(Apologies. It turned out longer than expected.)
In my defence, they were cheap (in a retailer's bargain section) and I was curious. They looked related to the Oberwerk Mariners and United Optics BM2 that Ed Z and Holger Merlitz have reviewed a few years ago and gave them an encouraging assessment (links at the end). In fact these have turned out to be a genuinely enjoyable, excellent bargain. They're hardly going to replace my little 7x for general use, but I'm going to get a lot more fun out of them than I may have imagined.
I'd been looking around for a robust and affordable porro. The Nikon action EX or the Bushnell Legend is probably the sensible choice, but the Oberwerk Mariner amongst others seemed an interesting alternative. I've seen it referred to as the 'poor man's SE'. Impressive if true. Only the 8x40 is sold in the UK and it's currently out of stock.
I spotted this 12x50IF described as an “unbranded sales sample” and as far as I can tell this model is not generally available for sale. While it was obviously unused I have no idea how old the pair was. However I'm confident it was made by one of the United Optics group of companies and belongs to their BW6/BM2 series but could be a hybrid with objectives from another model. There is no information to confirm this.
http://www.united-optics.com/produc...6%20Series.html
My pair look identical to the middle photo. They are also closely related to the CF marine versions.
http://www.binocularschina.com/binoculars/Marine.html
In the UK, design and specification related pairs sell as Oberwerk Mariners (CF), Olivon FZ (CF), Strathspey Marine (IF) (links at the bottom) and I'm sure a number of others elsewhere. These sell for between £100 and £200. While these all appear to have a common origin I have no documented evidence for that or indeed that they are specified to the same standards by the manufacturer/distributors. For instance Kunming Optical Instruments offer different coating levels described here:
http://www.binocularschina.com/coating.html
At least two of the retailers describes their range as having level IV coatings and I expect it applies to the other and probably my 12x as well. Just gauging from the advertised prices, I'm guessing my pair might normally be expected to retail for around the £120 mark. I paid quite a bit less.
The general description for all of these pairs is that they are designed to military standards, waterproof (1 hour immersion at 1m) shock resistant (20xG or a drop from 5m), mil-spec vibration tested, aluminium bodied, rubber armoured, -40C to +50C and ruggedly built (heavy). The “civilian” versions have different coatings and no reticule. No kid-gloves required!
This pair is about 7” long and about the same wide at my IPD. This version has the smooth rubber armour. They sit very nicely in the hand with the weight resting on the palms with the thumbs on a textured surface and in my case with 3 fingers on the prism housing and the pinkie on the barrel. At 1.23kg, 43oz their weight can't be ignored, but once up to the eye the balance is very good and the viewing very comfortable and surprisingly manageable. The hinge is pretty stiff and the eye piece focus can stick a little from resting but otherwise turn smoothly. They are marked with +/- 4 dioptre, and with my glasses the settings at infinity focus are close to zero. The accessories that came with this sample are serviceable but cheap and probably don't represent those with the branded options.
One of the reasons I normally prefer a 7x is the steadiness of the view. I have 8, 9 and 10x but due to shake I really don't see any more detail without using a rest. This 12x is rather different. The combination of the weight and balance means I hardly see any more shake than I get with an 8x. The result is a real practical benefit from the magnification. Standing, a quick look at the USAF chart at the bottom of the garden gave me 15.8, 15.8, 14.1, 15.8 and 10 arcsec for the 7, 8, 9, 10, and 12x respectively (some days I do better
).Does the view justify “the poor man's SE” tag. In short, no, but I'm probably being excessively critical given the price. It gets close enough in a number of areas to more than keep me happy, but the shortfall in one aspect in particular stops me from agreeing with the accolade.
I'd rate the view/£ as excellent. The view is virtually flat for practical purposes. What field curvature there is, is less than the DOF. The sweet spot is very broad and the deterioration in sharpness towards the edges is comparatively modest. It is labelled as 98M@1000M (5.5* FOV, 66*AFOV), which is probably a slightly optimistic claim. All of the view feels 'usable' and should satisfy all but the most discriminating users. In common with all it's relatives, the exit pupil is less than it should be. I measured 3.6mm making it an 12x43. It's been suggested that the fairly sturdy baffle (+prism clamp?) in front of the prism is the cause. The pin cushion is more pronounced than usual, but I've not felt it problematic in use so far. It's not easy to look around the field of view without blackouts.
The coatings appear to be pretty good with a very bright image and no obvious colour cast. However there is not the colour vibrancy I look for, but only occasionally find in reasonably priced pairs. I suspect that the transmission spectrum may not be as flat as some, particularly in the blue. Probably no worse than an number of popular pairs, but the one area where I would wish for better. In spite of the limited EP, the colours and detail hold up very well in very low light conditions compared to my other pairs suggesting the mid spectrum transmission levels are very high. I don't know if this reflects the current offering. The contrast is very good and internal light scatter, glare and flare very well controlled. I've had to hunt around to find CA at all. It is there in the outer sector but the levels are low with very thin banding. Much lower than found in some ED pairs I've tried.
In a very crude set-up using a hand-held boost, I could clearly see 3.6 arcsec/Lp in a resolution test (it may be better), so the centre performance at least is pretty respectable. The eye relief is short. With the rain guards folded down I can see only about 75% of the view with my glasses on. The eye pieces are 45mm in diameter and the IPD range is 60-74mm. At the shorter IPDs it doesn't leave a lot of room for large noses. Quite a snug fit for me. The short focus is about 15m.
Rating the view is pretty difficult as I've not tried anything directly comparable before. I've tried quite a few 10x42 roofs in the low to mid range, and think this beats them on resolution, brightness, contrast and of course 3-D view. It doesn't have the vibrancy/colour rendition of the better affordable roofs like the Bushnell Legend Ultra HD or the likes of the Opticron/Minox/Cascade waterproof porro but does better in other areas. I briefly tried a Nikon Action EX 10x50 a while back and if my memory serves me well, view wise, it's a close call. Colour was maybe better on the Nikon, but I feel this pair has better contrast, CA, and a flatter, steadier view at this magnification which wins it for me. I've not tried a SE but I can't imagine these are a serious challenge.
Individual focussing is not an obvious choice for birding. In fact it hasn't proved to be a problem at all. I've quickly learned to set the focal distance before lifting them to my eyes, and don't anticipate any inconvenience at all for longer distance viewing. Fine adjustments with a “synchronised twist” are easy. Switching with and without glasses is straight forward as well with a simple 1 and 0.5 diopter adjustment in my case.
I had our local nature reserve in mind when I bought them. Most of the waterfowl are 100-300yds away. These should be perfect (particularly as they have an elbow level rail at the viewing points). Curiously, it was easier to follow Swifts feeding overhead with these than my light weight 10x with the advantage of being able to see the bugs they were catching. An activity to approach with caution if you wish to avoid medical bills! While the weight would undoubtedly discourage many, it's turned out to be a definite advantage.... at least for short periods.
I'm very pleased with my purchase. A pretty crude design, but a very capable tool for middle distance observation. For the price level the performance is excellent. I could I could wish for better AR coatings, but then I could say that about many pairs costing several times the price. It would be interesting to find out if they are improved in the current offerings. The surprise was the stability of the view which really makes it a practical option.
I doubt the models currently offered in the series (8x40, 7x50, 10x50) would be a first line birding choice. I understand that astronomers, mariners and hunters are the main buyers. But if a high quality view in a tough, waterproof, and cheap package are at the top of your priorities then I suggest, based on this pair, they are definitely worth a look.
David
PS. If you think 1.23kg is a problem have a look at this. 50lb!!!
http://www.cloudynights.com/item.php?item_id=1277
Holger Merlitz BM2 8x40 review:
http://www.holgermerlitz.de/bm20840.html
Loava 10x50 HG review:
http://www.holgermerlitz.de/loava10x50.html
Ed Zarenski Oberwerk Mariner 8x40 review:
http://www.cloudynights.com/item.php?item_id=1761
Lyra Optic, UK Oberwerk sales
http://www.lyraoptic.co.uk/
Strathspey. I believe they are the only one to source directly. Very helpful guy.
http://www.strathspey.co.uk/
Optical Hardware, Olivon distributors
http://www.opticalhardware.co.uk/