HEQ5 Syntrek + EQMOD

[jbrazio]

Hello all,

To start I do not own the mount, I'm just evaluating the possibilities before buying. I'm not looking forward to spend the extra cash over the Syntrek to the Synscan mainly because I'm planning to guide the mount by means of a computer. I've read a lot on the topic specially about using the (H)EQ5 with the EQMOD RS232 TTL adapter, but some misleading information is poping up.

This mount is listed as supported on the EQMOD under the name "HEQ5 Syntrek (No Synscan)", the EQDIRECT RS232 TTL converter (http://j.mp/Jfbfzz) lists RJ45 as the output plug into the EQ5 mount.

I've downloaded the Syntrek pdf manual from Skywatcher and I can't find any information about the mount built-in "autoguider" port which is the port I assume the EQDIRECT will connect to; then I downloaded the Synscan manual and there I could find the port pin-outs but now the problems arise.. the only port listed as RS232 RJ11 is on the hand controller itself, the "autoguider" port on the mount seems to be also a RJ11 but a ST4 connector and the listed pin-out has nothing to do with the common GND/RX/TD RS232 connections.

Further down on the document there is what they call "Physical Connection Diagram" for a RJ11 to DB9 converter but based on the above info I assume is for the hand controller port.

Can someone put me on the right track ? Thanks.

[RogerTheDodger]

The HEQ5 Pro Syntrek is back on sale http://stargazerslounge.com/showthread.php?t=188244 http://www.firstlightoptics.com/skywatcher-mounts/skywatcher-heq5-syntrek.html

You can buy or make the EQDIR adapter and it plugs in to the RJ11 port on the HEQ5 Pro.

[Cornelius Varley]

The eqdir module replaces the handset and plugs into the rj45 (handset) socket on the mount. The ST4 port is for auto guiding only.

ps if use use EQMOD you can pulse guide through that program without the need for extra cables to the mount EQMOD tutorials

Peter

[jbrazio]

The eqdir module replaces the handset and plugs into the rj45 (handset) socket on the mount. The ST4 port is for auto guiding only.

Clearly my issue was due I not owning the mount thus unable to see the available plug sizes. Now it's clear and makes sense the EQDIRECT RJ45 plug.

ps if use use EQMOD you can pulse guide through that program without the need for extra cables to the mount EQMOD tutorials

What do you mean by this ? The connection I'm seeing is:

PC - EQDIRECT - HEQ5

[Cornelius Varley]

What do you mean by this ? The connection I'm seeing is:

PC - EQDIRECT - HEQ5

EQMOD has the ability to autoguide without the need to connect any other cables to the mount other than the cable from the pc to the mount via the the EQDIR module. This is explained in the documentation.

Peter

[jgs001]

You don't have to use the ST4 auto guider port on the mount. You can use the EQDIRECT connection between the PC and the mount to handle the guiding control. One less cable. I operate my HEQ5 Syntrek in this manner.

[jbrazio]

So why the additional ST4 port ? Does it have any advantage over the EQDIRECT or vice-versa ?

[jgs001]

If you have a guide camera, like a QHY5v then you can connect the camera directly into the ST4 port. For my usage, there's not a lot of point, I've got the computer there all the time anyway. If you were using something like a standalone guider, then you would connect that directly to the ST4 port.

[jbrazio]

So the ST4 port is used toghether with some kind of software that does the guiding based on the image coming from the CCD ? Then I'll reformulate my previous question.. :-)

What's the advantage(s) between using image recognition guide VS blind guide using a planetarium software ?

[jgs001]

I don't think any planetarium software can perform guiding.. they are used for goto, and you therefore don't need a goto handset.

Guiding needs to be capturing an image of a star and analysing a sequence of images for motion between them, so that an adjustment can be calculated and applied to the mount to keep the scopes on target.

[Stephen]

EQMod is not an OEM technology don't forget, the mount was designed to be guided through the ST4 port.

Pulse guiding (through EQMod) just helps remove some cables

[jbrazio]

Then I'm getting confused again.. :-/

By using the GOTO functionality either by using the Synscan stand alone controller or the computer planetarium software.. wouldn't the specific object be tracked ? I Imagine that the controller/PC will be continuously sending the object's updated coords and the mount would then be "tracking" the object.. am I wrong ?

[Stephen]

GOTO simply tells the mount to "move" to a point, this has nothing to do with whether the target is there or not : it's a blind move. (Obviously alignment and calibration should ensure the target is reasonably close to where the mount ends up.)

Tracking happens because the mount moves at a constant (sidereal) rate as the Earth rotates.

Guiding takes an image from a camera and sends short corrective commands to the mount to compensate for a variety of things that may cause the mount to be pointing slightly askew from the target you are attempting to image.

[jgs001]

I'm afraid so... Goto is only active whilst aligning the mount with the target. You have to align the goto system for accurate slews. But once on target, goto is no longer active. The mount motors should be active for tracking, but if you're wanting long exposure imaging, 5 or 10 minutes or more, the errors in the mount drive mechanisms etc will affect the images, which guiding corrects. Guiding only comes active once you are on target.

[Cornelius Varley]

Then I'm getting confused again.. :-/

By using the GOTO functionality either by using the Synscan stand alone controller or the computer planetarium software.. wouldn't the specific object be tracked ? I Imagine that the controller/PC will be continuously sending the object's updated coords and the mount would then be "tracking" the object.. am I wrong ?

Sort of wrong. Goto sends the telescope to the coordinates of the object and then continues tracking at sidereal rate. How accurately the mount tracks after that depends on the accuracy of the polar alignment.

Peter

[jbrazio]

Thinking about astro-photography.. would could you use the CCD tracking + DSLR at the same time ? Does it even makes sense to think about using guiding instead of GOTO/tracking ?

[Stephen]

Thinking about astro-photography.. would could you use the CCD tracking + DSLR at the same time ? Does it even makes sense to think about using guiding instead of GOTO/tracking ?

Guiding is an addition, not a replacement. Guiding corrects errors in tracking after you have GOTO-ed remember.

Typically you image with one scope plus DSLR, and guide with another scope plus CCD.

[jbrazio]

Would it be possible to sort of hack the software to make it send the recalculated GOTO coords once in a while instead of just relying on blind tracking ?

Guiding is an addition, not a replacement. Guiding corrects errors in tracking after you have GOTO-ed remember.

Typically you image with one scope plus DSLR, and guide with another scope plus CCD.

What could be a good companion guiding scope for a 8" newt ?

[Stephen]

Would it be possible to sort of hack the software to make it send the recalculated GOTO coords once in a while instead of just relying on blind tracking ?

What could be a good companion guiding scope for a 8" newt ?

What you are describing is what guiding does, but rather than use a GOTO command, it nudges the mount based on image movement.

Think about it this way, if you calibrate your GOTO, then a gust of wind moves your OTA, your GOTO is going to be always off.

Your guiding will always compensate for that though.

Typically an ST80 or similar is used.

[jbrazio]

What you are describing is what guiding does

Would that be more accurate than only relying on the EQ's built-in sidereal tracking ? Is there any known software that already does this ?

Think about it this way, if you calibrate your GOTO, then a gust of wind moves your OTA, your GOTO is going to be always off.

I understood perfectly your point and just to wrap this one out, what kind of adapter is used between the PC and the ST4 port on the EQ ?

[jgs001]

Something like PHD is free and does the guiding easily.

Normally, you'd have an ST4 cable, between the ST4 port on the guide camera and the mount.

[Stephen]

As John says, PHD is free and works well for me. Yes, guiding is much more accurate than relying on pure tracking alone.

I have used PHD both with an ST4 cable (from guide camera ST4 port to ST4 port on mount) but now I use it without the ST4 ports at all (just using EQMod which PHD can talk to / through.)

[jbrazio]

Normally, you'd have an ST4 cable, between the ST4 port on the guide camera and the mount.

So there are specific guiding cameras that will directly connect to the ST4 port on EQ ? I was thinking more on a low budget using webcam and some sort of processing on the PC side..

now I use it without the ST4 ports at all (just using EQMod which PHD can talk to / through.)

Do you known any howto about this ? I've quick Googled around I wasn't able to find any.

[Stephen]

So there are specific guiding cameras that will directly connect to the ST4 port on EQ ? I was thinking more on a low budget using webcam and some sort of processing on the PC side..

If you plan to use a webcam with ST4, you will need to also purchase a USB guider : this connects to the PC and has an ST4 output to connect to the mount.

Do you known any howto about this ? I've quick Googled around I wasn't able to find any.

http://eq-mod.sourceforge.net/docs/2010EQMOD-5%20Guiding.pdf

[jgs001]

For a webcam, use the ASCOM/EQMOD connection directly to the mount from PHD and allow EQMOD to handle to guide instructions, then you don't need any ST4 capability.