Thread: Newbie: Suggestions for first binoculars?

Originally Posted by Cordite

To clarify the porro vs roof prism thing, each has advantages and disadvantages. The prisms are there to upright the image, or you'd have to view game upside down.

The porro prisms are the "old fashioned" style, with a kink in each tube. The wider distance between the objective lenses adds a slight 3D effect on closer objects, but over 50-100metres matters little. The other advantage of the porro is total internal reflection, meaning no need for special mirror coatings to achieve optimal transmission.

Roof prism binoculars (roof prisms are shaped like a house with a tented roof, hence the name) are characterised by their straight tubes, and the roof prism is also smaller (read lighter). The main "disadvantage" of the roof prism is that it does not quite fully achieve internal reflection, so to get around the loss of light from this, some of the prism's external surfaces must be coated with a mirror surface. Cheap ones have aluminium coatings, which do well, but are not as bright as those with silver coatings. There is a lot of expensive hi-tech involved in achieving the best coatings - and in protecting them from corrosion - which add cost. But basically an expensively mirror coated roof prism will achieve the same light transmission as a cheap porro prism with no mirror coating.

If you compare cheap roof prism binos and cheap porro binos with same specs, say fully coated 8x42, the porros will be brighter. Pay more for special prism mirror coatings and enhanced waterproofing to protect the mirror coatings and they have equal brightness. So...
cheap porros bright
cheap roofs darker, but lighter weight
expensive roofs bright, and lighter weight.

They both remain subject to the principle of more magnification thicker lenses, and then wider lenses to regain the lost light.

In regard to weight, lightweight (<500gram) binoculars are lighter than one might suppose, because heavier binos require the added weight of a binocular harness.

Some really good info there. Cheers for clarifying.

I just thought I'd add: it makes sense for a shop assistant at a hunting store to praise the virtues of a 10x binocular over something with less magnification, because generally you'll pay more for the same model binocular if it's in a higher magnification. Not a lot - but I guess it depends on how keen they are to squeeze every penny out of you.

Glass is all about your eyes and your needs. Some like larger binos, some smaller. Some like extra magnification, some less. Some of us have deeper-set eye sockets and require more eye relief, and vice versa.

There just aren't any concrete rules (other than what Physics dictates i.e a larger exit pupil = more light), and the internet (as useful as it is at times) can be one hell of an echo chamber. Everyone's got an opinion, but at the end of the day, one person's treasure is another person's...

It really is akin to buying shoes. You've gotta try before you buy. Even with the high end models.