EQ5 Periodic Error Correction

[AstroBloke]

Hi. Having read lots of useful posts on SGL in the past, I thought it was about time I became a member. I've had my Skywatcher 1145P for about two years now, and am very happy with it. I've re-built the mount to include proper bearings and make the motor drive more compact, but it's time to upgrade.

I'm thinking of buying a good mount, but one that's light enough to transport and set up easily. So I'm thinking of one of the EQ5 mounts (EQ5, EQ5 Pro, EQ5 Pro SynScan, HEQ5), but am not sure of the differences between them. I like to dabble in astrophotography using a DSLR, but want the equipment to be as minimal and self-contained as possible, i.e. I don't want to connect up a laptop. So I'm tempted to get one of the mounts with periodic error correction. Can anyone tell me which of these mounts has periodic error correction, and whether it stores the correction data itself, without the need for a laptop?

[boabsta]

The heq has pec but i'm not 100% sure on how it works. I'm still learning the mount myself.

The handset that controls the mount deals with the pec.

Here is the user manual for you to read http://www.opticstar.com/download/Astro/Doc/mounts/Skywatcher/SkyScan-manual.pdf

I hope this helps.

[glowjet]

As far as I am aware, but I could be wrong, none of the mounts have their own built in PEC as this is controlled through the ST4 port in the mount, by whatever guiding equipment you have attached to it. If you do not want to use a computer, you are left with the option of commercial stand alone devices, or you can consider a Losmandy mount which does have its own form of built in PEC in the control panel

John.

[Cornelius Varley]

The handset has a PEC function, the use of this is covered in the manual. Briefly, the handset needs to be trained to control the periodic error. This is done by centring a suitable star in a recticule eyepiece and recording the periodic error (8mins for the EQ6 Pro, 10mins 30secs for the HEQ5 Pro). The handset then plays back the recorded corrective inputs made by the user to keep the target centred.

Peter

[chrisshillito]

Yes, all of the synscan mounts have PEC capability via their handset. Don't expect too much from this though as the design of the synta mechanics is such that the error signal produced is not at all periodic over any practical timescale. As a result the correction algorithm based upon a single worm cycle of corrections is unlikely to improve the error to below +/- 5 arcseconds (typical un corrected movement is +/- 15 arcsecs but can vary widely between mounts).

Chris.

[glowjet]

Thanks Guys, I was not sure whether the range of mounts had PEC control, I am now that much wiser and regret any misleading comment. I have a Losmandy GM8 which does have error control using worm cycle correction, however, on the other hand, the mounts quality of engineering is really superb

John.

[AstroBloke]

Brilliant! Thanks for all your help, people. Useful to know those timings and tolerances. I would love to get a Losmandy mount, but they're a bit out of my price range, so it'll be one of the Synscans, since they have PEC. I reckon 5 arc sec will be OK, as I'm mainly interested in wide field deep sky objects.

So I'm just left wondering if whether the HEQ5 has any advantages over the cheaper (N)EQ5 Synscan. Does the HEQ5 have a higher load capacity? I have to say I don't understand Skywatcher's code numbers. It seems that the HEQ5 is really an EQ6, and I don't know what the H or N stands for at the beginning of some of these mounts.

Anyway, thanks again for your help.

[chrisshillito]

The HEQ5 more beefier than the EQ5 and is beleive what most folks would reccomend as the minimum entry level mount for long exposure astrophotography. The 'H' stands for Heavy.

The EQ6Pro is and even bigger and sturdier mount than the HEQ6. Skywatcher made some minor upgrades, including a losmandy type dovetail clamp and named this the NEQ6 where 'N' stood for Newtonian indicating its suitability for mounting long Newtonians. The NEQ5 is I assume is just a minor rebranding of the EQ5 to follow what they did with the EQ6Pro - perhaps it too comes with a losmandy type dovetail clamp?

Chris.

[AstroBloke]

Thanks Chris.

I'll think I'll go for an HEQ5 with Synscan.

Mike