EQ mounts info please

[jnp]

I have just built my own 90mm f11 refractor which is currently sharing the mount with my motor driven Astromaster 130 (CG3 mount). I am finding that my prime focus astrophotograhy (with Canon 1000d) is limited to about 8 seconds before star trails are a problem. This is limiting me to m13,m57 and other low hanging celestial fruit. I am therefore looking for a better equitorial mount solution.

My impression is that I need to consider an EQ5, but is there a definitive explanation of what each type of mount is best for, e.g. whats the difference between EQ1, EQ2...EQ5, EQ6. (and where does CG3 fit into this?). This might be a useful primer for others too?

Finally, is building your on mount a viable proposition (I can only forsee lots of issues)?

[RichieP]

The EQ mounts are built by the Chinese company Synta - marketed as Skywatcher here, and under the Orion label in the US. As the number rises, so does the size and load capability of the mount. EQ3-2 mounts and above can be equipped with GOTO.

The CG mounts supplied with Celestron mounts are very similar, although slightly higher quality I am told. A comparison would be

EQ1

EQ2 --- CG3 (I think!!)

EQ3-2 --- CG4 (Both copies of the Vixen SP mount)

EQ5 --- CG5 (Both copies of the Vixen GP mount)

HEQ5

EQ6

I think a EQ5, CG5 or Vixen GP mount would be a good starting point for you.

[jnp]

Thanks, that helps clarify the "EQx" and "CGx" designations. Are there any standards/specifications that define the different mounts across manufacturers. We would all know what we are getting for out money then.

Incidentally, I got a second hand Symaster EQ3-2 (mechanically sound, but controller is shot - reflected in the price). I was impressed with the improvement over the CG3. Overall its a much better thought out design. Things don't collide in certain positions, it's more stable, easier to adjust and it's great having a hollow mount axis to align to Polaris.

I found the cheap (£28) motor from the CG3 worked on the EQ-2, albeit not as well as if the controller worked. Currently considering using generic stepper motor circuits driven from a PC. This has the potential to develop into a goto project.

cheers

John