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Anyone make a cheap but useable eq mount???

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#1 kbastro

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Posted 02 February 2011 - 02:56 PM

This post is for another person, and they want to mount a camera and a 200mm lens on a cheap eq mount with a motor drive.

All the "driven" mounts seem to be in the 6$600 - $700+ range and she doesn't want to spend that much on something that may or may not work for her.

Can anyone reccommend a mount that can move a camera and track fairly well and cost in the $200 - $400 range???

kbastro

#2 mcoren

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Posted 02 February 2011 - 04:02 PM

$600-700 seems a lot for just a driven mount. Does she need GOTO? If so, that's probably what she'll need to pay.

If all she wants is an equatorial mount with tracking, a 200mm lens should be fine on something like an EQ-2 mount for $180 (9 lb payload rating). The motor drive is another $73, for a total investment of $253.

#3 Falcon-

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Posted 02 February 2011 - 04:44 PM

Having used an EQ-2 mount for AP I think there may be problems with that mount and a 200mm lens. Now my particular EQ-2 is 35 years old and rather beat up, so perhaps it performs poorly compared to new EQ-2 mounts, but I found the periodic error too large to successfully image at anything longer then about 90mm focal length with my mount.

A used CG-5, LDX-75, LDX55 or EQ-5 might be a good way to go. In fact there is a used CG-5 with dual axis drives on astromart right now that even includes a mod to allow autoguiding.

Alternately a new Skywatcher EQ-3 or Celestron CG-4 might work if you can find one with at least a RA drive. Sometimes "CG-5 Clone" mounts show up on ebay too that are basically the skywatcher EQ-5 or EQ-3.


It is possible that a well polar aligned brand-new well cared for EQ-2 would be perfectly fine at 200mm, but if it can be afforded one of the higher mounts would be more of a sure bet. For myself I used my beat up EQ-2 for about 4 months till I could afford a brand new CG-5 and have been able to do so very much more since I got it!

#4 Ad Astra

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Posted 02 February 2011 - 05:41 PM

Orion makes a camera tracking platform for about $200 ... teletrack??? something like that. It's on their website and designed to track a DSLR and a big lens (or a very small scope) easily.

Hope that helps!

Dan

#5 Lane

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Posted 02 February 2011 - 06:57 PM

This music box tracker looks pretty cool.

#6 orlyandico

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Posted 04 February 2011 - 02:19 AM

I'm using a Vixen GP that I got for $180. But then I attached Vixen MT-1 motors to it which cost $300. Not so good..

The Orion dual-axis drives can be had for about $110 and will bolt up to an EQ-5, CG-5, or Vixen GP. All will work well.

How long are the shots going to be at 200mm? I noticed that around that focal length, with an APS-C DSLR (Pentax K20D), a fairly accurate drift polar alignment is needed to avoid oblong stars even at 30 second exposure times.

#7 neveruseforever

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Posted 04 February 2011 - 07:30 AM

For several years I have collected and kept updating a list of small equatorial mounts and their data:
http://www.mitbbs.co...y/31167323.html
It's in Chinese, but you can at least check the models and their official websites. All data is taken from internet so I don't guarantee anything. You need to do more research before you buy.

If people are interested I may make a english version in the future.

#8 neveruseforever

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Posted 04 February 2011 - 07:58 AM

If astrophotography with a camera lens is your primary purpose, the most popular mount I know are AstroTrac TT320X-AG and Eyebell CD-1. They are light and small, easy to carry for a long journey.

#9 gnowellsct

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Posted 04 February 2011 - 10:44 AM

I would look for a used super polaris with single axis drive. Greg N

#10 dymy24

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Posted 04 February 2011 - 02:59 PM

If the criterion are "track fairly well" and "hold a camera" and "cost in the $200-$400 range", then a Barn Door Tracker might fit the bill. They require assembly, but dozens of plans are available for free.

#11 wasyoungonce

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Posted 04 February 2011 - 03:30 PM

This music box tracker looks pretty cool.


Now that's a cheap good idea that entertains to boot! :lol:

#12 orlyandico

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Posted 05 February 2011 - 04:21 AM

the trouble with the barndoor tracker and the OPT music box is that it would be hard to polar align.

i have noticed that at 330mm focal length, even a 30-second exposure shows oblong stars at 30 seconds, a drift alignment is needed.

#13 dymy24

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Posted 05 February 2011 - 09:29 AM

the trouble with the barndoor tracker and the OPT music box is that it would be hard to polar align.

i have noticed that at 330mm focal length, even a 30-second exposure shows oblong stars at 30 seconds, a drift alignment is needed.


Wonder why that is? I've been able to take 60 second exposures on AltAz mounts at 400mm (prime) without too much field rotation. Does drift on an Eq mount with a rough polar alignment have a greater impact than field rotation an an alt az with no alignment?

#14 orlyandico

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Posted 05 February 2011 - 09:39 AM

depends on your tolerance for oblong stars i guess... what i'm talking about is oblong stars at 1:1 on a 15MP APS-C sensor. of course at web resolutions the non-round stars aren't visible..


EDIT: i haven't seen field rotation but drift in an imperfectly-aligned polar mount shows up as a straight line. so even a tiny bit of drift causes the stars to elongate.






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