For Compacts (probably 8x25) under £100 there seems a preference for Porros rather than Roofs - is this for brightness and sharpness ?
But weight and size can't be ignored, if I'm actually going to carry them.
And maybe I should I give more importance to FULLY multi-coated and waterproof ?
What are your priorities for Compacts ?
It's often suggested here that you need to pay 2-3 times as much for a roof as a porro of the same optical standard. Quite complicated to explain but I'll try to address some of the points.
Full multi coating is important for brightness and contrast, but note the quality of the coatings goes up with price.
Most roof prism designs require the addition of mirrored prism coatings which are generally less efficient than the total internal reflection of porro prisms, but increase cost. They also require something called phase coating to overcome light loss due to polarisation. This again increases cost, and is usually absent on cheaper pairs. The light losses in these two steps not only lead to decreased brightness but the light may also be reflected internally reducing contrast. Water proofing and nitrogen purging adds a little as well. The short focal lengths in compact design imposes even greater challenges. All in all it usually means that cheap compact roofs tend to be rather disappointing and the reverse porros fare rather better. That's why I pointed out the favourable report on the Hawke compact in the other thread which, unusually for the price, is phase coated.
Hope this helps a little.
David
Porro compacts, despite their optical quality/price advantage, are aggravatingly thick, and not very compact after all. If you really need a "pocket binocular" for some important reason, you may just have to compromise optical quality with a cheap roof model, to get the necessary functionality.
Ron