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Orion 180mm Maksutov-Cassegrain Questions

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#26 Illinois

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Posted 25 March 2013 - 06:32 AM

I love my Orion 180mm Mak-Cass! Great for planets and Moon!


So most people love them but have issues with up to 3 hour cooling. You're in Chicago area. How do you cool it down and how do you handle going out at 30 degrees and it drops to 15 degrees in an hour or two? Does the scope adjust for very good seeing? Your input is appreciated.


Thats easy! If I know tonight will or suppose to be clear then I put my 180mm Mak-Cass outside in shade 3 to 4 hours before sunset. One thing I wouldnt do at 3 in morning unless If I want left my scope outside all night. I use my 4 inch refractor most of the time. 3-4 hours for my 180mm Mak-Cass, 2 hours for my 16 inch dobsonian and 1 hour for my 4 inch refractor. I live about 100 miles from Chicago now.

Drop 30 down to 15 degrees I wouldnt put my scope outside that long. My Garage is cold!

#27 spongebob@55

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Posted 25 March 2013 - 10:40 AM

I have a 228 mm Rumak and it is an incredible instrument. The images of solar system objects and double stars are very pleasing with good contrast. Globular and open clusters, many faint fuzzies and planetary nebulae are great in the Rumak, too.

Best,
Randy


Very, very nice. Where a site or from whom did you buy that so I can check it out online?
Bob

#28 spongebob@55

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Posted 25 March 2013 - 10:54 AM

I love my Orion 180mm Mak-Cass! Great for planets and Moon!


So most people love them but have issues with up to 3 hour cooling. You're in Chicago area. How do you cool it down and how do you handle going out at 30 degrees and it drops to 15 degrees in an hour or two? Does the scope adjust for very good seeing? Your input is appreciated.


Thats easy! If I know tonight will or suppose to be clear then I put my 180mm Mak-Cass outside in shade 3 to 4 hours before sunset. One thing I wouldnt do at 3 in morning unless If I want left my scope outside all night. I use my 4 inch refractor most of the time. 3-4 hours for my 180mm Mak-Cass, 2 hours for my 16 inch dobsonian and 1 hour for my 4 inch refractor. I live about 100 miles from Chicago now.

Drop 30 down to 15 degrees I wouldnt put my scope outside that long. My Garage is cold!


Yes, I would keep mine in an unheated detached garage. And I also do the same, keeping an eye out for a clear night. I put my C14 out, and cover it with a white sheet hours before night. Its coming from said garage, so its not bad. And I'm home all the time, so I can do it. I guess that's what the others issue is, they can't get it outside during the late day time for its longer cool down time. I can plan, and that's my benefit I guess.
GUYS WITH COOL DOWN ISSUES- is that the problem, not being able to plan a cool down period before darkness? Or do you feel its just a pain to wait?
Thanks
Bob

#29 iluxo

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Posted 25 March 2013 - 09:50 PM

Mine is stored in its case in an unheated garage - after setting up for observing the cool-down time is under 1 hour.

I also discovered a little trick - if you quickly rotate the tube several times (like shaking a can of soup) and force the air inside to mix, you can disrupt the internal tube current enough that seeing will be ok for a while.

#30 Illinois

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Posted 26 March 2013 - 06:38 AM

I love my Orion 180mm Mak-Cass! Great for planets and Moon!


So most people love them but have issues with up to 3 hour cooling. You're in Chicago area. How do you cool it down and how do you handle going out at 30 degrees and it drops to 15 degrees in an hour or two? Does the scope adjust for very good seeing? Your input is appreciated.


Thats easy! If I know tonight will or suppose to be clear then I put my 180mm Mak-Cass outside in shade 3 to 4 hours before sunset. One thing I wouldnt do at 3 in morning unless If I want left my scope outside all night. I use my 4 inch refractor most of the time. 3-4 hours for my 180mm Mak-Cass, 2 hours for my 16 inch dobsonian and 1 hour for my 4 inch refractor. I live about 100 miles from Chicago now.

Drop 30 down to 15 degrees I wouldnt put my scope outside that long. My Garage is cold!


Yes, I would keep mine in an unheated detached garage. And I also do the same, keeping an eye out for a clear night. I put my C14 out, and cover it with a white sheet hours before night. Its coming from said garage, so its not bad. And I'm home all the time, so I can do it. I guess that's what the others issue is, they can't get it outside during the late day time for its longer cool down time. I can plan, and that's my benefit I guess.
GUYS WITH COOL DOWN ISSUES- is that the problem, not being able to plan a cool down period before darkness? Or do you feel its just a pain to wait?
Thanks
Bob


:waytogo:

Always make plan and ahead of time! Simple! :cool:

#31 Illinois

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Posted 26 March 2013 - 06:39 AM

Mine is stored in its case in an unheated garage - after setting up for observing the cool-down time is under 1 hour.

I also discovered a little trick - if you quickly rotate the tube several times (like shaking a can of soup) and force the air inside to mix, you can disrupt the internal tube current enough that seeing will be ok for a while.


:waytogo:

#32 spongebob@55

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Posted 28 March 2013 - 06:58 PM

So which 1-1/4" E.P.s work best? I have mostly 2" EPs, and my longest one is a Sterling Plossl 25mm. Are there longer EPs in 1-1/4"?
thanks
Bob

#33 garneroutlaw

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Posted 28 March 2013 - 11:18 PM

I am fairly new to the hobby, and I purchased the 180mm Mak. Something about it being a 'planet killer' was definitely appealing. I quickly realized that cool down with this scope is appalling. Expect two hours of cooling minimum with this scope on cooler nights. Even after two hours last night, stars were 'bleeding' and Jupiter had a fuzziness to it. I star tested it to confirm my suspicions. Collimation looks good but got the typical distorted pattern from an uncooled scope. It really is a big issue with this OTA, and I recommend finding something with a bit more reasonable process to cool unless there is a way to cool this scope faster that I am unaware of. I am still debating returning this scope due to that factor. It just simply isn't any fun sitting outside for 2 hours waiting to use it. If I do keep it, does anyone know where I can purchase a screw on cover for Orion Mak-Cass adapter ring?

#34 watcher

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Posted 29 March 2013 - 07:41 PM

If I were to have one of the Synta 180s, I would seriously look into modifying it with a cooling fan. I have an IM715 with a fan, and cooldown is not nearly as severe. I usually don't observe in very cold temps, but early Spring and late Autumn are not much of a problem with an hour - 2 hour at the most. It's actually quite usable in as little as 45 minute if the temps aren't too extreme. Anyway, a fan, a drill, and a little courage could make a big difference in wait time.

#35 eyepiecedropper

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Posted 30 March 2013 - 09:35 AM

hi, here´s my cat cooler. 15 euros. no beauty, but it works. strong radial cooler. 20mm diam. plastic tubing and tube endcaps from my local diy market. 4 angled holes in the endcap. no filter.

greets, martin

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#36 payner

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Posted 30 March 2013 - 12:09 PM

I have a 228 mm Rumak and it is an incredible instrument. The images of solar system objects and double stars are very pleasing with good contrast. Globular and open clusters, many faint fuzzies and planetary nebulae are great in the Rumak, too.

Best,
Randy


Very, very nice. Where a site or from whom did you buy that so I can check it out online?
Bob


Hi Bob: You can see the specs on this telescope here: http://stellaroptica...santel-mk9.htm.

This instrument is no longer produced, these were handmade and the optician was with Intes (INTES MK91)before they were dissolved after the cold war. The mirror is Sital, and even though the tube is closed, the effects of thermal cooling is not a big deal in all but extreme conditions (January/February) because of the properties of the Sital mirror.

Unfortunately, the optician/owner of Santel (Anatoly Sankovitch) now makes professional-size instruments only. See the webapage http://astreya-optic.../eng/links.htm.

This doesn't help you but for the history and specs. If you ever see one for sell and really want a RUMAK of this size, they don't get much (if any) better.

Best,
Randy

#37 Calypte

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Posted 30 March 2013 - 02:45 PM

Randy, I got a 404 error when I tried the link.

#38 payner

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Posted 30 March 2013 - 07:34 PM

Try http://stellaroptical.com/cass.htm and for the Russian site:
http://astreya-optic...u/eng/links.htm

Anatoly Sankovitch is the gentleman's name that produced the Santel telescopes and Andrey at Astreya Optics can (or could) get one in touch with him. I understand Anatoly has a hard time with English.

Best,
Randy

#39 spongebob@55

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Posted 21 April 2013 - 09:07 PM

hi, here´s my cat cooler. 15 euros. no beauty, but it works. strong radial cooler. 20mm diam. plastic tubing and tube endcaps from my local diy market. 4 angled holes in the endcap. no filter.

greets, martin


Thanks Martin, I can't really understand what you did here, could you go over it again? did you drill holes in the OTA? What's the 20mm tube for? Sorry to have you go over it again, but its interesting for a few of us, or at least me.
Regards,
Bob

#40 spongebob@55

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Posted 24 April 2013 - 10:28 AM

Hello again.
I'd like to mount an Orion ST-80 to this scope. There's no way to mount a vixen dovetail to the OTA according to Orion. Any ideas? Could that shoe actually handle a set up of a single stalk big ring system with a ST80 in it? I also see Stellarvue has a f/3.75 finder.....but I'd like at least the f/5. Your thoughts?

#41 eyepiecedropper

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Posted 24 April 2013 - 01:14 PM

hi bob, it´s just a crude variation of a commercial cat cooler.

http://www.lymax.com/sct/photos.php
http://www.lymax.com/sct/how.php

the air duct on mine is not centered but the concept is exactly the same.

#42 dweller25

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Posted 24 April 2013 - 01:53 PM

Here's how I cool my 7" Mak......

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#43 rob cos.

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Posted 24 April 2013 - 02:01 PM

Here's how I cool my 7" Mak......


David, did you drill a hole in the diagonal and just attached the fan to it? Is there some kind of filter at the eyepiece end of the diagonal?

Thanks for sharing!

Rob

#44 dweller25

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Posted 24 April 2013 - 02:21 PM

Here's how I cool my 7" Mak......


David, did you drill a hole in the diagonal and just attached the fan to it? Is there some kind of filter at the eyepiece end of the diagonal?

Thanks for sharing!

Rob


Hi Rob,

Yes I just drilled a hole in the side of the diagonal - a cheap 2" Skywatcher - which is surprisingly good !!

I have removed ALL filter fabric :shocked: :shocked: :shocked: - the Mak mirror is much easier to clean than my 8" Newt :)

#45 spongebob@55

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Posted 24 April 2013 - 07:09 PM

hi bob, it´s just a crude variation of a commercial cat cooler.

http://www.lymax.com/sct/photos.php
http://www.lymax.com/sct/how.php

the air duct on mine is not centered but the concept is exactly the same.


Look at that! Now I understand. I didn't even know these existed. I'm going to have to see what I can do here....I have a 14" SCT now, and if I can have two tubes, we're in business! Thanks so much for your posting. :jump:
Regards,
bob

#46 spongebob@55

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Posted 25 April 2013 - 11:49 AM

does anyone know what the prime focus for the Orion 180mm is? I mean how far beyond the rear of the rear cell it focuses? I'm trying to figure out if I order the adapter to schmidt-cass ring, and add a 2 speed focuser, if it'll have enough in-focus with a 1.5" focuser body and 90* diagonal......
Thanks
Bob

#47 Asbytec

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Posted 25 April 2013 - 01:15 PM

Bob, that seems to depend on the mirror lens spacing. You can come to focus quite a bit outside the visual back by changing that spacing using the focus knob. If you mean "prime focus" as being the proper mirror lens spacing, really I am not sure. Maybe somewhere near the top of the diagonal, as a guess. I am not sure how to set the proper spacing to check the focus.


#48 dbledsoe

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Posted 26 April 2013 - 08:27 AM

What is the origin of those two little fans shown in this thread? I could use one for my Intes 6" f/12 Mak.

#49 spongebob@55

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Posted 26 April 2013 - 11:00 AM

does anyone know what the prime focus for the Orion 180mm is? I mean how far beyond the rear of the rear cell it focuses? I'm trying to figure out if I order the adapter to schmidt-cass ring, and add a 2 speed focuser, if it'll have enough in-focus with a 1.5" focuser body and 90* diagonal......
Thanks
Bob


Here's the 'answer' I got, I must admit, quite fast, yesterday about prime focus and a 2" visual back/focuser....

Dear Bob

Thank you for contacting Orion.

Unfortunately I don't have the spec for the point of focus for the 180mm MC
but it is quite far back.

One caution, the port in front of the visual back is relatively small (less than 1.25") so I'm not sure how you would benefit from going to 2" accessories.
Clear skies and good observing,
XXXXXX

OK, then why does Orion sell an adapter to 2" SCT like accessories for it? Ug.

How do you define 'quite far back'?

If its true that the 'port' is less than 1.25", going to 2" would be worthless, except that you can use your 2" stuff. But then you'd have to be sure you could come to focus.

Does anyone make a 1.25 SCT dual speed focuser?

Can an owner of a 180mm Mak, either Orion or Skywatcher confirm the diameter of the visual back 'hole'? Thanks
Bob

#50 astro_baby

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Posted 26 April 2013 - 01:27 PM

The hole is quite narrow. I use a moonlite dualmspeed on the back of mine with a 2" diagonal. You can get away with 2" fit EPs so long as the field lens is no bigger than the hole in the back.

I will be able to measure mine tomoz if no one else has answered by then. I have yet to have a 2" EP fail tomcome to focus. Theres a lot of focuser distance in the Mak 180, well mine has at any rate.

Widefield EPs ? Some are tolerable in the Mak some less so. The ES14mm 100' works ok ish. The 30mm 82' less so.

Mostly I use a 2" diagonal and 1.25 orthos in the scope.

Hope tha answers some questions at least.






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