Lomb:
The main decent quality choices seemed to be: Donegan Optivisor DA ($36 - glass lens - this review) or LX ($26 - acrylic lens), MagnifyLabs Headband Magnifier ($26 - glass lens) and less-known knock-offs, and Bausch & Lomb Magna Visor ($36 - acrylic lens). The Bausch & Lomb had too many bad reviews. The MagnifyLabs apparently has glass lenses like the Donegan DA and is cheaper and well-reviewed. But for only $10 more I preferred to go with the proven original - the Donegan DA. The headband has a huge adjustment range to accommodate a-n-y head size and is remarkably comfortable due to the padded forehead. The plastic adjusting size and flip-up tension knobs are hokey but they work.
DA vs. LX / AL
Regardless of misinformation by others, the Optivisor "DA" models have the two-piece glass-lens-in-blue-tinted-plastic-frame lens plates, while the cheaper Optivisor LX (= AL lens) models have the single-piece-all-clear-molded-in-acrylic-lens-plate. No idea why Donegan chose to confuse things by using Optivisor "LX" for the headband but "AL" for the lenses. My box said "DA-5" and I scratch-tested the lens - it's glass.
You can wear your glasses with this - plenty of room - or no, as the lens acts like near-sight glasses anyway. I prefer to wear my normal prescription glasses with these since they correct both my eyes for crystal clear starting vision, with two interesting side effects: 1) the overall magnification is noticeably greater due to the magnification added by my glasses (great!); and 2) the focused working distance is reduced - for me for the 2.5x lens from the nominal 8" to 5-6". So if you wear glasses, consider this in your lens power choice, as your glasses will add more magnification themselves, plus reduce your working distance further than the nominal number claimed.
For me, the 2.5x magnification lens (5 diopter) is perfect for general usage inspecting things like splinters, coins, golf club grooves, electronics, bugs, super-glueing very small stuff, etc., because it shows everything of possible interest while still allowing a comfortable 6-8" distance from the work and a reasonably broad and deep field of view. This is as opposed to, say, the highest 3x magnification (10 diopter) which makes you work excruciatingly close at 4" (or 3" with glasses) and also with a narrower field and depth of view. With a 3x lens at 4" you can't even get your fingers in there to do anything - only for specific professional use. So I think most would find opting for a comfortable working distance more important than trading that off for any extra magnification. A modern car key is about 4" long so try it - put a newspaper down and bend down until your glasses meet the car key and try to do anything in front of the lens. Plus you can just add a $10 OptiLoupe (see below) to a medium magnification lens for the rare times you want to scrunch down to 2" to check out something further at 4-5x.
OptiLoupe LP-1 ($10):
I added the separate 2.5x OptiLoupe for the occasional super-close-up. The loupe mounts on either side you prefer - just pull the original lens mounting screw or pin out on that side and shove the OptiLoupe on with its longer screw in its place. The loupe lens was maybe glass at one time but it definitely is acrylic now (I scratch-tested it), but that seems irrelevant given the perfect clarity. You have to close the other eye when using the loupe, but that works fine. (You can't use one for each eye because your eyes won't focus properly through both together.) Assuming you'll rarely need/use a super-close-up, this is a much better solution than having to switch a separate high power lens plate in and out of the headband. With my glasses on and this flipped down, the working distance is reduced to 2" but the clarity is great.
Quasar LS (Lighting System) model 6010 ($25) - not Donegan
You can see things with normal room lighting, but for serious views, actual detailed work, or long use, the more magnification, the more light required. The Quasar is very convenient - very bright lighting comes with you and I haven't felt the need to add external light. To add it on, you pull the two original lens mounting plate screws out, slap the Quasar LED frame on the front of the lens plate, and stick both back on with the longer plastic pins supplied. Then you just place the battery pack on the side of the headband and strap it on with the supplied velcro strap. Simple on-off switch on the side of the battery pack. Unnoticeable when mounted. Takes 2 AA batteries that come with it (nice surprise - Energizer alkalines!). Batteries claim 100+ hours of life, which given LEDs, seems likely. Fyi, works with the MagnifyLabs headband also. Donegan offers the VisorLIGHT, a single non-LED bulb alternative but it seems pretty lame in comparison given 5 hour battery life, $10 replacement Xenon bulbs, and review quality issues.
Additional/Replacement Lens Plates:
This is extremely confusing because of the supplier misinformation as of June 2016. So I talked with the manufacturer Donegan. They confirmed they do offer both glass and acrylic additional/replacement lens plates through their dealers (although, oddly, you can't find these on their manufacturer website). They confirmed their glass lenses are two-piece, with the lenses glued into a blue-tinted surrounding acrylic frame and designated LP-2/3/4/5 with "LP" standing for Lens Plate. Their acrylic lenses are a single-piece of clear acrylic, with the lenses molded directly into and as p[art of the overall acrylic frame and designated AL-2/3/4/5 with "AL" standing for Acrylic Lens. So glass lenses have a blue-tinted frame and acrylic lenses have a clear frame. Confusingly, all the "LP" lens plates currently listed on Amazon indicate in their details that they are acrylic, not glass, which conflicts with the "LP" designation. Counter-confusingly, the pictures show blue-tinted frames which would indicate glass lenses. So either they are glass and the "acrylic" in the detail description is wrong, or they are acrylic and the LP and picture are wrong. So check what you get accordingly - maybe they'll correct this corrected after our talk.
Optical Power (Diopter) vs. Magnification Power:
I did a little research to figure out what the Optical Power ("Diopter") vs. Magnification Power thing is all about. Turns out Optical Power ("Diopter") is the fundamental measurement optical professionals use because it integrates naturally with the compound optical equations typically required in their profession. Technically, the Optical Power (Diopter) of a lens equals the reciprocal of its Focal Length measured in meters. So, for example, a lens with a 20 centimeter focal length (1/5th of a meter) has a Diopter of 1 / [1/5] = 5, and a lens with a 10 cm focal length (1/10th of a meter) has a Diopter of 1 / [1/10] = 10. "Magnification Power" = the increased size of the image viewed, not the Focal Length, so it is not a one-to-one linear relationship, but is generally related to Diopter as follows: Magnification = [Diopter / 4] + 1. So, for example, a 5 Diopter lens has a Magnification Power of: [5/4] + 1 = 2.25x while a 10 Diopter lens = [10/4] + 1 = 3.5x magnification. Usefully, you can add Optical Powers (Diopters) to understand the Magnification result, but not Magnification Powers. So adding a 5 Diopter OptiLoupe (2.5x) to my 5 Diopter headband (2.5x) = 10 Diopters => which converting = [10/4] + 1 = 3.5x overall magnification ... similar to the maximum 10 diopter 3.5x lens plate option.