



When I recently went to a dual PVS-14 setup I had to consider if I was going to add another POORMANS DOF DIOPTER like the one I had put on my single tube rig.
Having ran that setup for about 4 months (~3hrs) I came to the conclusion that I would NOT be adding another to the second tube.
WHY NO MORE ADJUSTABLE DIOPTER?
While the diopter has a much lighter tension than the tubes main focus, whenever I would hit the end of its travel the main focus would get bumped before I realized I was at the end of the diopter stroke, requiring me open the diopter so I could focus to infinity again with the main focus knob.
I also found that running it turned down enough to see from 3ft to infinity (3ft will be used from here on out to indicated minimum distance in focus, results may vary) tends to block a ton of useable light making the GEN3 feel like a GEN1 without adding an IR light source.
In reality, the only time I find myself using it is when working up close on something under 3ft (like my gun chamber @ 1ft) which requires the onboard IR to add enough light to see through the now tiny aperture.
The larger housing of the diopter also blocks the path of the onboard IR illuminator and casts a shadow, albeit you have to look for it to notice it really.
Since the only time I find myself wanting to see that close is when I’m using an IR light, it’s just as easy to turn on the IR light and adjust the main focus back from infinity in that scenario, but in the field, I would not want to be illuminating myself unless I could not clear the weapon by feel and had no other choice.
A gun down under NODs is a very bad day night to begin with, best to light it up adjust main focus in and fix the issue then adjust back out to infinity on the gun’s red dot is the way I see it. Priority is on the gun, you have already shot it, so they likely know where you are, and total light discipline takes a back seat to getting the gun back up.
WHEN WOULD I WANT INCREASED DOF?
There is a case we’re having a 3ft to infinity DOF becomes desirable to me, all be it not a common scenario I can imagine myself in. That scenario is using my vampire IR light on my carbine to clear a large building like a shop or barn where I need to see from 3ft - 50ft all at once.
With a powerful IR light inside a building there is plenty of light to run a diopter at minimal opening to gain maximum DOF. So much that an infinite adjustment (light feathering) like the MATBOCK TARSIER ECLIPSE NVG FOCUS ENHANCEMENT DEVICE or the POORMANS DOF DIOPTER gives you is really NOT needed, only a minimal setting is needed with all that artificial light being added to the scene.
So, for me, it makes more sense to use a simple nine-dollar 07 Objective Butler Creek Scope Cover with a 5mm (I use 3/16th and deburring finished at 5mm) hole to get the DOF needed in that rare circumstance of needing to see 3ft to infinity in a lit room with an IR WML.
Up close weapon manipulation without an IR light might be possible depending on the ambient lighting (moon %) by adjusting the course focus in on a PVS-14 with no restriction on its light gathering, but even if it’s not, and you need to turn the IR on, you have lost nothing since a dialed down diopter is going to demand a light source to see also.
Any other time outside of the building clearing scenario, I am going to want max light transfer through the tubes, and I wanting to K.I.S.S. the choice of a flip-cap seems logical.
I’ve already got a quality sacrificial lens in the form of a simple $6.00 30mm UV filter (make sure you stock extras, Amazon.com won’t be running forever) and the scope cap works as a daylight cap for tube protection as well as gear checks before packing.
ON THE SUBJECT OF A SACRIFICAIL LENS
To me, having a sacrificial lens is critical, so I don’t understand why the military uses a cheap plastic version that reduces light transfer and is easily lost without a dummy cord? Compared to a $6.00 screw in lens that’s smaller and has better light transfer it’s not a hard choice to make IMO.
One of my main reasons for going with the POORMANS DOF DIOPTER was that I was getting a quality glass sacrificial lens with it that could replace the “MILSPEC” plastic slip-on cap.
A sacrificial lens is built into the PHOKUS HOPLITE NVG FOCUSING COVER but at $100.00 each, verses $15.00 for a 30mm lens and scope cap, I don’t see the added value.
“IT’S NIGHT VISION IT HAS TO COST A LOT”
I know everything is marked up in the world of night vision but paying $500 for a pair of Tarsier devices or $200 for a pair of fancy scope caps when $30 worth of UV lenses and normal scope caps does the same job is just ridiculous IMO.
The poor man’s adjustable aperture appealed to the inner geek in me since it had infinite adjustment points compared to a flip-cap with only two, I mean more has to be better, right?
But in the long run, like an LPVO, you tend to use the bottom of the scale and top, rarely needing anything in-between.
LAST WORD
Outside of a “combat” role, I could see running two diopter lenses when you have all the time you need to adjust them perfectly, a task ever more complicated by dual tubes.
For nature hikes and etcetera, but from a “Minuteman perspective” they do not adhere to the Keep It Simple Stupid (K.I.S.S.) principle I try to stick to.
If you need to see from 3ft to infinity and have the ambient light (usually artificial) to retain a clear image, then the flip-caps make a lot of sense with their preset sizing and simple operation.
TWO IS BETTER THAN ONE:
One nice thing about duals, is that in a hurry you can just refocus one tube “in close” on the gun and leave the other at infinity without reducing the transmitted light at all, so the second tube pretty much negates the need for a diopter at all IMO
The one exception being that of clearing large buildings were setting a “medium DOF” would not allow you to have focus from 3ft to the end of the “room”.
A 1/4" fender washer to center a 1/16th pilot bit on, then a 3/16thg bit, then deburring of both sides to finish at 5mm.



SIDE NOTE:
The flip caps when set correctly will give you an index as to where infinity focus is. When the caps are flipped straight up you know your focus is on infinity. Even when they are closed you can tell by looking at them that they are “in focus” by correlation of the hinges.
Adding a witness mark for infinity focus helps even more.
Focusing on your red dot is the quickest way I find to set infinity focus; the dot will be roundest when you find it.