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Alt-Az mount for a large refractor?

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#1 Trever

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Posted 29 April 2009 - 11:53 AM

Does anyone know of an Alt-Az mount of some kind that is available for large refractors such as my Meade 152ed refractor? I was thinking of getting another CGEM with an extender in the near future but I wanted to check first.

I will say that these scopes are bigger than the standard F/8's offered by Synta so it would have to he hefty.

#2 zjc26138

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Posted 29 April 2009 - 12:09 PM

I think a DM-6 will work.
here

or a APM Max-load Alt-Az mount.
here

#3 Trever

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Posted 29 April 2009 - 01:26 PM

Good suggestions. I will check them out.

#4 zjc26138

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Posted 29 April 2009 - 01:30 PM

I had a chance to play around with the Max mount at NEAF. Boy is it a beast, as well as a joy to use. Marcus(owner of apm) had a Meade 127 Triplet on it and on the other side a 8in f/8 Archo. I figure about 25 pounds for the Meade and close to 45 or more pounds for the Archo. Thats close to 70 pounds. I would recken that the mount probably could easily hold 50 or more pounds on one side, given you had a big enough tripod.

*I just remembered. I played around with a DM-6 also. It had a TEC140 on it and the motions were smooth as silk.

#5 Herenomore

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Posted 29 April 2009 - 03:03 PM

Trever:

The DiscMounts DM-6 will easily handle loads heavier than your Meade 152. For example, some of the scopes pictured here:

http://discmounts.co...ust_gallery.htm

here:

http://discmounts.co...lleryframe.html

and here:

http://www.discmount...y3/DMG3_p1.html

Tom

#6 Trever

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Posted 29 April 2009 - 04:15 PM

Ive been looking through their site. Seems that is the way to go. Looks like it will also support a sky commander.

Seems to be a good quality mount.

#7 zjc26138

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Posted 29 April 2009 - 04:17 PM

Ive been looking through their site. Seems that is the way to go. Looks like it will also support a sky commander.

Seems to be a good quality mount.


There very nice, both the DM-4 and the DM-6. I got the feel for them the Friday of Neaf, when there weren't people around. I think you'll be very happy if you go with the DM-6.

#8 Herenomore

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Posted 29 April 2009 - 04:24 PM

Trever:

Although it can be used without them, Tom Peters designed the mount to be used with DSC's. Tom Trusock reviewed the DM-6 here when it debuted in '03:

http://www.cloudynig...php?item_id=611

(Not pictured in the review is the DiscMounts tray which is now available)

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#9 JumboFlex

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Posted 29 April 2009 - 05:18 PM

Last time I checked the DMs were considered the best altaz mounts around, you pay for that though, but numerous people feel that its worth it.

The DM6 can handle some big scopes.

#10 ad701xx

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Posted 29 April 2009 - 06:11 PM

The Giro III does great with my TEC 140 which weighs somewhere around 27 lbs all up.

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#11 maknewtnut

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Posted 29 April 2009 - 06:28 PM

As others have mentioned, you may not need a monster a/a mount, just a good one. In the scheme of things, the Meade ED's aren't too hefty. The keys are not only a good mount, but a great tripod. This is often overlooked in the effort to remain as portable as possible. That can still be accomplished, but scrimping on the tripod, especially when used to support a scope with significant moment arm, will detract from the experience.

#12 Trever

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Posted 29 April 2009 - 09:11 PM

Would the ash tripod that they offer for the DM6 be sufficient or should a G11 tripod be recommended?

#13 Jim7728

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Posted 29 April 2009 - 10:09 PM

That G-11 tripod with riser column would be my choice for the 152ED. ;)

http://discmounts.co...ount_cust89.jpg

#14 drshr

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Posted 29 April 2009 - 10:31 PM

I use the Orion AZ, also known as the skytee here in OZ. Rated at 50lb I thought I would test it out with my 8" and 6". The mount has handled them with ease. A pier would help.
2 scope setup also has its advantages.

#15 darylf96

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Posted 29 April 2009 - 11:35 PM

If you want a great mount for visual observing, the DM-6 with Sky Commander DSCs on a HD tripod with an extension would be super. I have the DM-6 with the DSC unit on a HD Meade tripod (with leg spreader) and a Losmandy extension, and it handles my 6 inch refractor like a dream. It also handles my 10 inch SCT with ease.

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#16 Herenomore

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Posted 30 April 2009 - 09:15 AM

Would the ash tripod that they offer for the DM6 be sufficient or should a G11 tripod be recommended?

Trever:

DM's ash tripod is furniture quality and very solid but without knowing the weight/length of the 152ed, I can't say whether it would be sufficient. Your best bet would be to contact Tom Peters @ DiscMounts and ask him (if it's not sufficient, he'll tell you) and/or ask the members of the DiscMounts yahoo group:

http://tech.groups.y...oup/discmounts/

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#17 Trever

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Posted 30 April 2009 - 09:50 AM

At least there are other options such as the G11 or Meade Giant tripod. Also maybe a CGE tripod. I will see what I can afford and then talk to Tom Peters to see what he suggests. I would like to get the whole shebang along with the sky commander. I have never used one but I assume it is a more accurate version of Orion's?

#18 Herenomore

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Posted 30 April 2009 - 11:35 AM

Trever:

The Orion (I've never used one...are you referring to the IntelliScope?) like the Sky Commander, Argo Navis, SkyTour, etc., are computers reading what the mount tells them. "Accuracy" is really dependent upon the orthogonality of the mount (how close the alt and az axes are to making a perfect 90-degree angle) and the quality and resolution of the encoders.

As for orthogonality, Tom Peters told me that the alt axis and az axis of my DM-4 are within 1/50 of the diameter of a human hair of being perfectly 90-degrees to each other. I don't know what that computes to in hundredths of a degree but it is, for all intents and purposes, perfectly orthogonal. You can also read Tom Trusock's review of the DM-4 in which he said:

The accuracy of the DSC pointing depends heavily on the construction of the mount. In short, it requires that the mounts axis be perfectly perpendicular to each other – orthogonal – for best results. To make a long story short, the DM-4 is orthogonal. Period. DSC pointing accuracy was everything one could want. It easily allowed me to center objects at high power.



As for encoders, the Sky Commander will handle up to ~26K-tic encoders (the higher number of tics, the greater the resolution and pointing accuracy). Although Tom will install higher tic encoders if you request them, he recommends and uses 2" diameter 4000-tic encoders for the DM (which, btw, were the encoders installed in the DM-4 in Tom Trusock's review). Simply put, the 4K-tic encoders will give you as much resolution and accuracy as you'll ever need to bring objects to dead-center of your FOV while at the same time not taxing the Sky Commander's internal 9v power supply (the higher the number of tics, the greater the power requirement).

For more on DSC's generally, Tom Trusock has written an excellent primer:

http://www.cloudynig...ts/dscintro.pdf

Tom

#19 Tamiji Homma

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Posted 30 April 2009 - 11:40 AM

At least there are other options such as the G11 or Meade Giant tripod. Also maybe a CGE tripod. I will see what I can afford and then talk to Tom Peters to see what he suggests. I would like to get the whole shebang along with the sky commander. I have never used one but I assume it is a more accurate version of Orion's?


I don't know about Orion's but SkyCommander is pretty accurate with DM-6 and it makes you lazy, not looking at sky map after you are done with 2 star alignment.
If you already know what stars to choose for alignment, alignment takes less than 2 minutes, probably one minute.

Regarding DM-6 and G11 tripod, I feel the combo is solid Alt/Az solution for 6 inch f/8 scope. Here is my setup (FHD tripod, Foldable HD tripod) and DM-6. I also use Vixen VMC260L with DM-6/FHD.

Scope weight is about 20Kg (WO FLT 152 f/8, dovetail plate/rings, binoviewer, SV 60mm finder)
DM-6 and FHD tripod weight is about 32Kg.
The photo shows the lowest 47 inch high to center of dovetail. The highest is 62 inch high when tripod legs are fully extended.

Posted ImagePosted Image
Posted Image

Good luck in your choice and enjoy 6 incher :)

Tammy

#20 Herenomore

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Posted 30 April 2009 - 11:54 AM

Beautiful set-up, Tammy :waytogo: Looking at it, the G11 would probably be the best bet for Trever's 152ed.

#21 ottovonrotton

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Posted 30 April 2009 - 05:35 PM

Hello all. What about a stellarvue M7. I use an older M6 for visual use with a
Pier extension and a U.A. heavy duty tripod, works great and holds alot.

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#22 Trever

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Posted 30 April 2009 - 06:19 PM

I will have to check that one out. I havent considered this one.

Otherwise, if I can work out the financials, the DM6 is the way I will go. Just have to decide on the tripod....

#23 Tamiji Homma

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Posted 30 April 2009 - 07:01 PM

I will have to check that one out. I havent considered this one.

Otherwise, if I can work out the financials, the DM6 is the way I will go. Just have to decide on the tripod....


There is mount called "DoubleStar Mount" by Universal Astronomics, supporting 30lb and 40lb side-by-side.

If 152ED is less than 40lb, this might work, too.
http://www.universalastronomics.com/

I am looking at this mount to replace retired WO EzTouch to mount 5" and 4" refractor side-by-side.

Tammy

#24 davidpitre

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Posted 01 May 2009 - 07:30 AM

One thing the Disc Mounts lack is slow motion control.
I've heard people say they are so smooth they don't need one, but I find it hard to imagine they could track at high power as well as a nice slow motion control knob.

#25 Jim7728

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Posted 01 May 2009 - 07:47 AM

I played around with the Discmount everytime I went to NEAF and thought the motions were smooth, but a little stiff. I can see advantages as far as changing eyepieces with no movement and vibrations being controlled better, but thought it took a little more effort to move the ota then with other alt/az mounts. Just an observation, I'am sure tension can be adjusted.






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