Click here if you are having trouble logging into the forums
Privacy Policy |
Please read our Terms
of Service | Signup and
Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User
drollere
Pooh-Bah
Reged: 02/02/10
Loc: sebastopol, california
|
Re: One great aperture rules lesson
[Re: Doug Culbertson]
#5373178 - 08/17/12 01:16 PM
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
the more obsession about aperture, the less obsession about the skies.
the more obsession about eyepieces, the less obsession about what you are looking at.
i find that is the most basic distinction among amateur astronomers. more basic even than differences in experience or preferred type of activity (astrophotography, visual, comet hunting, etc.).
|
Sgt
Pooh-Bah
Reged: 12/17/05
Loc: Under the southern horn of the...
|
Re: One great aperture rules lesson
[Re: Jitou]
#5373270 - 08/17/12 02:14 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Jitou,
Did I imagine it or did you downgrade to a 12.5in dob from an 18in dob?
|
BillP
Postmaster
Reged: 11/26/06
Loc: Vienna, VA
|
Re: One great aperture rules lesson
[Re: Jon Isaacs]
#5373451 - 08/17/12 04:10 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Quote:
24" fast dobs do not need a ladder.
No telescope needs a ladder, some observers do though.
Jon
At the USNO with the 26" Clark, even the shortest of observers does not need a ladder...all you do is press the big green button on the hand controller attached to a long cable laying on the floor, and the entire floor rises to meet the focuser  Now that's livin!!
|
Mike B
Starstruck
Reged: 04/06/05
Loc: shake, rattle, & roll, CA
|
Re: One great aperture rules lesson
[Re: BillP]
#5373580 - 08/17/12 05:37 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
...all you do is press the big green button on the hand controller...
I'm just sure JMI makes one of those, too...
|
Jitou
super member
Reged: 07/29/08
Loc: France
|
Re: One great aperture rules lesson
[Re: Mike B]
#5374261 - 08/18/12 07:29 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
@Bob S. Jitou, I notice that you own a 12.5" f/5 ZOC mirrored scope.
Quote:
@Sgt Did I imagine it or did you downgrade to a 12.5in dob from an 18in dob?
Not yet, this better instrument for me is at a project stage so I don't have it in my hands for now ! I will order the ZOC mirror in a few days (9 months delay Carl said !) and then I'll ask TheDobsonFactory to build a dobsonian truss structure around it, though I still own the 18" F/4 Ostahowski in the mean time.
Agree with you also *skyguy* It certainly doesn't worth the better view when climbing a ladder but for me it's the transportability issue that lead me to go for another smaller instrument, even broken into parts a 18" is still too heavy to handle for me however I reckon that optically speaking the Ostahowski mirror set is truly a wonder and has shown me stunning images of the sky I will regret it after I sold it.
Quote:
@BillP At the USNO with the 26" Clark, even the shortest of observers does not need a ladder...all you do is press the big green button on the hand controller attached to a long cable laying on the floor, and the entire floor rises to meet the focuser Now that's livin!!
No kidding that must be something to see thru this mythical refractor !
Edited by Jitou (08/18/12 07:32 AM)
|
Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
|
Re: One great aperture rules lesson
[Re: Jitou]
#5374499 - 08/18/12 11:08 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
And also knowing that practical resolution will be limited by other factors most of the time, then there should be an ideal aperture that would maximize the benefits and keeps the burdens at a very low level. I am sure that many of the most experienced observers here have already found the Grail just ask them.
There is no one answer that works for everyone, each of us has different interests, different resources, different situations. The solution that works best for you is unlikely to be the solution that works best for me. Mike's equation:
"money + space + hassle factor = is it worth it for you? "
pretty much sums it up.
In my situation, I have the space, the location, enough money, my solution is multiple scopes, there larger ones being a 12.5 inch, a 16 inch and a 25 inch. The scopes live out in the mountains where it is most often clear and dark so the hassle factor is minimized, it takes 5-10 minutes and any one of them is up and ready. The 12.5 inch and 16 inch scopes are also travel scopes, they both fit easily in our older motor home...
This is my Holy Grail at this particular time in my life.
Regarding Globulars and aperture... The eye is a strange thing.. there is no doubt in my mind that I resolve more stars, see more faint stars in a larger scope, than a smaller scope. It might not be so apparent looking at the big bright globulars that this is true but lesser globulars come alive with a larger scope. M30 is relatively bright but compare M30 in a 12.5 inch vs a 25 inch... that might be comparing them a 250x and 500x... Or one can compare smaller globulars like NGC6453 (inside M7) or nearby NGC6441... there are definitely more stars to see in the bigger scope.
Jon
|
auriga
Pooh-Bah
Reged: 03/02/06
|
Re: One great aperture rules lesson
[Re: Darren Drake]
#5375008 - 08/18/12 05:45 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Darren,
Great post. My own observations of a series of telescopes on a deep sky object side by side at the same time, yielded results like yours.
Contrary to what is often said here, I found then, and have found subsequently, that a difference in aperture of two inches produces a significantly better image of DSOs.
Calculations frequently appear on this forum giving percentage increase in light gathering power among the various apertures, and concluding that only an aperture increase of 1.4x, or more, yielding a twice as bright image, are worth while. Some even state that only an aperture increase of 1.6x, giving increase of a full magnitude of brightness, 2.5 times as bright, is worth while.
These calculations don't square with the observed data, such as what you and I report. Since we are mostly engineer and scientist type people on this forum, our calculations and theorizing must be right and the observational data must be wrong.
The comparison you report is to me a definitive way of assessing the results of viewing at different apertures.
Notice that it is a different financial and logistical question, deciding whether to buy an 8" or a 10" Dob, versus deciding whether to upgrade from an 8" you already own, to a 10" Dob.
Bill Meyers
|
waso29
sage
Reged: 05/12/10
Loc: Chi-Town, USA, mother earth
|
Re: One great aperture rules lesson
[Re: auriga]
#5375044 - 08/18/12 06:12 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Good stuff, Darren. We should have more of these astro camps around the world.
Aperture doesn't always rule, but size does matter.
|
Mike B
Starstruck
Reged: 04/06/05
Loc: shake, rattle, & roll, CA
|
Re: One great aperture rules lesson
[Re: auriga]
#5375351 - 08/18/12 11:45 PM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
Notice that it is a different financial and logistical question, deciding whether to buy an 8" or a 10" Dob, versus deciding whether to upgrade from an 8" you already own, to a 10" Dob.
+1 for a to-often neglected aspect of the issue, one that is typically drowned out in the hoopla.
Quote:
Since we are mostly engineer and scientist type people on this forum, our calculations and theorizing must be right and the observational data must be wrong.
 
|
Jeff Morgan
Post Laureate
Reged: 09/28/03
Loc: Prescott, AZ
|
Re: One great aperture rules lesson
[Re: bassplayer142]
#5375704 - 08/19/12 10:13 AM
|
|
Edit
|
Reply
|
Quote |
Quick Reply
|
|
|
Quote:
The only real questions in my opinion when getting large aperture is.
1. Do you have the money and storage space?
2. Do you mind the hassle of dealing with such a large scope?
3. Does the views you get from it make it worth it?
And you can also add thermal equalization to the list. If you live in an area with large day/night temperature swings that lovely large mirror won't catch up - until morning twilight starts.
|
|
21 registered and 24 anonymous users are browsing this forum.
Moderator: Jarad, ausastronomer, okieav8r
Print Thread
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Thread views: 2206
|
|
|
|
|
|
|
Previous
Index
Next
Threaded
