I always enjoy a walk in the woods. Yet, simply by making sure you have the wind in your face and your binoculars around your neck, you can magnify this simple pleasure a hundred fold. I am constantly amazed by how much more can be seen with some kind of optical aid. For example, in the Northern Highlands recently, I could see bare heather clad hills and no deer. The deer were there though - and a few minutes 'glassing' the hill with telescope or binoculars showed me what other people were missing.
In woodland, binoculars allow you to focus at different distances and 'see through' the trees. At dusk and dawn, the light gathering power of 8x42mm binoculars far exceeds the 1x7mm Mark One Eyeball. This is important for bushcraft folk, who in camp often get up at dawn for 'the dingo's breakfast' (Aussie slang for 'a stretch, a leak, and a damn good look around.')
I am not an expert, but I am genuinely interested in optics, have read widely, have a scientific background, and at the Game Fair you will often find me at the Zeiss or Leica tent trying out their latest wares. I'm going to set down my thoughts on optics for the bushcrafter. You may disagree, and if so, please post your disagreements!
Binoculars described as '8x40' mean that they make the image eight times bigger, and the objective lens (that furthest from your eye) has a diameter of 40mm. If you divide the second number by the first (40/8=5mm) you get the 'exit pupil'. This is the diameter of the light coming out through the eyepiece, and the bigger it is, the brighter the image, and the better the performance in dim conditions. It therefore follows that big objective lenses and lower magnification mean a brighter image.
However, the human pupil only dilates up to 6 or 7mm, and for people over 40 it is even less than that. So an exit pupil over 6 or 7mm carries little advantage. Also, large objective lenses mean heavy, cumbersome binoculars.
About 2/3 of birdwatchers use 8x binos, the remainder being 7x, 8.5x, 9x or 10x. Bushcraft people spend a lot of time in woodland where a bright image is important, and I would advocate 7x or 8x. I myself have a 10x42 pair, but that is because I spend time on the open hill (red deer stalking) and the estuary (wildfowling) where distances are greater. For woodland use you want 7x or 8x.
Birders often say that 8x30s will show you all the detail that is there 90% of the time. The other 10% is dusk, dawn, and dim woodland, and I believe the bushcrafter should consider 8 (or 7)x42 as a better option.
In order to give a good image, the eyepiece and objective lenses need to be a good distance apart. There are three ways of doing this. [IMG][/IMG]
The binoculars on the left (Steiner 8x30 Fero D12) use 'porro prisms'. The light is bent 90 degrees by a prism, and then a further 90 degrees by a second prism, so the eyepiece and objective lens are not in the same line.
The binoculars in the middle (Helios AM6 8x42) use 'roof prisms'. The light is bent forwards and then backwards, and the objective lenses are directly in front of the eyepiece.
The telescope on the left (USSR 10x30 Turist 3)does not have any prisms, and so a long metal tube is needed. The optical quality is good, and chromatic aberration (purple fringing of high contrast objects, such as a bird against a bright sky) is very low. However, it is awkward to use for quick observation.
Porro prism binoculars are cheaper to make, so a £100 porro bino will usually be optically far superior to a £100 roof prism. Also, the porro binos give a better '3D' effect at short range. The downside is that the porro is bulkier, arguably less robust, and very difficult to make fully waterproof, compared to a roof prism. Of the top three manufacturers, Leica and Zeiss have stopped making porro binos, and Swarovski are soon to discontinue theirs.
The better roof prisms are filled with dry nitrogen and fully waterproof. One disadvantage of roof prisms compared to porros is that roof prisms introduce a 'phase error' which reduces brightness and sharpness. However, Zeiss developed the P* phase correction around 1990 to solve this problem and now all high end roof prisms have phase correction. The interesting thing here is that modern £100 Chinese roof prisms with phase correction have been shown to outperform older (pre 1990) non phase-corrected Zeiss Dialyts that cost three times as much - see: http://www.holgermerlitz.de/dialyt10x40.html
Newer does mean better.
So, what is the best choice in optics for bushcrafting? In one way, that is a simple question - I would suggest the Leica Duovid 8-12x42. It is waterproof, nitrogen filled, has phase correction, gives you the option of 8x or 12x, is very bright, built like a tank, rubber armoured, keeps its value and is used by Ray Mears. It also costs £1200.
I don't have that sort of disposable income, but here are some recommended and not-recommended choices:
8x42 current production roof prisms by Zeiss, Leica or Swarovski
RSPB FG 8x42 roofs. Japanese made, very good images.
Kahles 8x42. Austrian, well regarded in the hunting community.
Nikon Superior E Porros. not waterproof but optically good
Swarovski Porros. Not waterproof but optically good.
High end Minox/Steiner
£100 to £300
Various waterproof, nitrogen filled Chinese or (better) Japanese made 8x42 roofs with phase correction. This is important. Phase correction seems to be only used on the better models and genuinely improves the brightness and sharpness. Examples include Bushnell Excursion, Nikon Monarch, Viking, Avian, some RSPB, and the Japanese Helios High resolution AM6. The Helios goes for around £200 and I bought a nearly new pair for £50 on ebay. Compared to the £600 Leica equivalent it has slightly more chromatic aberration and is slightly less bright, but the difference is not great. It was voted best buy by one of the magazines.
There are some good non phase corrected 8x42 roofs- I have heard that Maushaus and Strathspey are good. The Viking Navigator at £100 impressed me greatly.
East German Carl Zeiss Jena porros Available on ebay £40 up. Optically good but not weatherproof. Avoid Japanese copies: http://www.holgermerlitz.de/jenoptem.html I feel ebay prices are a bit high. Try the local camera shop!
The Hensoldt D16 (German army surplus) is in fact a Zeiss and got a good write up. The laser protection filters make the image slightly darker but it is very robust. Available cheaply used from German ebay and definitely superior to my Steiner D12s which preceeded it. http://www.holgermerlitz.de/zeiss8x30.html
Kern (Swiss) also got good reviews.
Russian Porros are a bit of a mixed bag. I have a 8x30 Russian monocular which is excellent, [IMG][/IMG] and both the RSPB and Scottish wildlife Trust use the bino equivalent for visitors. Available cheaply on ebay. Many have a slight yellow cast, which I don't mind as it improves contrast. However, I and others have seen Russian binos that have been rather dim and dubiously collimated. I think this is rare though and I still favour them The Russian telescopes are very good.
Cheap 8x20 Chinese made roofs, especially with red lenses. They seem okay until you try them next to something decent. A friend had one and could not believe how much better my Russian 8x30 (costing only £15) was in terms of brightness and clarity. Having said that, even cheap optics are usually sharp in the centre of the field and will show you more than the naked eye.
Chinese binos marked 'Minox'. Minox are quality German optics. For some reason some cheap binos have Minox written on them. Don't be misled.
Barska. Lots of adverse comment on the net. I tried some in a shop and felt ill. Avoid.
Pre 1990 Zeiss/Leica roof prisms. These do not have phase coatings and are simply not as good as post 1990 models, yet they still command high prices on ebay..
Anything pre 1960. They will have no lens coating or just single layer coatings.
Usual disclaimers: I have no connection with any firm, your mileage may vary, etc, etc.