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Equipment Discussions >> Cats & Casses

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: bsim]
      #5585301 - 12/23/12 10:01 AM

I like the looks of the Orion/Sky-Watcher slimmer OTA better, for sure. That was a good deal.

- Jim


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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: jrbarnett]
      #5585545 - 12/23/12 12:49 PM

I will be at the top of the Great Lawn in Central Park at 4:30. I figure I should set up while it is still light so I can see what I am doing...

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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5585553 - 12/23/12 12:52 PM

Ill be setting up behind my condo around 9. Lol ok so it's over 75 miles from Central Park.

Details.

Pete


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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: azure1961p]
      #5586161 - 12/23/12 07:27 PM

FIRST LIGHT!

Just got back from the park. Mostly looked at the moon and Jupiter. I tested out the two eyepieces and the barlow. It was clear and chilly, but the atmosphere was pretty unstable(there was lots of waviness at x124.) I could very easily see Jupiter's two stripes at x62 and x124.
Both the Jupiter and the moon started to get fuzzy at x124. Probably more due to poor seeing rather than poor focusing!
I had no real problem using the cheap finder, so I may hold off replacing it for now.

I had no problems with wobbles using my Benro tripod(rated for 25lbs.) I was using a standard photo head. It wasn't too terrible, but a bit of a pain. Hopefully it will be replaced soon!

I did notice flaring from off axis bright objects. I replaced the original 45 degree diagonal with a star diagonal, so there was no problem with diffraction spike off a prism. I was also thought that I saw some chromatic aberration around the moon, is that possible? I didn't use a moon filter..

I had fun and can't wait to go out again!!
~Rafael

p.s. anyone have recommendation on a portable sturdy photo tripod, fits into luggage(close to around 24")that would work for this little guy? I will be going to Colorado in a week!

Edited by RafaelP (12/24/12 08:15 AM)


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5586393 - 12/23/12 10:33 PM

Rafael,

I am so glad it worked out for you and I would expect it to given the reviews and testimonials on that scope. As I type this my reflector is cooling on my condo's back porch and I'm going to give Jupiter and the moon sometime - specifically the straight wall and the Apollo 15 landing site - the landscape not the machinery!!

Have a 90mm aperture scope stopping at 124x is probably a couple things...
1. This time of year the seeing is particularly tremulous due to the jet stream coming down from Canada - too dry air tends to be livelier than heavy hot humid summer night air.

2. Jupiter generally tops out between 100x and 150x for that scope with 120x being a nice medium. On the best nights it's amazing how sharp it can remain at higher power but overall contrast are often best at 30x per inch of aperture. Saturn stands magnification better and the moon can be great at 200x if the sky is willing.

Too, did u give at least a full 60 min for cool down to ambient? It means sooo much. If u kno this already my apologies.

At any rate 120x ish isn't bad at all. REALLY bad seeing will have you at 85x and miffed!

Pete


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: stevenf]
      #5586532 - 12/24/12 12:46 AM

Raf I just got in - the seeing is lousy tonight. If you got what I got you'll have much better nights ahead .

Pete


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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: azure1961p]
      #5586705 - 12/24/12 07:05 AM

Quote:

I was also though that I saw some chromatic abberation around the moon, is that possible? I didn't use a moon filter..




RaphaelP, Yes this is possible as I had an older C90 do this as well. After investigating the cause, I discovered that the meniscus spot/baffle was not centered properly and when I used a cheshire eyepiece confirmed that the scope was not collimated. This indeed produced CA or blue fringe around objects at powers above 100x. Check for this in a star test and ensure that you have perfect collimation.


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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: t.r.]
      #5586759 - 12/24/12 08:22 AM

I may have just been imagining things, but I think I did see some blue and red fringing. Unfortunately it looks like it will be cloudy the next several nights and possibly poor seeing when it is clear. I guess I should do some research on how to do an artificial star test and how to read the results. Any favorite methods out there?

I wanted to bring this scope to Colorado next week, hopefully it isn't an issue. I suppose I can always switch it out at B and H for another one.

Pete - I didn't bother to wait for the cooldown to start looking. There was an improvement of sharpness after half an hour or so. I can't say it was because of the scope getting to ambient temperature, or Jupiter and the moon were higher in the sky. It is probably a combination of the two!

Edited by RafaelP (12/24/12 08:44 AM)


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5586869 - 12/24/12 09:32 AM

The chromatic aberration sounds like atmospheric refraction - particularly in lieu of last nights seeing. Too with all the contortions glass is experiencing I wouldn't doubt that caused it as well. True it could be a misaligned component but even my reflector sees color fringing in bad seeing. Last night was what Id call 4/10 seeing. Wait till you get 9/10 seeing though.

Pete


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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: azure1961p]
      #5588851 - 12/25/12 08:13 PM

Pete- I hope that is the only issue! I'll do some star testing when it finally clears up here.

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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5588889 - 12/25/12 08:47 PM

I'd strongly wager it is. The quality control coming out of china is as good as amateur astronomy has ever seen it. While local seeing here in the northeast in winter is - well... What it is. But the good nights do come.

Pete


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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: azure1961p]
      #5589283 - 12/26/12 08:08 AM

Well, I did indeed receive the C90 from the Mrs. and cosmetically, it looks nice. FIrst light of the moon however was dicey...even at low powers the image was not as crisp as I'd like and when I went to 125x, well, not so good. Collimation appears on, star test inconclusive for now. I'll give it a shot and work with it a bit, but this one may need to be exchanged. A previous one ran to 200x without issue, but it was with summer seeing. I do love the little package and at worst, will exchange or exercise the warranty.

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: t.r.]
      #5590244 - 12/26/12 08:15 PM

Perhaps very poor seeing like Pete and I experienced?
I still haven't been able to take mine out for a star test.
I did end up ordering the Dwarfstar mount, so I will report on that when I get it!


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5590255 - 12/26/12 08:28 PM

TR,

Id hold off till good seeing. Even with the 8" I was doing the 70x-91x power ceiling with soft results at 173x and this from a scope that has no problem at 40x per inch on any planet. Its been crummy - such is the winter jetstream. I did luck out an get a 7/10 night during thanks giving. At anyrate, I dont see how your scope could have done anything like 200x recently. Its supposed to be clear tomorrow night - but it is winter after all and that $%##$ jetstream overhead.

Pete


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5590983 - 12/27/12 11:00 AM Attachment (29 downloads)

Just as a coda to this thread, since it is winding down, I guess...

I was lazy last night, but I wanted to take a look at Jupiter and the Moon so as to be able to say I'd seen something after days of bad weather. The obvious grab and go was Stella, my Orange Tube C90. Believe it or no, she's quicker to acclimate to cold weather (it was in the 40s!) than the StarBlast.

Mounted her on the SkyWatcher AZ-4 and headed for the front yard. Got a quick look at the Moon, which was nice and sharp at 40x. Before I could up the magnification, dadgummed old clouds moved back in, covering poor Hecate. Jupe was still in the clear more or less, though.

In truth I didn't expect much from a 30+ year old 90mm MCT that had just been moved from house to cold yard. And yet, at 90x Jupiter was very sharp. There was a little differential refraction showing, but not bad. Four belts were easily visible and contrast was amazingly good. Had the seeing been a little better, I have no doubt Stella would have happily taken on more magnification.

The bottom line? This is a good C90 BUT the optics of the current C90s I've run across have been at least--AT LEAST--as good...

Edited by rmollise (12/28/12 08:32 AM)


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LateViewer
Pooh-Bah
*****

Reged: 11/17/05

Loc: Manhattan
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: rmollise]
      #5591770 - 12/27/12 08:30 PM

If this were FB I would click the like icon Uncle Rod.

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: LateViewer]
      #5593511 - 12/28/12 11:03 PM

So I took the C90 on the roof for the first time tonight. I let the scope cool down for 20 minutes this time, there still was some atmospheric turbulence, but it didn't seem quite as bad as the other night.

I looked at the (almost?) full moon and Jupiter. I was able to see three stripes on Jupiter at x62 and x124. I also looked at the Orion Nebula(which was surprisingly bright) and the Trapezium. I was out about two hours, and now my feet are frozen!

I got a Orion 6x30 RACI finder which much better then the supplied finder. The Dwarfstar mount came in too, it was very intuitive and easy to use.

I did a star test, and I think the scope has spherical aberration. I get an nice defined ring pattern on one side of focus, and very soft less defined rings on the other. How do I know when it is unacceptable? Since this is my first scope, I don't know haw sharp the stars and planets are supposed to be, but focus does feel a little soft(everything looks sharper through the new 6x30 RACI finder than the scope at x39.) I still don't know if I should attribute it to poor seeing, too high expections or poor optics.

Edited by RafaelP (12/28/12 11:17 PM)


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5593930 - 12/29/12 08:44 AM

Sounds like your scope is doing very well indeed. Have fun with it and don't worry about it. When spring rolls around seeing will improve and your scope will do even better.

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? [Re: rmollise]
      #5594761 - 12/29/12 05:33 PM

Thank Rod!
I will be taking the C90 along with me to the mountains in Colorado this week. I am hoping for dark clear skies so I can really test it out!


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Eric63
scholastic sledgehammer


Reged: 06/16/12

Loc: Ottawa, Ontario
Re: Which 90mm Mak for tiny Apartment and travel? [Re: RafaelP]
      #5594835 - 12/29/12 06:19 PM

I have a 127Mak and I was also concerned with my star test. The rings were well defined on one side of focus and softer on the other. I then read that it is normal for Maks to be a bit soft on one side of focus because of how the scope is made. In the end, the scope spoke for itself. The views of Jupiter are great and I can split the double-double at 75X. I think that when the seeing improves, your eyes will be the judge.

Eric


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