No replies to this topic

[Tom T]

Observing / Equipment Report

(10" F7.5 dob, Multi-coated Denkmeier BV, multiple eyepeices)

Well, I was out last night with a friend, and we had a chance to put the MC denks through their paces on DSO's.

If I've ever had a complaint about binoviewers, it's been the light loss issues. The standard denk's performance, really can't be faulted. It's killer on planets, and the brighter dso's are fantastic. And, it's throughput is noticably higher than the other units I've looked through.

On some DSO's tho, I've still found my self reverting to mono mode. I estimate I've been seeing about a .3 - .4 mag loss with the standard binoviewer, which is pretty significant. (Because of the way the brain integrates images, I have a pretty strong feeling that YMMV, and this is a personal thing. I'm not sure that there will ever be a formula to compute it correctly, as it would have to take individual biology into account.)

I've heard time and time again from the "experts" that you aren't supposed to be able to notice a difference in throughput till it gets over 10%. In my personal experience, I'd have to disagree with that.

The MC denks have an increased throughput of around 7%-8% (I believe I read on the site - if I'm wrong, please correct me).

While the light loss is still there, to me, this was a noticable improvement.

Transparency varied over the 3-4 hours I was out (NELM went from (appx mag 5.5+ to mag 4 and then back to mag 5), but I spent 1/2 the time in mono mode, and the other half in binoview mode, often returning to the same target multiple times for comparision. On the brighter DSO's, the MC denk performed better than the Standard (which was already pretty great). The improved throughput really showed on items that I thought were "borderline" before.

There were more globulars (in particular) that simply looked specatcular in the binoviewer.

I'm also not quite sure why, but for the first time last night, I finally experienced the 3-d illusion. If it was the slightly increased througput or just that something finally clicked in my brain, I can't say. I can say that it's amazing. M82, M81, M27, and M57 were spectacular, and all showed tons of detail. M13, M92, M5, M4, M71, M10, M12 and M56 were simply supurb and showed a fair amount of resolution - M13 and M5 in particular were simply spectacular. M13 has always reminded me of fireworks, and the 3-d effect was simply astounding. M97, and M101 (hints of arms were seen in 101 - a clumping that to me indicated spiral structure) were boderline visible (this was partly a transparency issue). M14 was a blur with no resolution.

The MC denk really is a notch above the standard. I can hardly wait to get a look through a denk II.

Tom T.