akemag
professor emeritus
Reged: 10/26/07
Posts: 548
Loc: Sweden
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I´ve had two great days with the moon lately, and i never seem to stop beeing amazed at how much more details i see with my 10". Details often looked a bit washed out on the brightly lit side in my refractor. But in the 10", theres just details everywhere. Dont get me wrong, the 4.7" is great. But here, shear aperture force seems to be owerhelming.
With the refractor i easily could go to 300x, but i now wonder on a good night how high i can expect to get without loosing to much sharpness.
While great sessions, highest usefull mag has been 250x. I want more. I remember one such session last year when the moon was rock steady at just about any mag. I ran out at 400x, and it wasnt a bust at all.
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Celestron Omni XLT 120
Celestron Powerseeker 80EQ
Bresser Skylux 70mm
10" GSO DOB
5mm Ortho
6.5mm, 25mm, 32mm Plossl
3.6mm, 10mm, 25mm MA
20mm Erfle
4mm, 10mm, 12mm, 18mm RK20mm Kellner
8mm, 20mm Huygens
1.5-2x Barlow
Orange, Green, Variable Polarizing Moon filter
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revans
Carpal Tunnel
Reged: 09/26/05
Posts: 1536
Loc: Fitchburg, MA
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For my 10 inch reflector, 300 x is about my useful limit except on very rare nights of exceptional seeing. Usually I don't exceed 250 x. But seeing is usually not very good in my area...
Rick
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Rick Evans
http://www.freewebs.com/revans_01420/
"The universe is there for us to see, but it cannot be understood without learning its language -- mathematics." Galileo Galilei
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desertstars
Please stand by...
Reged: 11/05/03
Posts: 35872
Loc: Tucson, AZ
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Seeing conditions, more than anything else, will put the cap on how high you can go on a given night. The way I determine the limit is to push until I don't like the view, then back off to the highest magnification that was still workable. With the Newt, the max is usually between 200x and 250x.
On the rare occasion that I've been able to go higher, it took my breath away!
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Tom W.
Collinder's Catalog
Standing in a garden, contemplating the stars, and wondering how to put it all into words.
Carpe Lunam
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Tim2723
The Moon Guy
Reged: 02/19/04
Posts: 5153
Loc: Northern New Jersey
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I think you'll find that the imagers are able to make more use of their large apertures than visual observers, as they can take hundreds of images and sort out those that are ruined by turbulence, stacking the best of the best. That makes for a stunning result that you'd probably never see with your eye at the scope. I've had the pleasure of looking through large scopes, yet never found any particular advantage visually over a 6 - 8" scope on average nights. Yet when the night was perfect, I've pushed a 6" scope to 600x and wished I had more power, because there's plenty of light to work with if the optics are superb.
But I've also noticed that things tend to get less interesting (for me at least) at super-high mags. At 1000x in a big scope you mostly see a dim gray circle that you're not really sure is in focus. I believe that the story of the Moon is written in bigger features and their relationships. For me, if you've seen one craterlet you've pretty much seen them all.
For most nights though, it's 300 times, 200 times, or go watch TV time.
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The crwth will set you free!
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akemag
professor emeritus
Reged: 10/26/07
Posts: 548
Loc: Sweden
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Yes, i guess those nights like i had last year can be far in between. Still i could push my refractor to 300 on many nights, without going overly soft.
Even though i´m a "high mag lunie" on the Lunar when possible, i spend most of my time with my 18 and 10mm ep´s. These give the best views usually. A new 8mm workes fine also.
It´s when you see those exceptional images of a crater with so many details, that you go crazy with the barlows. But as you say, imaging isnt the same as visual observing. Great pictures though!
Even though a larger scope isnt supposed to be more challenged by seeing or turbulence, it feels like it is comapred to the refractor. Or perhaps is the lack of the finest details in the refractor, that makes it feel like the seeing is more stable more often.
When pockets of steady air comes in the 10", it goes from good to great.
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Celestron Omni XLT 120
Celestron Powerseeker 80EQ
Bresser Skylux 70mm
10" GSO DOB
5mm Ortho
6.5mm, 25mm, 32mm Plossl
3.6mm, 10mm, 25mm MA
20mm Erfle
4mm, 10mm, 12mm, 18mm RK20mm Kellner
8mm, 20mm Huygens
1.5-2x Barlow
Orange, Green, Variable Polarizing Moon filter
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revans
Carpal Tunnel
Reged: 09/26/05
Posts: 1536
Loc: Fitchburg, MA
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I think that a larger scope is more challenged by seeing condition and atmospheric turbulence than a smaller scope is.
Your refractor performs better likely because it has better image contrast (no central obstruction), is less susceptible to atmospheric turbulence, and is always in perfect collimation.
Rick
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Rick Evans
http://www.freewebs.com/revans_01420/
"The universe is there for us to see, but it cannot be understood without learning its language -- mathematics." Galileo Galilei
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Tim2723
The Moon Guy
Reged: 02/19/04
Posts: 5153
Loc: Northern New Jersey
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There's also the effect of tube currents with a Newt to consider. Even heat from the observers body can affect the view in a Newt. When discussions of turbulence resistance in large vs. small scopes comes up, the large scope in question is often a Newt.
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The crwth will set you free!
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Achernar
Postmaster
Reged: 02/25/06
Posts: 5212
Loc: Mobile, Alabama, USA
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If your optics are well made and collimated, you could exceed 500X on the Moon, but tracking it with a Dob will be difficult to say the least. Even 600X is possible, but the seeing is usually too poor to let you go anywhere near that high of a magnification except on those rare ultra-calm nights. I have had some great views of the Moon and planets with my own 10-inch at 375X when I used my 3.5mm Orion Stratus eyepiece in my Paracorr. The Moon looked like I was in orbit above it and Saturn looked like I was in an approaching spacecraft, with Titan as a tiny orange disk. I've never gone higher than that because the seeing is usually so-so here at best.
Taras
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15-inch F/4.5 Dob under construction
10-inch F/4.5 Discovery Dob
6-inch F/8 Homebuilt Dob
4 1/4-inch F/4 Homebuilt reflector
A whole bunch of eyepieces, filters and other accessories....
One curious cat
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akemag
professor emeritus
Reged: 10/26/07
Posts: 548
Loc: Sweden
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It´s nice to know that given the right conditions, one can achieve such high mags. I think that one time last year was one of those (rare) occasions.
I can also think that tracking will be a chore at those mags.
Not one session (havent had that many due to weather) this season, have had any particularly good conditions.
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Celestron Omni XLT 120
Celestron Powerseeker 80EQ
Bresser Skylux 70mm
10" GSO DOB
5mm Ortho
6.5mm, 25mm, 32mm Plossl
3.6mm, 10mm, 25mm MA
20mm Erfle
4mm, 10mm, 12mm, 18mm RK20mm Kellner
8mm, 20mm Huygens
1.5-2x Barlow
Orange, Green, Variable Polarizing Moon filter
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Dean Norris
professor emeritus
Reged: 11/05/08
Posts: 568
Loc: Santa Cruz, Ca
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On my 10" f/6 Cave reflector I usually settle for the view at 208X thru my 7.4 Televue plossl. At that magnification I find the views to be fantastic. On rare ocassioins I've been able to use magnifications as high as 400x. These special times I can count on one hand. Dean
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1971 10" Cave Newtonian F/6 with Protostar secondary
MoonLite CR Focuser Telrad Finder 9x50 SV finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, 4mm ortho, Meade 2x Barlow
7x50 Binoculars
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isramirez
Pooh-Bah
Reged: 11/04/05
Posts: 1391
Loc: Mexico City
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770x and 1080x with amazing detail but only when the moon is exactly at the zenit of my location...telescope is IM715 with 3.5mm and 2.5mm nagler t6 eyepieces... i believe you can go for more with a 10in
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Santel MK9 & MK6
IntesMicro 715
Celestron SCT6 & ONIX80 EDF
Meade SN6 & AR6
HiOptic 6in MakCass.Gregory
DBK + DMK + NexImage + LPI
CG-5 & LXD75 Mounts
many EP's, Barlows and Binoviewers
Great astronomic passion 
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akemag
professor emeritus
Reged: 10/26/07
Posts: 548
Loc: Sweden
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Yes, i dont think i understood just how good conditions i had that one time. Lately, it just havent been too good for any high mag escapades.
770x and 1080x must have been sweet. Next time the conditions allow it, i´ll be ready. Now, that could take a while.
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Celestron Omni XLT 120
Celestron Powerseeker 80EQ
Bresser Skylux 70mm
10" GSO DOB
5mm Ortho
6.5mm, 25mm, 32mm Plossl
3.6mm, 10mm, 25mm MA
20mm Erfle
4mm, 10mm, 12mm, 18mm RK20mm Kellner
8mm, 20mm Huygens
1.5-2x Barlow
Orange, Green, Variable Polarizing Moon filter
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buckeye_hunter
super member
Reged: 12/07/08
Posts: 174
Loc: Ohio
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I recently bought a Meade 10" f/10 SCT. Had a very clear night tonight with moon almost straight up. I used my 14mm Meade UWA...Beautiful!!!, then my 3.5mm Hyperion. Incredible!!! By my calculation that would be 2500fl/3.5fl=714x magnification. Then I added a 2x Barlow, this would make magnification 1428X. Detail was INCREDIBLE!!! The rotation of the Earth and the revolution of the moon (?) was enough to allow me to scan the surface of the moon without touching the 'scope!!! Seemed like I could keep increasing magnification!!!...How far? How to get there? Am I a Lunatic?
My guess is that this was just a perfect night!
Clear Skies and Peace Out!
Bob Hart
p.s. I posted a similar post in the beginners forum. Maybe I should have posted here.
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WO TMB Design 80/480 LOMOS
Meade 102ED
Tac FC-100
Tak EM-2S
A-P Star12
A-P 400 w/ DSC w/ A-P Tripod and Lapides Spreader
MN86 with FT Focuser
A-P 800 w/ DSC w/ portable pier
15" Obsession f/4.5
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 6271
Loc: Inner Solar System
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1428x is pretty amazing! I have to suspect your view was at least a little soft, but who am I to say?
Send some of that seeing out Arizona way, will you?
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- Rick
14" LX200GPS
Dyslexics Untie!
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David Knisely
Postmaster
Reged: 04/19/04
Posts: 8803
Loc: Beatrice, Nebraska
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I have used some really high powers on the moon as well, but when I started comparing detail and sharpness, I found that overall, the actual lunar detail visible sort of "maxed-out" at around 350x or so. Oh, I could use a lot more successfully, but as I went higher, the image brightness began to fall off, and floaters became more and more of a problem. Much past 500x, things were just bigger and not necessarily better. It was impressive, but it just wasn't providing me any more "information" than I had seen at somewhat lower powers. Thus, I rarely go much past 400x on the moon with my 10 inch, as I like the quality of the view better than that revealed at higher magnifications. Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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buckeye_hunter
super member
Reged: 12/07/08
Posts: 174
Loc: Ohio
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I have to correct my post. The 3.5mm was a Stratus. I am pretty new to this hobby, and it was the first time I focused the SCT on the moon. I thought the image was pretty crisp! but nothing to compare. The magnnification was much more than when I used my SV102DN with 26mm plossl and the barlow (only EP I had at the time).
I am really hoping for another chance this evening! My wife and son were "WOWing" with me at last night's session!
Clear Skies and Peace Out!
Bob Hart
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WO TMB Design 80/480 LOMOS
Meade 102ED
Tac FC-100
Tak EM-2S
A-P Star12
A-P 400 w/ DSC w/ A-P Tripod and Lapides Spreader
MN86 with FT Focuser
A-P 800 w/ DSC w/ portable pier
15" Obsession f/4.5
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arpruss
scholastic sledgehammer
Reged: 05/23/08
Posts: 964
Loc: Waco, TX
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I've lately been finding that 225X works great (6mm TMB/BO with a 2X Barlow's cell screwed on for a 1.5X effect), but 300X (6mm TMB/BO with 2X Barlow attached the normal way) has always been too much on any target on my 8". I'd like to try something in between, but I don't have anything in between unless I find some way of securely attaching the Barlow cell at an intermediate distance.
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Coulter Odyssey 13.1" split-tube
Coulter Odyssey 8"
Home-made 7.8" F/4 dobsonian travel scope
Home-made 68mm F/5.3 achro (typically used as finder on 13.1")
Skymaster 15x70
BPTs4 8x30
32mm Plossl, 30mm GSO SV, 30mm Rini, 27mm Kellner, 13mm Hyperion, 6mm TMB/BO Planetary, Owl 2X Barlow
Palm TX with AstroInfo and RescoViewer
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StarStuff1
Pooh-Bah
Reged: 04/01/07
Posts: 1135
Loc: South of the Mason-Dixon Line
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When I received my AT 66 in 2007 I had a clear and steady night with a 7 or 8 day old Moon. That little scope worked like a champ up to 160X with a TMB/BO 2.5mm ep. On nights of so-so seeing I stop at 125X.
With my 8-in newtonian I rarely go above 200X due to seeing.
The nearby Bays Mountain Park and Planetarium has an 8-in f/12.1 triplet apo refractor in a domed observatory. One night there a few years ago the Moon was near the meridian and seeing was unusually good. We cranked her up to 600X before the image became too soft to be useful.
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Tools that make objects very far away appear much closer than they actually are.
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HellsKitchen
sage
Reged: 09/05/08
Posts: 443
Loc: Melbourne Australia
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the highest I got on the moon with satisfactory results was 400x. Usually, I am at around 200-250x however, as seeing (like the weather) in my area is complete garbage 99.999999999% of the time.
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S 38º 00' E 145º20'
http://sabastronomy.webs.com/
Custom 12" F/4.6 dob
10" GSO dob
Intes M500 Mak
Skywatcher 120x600mm refractor
Set of Vixen LVWs + TV barlows + powermates
Astronomik 0III, UHC, H-beta filters
Edited by HellsKitchen (02/19/09 09:05 AM)
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Dean Norris
professor emeritus
Reged: 11/05/08
Posts: 568
Loc: Santa Cruz, Ca
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Since I first replied to your post I've installed a primary fan on my 10" newt and I have to say I was really surprised with the ability to go much higher in magnification. Last night was the first time using my scope with the fan. 416X was clear and sharp on the Moon . The view of the Moon was really cool. A great improvement. I wish I had added the fan sooner. So if you want to get the most out of your newt with higher magnified views, install a fan. Dean
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1971 10" Cave Newtonian F/6 with Protostar secondary
MoonLite CR Focuser Telrad Finder 9x50 SV finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, 4mm ortho, Meade 2x Barlow
7x50 Binoculars
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