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Second Light with Binoviewers

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#1 tomhole

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Posted 13 May 2003 - 10:14 PM

Had a chance to go out tonight to take a look at the binos again. Tonight was a little better for seeing, maybe a 4 out of 10, but the clouds were rolling in and out. Equipment was an XT10, 1200mm f/4.7 dob on an equatorial platform, Denk binos with 25mm Sirrius plossls. LNEM 3.2.

Tonight proved to be the bino convert night. First was the moon, but that's too easy for the binos. Almost worth the price of admission just for the moon. There was nothing in the cyclops arsenal that could even come close. There IS a 3D perception with the binos and it makes for a very sureal view. Maybe that's what it feels like to orbit the moon. You guys already know this, but I have to write it down.

Next was Jupiter. This was disappointing last time, but the seeing was very bad that night. Seeing was only a little better than my first light, but the bino clearly won, in spades. I tried everything in my cyclops arsenal (not extensive, but I do have a Pentax 10.5 and Meade 14mm UWA + powermates). The binos with the free 25mm Sirius plossls walked all over the expensive cyclops stuff. I can't imagine what premium ep's can do in this thing. In cyclops, 2 bands with occasional definition and a glimpse of the STB and no sign of the NPR and SPR. This was at 214x with the Meade 14mm UWA and 2.5x powermate. This has proven to be a very good cyclops combo in the past. Tonight looked like any other night in cyclops mode with a 4 for seeing, kinda boring.

Now the binos. 5 bands easy. The polar regions were obvious and the STB was there 75% of the time. Started to get barges and festoons in the SEB and NEB. The view was clearly better with the binos. I must have switched back and forth 25 times between cyclops and bino mode to make sure it wasn't wishful thinking. It wasn't. The binos were running at 192x (2x TV barlow). This configuration seems like it would be a disadvantage for the binos, but it wasn't. I also checked 286x (cyclops) vs 288x (bino), but the seeing wouldn't allow this. Even so, when the fleeting moments of better seeing were there, clear advantage to the binos. Just not the same telescope in bino mode.

Now I'm feeling frisky, so I grabbed a utility knife and a piece of cardboard and cut out an aperture mask (hard to do in the dark). It was square with a piece of pie shape cut out of it. The plan was to hold it in front of the OTA and move it around until the diffraction spikes disappeared. Well, this turned out to be a remarkable experiment. Blocking off everything except 1/4 of the tube where it was free from blockage was not the best place for the mask. Putting the odd shaped hole right over the middle of the OTA was the best place. And that's with a whacky pie piece shaped hole. The results were immediately obvious. I had a period of 2 minutes 30 seconds of improved seeing. With the whacky mask, 7 bands and much greater detail in the SEB and NEB. I had enough time during this better seeing to determine that the mask DEFINITELY improved seeing. I only tried it in bino mode, not cyclops. The image without the mask just got too bright to make out fine details. I think the reason it worked so well was it allowed my eyes automatic gain control to open up. I've worked on enough electronic AGC systems to know that the best sensitity is not necessarily achieved with the maximum input. I'm thinking the old Mk1 Mod0 eyeball is just getting overloaded by all the light and is losing sensitivity. Anyone else seen anything like this? The view I had during those 2.5 minutes was as good as anything I have had since I got the XT10 in Feb (and I had 1 really great night that I thought I would never see again). And this was not a great night for seeing. I'd guess during that 2.5 minutes I went from a 4 to a 6. But, that 2.5 minutes is the #3 moment so far in my short observing career (#1 is the very first time I looked at Saturn and #2 is that night I mentioned earlier).

That was it for the night. Clouds finally ended the evening. Binos can stay. I know most of you old salts already know this, but I have to share it with you. Very, very satisfying night. If the binos just improved the views they would be worth it. But they do much more than that. I have never been so comfortable viewing. I do have a good observing chair and an equatorial platform, but I had those for cyclops mode as well.

Anyway, I'm rambling, but I feel like a little kid that just found an Indian head nickel buried in the backyard and I have to run and tell someone. I was worried after the first light with the binos that resulted in an unimpressive showing. Now I'm grinning from ear to ear. If you are wondering whether to get binoviewers, do it. Do it now. Especially with Mars coming up. I have never looked through a $750 Zeis Abbe Ortho, but I bet my binos with my junky ploslls will beat it (IMHO, my $.02, YMMV, etc...)

Clear skies,

Tom

(I'm going to post this around some other groups as well. I know a lot of folks read several groups, so I apologize in advance. I gotta tell everybody). :jump:

#2 Guest_**DONOTDELETE**_*

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Posted 13 May 2003 - 10:41 PM

Hi Tom,
It looks like you have found a very effective combination
for use on the planets.It's also more cost effective than a very expensive pair of short focal length eps.Magnifying the image ahead of the binoviewer takes the burden off the binoviewer[ie you don't magnify any of the distortions that may be present in the beam-splitter or prisms].Very short FL
eps,those under 10mm,tend to do this at the expense of image quality.I will have to look into the used market for
one of those 2.5 Powermates.Clear skies and don't grin so much that your face hurts,Scotty :grin:

#3 tomhole

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Posted 13 May 2003 - 10:52 PM

Scotty,

I was actually using the 2x Televue barlow tonight as the OCS. I think that gives about 4x. It seems like an inefficient use of light but it worked great on Jupiter tonight.

The Powermates are interesting. The 2.5x powermate as an OCS is very close to 2.5x. I couldn't tell a difference in magnification on the moon tonight between the 25mm plossl in the 2.5x powermate cylops, or the 25mm's in the bino with the 2.5x powermate. The 5x powermate is definitely higher than 5x as an OCS, but I haven't figured out by how much yet. Might be as high as 7x. Maybe I'll get around to doing some drift tests later.

I haven't revisited deep sky viewing yet, but I will. I am a fan of everything as it is all new to me. But even if all I get are the moon and Jupiter, the binos are staying.

Clear skies,

Tom

#4 John_Gillies

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Posted 14 May 2003 - 06:22 AM

Good morning Tom. I'm glad to hear that you had what sounds like a great night with the Denk. After what I interpreted as a less than "stellar" first light, I figured that there would be nothing left that could impress an F-18 Jockey.
Well what do you know! Someone who always has the opportunity to "set his hair on fire" with afterburners can sit still long enough to be amazed.

I enjoyed your report. It helps be believe, and hopefully others that I'm not just talking out of the side of my mouth when I hype my binoviewer.

You will continue to be amazed!


#5 Guest_**DONOTDELETE**_*

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Posted 14 May 2003 - 03:34 PM

TomH,

Very good observation report. It's good to see that another person has found the advantages of a binoviewer for observational astronomy ( no matter what make binoviewer was used ).

DonR.




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