USB to ST4 cable needed ?

[cadman342001]

Right,
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So I now have a guide scope (ZWO 60mm) and a Celestron Skyris 618M for my guide cam.
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My other gear :
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65mm EDQ OTA
HEQ5 mount
laptop with Backyard EOS, PHD2
Serial to USB convertor cable
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Thought I was all set but the 618M only has a USB3 port on the back so I think I need some more gear to connect it all up.
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What else do I need to buy ?
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Do I need one of these - https://www.bintel.com.au/product/shoestring-usb-guide-port-interface/
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and if so do I need a cable to connect it to the ST4 port ?
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Is that right ? Any other alternatives ?
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this for example - https://www.bintel.com.au/product/zwo-usbst4-adapter/


Thanks in advance

Andy

[Merlin66]

Andy,
The Shoestring adaptor is the way to go where the guide camera doesn't have a integrated ST-4 port.
Your second link didn't work for me, but you need a dedicated ST4 to ST4 cable (not the same as a phone cable!)
Having said that....I'm not sure the Skyris camera is the best option for guiding.
With the additional costs of the Shoestring adaptor etc. you could probably pick up a used ASI 120 or QHY5 camera which have excellent guide capabilities.
Hope this helps.

[cadman342001]

I have just bought the Skyris to use for guiding, and it doesn't have a ST4 port so I will need one of the 2 options listed I believe.

Why do you say the Skyris may not be the best option ? The lack of an onboard ST4 port for one thing :D but what else?

I'm stuck with it now anyway

[Merlin66]

Andy,
My opinion was based on experience using simpler, cheaper cameras for guiding and spending the extra cash on the real "heart" of the system - the imaging camera.
Just my 2c

[cadman342001]

No worries, thanks. I've ordered the 2nd option, the ZWO USBST4 adapter (link fixed)

I have a modded canon t2i as my imager that I bought used on here which should keep me going for now.

The Skyris was on sale at Bintel for 199 reduced from 499 so thought it was a good option both as a guide cam and perhaps for planetary but the T2i also has a cropped 640x480 video mode too which is the same resolution as the Skyris iirc.

[kens]

Didn't they have the Shoestring EQDIR cable? It would have given you more control over the mount.

[cadman342001]

Hi Ken,

Can you explain how/what the EQDIR cable does for me compared say to connecting via the USB/RS232 cable connected to the hand controller (which is what I have now) ?

I'm not "getting" how the EQDIR cable enables me to control the mount for autoguiding as I presume it doesn't connect to the ST4 port which is why I ordered the ZWO USBST4 adapter.

Andy

[Merlin66]

Andy,
If you want to control the mount- slewing etc GOTO using a planetarium program CDC etc the EQMOD is very good.
The developer of EQMOD feels that the direct cable connection between the PC and the mount bypasses any signal issues when used via the hand controller. I've used both - direct and hand controller and honestly haven't seen any differences.
Hope this helps.

[kens]

With the EQDIR cable (or RS232 connection via the handset) any laptop software can communicate with the mount to get its RA/Dec, guide rates etc.and send it slewing and guiding commands. In addition to being able to do gotos from planetarium software you can also star align the mount with plate solving. For guiding, you would no longer have to calibrate on every target as PHD2 would adjust the reference calibration depending on where you are pointing.

The main advantage of EQDIR over the RS232/Hansdset is fewer connections to go wrong. And along with some other people, I often have trouble getting the handset to intialise properly and it takes a few goes. But mine is an old mount so maybe newer ones have more reliable handsets.

By all means use the RS232 cable with the handset in PC direct mode but running a separate ST4 cable from the laptop is a waste of time IMO.

[cadman342001]

Why would using an ST4 cable be a waste of time ? How can I autoguide without it ?

[Merlin66]

Nothing wrong with the ST-4 guide system many of us use it.
When using EQMod you have the option of pulse guiding, this doesn't require the ST-4 connection.
Instead EQMod sends the guide corrections to the mount using the EQMod cable, (This can be via the hand controller or via a EQDir connection.)
Pulse or ST-4 the outcome seems to be the same.....

[cadman342001]

Thanks. Order changed to EQDIR cable :D

[kens]

I agree with the other Ken that ther is nothing wrong with the ST4 system. Normally you would connect the camera directly to the mount so you don't have an extra cable from the computer.
But, as in your case, if you are going to fork out for another USB cable and adapter from the computer anyway, you may as well get the extra benefits of using EQMOD via either EQDIR or RS232.