I intend to line up the 18" (Sutching mirror) against the 130EDT. Both will be on GoTo mounts and both at the same magnification - either 75x or 150x (27mm pan, 13 & 7mm naglers)
It will be interesting to compare the views, and how pleasing each view is. My initial impression is that the Starfire 130EDT will not be disgraced.
Hence my support of Damien's initial intention to purchase a high quality refractor.
Hi John,
You're missing the entire point of where the larger aperture has a big advantage. Sure on bright objects heavily affected by local seeing like Jupiter, the Moon, or Saturn there may not be much difference between them. The 18" SDM has the capability to observe more than double the number of objects in the sky compared to a 5" refractor.
Point them both at a 12th magnitude galaxy or a 6th or 7th magnitude globular cluster and see which one gives the best view, at the same magnification. It will not even be a remotely close contest.
Line your 5" refractor and your 18" SDM up at the next South Pacific Star party beside Lachlan McDonalds 30"/F4.6 SDM and see which telecope has the longest queue of people waiting for a look, that's usually a fair indication. I don't know that I've ever seen the longest queue at any Star Party near a 5" refractor.
Some very interesting reading in this thread,
just another consideration : size does matter !!!!!
What the OP is proposing vs. what 'visual' wisdom advocate
I agree that something like a Lightbridge 12 would give the op far better visual experience than a 4" refractor but the op may not have the wish or ability to own or handle the larger instruments, especially SDM sized light-thieves, horses for courses.
As a travel kit for visual with AP capability, I would think a high quality 4" refractor would be quite nice. My own lightweight kit is the Vixen GPD2 mount with Vixen R200SS 8" F4 reflector. So far I cannot fault the mount, beautiful Japanese engineering.
You're missing the entire point of where the larger aperture has a big advantage. Sure on bright objects heavily affected by local seeing like Jupiter, the Moon, or Saturn there may not be much difference between them. The 18" SDM has the capability to observe more than double the number of objects in the sky compared to a 5" refractor.
Point them both at a 12th magnitude galaxy or a 6th or 7th magnitude globular cluster and see which one gives the best view, at the same magnification. It will not even be a remotely close contest.
Line your 5" refractor and your 18" SDM up at the next South Pacific Star party beside Lachlan McDonalds 30"/F4.6 SDM and see which telecope has the longest queue of people waiting for a look, that's usually a fair indication. I don't know that I've ever seen the longest queue at any Star Party near a 5" refractor.
Cheers,
John B
There is a portability issue too, John-I know which one I would rather be carrying! Portability is a big issue for me because of medical problems.
If one has a permanent observatory, then size and weight doesn't matter, but I have always found the bigger and heavier the scope, the less I used it.
Cheers
Laurie
I have been observing for 40 years this year and I've never been able to see anything through a 5" telescope ( and I own a very high quality APO) that gets me remotely as excited as what I can see through a quality 10" plus telescope.
An 18" has sufficient light and resolution to keep a dedicated observer occupied for life. And the quality of the views will not reveal as easily as a small scope with relatively poor resolving power, that gives images that appear sharp almost always but offer little detail. One has to really have a grip on finding a suitable site free from localised seeing issues- understand cooling and collimation and understand atmospheric seeing . When everything comes together views can be revealed that will be etched on your mind for life.
A quality 5" scope is not able to transcend the laws of physics no matter what type. My general rule of thumb is that refractor can give views similar to a high quality Newtonian around 20% larger . But that puts your available light gathering at around 8" at best.
Just a quick comment. Maybe you should see someone in store locally to get an idea of what might suit your scope. Maybe your store will have a night where you can try before you buy (the one here does). I think your choice is great and I'm sure that when you start astrophotoing it will really shine. It doesn't matter how big your scope is as long as you just enjoy what your doing. The sky is a awesome thing and I hope you find what your looking for. Just look at some of the photos that are on this site as I'm amazed every time I look at them and wish that I could do this too. Good luck and please share your photos when you start!
I have not had my SDM long, but hope next winter to present a big test to as many as possible at a major star party. I intend to line up the 18" (Sutching mirror) against the 130EDT. Both will be on GoTo mounts and both at the same magnification - either 75x or 150x (27mm pan, 13 & 7mm naglers)
It will be interesting to compare the views, and how pleasing each view is. My initial impression is that the Starfire 130EDT will not be disgraced.
John - reading between the lines you sound disappointed with your early work with your 18" SDM in relation to results and your contention perhaps that your 5" Starfire APO 'would not be disgraced' against an quality 18" Newt - is a little mystifying without further background on you and the circumstances under which you have used your telescope. . Even on the planets I've seen a 7" Starfire well and truly outgunned by a quality 10" Newt - it is simple physics.
I am interested in your `shootout' purely for educational value. . Do you attend the SPSP ? If so I would like to join you and ensure that your scopes are properly collimated , that the Newt mirrors are clean and within 2 degrees of ambient as minimum , and that the seeing conditions are at least fair .
We can observe a broad range of objects from planetary nebulae to distant galaxy clusters, and I will take notes on comments of various different observers which I can report back to the forum. . Perhaps that your APO " will not be discraced " requires further expansion if you are looking for a more meaningful result of a "shootout" ?
Mark
Mark,
I would much appreciate any help with little comparo. I last attended the SPSP in 2005, was a regular in the 1990's, and am hell bent on making the 2013 affair. (it was one look back in 1993 with the re-figured 17" club telescope that led me to want something similar)
Let me say that any comparisons so far between the 18" and 5" have been made after a very brief aquaintance with the SDM. The mirror is very dusty on this scope, observing was from my Bowral backyard which over 20years has had much light encroachment. So I am comparing the views in the 18" to those best views I have had from a dark sky with the 5".
Just a few notes from my obs of 11th Nov:-
Star test v.good. Mirror/ambient diff around 2 degrees NGC 253 large at 75X. Not sure this scope reveals much more than my 130EDT. Shows galaxies brighter and more detail but not doing much 130 cannot do. Failed to find NGC246 and 255. Plenty of galaxies noted in Fornax cluster. NGC 1360!! planetary with bright star near centre. IC 5332 - noted small double star nearby. Helix nebula - very diffuse, large not much contrast. NGC 55 - almost as good as 253 NGC 300 - disappointing. Beta phoenix - not resolved at 288x. 47 tuc - spectacular SMC looks very interesting in this scope.
In relation to the above, I have never resolved Beta phoenix in any scope, and the 130 shows NGC300 clearly from a dark site.
A couple of days after this I was back at work in Whyalla. Won't be home again until Christmas, but looking forward to making this SDM really work!
I have used your scope on quite a few occasions, when it belonged to Phil Townsend. It has one of Mark Suchtings' mirrors in it and it's an outstanding mirror. I know exactly what your scope is capable of, having used it a fair few times. It's fairly obvious to me (and to Mark) that you are currently not getting the best out of your new scope.
If you are interested I would be happy to drive across to your place from Kiama one night and help you set it up properly, in terms of collimation and cooling.
I would be happy to bring along either my 10" or 14" SDM for you to also compare that against your 5" and new 18" scope. My 10" scope has one of Mark's mirrors in it and the 14" scope has a Zambuto mirror in it. Both mirrors are excellent.
At present I think you have a Ferrari jammed in first gear.
If you are interested I would be happy to drive across to your place from Kiama one night and help you set it up properly, in terms of collimation and cooling.
Cheers,
John B
If time allows me i will come down to , i have had many great night observing with this scope & have full confidence in it to perform well .
Yes the mirror was dusty & needs a clean & i intended to have it clean for you but as our transaction was drawn out over a long period i got caught out at the end so i owe you a mirror clean John
phil
Seems that in this discussion about the need for visual astronomers to have a Newtonian Reflector at least 10" and preferably bigger we have forgotten that the original question of this thread was about a mount for a 4" refractor that the OP probably has had his heart set on for ages.
I see no problem as to the direction the thread has taken. This is the nature of forums. The original poster has had advice on mounts and additional advice on scopes as well. I am sure he is not complaining.
The thread then took the direction as to whether a small high quality refractor is a reasonable choice for a first serious scope. This was still very much on topic. The later discussions are very much related to this matter, I have found them informative and interesting.
Just becuse a thread takes a slightly different direction from the original post does really matter. What does matter is the depth and breadth of the following posts in relation to the discussion. A new thread is not the always the way to promote good discourse.
Phil T
I am in no way disappointed with the SDM - I just have not had the opportunity to stretch its legs as yet. Hope to see you at the next SPSP with your new 28"!
Don't get me wrong John, the information and discussion is excellent but it might be a bit daunting for someone getting into the game for the first time.
Thought I'd chime in a little. I haven't had much time to take out my new 14.5" sdm at all, only 3x and thats with 50-100% moon so I haven't stretched its legs out much. However what I can confirm is with a 6mm radian plonked into the eyepiece and 2x/3x barlow, effectively giving me ~600x magnification and ~900x, I have had some of the most magnificent views of the lunar surface I've ever seen. Tack sharp, beautiful contrast, and (blindingly) bright. Most observing reports I read of people using premium refractors boast of 250-350x!
I haven't ever looked through a premium refractor, but if it's any better than what I've seen so far i'd have my SDM for sale immediately.
If you guys do decide to meet at an observing field somewhere I'd love to bring my sdm along for a visual comparo as well if it's ok with you guys?
I have no problem with the direction this thread has taken and am greatful for all the advice.
My revised plan is to buy a Skywatcher EQ-[something] mount and a 8-10" Newtonian first. That will get me started with observation and allow some basic astrophotography with my existing cameras and lenses.
The mirror is very dusty on this scope, observing was from my Bowral backyard which over 20years has had much light encroachment.
So I am comparing the views in the 18" to those best views I have had from a dark sky with the 5".
John- so the plot thickens Look forward to a 'shootout' in similar conditions.
I know that on most nights in a semi light polluted sky on the northern edge of sydney I would not even bother taking out the APO- in these conditions the 14" Dob is the only thing that gives a view that is just enough to impress someone who has not seen the sky through a scope at all.
Look forward to a 'shootout' in similar conditions.
