Posts Made By: Tom Hole

Don,

Thanks for the report. Is it cold up there in OH?

I am interested in the magnifications you measure. I know the 2.5x Powermate magnification actually decreases the further you get from the design point (it is 2x as a corrector). The 2x Powermate stays fairly constant and the 5x Powermate mag increases as you move further out (it's about 7.5x as a corrector).

I haven't weighed my BB's yet. I forgot to this morning. I imagine they are the same weight as the BC&F Binomates and those weigh 17.5 ozs, but I'll weigh them tonight.

Tom

Harry,

I was a submariner for 8 weeks in '85 on the USS Hyman G. Rickover (SSN 709). Twas my 3rd class midshipman cruise and it was one for the liberty books. Great food on those boats.

Tom

Dan,

Is there a budget? If not, an AP Traveller f/5 on an AP 400 GTO mount.

If so, then we might have to go with a cheaper mount

Actually, if the parents can swing it, I think the Canon IS 12x36's would be the cat's meow. My neighbor's kids use them all the time. Those and the XT4.5 that I sold to my other neighbor.

If you are on tight budget, the Starblast would get the nod from me.

Tom

There seems to be a flock of them.

Peter,

Call Denkmeier and see if he has an adaptor that lets you use the Denk corrector on the Z/B.

Tom

Dave,

I have had an opportunity to try it out and form an opinion.

The views are much more pleasing to my eye. Saturn was my best target for evaluation, but I also looked at Jupiter and globular clusters. The lack of spikes is outstanding. I love it. Where did the diffraction go? I dunno, as I cannot do a side by side comparison, but I like the fact that it is subtle and not a big bonk on the head (or 4 or 6 bonks as the case may be).

I did find that mounting it just to the Kydex worked fine until it got windy. In calm conditions, there it was rock solid. One windy night, it established a harmonic oscillation and all the starts turned into itty bitty lines. So, I have to mount it to the wood dowels on the UTA. Not difficult, and I expected this.

Collimation is as solid as my 4 vane. I roll the scope around on a wheeled eq platform and rarely take it apart. I have not collimated it since I put it together, although I check it every night. I'd say it is as consistent as the 4 vane, in my particular case.

Nottom line: the curved spider stays. I love the spike free views.

Tom

Well, not really. The clear aperture at the nose is 24mm. The beamsplitter clear aperture is 22mm. But there is a baffle at the base of the ep holders that acts as a field stop and limts the actual clear aperture to 17-18mm. That is what I would use to compare the current BB's. That means a 20mm plossl will not vignette noticably, but a 32mm plossl will vignette badly (probably down to a 32 deg AFOV or less).

The BB's are good binoviewers, regardless of price, but a great value if you include price. I would buy them over the BC&F as they are 1. cheaper 2. include a decent pair of ep's and 3. use better prisms. For $200, I'm not sure you could go wrong.

The lack of a low power corrector will frustrate you if you are using a refractor or dob. Harry Siebert has a low power corrector that will work and I would recommend considering one. With the limitation on widefield ep's, getting a low power corrector is important. As much as I enjoy planetary viewing with my binoviewers, widefield is even better.

Hope that helps.

Tom

A pair of 24 Pans will give you a nice setup:

58x, 1.17 deg TFOV
134x, .51 deg TFOV
233x

You could go a whole night with just that.

16 Naglers would be nice as well, but you won't get that wonderful 1.17 deg TFOV (only .96 TFOV).

I would test it out, but I'll bet your .5x is actually more like .7x, but still quite nice. Like a pair of 34 Pans.

Any less expensive equivalent would do as well. A pair of 32 plossls would be just marvelous.

Have fun.

Tom

Don,

Did you get the Power Wheel for newts? Anxiously waiting on mine.

Can you do us a favor? Remove the nosepiece on the 24's and point them at the sun and measure the size of the circles on a piece of paper that come out the ep holders. That is a good indicator of the real clear aperture of a binoviewer.

Might have to order me a pair of those 24's.

Tom

Don,

Good data. Hard to tell what the manufacturers might have used to determine path length, but your data is what is the most interesting and normalized. Were you able to measure your 2" Elites?

Tom