For keeping in my back pack? budget up to £100.

8x is most you can use without a steadying support. 8×40 is probably most versatile. Worth stretching your budget as they will be much brighter and last a lifetime. I have Opticron 8×40 for 5-6 years and are brilliant. Swarovski are the best but cost a fortune. Do not buy off the internet without trying some in a shop. You will be amazed how much better the more expensive ones are

Cap’n’s right.
A long while ago bought some 8×42 Opticrons, and went for walk at dusk along the canal. My partner had her brother’s cheap bins. We both looks at a wader, then a duck, I was marvelling at the colours, she just saw a silver silhouette! Treated herself to a set after that. It’s at the poorer conditions when you notice how good bins are.
General rules being;-
8×40 = ‘8’ is the magification in this case 8 times.
40 = size of end lens, 40mm.
Divide 40 by 8 = 5, to get a ratio ( 5 ).
Your eyes work at a ratio of 6 ( or is it 7?) and so the better bins are 7×42’s and gather as much light as your eye’s can use.
Tiddly 8×20’s fit into your pack well but suffer image quality if not in really good light.
Birders also don’t generally use anything over x 10 magnification as you then start to pick up noticable hand shake, so the image gets blurred. Also as said above, try different makes, though the magnification might be the same, they will feel noticably different, some will feel good and others not quite so good. Only you can then choose what’s good for you!
cheers
Q

I got Opticron Traveller 8×32. I went into a decent binocular shop (infocus in Denby Dale clicky – there are 7 shops around the country) and tried loads, originally with a budget of 100 quid. After about an hour of deliberation I paid another 70 quid and got the ones above. There are cheaper and more expensive Opticrons but like others you should go and try them and talk to the experts to see what suits you – they’re not all the same. Also these specialist shops will do you a deal if you ask nicely.

I was just given a pair of Nikon Sport Lite 10×25 DCF for my birthday.

Never had my own binocs before ((I’m more used to looking through camera lenses) so I’ve no idea how they rank in comparison to others, but I took them down to the local pond last night and I was impressed with the clarity of the image.

Nice and light too.

I went up to Coventry to visit extended family, and closeby is Focus Optics, a brilliant place to choose bins. They had a quick chat, explained some basics then simply laid everything out in front of a viewing area to let me use the bins whilst looking at birds on their feeders and lake.
Sometimes the RSPB in hand with other large optical sellers arrange similar events, bit like the bike dem days we see advertised here. Though you might not be into birding, it’s a good place to see a lot of bin’s and try them.
Some decent camera shops nearby might well carry a good range……
Q

cheers many ideas. Went to a gamefair years ago and there was a pair there that had autofocus, found those very clever.