Pentax VD 4x20 WP Binocular

Pentax. The name resonates in the heart of many a photographic enthusiast. And with just cause. The brand first came to the fore in the 1950s and has figured prominently ever since, originally producing 35mm gear and still well to the fore in today’s digital age.

It’s probably fair to say, however, that the company is perhaps not one of the first which leaps to mind when it comes to choosing a new binocular or telescope. But could it be that we’re missing a trick here? Last year, I wrote fondly of my experiences with my then recently purchased Pentax Papilio ll 6.5 x 21 binocular. My thoughts on the subject (which have changed not one jot since those heady pre-pandemic days) can be viewed here >

This being the case, I was intrigued to learn of the release of not just one but two completely new optical products from Pentax. Launched as part of the company’s V-Series, the VD 4x20 WP binocular and VM 6x21 WP Monocular appear to represent two innovative and, in my view, very imaginative products, the like of which I certainly haven’t seen before. I’ll review the latter product in a future blog post but, for now, it’s the VD 4x20 VP which is under the metaphorical microscope.

First thoughts?

So, what can we say about this little binocular? The 4x20 designation confirms that we have 4x magnification coupled with 20mm diameter objective lenses. On the face of it, 4x magnification might seem to be a tad on the low side but I’ll come back to that shortly. The ‘WP’ designation confirms that the binocular is waterproof. Indeed, Pentax claims that the model in question can be immersed to a depth of one meter (I didn’t put this to the test) and can safely be washed if required. Naturally, waterproof construction also means that the binocular can be used outdoors in all weather conditions; a definite advantage with any optic, particularly here in the UK.

Those 20mm objective lenses mean that the VD 4x20 WP definitely falls into the compact binocular category. Weighing in at 345g and measuring just 95mm tall and 117mm wide, this is an instrument designed with portability in mind. That 4x magnification, appreciably lower than the 8x and 10x we’re used to seeing in most binoculars, serves to give a large exit pupil of 5mm, thus allowing plenty of light to reach the user’s eyes in low light conditions. A further advantage of lower magnification – and something I noticed straight away with my Papilio II 6.5 – is that it allows for a very steady image which is refreshingly free from the effects of shake. So the reduction in power is not without its advantages.

Minimum focusing distance is given as approximately 1.5 meters when used as a binocular and an impressive 0.5 meters when in monocular mode. All lenses and prisms are fully multicoated. This is a good thing as it protects against unwanted reflections. Phase-coated roof prisms and dialectric coatings are included to maximise light transmission, reduce flare and ghosting and generally give the sharpest, most high contrast image possible.

Comfy and functional

In the hand, the binocular feels compact but reassuringly solid. The rubber eyecups can each be twisted up and down to any one of three positions, thus allowing use with and without glasses. Each barrel has a thumb recess on the underside and a focus ring towards the objective end. Included accessories consist of…wait, what…a focus ring towards the end of each barrel?! But binoculars have a single focus ring between the barrels, don’t they? Well, yes, in the vast majority of cases they do. But this is no ordinary binocular. Oh no, not by any means…for reasons which I will now explain.

Because here’s the thing. When you invest in the VD 4x20 WP, you’re not just buying a binocular. What you’re buying is a binocular, two individual monoculars and a small telescope. Remember what I said right at the start of this review when I described the V-series as containing innovative and imaginative products? This, dear reader, is what I meant. Straight out of the box, the VD 4x20 WP emerges as fairly innocuous-looking compact binocular. When the need arises, however, the left and right barrels can be separated to produce two 4x20 monoculars. Remember those individual focus rings I mentioned? Suddenly, they start to make a lot of sense. As if that isn’t enough, the VD 4x20 WP has another trick up its sleeve: when more magnification is required the two monoculars can be joined end-to-end, thus morphing into an extremely compact 16x20 telescope. These, as far as I’m aware, are unique features and represent true innovation in the world of optical equipment.

The Real World Test

Of course, this is all well and good but how does Pentax’s latest offering stack up in real-world use? How easy is it to change from binocular to monocular to a telescope? And how easy is it to change back? Does everything break apart and fit back together again as it should or does it put up a fight? And, crucially, are the optics any good? It’s all fine and dandy producing a cunningly designed ‘Transformers’ style optical product but all this would be a mere bagatelle if the optics weren’t up to scratch. Well, in order to shed some light on the above, I’ve been living with this innovative little binocular for three weeks and am now in a position to share my findings.

First things first (and this is the aspect with fascinated me most when I first took delivery): how does this whole ‘transform from one thing into another’ business actually work? I am happy to confirm that changing from binocular to monocular to the telescope is as easy as falling off the proverbial log. Straight out of the box, the product emerges in its conventional binocular form. When monocular mode is required simply open the barrels to their widest extent, continue to apply a bit more pressure and…Hey Presto! It really is that easy. Fancy morphing the aforementioned monoculars into a single telescope with 16x magnification? No problem at all. Just decide whether the left or right barrel is going to be at the front (it doesn’t matter which one), make sure the relevant rubber eyecup is in the ‘down’ position, then push the objective end of the rear barrel onto it. And that’s it. You’re done. In order to revert from telescope back to monocular mode gently pull the barrels apart. When the binocular is required again, line the two barrels up side-by-side and push together. The pair comes together with a solid click so you’re left in no doubt that the left and right sides are securely attached. I would like to emphasise just how easy it is to make all of these transformations: the VD 4x20 WP really is a true optical shapeshifter of the highest order.

So, having established that Pentax has hit the nail on the head with regard to mechanics, we now need to turn our attention to that all-important optical performance.

Optical performance

As a conventional compact binocular the Pentax acquits itself very well. The image is very clean and chromatic aberration (a real pet hate of mine) is barely discernible. The image appears brighter than some compacts, helped, no doubt, by the low magnification and correspondingly large exit pupil. The fact that each barrel focuses separately means that the VD 4x20 WP works in much the same way as a marine binocular: once focused on a target approximately 6 meters away (by my measurements), it’s then possible to go all the way out to infinity without having to adjust focus. Which is nice.

Breaking the binocular asunder (so to speak) produces the two extremely compact 4x20 monoculars I mentioned. In essence, everything I said about the binocular relates to these but it’s worth noting that the manufacturer’s claim of 0.5 meter close focus is no idle boast. I know this because I measured it. Several times. Just to be sure. I was further pleased to discover that the supplied binocular strap splits into two to produce two monocular wrist straps. A neat touch, in my view.

Once the monoculars have been joined end-to-end we find ourselves with the aforementioned 16x20 telescope. For me, this is the weakest link in the VD 4x20 WP’s optical chain but, in fairness, this is what I expected. There are two issues here, the first being light-gathering. A 16x20 optic has an exit pupil of just 1.25mm, a significant reduction from the 5mm we have when used in either binocular or monocular format, and this is immediately apparent in use. The second issue is stability. Holding 16x magnification steady is difficult for most people and I certainly struggled with this little scope. Having said that, the product does have a tripod socket and Pentax produces a tripod adapter (the TP-3) which offers one way of improving stability. The other tactic, of course, is to use a nearby wall/gatepost/family member as support. Ultimately, the very fact that we have the potential of 16x magnification in a pint-sized package at all has to be a good thing, even if only for occasional use, and Pentax has to be applauded for giving us the option.

Final thoughts?

So, now that we’ve covered mechanical and optical performance what can we say about the VD 4x20 WP in conclusion? Well, when I first read about Pentax’s new release one of my first thoughts was ‘OK, clever product but who is it for?’ Having spent some time with this little binocular I think I know the answer: families, couples, cyclists, walkers, garden birdwatchers or anyone else who might benefit from owning an optical device which makes sharing easy. ‘Made for sharing’ to quote a well-established advertising phrase.

On a recent cycle ride with my daughter, we each carried one of the monoculars in our bike pouches. We always like to stop at certain points to take in the surrounding views and look for any wildlife which might choose to show itself. Usually, we don’t carry a binocular due to weight and lack of space in the pouches but the twin monoculars are perfect for this type of use: incredibly compact and lightweight but easy to deploy when needed. Back at home, I was standing near one window with the binocular to hand when some Goldfinches landed on one of our feeders. It was incredibly quick and easy to separate the two barrels and hand one to my wife. The birds didn’t stay long but we were both able to get great views before they flew off. Traditionally, it would be a case of one party taking a look through the binocular with the other having to wait and risk missing the birds altogether.

Ultimately, I think Pentax has really delivered with this one. The VD 4x20 WP represents a very clever, very well-executed concept and provides a level of versatility unmatched by anything else that I’m aware of. Yes, it has are some limitations, particularly when in telescope mode, but overall this really is a very, very useful little optic which has definite advantages for a broad spectrum of users. Which, in the eyes of this reviewer, is no bad thing at all.

By Martin Drew
24 Nov 2020

Pentax VD 4x20 WP Binocular