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View Full Version here: : DREAM scope Part 2 (revenge of the triplet)


Stu
08-01-2006, 02:08 PM
Well it all started with me at a fancy dress party dressed as a Red M&M (true!) my wife was Yellow. We had just finished the traditional barbque dinner and my phone beeped with the text msg, OMG in the 5" - sender Dave47Tuc.

It was a sign. It was as if the Astronomy Gods :prey2: looked down on me and said, "Stu, it is time you look though an Astrophysics oil spaced triplet my son. Gather your things. You are ready." :2thumbs:

So I am outta there flinging off bits of Red M&M costume as I ran past the Karaoke in the lounge room and out the front door...

First sight of the 5" Astrophysics scope was as expected. It was big. The mount was big. 100% pure Astrophysics everything except for the power supply and extension cord. The scope is a rare 5" F8 oil spaced triplet. Almost all other AP refractors were built in shorter focal lengths but this one was a short production run "special" F8 aimed at planetary work. Traditional white in colour, EDF printed on the barrel (which should have read EDT. Gotta love those "specials"). There is one on ebay with a slightly different mount for USD$28,000

My very first impression when looking through the EP was that this scope was definitely special. It was *only* pointed at the moon through. The guys thought that between the three scopes (Intes 6" Mak, TeleVue NP101 and the "5 AP) the bright side of the moon did not look much different. But, looking at the dark side of the moon the AP was clearly better. All I want to do was point this thing at the Jewel Box! (NGC-somethingorother)

So it was quickly over to the milky way to look for some star clusters and doubles. I could not believe how small the background stars were. I did not think the human eye could see dots that small. Generally all stars viewed through the 5" AP were much smaller than "normal" and showed no signs of diffraction at all. The sky was jet black. The baffles in this thing are about 2cm tall, like knives sticking out from the inside of the barrel, over the whole length of the tube. The tube and baffling is CNC machined from one piece of metal.

To say the view was stunning is an understatment. Looking at the Jewel Box (once Crux got high enough in the sky) was something I will never forget. Bright tiny little stars so contrasting in color - red, blue, white, yellow... could have looked at it for hours. I had forgotten about the NP101 (it had dewed up earlier and was back in the house).

On to doubles where Dave was our AutoStar! :camera: :cheers:
Apha Crux - I saw airy disks! Wow, cool stuff. There were some really nice colored doubles we looked at too. Such a clean image in this scope it looks almost fake, like it has been processed on computer or something.

I couldn't really compare the 5"AP to the TeleView NP101 because they were never pointed at the same thing at the same time. But I was left with the impression that the NP101 had a much flatter field. Apart from that I think the AP would have won most other catagories but only just, it's hard to tell. Apart from the brightness difference which was obvious.

SATURN WAS AMASING! Someone must have cut out a computer generated image of Saturn and stuck it in the blackest area of the sky. Contrast was unbelievble, the gap between the rings was black. The shadow of the rings on the planet was black. Cloud belts and moons everywhere! Easily the most enjoyable image of the great planet that I have ever seen.

So, if I had to review this scope in one word: Wow. :jawdrop:

Dave47tuc
08-01-2006, 02:22 PM
Stu like a kid in a lolly shop :P

Here is some pics of the lollies used :lol:

Yeh great night some fog but who cares when sucking on those lollies :P

asimov
08-01-2006, 02:59 PM
Geepers creepers! You actually bought this piece of equipment?? Awesome!!

What, do you do...brain surgery for a living!?? Congrats on the aquisition of such a fine instrument! :scared:

I'm requesting hundreds of pics of......everything! :P

Dave47tuc
08-01-2006, 03:14 PM
No No, I own the Maksutov. Stu has a 80mm WO.
A friend of ours owns the AP 5" & 4" Tele Vue. He is a nice guy who lets are look through that fine glass. :)

asimov
08-01-2006, 03:29 PM
Oh HELL! Sorry about that, lol.:o

Robert_T
08-01-2006, 03:39 PM
damned expensive lollies ;) - don't look Stu, if you never look through anything like this you won't know what you're missing - ignorance is bliss (and cheaper) :nerd:

Stu
08-01-2006, 10:21 PM
To late! :o Look at my Save-O-Meter below...:sad:

Gama
09-01-2006, 03:51 AM
Nothing beats raw aperature, add with it the new optic design of Meades RCX, and you get stars like dots as well.
I bought the 14" RCX-400 (first in Aus too), took me many many months to save for it.
Apart from QC problems Meade have with these scopes, the views are Flat to the edge, no change in shape and very sharp. I remember the first night, i was so amazed and lost in the views that my brain forgot to give the signal to swallow and i actually drooled down my chin and onto my shirt, and its no bull, i really did drool and had a chuckle over it too.
Having owned many scopes, and currently own a 10" LX200, 20" Obsession, and now the 14" RCX400, i can say the sharpest and tack point images is the RCX, but ya just cant beat the image from the 20".
You really need to see a well colimated RCX400.
Then you too will come to the Dark Side..

Stu
09-01-2006, 06:40 PM
I ever judge a telescope before I have looked through it so I am more than happy to take up the challenge! I will PM you in a few weeks.

janoskiss
10-01-2006, 12:27 AM
Stu, have you looked through a less expensive apo, like the Synta ED100 for about 1/6 of the price of the TV NP101 or one of the Vixen 4" apos for about 1/3, or a Tak 4" for less than 1/2? I wonder if the Televue betters all these scopes by such a huge margin...

Regarding the Ritchey-Chrétien design, I believe it is meant to keep the field flat and aberration free over a larger area than other designs, but in-focus star images are still the diffracted projections of the aperture along with its central obstruction, i.e., not up to the contrast of an equivalent aperture refractor.

... but this is all academic for me. I haven't had the privilege of looking through any such fine instruments. (Hey, I thought the ED80 was a really top scope, just lacking a bit in aperture.. Maybe I'll be happier if I never look through a high-end refractor. Having looked through a Nagler is still eating away at my wallet, even though I decided Naglers, type 6s anyway, are not for me.)

Dave47tuc
10-01-2006, 10:42 AM
Steve,
We are hoping to have the AP130 (the 5" in the photo above post)
At Snake Valley in March. :scared:

I know Peter is coming from SA with Paul and he has a Tak TOA 130,
not sure if it's coming over :confuse3:

As Gamma said nothing beats raw aperture. But there's nothing like a APO for some people.

Some people like Dobs some like SCT some like Refractors. Thats why we have a mixture of lollies :P

I say buy the scope you like and will use no matter what type. ;)
And enjoy. :)

xstream
10-01-2006, 11:28 AM
Steve,
You'll get the oppurtunity to look through aperture at Mount Buffalo. The 18" won't be there unfortunately because of work commitments but the 30" will.
It's a funny thing after looking through large aperture, smaller aperture never quite seems the same. :)

janoskiss
10-01-2006, 11:37 AM
:jump2: Awesome! I am normally not a religious person but in this case I think I will :prey: and :prey2: for :stargaze:

davidpretorius
10-01-2006, 12:46 PM
wow right back at you.

that is so right that Dave is an auto star, who needs goto???

There can be no winner, but i am convinced most guys will end up with 1 refractor and 1 reflector. I know i will!!

Dave47tuc - you are charged with gama and his 14" RCX or just his RCX and these beautiful refractors to snake valley.

You wanted to know what we would do if it rained, then your answer is here.....drool at the nice scopes!!!

Stu
10-01-2006, 07:48 PM
Not really. I have looked through a 5" FS Tak (Doublet with flourite at front) which I think was great, but they are not made anymore. Replaced by triplets.

The thing I am concerned about is compromising, and everything starting off OK and after at few weeks I can't overlook the faults. The advantage with the NP101 is that the Petzal design is better corrected and has an incredibly flat field, which is awesome when panning around in wide field. Even the AP triplet above is not as good in this regard (and the shorter you go with a triplet the more field curvature you get).

According to reviews on cloudy nights a long focal length triplet can beat the Petzval design but a long focal length can't get shorter. A short scope can get longer by using powermates or shorter EP's. Most doublets are long.

ED100 F9, NP101 F5.4. I would like to compare them though.

The intresting thing is that the TeleVue NP101 ($7000) and TeleVue TV102 ($4300) share the same front lens cell from all reports. The difference is the NP101 then uses another (flourite) doublet near the focuser to correct the image further and bend the light to F5.4 from F8.6. This is why the tube size of the two scopes is identical.

Takahashi make a short dual flourite Petzval, the FSQ106 I think, which is supposed to be stunning. Expensive too.

I guess I won't know how much better the NP101 will be. But I have plenty of time to figure that out and I am the type person that will choose performance over cost. If it is only a little bit better, I will spend the extra money. Some poeple may not agree with that, but when I am looking through the eyepiece I am not thinking about money. ;)

The trade off is I don't want to die before I get I good scope, so can't save for too long. :)

Stu
10-01-2006, 08:34 PM
Just found the Sky and Space review of the NP101 that the guys were telling me about.

"Great optics are easy to evaluate -- the NP 101 showed no sign of any aberrations, period. End of review!"

Ha! funny

Striker
10-01-2006, 08:53 PM
Stu I love that save-O-meter

Wouldgreat scope.....good luck

Exfso
11-01-2006, 10:05 AM
Yeah people, the Tak is coming in March. It will be interesting to compare it with the AP 130.
Regarding long focal length scopes, I know I can reduce the focal length on the tak with a focal reducer. I think it brings it from an F7.7 to about F5.3, afaik this can be done on all refractors, though I am very much a beginner at the theorey of things.

;)