Bees
member
Reged: 12/28/07
Posts: 80
Loc: Saskatchewan, Canada
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Check this out: http://demeautis.christophe.free.fr/ep/pe.htm
It's in french but you get the idea.
Some of the old G11s were really bad. One other point I wanted to make was that the reason I went with the EM200 over the G11 was because one of the more experienced forum users said he had been tracking both mounts for years and it seemed like on the support groups for both mounts many many more people for the G11 had to do tweaks or mods to get their mount to behave how they wanted to. Things like replacing gears, applying certain types of grease, checking wiring and placement etc. Some send them into Dr. Clay to get them supercharged straight from the factory before they receive it.... then he said he had never heard of these problems with any of the Tak mounts on the sites.
I know this isn't a scientific analysis and there is bound to be variation in any produced product but I just trust Tak more to fork over the extra cash. I know there are many fine G11s out there though. The CCD imaging forum is proof of this.
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skyler
Pooh-Bah
Reged: 08/16/06
Posts: 1231
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Hello Blueman.
Thanks for for your position on the G11 as it is a very good mount and BTW, yours is exceptional as I think others who have owned or own one would attest.
If I was going to do it again, I would have bought the G11 over the CGE if I knew what I know now.
Also if I had a chance to purchase YOUR G11 over an EM200, I would seriously consider it.
Thanks,
S
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Truth is, many of the older G-11s did have problems. I think some of the problems were caused by their owners, but some were just plain poor engineering.
The new ones, such as mine, with the new precision brass worm seem to be much better. I am quite happy with mine and enjoy the great Go-To when taking photos, as well as the good tracking.
Blueman
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Thanks Skyler,
I am sure that there are some G-11s out there that are not set up correctly or maybe better stated, not adjusted properly.
I have had mine for 9 months and I have adjusted the worms once, just because I wanted to see how easy or hard it was to accomplish.
No way I would sell it though. 
One thing I really like about the G-11 is the ability to keep shooting way past the Meridian.
Blueman
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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skyler
Pooh-Bah
Reged: 08/16/06
Posts: 1231
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Speaking of meridian flips, how does the Tak address this?
One other... what should I expect to get if I am buying a new USDIII model ? What should I expect to get in the used market for about $4300-4500 ?
S
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EricCCD
Pooh-Bah
Reged: 04/14/04
Posts: 1471
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>> Speaking of meridian flips, how does the Tak address this?
Tak mounts will happily track past the meridian. Until they happily run into something. Then they won't be so happy ...
USDIII models don't have GOTO. You should (though to qualify this statement I haven't followed used EM200 prices lately) be able to get a EM200 Temma II used for US$4300-US$4500.
HTH,
Eric
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Hi,
Ok, I have some RAW data files to show for comparison.
Each of these was taken during guiding, so understand it is not showing PE exactly, but rather guiding.
This is important as well are talking about using mounts for photography and I think we would all be autoguiding during exposures.
Here I will post three graphs, each taken by PHD and interpreted by PEAS. I have tried to scale them the same so that the graph is fairly close.
The first is my G-11
The 2nd is the EM-200
the 3rd is an AP900
The pixel scale is different in these, but the size is listed in the data entries so you can see what it is as well as the max +- PE for each.
Blueman
G-11 Raw Data 4 worm periods in graph
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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This is the EM-200 raw data file 1 worm period in graph
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Now the AP900 Raw Data 4? worm periods in graph.
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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skyler
Pooh-Bah
Reged: 08/16/06
Posts: 1231
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Hello Blueman -
How were you able to come up with the Tak and AP data so fast? Interesting PE curves no less.
What was your take on the Ovision worm?
If you keep this up, I might have to buy a G11 instead
of the EM200... : )
S
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lineman_16735
3.14159265
Reged: 12/04/04
Posts: 1540
Loc: At home
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None of this data makes sense. The EM-200 is over 7 arc seconds of error WHILE autoguiding? Of course spica is mighty bright, I would have to guess that the centroid was saturated. Like I said unguided graphs will show where the dollars go on these mounts.
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Chris
AP 900
TSA 102
SBIG ST-2000XM
Astrodons
Lunt 50mm HA and BF1200 on Z Tak
Pyxis
http://home.dejazzd.com/prowatt/
"quidquid Latine dictum sit altum videtur"
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Hi Skyler,
I had the AP900 graph, I just had to find it. I was interested in a graph done with the same software that I was using and with a know excellent mount. I just wanted something to compare my graphs too and this man supplied this graph for me.
The same with the EM-200 graph, my friend sent this one before the smoothed data one, it was on my laptop and I had to find it in my Email that I had deleted. :^)
I would have to say that the first part of the EM200 graph must have been the guiding trying to center the star. Not sure, but this was his first graph that he made and he sent it to me to try to tell him what it meant. I think that the last 25% of the graph is more like the real guiding. I will try to get other data later.
The AP900 graph was also one that was taken by a fellow that had just bought the mount and was trying to figure out how it was working.
The Ovision may be a good thing, depending on whether the mount is working at optimum or not. I will try to get an unguided graph in the next week or so if possible. Right now with the Moon full, I won't be setting up at the local site for at least a week.
I am not sure that all G-11s are as good as mine, but mine is totally stock with no mods or anything.
Blueman
I use PHD and a DSI Pro camera for a guide camera. No special stuff or setup.
Blueman
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Hi Lineman,
As to the high PE on the EM-200, as I stated in the last post, I feel that the first 50-70% of the graph may not be indicative of mounts performance, but the last 25-30% might be more realistic. It was just the only thing I had that showed RAW data, not smoothed data.
I will contact the fellow and see if he could take a unguided log and send it to me. As I say, he is in Columbia, so it might take a few days. I will also try to get some unguided data on my mount as well.
If you noticed, the AP900 was over 5 arcsec while guiding too and the data is the same for all 1000 seconds he recorded. Not sure what to make of that, conditions of course could influence the guiding. Difficult to be sure exactly what all was going on during their tests.
Blueman 
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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Dan G
Pooh-Bah
Reged: 06/27/06
Posts: 1002
Loc: Minisink, NY, USA
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I'm with you Chris. This data looks suspect. Not to suggest someone doctored these graphs but other variables affect this outcome. The total weight on the mount, the moment arm of the load, precision of polar alignment, distribution of weight, etc.
My EM-200 is regularly +/-.2 pixels with a 5" refractor and imaging load on it. Two of my friends have similar experiences. Been through the G11 and CGEs. Some are great some aren't - the Taks tend to be very reliable.
Dan in NY
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TV 76, Vixen VC200L, TV NP-127is
EM-200, NJP
ST-2000xm and ST-402
Tranquility Base Observatory aka "The Shed" by non-tranquil members of the house
www.nyskies.com Still a work in progress!
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Sorry to hear anyone that might suspect me of trying to post any data that is not exactly the way it was presented.
I am a man of considerable reputation for honesty and have been published for some of my views and I also run a forum on another site. Never once have I been accused of anything like falsifying data.
I have shown you everything as is was given to me, changed nothing and made no attempts to deceive.
Pardon me for interrupting your astute conversation. I just thought that someone might be interested in factual data presented so that they might make up their own minds on the Losmandy mounts.
I was intending to take a non guided log tonight as requested. But I realize this would be a complete waste of my time. I will probably go ahead and collect the data, but I will not post it here.
Please buy what ever you wish and be happy. I will not let your statements about my choice for mounts bother me, as I know better.
I have made no accusations about the quality of Tak, AP or any other manufacturer, though others here have. So I leave the thread with clear conscience.
Blueman
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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lineman_16735
3.14159265
Reged: 12/04/04
Posts: 1540
Loc: At home
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Where did that come from Floyd? I think you should reread Dan's post especially the part where he says, "Not to suggest someone doctored these graphs but other variables affect this outcome.". I also don't think that anyone made any statements regarding your mount choice geeze man! Please do post the log. I would be happy to see it. Just for giggles when my 900 finally arrives I will post a log as well. I urge you to download the trial version of Pempro though it will be a great tool for you to use.
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Chris
AP 900
TSA 102
SBIG ST-2000XM
Astrodons
Lunt 50mm HA and BF1200 on Z Tak
Pyxis
http://home.dejazzd.com/prowatt/
"quidquid Latine dictum sit altum videtur"
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skyler
Pooh-Bah
Reged: 08/16/06
Posts: 1231
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Hello Floyd -
Please don't leave the forum and sorry if there were any misunderstandings. I really want to see the results of the data and even though I might have leaned towards the EM200 from the start due to weight factors (I assume the G11 setup is heavier), that does not mean it is out of the question either.
Plus I hope you remember me when you decide to sell your particular sample since it is incredibly good. : )
Thanks again,
S
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blueman
professor emeritus
Reged: 07/20/07
Posts: 580
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Hello Skyler and Chris,
Sorry, but I do feel that there is little being gained by this. I believe that no matter what gets posted, it will always be suspected that there are things that make the data irrelevant.
Indeed, I did read his post and see where it is stated that he is not saying data has been manipulated, so I may have misread his intent. Sorry if I did, but at the same time, if the data is not to be taken at face value, then I do not see how it can be of any use.
I can never say for sure what someone else's conditions were like, or whether they balanced properly or even chose a poor star for their test. I can only present the data as it was presented to me.
You can be sure that my mount data is nothing more than just a typical night of imaging. The logs are saved by the program each time I go out and I will usually take a look at them to see how things are doing. Certainly there is some variation due to seeing on some nights.
But, unfortunately I have never felt the need to know what the actual PE graph looks like, because I have been quite happy with the guided images. But I am interested in knowing whether I could benefit from some of the new products being made that are reported to make the PE in line with the AP, TAK or any other high end mount. So I will take a night here in the back yard and do a test for this purpose. I may post it here, but I will have to think about that. I do not wish to cause any controversy over this.
The only reason I responded at all was the remarks about Losmandy being guilty of overstating or falsely making statements about the max loads and how they were really only good for 1/2 the stated rating. I feel that this statement is not true and that the ratings are fairly accurate. But that is my opinion and every one is entitled to theirs.
I will say this though, I would never intensionally try to make a claim or statement that I did not think was the whole truth.
Thank you,
Blueman
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WO 80mm f/6 APO
DSI III Pro Televue .8 focal reducer
Atik filter wheel Astronomik filters
Losmandy G-11 Gemini Auto-guided
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tim53
sage
Reged: 12/17/04
Posts: 306
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I didn't think people were saying that any manufacturer was misstating the load capacity of their mounts - just that there are no standards and so the way they are reported differs, making it harder for the buyer to make an informed decision if they're concerned about the weight limits.
Also, I remain confused about the PE issue. It seems that all the graphs you've shown are taken with guiding turned on? Some smoothed and some not smoothed?
This is fine, so far as it goes. But you must know that such plots tell more about how well the guiding was set up and is working, and less about the precision of the mount. Right?
In the end, so long as any mount errors are corrected with guiding or PEC (or both), maybe it doesn't matter all that much how precise the drives are.
It's just fun to know. Like my account of using the AO-7 on my SBIG on a spur-gear driven C-8 above - so long as the AO was able to keep the star steady, it didn't matter a hoot that the drive is full of erratic errors.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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Dan G
Pooh-Bah
Reged: 06/27/06
Posts: 1002
Loc: Minisink, NY, USA
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Floyd -
Sorry I ruffled your feathers. My intent was not to question your integrity or even of the owners of the mounts. I just wanted to highlight that using guide data to compare mounts adds so many variables it is difficult to glean a true understanding of which mount is better.
As Chris points out PE is a much better measurement. It removes most of the variables and we can identify how smooth the curve is. A smoother curve is easier to guide through than a rough curve.
No need to leave the group either. I enjoy your posts and would hate to have your voice silenced. I think the issue hear is many of us have moved through the mounts in questions and seen a marked improvement as we moved up the chain. You have a stellar G-11! That's great and there are others out there. But some of us did not enjoy ours quite as much.
Dan in NY
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TV 76, Vixen VC200L, TV NP-127is
EM-200, NJP
ST-2000xm and ST-402
Tranquility Base Observatory aka "The Shed" by non-tranquil members of the house
www.nyskies.com Still a work in progress!
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