Foam vs Knife-Edge Baffles

I've seen various references on other sites to advantages of foam ridged baffles versus knife-edge baffling. Statements such as the foam "absorbs" the light and a conical foam baffle is placed along the light path to provide extra baffling. Is this just marketing hype and can some of the gurus here spell out advantages/disadvantages between foam and kife edge baffling and maybe even explain what exactly knife-edge baffling is?

Obviously, one disadvantage of the faom baffle, as some of us have found out, is that it can come loose inside the scope and slide around, making a rather amuzing "vwoop" sound.

Thanks

I just look at it this way... AP,Tak,SV,TEC and TMB all use Knife edge baffling. Must be a reason why?

Hi Phil,

I found a picture in this review of knife edge baffles for you.
http://www.cloudynights.com/item.php?item_id=1274&pr=2x6x17

It sort of shows it.

I would bet that foam is cheaper, and my Megrez II 80 used to make the "vwoop" sound when it was really cold out, but I fixed it with a couple of self sticking black felt circles for next to nothing. I had a sheet of them from the store that we use to put on the bottom of things to keep them from scratching the surface of a shelf or table. I unscrewed the tube and lens from the focuser, and slid the foam baffles to the right spot and stuck two on the inside the tube so that it doesn't slide backwards anymore.

The foam contracts a LOT more than the metal, of course, when its below freezing out. I guess only those of us crazy enough to observe in cold temps found that out. The foam is surprisingly tight and hard to slide at room temps.

Take it easy bud!

Timm

Philip Good said:

I've seen various references on other sites to advantages of foam ridged baffles versus knife-edge baffling. Statements such as the foam "absorbs" the light and a conical foam baffle is placed along the light path to provide extra baffling. Is this just marketing hype and can some of the gurus here spell out advantages/disadvantages between foam and kife edge baffling and maybe even explain what exactly knife-edge baffling is?

Obviously, one disadvantage of the faom baffle, as some of us have found out, is that it can come loose inside the scope and slide around, making a rather amuzing "vwoop" sound.

Thanks