Posted By Dan D DuBal
Porro-prism binoculars don't have an inherent advantage in image fidelity, but it is "easier" & less costly to arrive at comparable image fidelity via porro prisms (versus roof prisms). An excellent 8x42 porro-prism binocular will very likely cost *significantly* less than an excellent 8x42 roof-prism binocular.
A roof-prism design gains very little beyond *potential* bulk savings, over comparable porro-prism designs. I stress the word "potential," because larger-aperture roof-prism binoculars can be just as bulky (if not more bulky) than comparable porro units -- particularly at or above 50mm aperture. As aperture shrinks, yes, the roof-prism design's advantage (bulk/weight) becomes more and more obvious.
If I were considering non-waterproof binoculars with larger aperture (say, 50mm), then I would eliminate roof-prism choices altogether.
If I required a waterproof design, I'd *still* go for a porro unit, so long as its weight/bulk and price remained reasonable (compared to comparable roof units).
The DCF 10x50 is indeed a nice binocular. However, the PCF WP (waterproof) 10x50 can be found for about half the cost of the DCF. The PCF WPs are fairly new, and I have no experience with them. If their optical qualities are shared with the standard PCF line, I'd expect them to yield equal or better image fidelity than the DCF. Of course, other factors are important: weight, bulk, field of view, fit/ergonomics. -Just an example, since you mentioned the DCF.
My own bias: for stargazing, I stick with porros.