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Equipment Help Camera,OAG,Guide Camera


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I'm sure this has been beat to death, but I have a Celestron C8, OAG (93648) Canon T2i and an ASI224MC. I am trying to get this all to work together. I set everything up as according to the manual for the OAG, but I am having trouble with the guide camera and phd2. I'm not even sure if I have the ASI in or out far enough and it doesn't seem to be sending commands to the mount (Atlas). They have updated PHD2 since the last time I used it, whole new interface. Anyone else have a similar set up? If so, which settings do I need? 

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Just a suggestion-   If it were me I’d ask for help in one of the more specific sections that deals with equipment, rather than this general section.

Hope you sort it, Ed.

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7 hours ago, Ozone said:

I'm not even sure if I have the ASI in or out far enough and it doesn't seem to be sending commands to the mount (Atlas).

How is your camera connected to the mount - Are you using ST4 connection? Have you checked if the ASI224 is receiving any image at all?

Edited by AstroMuni
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Mono guide cameras are usually recommended for OAG use.

A colour camera may not be sensitive enough, although I'm not familiar with the ASI224MC.

The sensor size 4.9 x 3.7mm is much smaller than the 12.5 x 12.5mm OAG prism.

Which will further limit the number of available guide stars.

"I'm not even sure if I have the ASI in or out far enough "

You've read the instructions, so you'll know that the T2i and the ASI224MC sensors have to be exactly the same distance from the prism centre.

So moving the ASI in or out should only be for fine focusing.

Focus the T2i on a distant landmark during the day.

Run the ASI with SharpCap in video mode on auto exposure .

Without altering the T2I focus, now adjust the ASI focus .

Lock that off and in future only adjust the T2i focus, the ASI will be in focus too.

Try 3 second exposures in PHD2 while you search for a guidestar, tricky with your setup.

Michael

 

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You need to set the spacing to the DSLR sensor at the correct distance, ie the spec says 105mm with the Celestron .63reducer or 5 inches( 127mm) without set this and focus the imaging camera..Then measure the distance between the prism and the imaging sensor and put the guide came sensor at the same distance( incorporating the backfocus distance of the guide camera)  slew the scope to a patch of sky with plenty of stars and put PhD on loop and fine tune the guide camera distance, micro adjustments...you might have a sensitive enough camera, you might not.. I tried initially with a skyris but ended up with a 290 which works perfectly well

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Posted (edited)

First off, thanks for the help. Maybe I will use my Orion starshoot autoguider. It's one of the originals (maybe had it for 10 years?). The only problem is PhD2 asks me the unbinned pixel size in microns? I know the chip is larger and mono. Does anyone know where I can find that info or old files?

Edited by Ozone
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14 hours ago, Ozone said:

I'm not even sure if I have the ASI in or out far enough

This is an easy one, but you'll need a Bahtinov mask. Point to a bright star and focus the main camera with the Bahtinov mask. Then target any bright star with the guide camera and focus the oag/guide cam with the Bahtinov mask. Don't touch the main focuser after focusing the main camera.

A dslr and wide bodied guide cam don't always go well together. You have to make sure that the oag sits on the bottom side of the dslr or the cameras may clash.

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Posted (edited)

Thanks for the help. I switched to my starshoot autoguider and had a lot better luck. I still have one problem (may have been my alignment, or slight breeze). On PhD2, there is the connection box camera, mount, etc. Which one do I choose for mount? On-camera, GPINT 278, 378, 3BC, GPUSB, INDI mount, On-AO? (May just be old school, but they seem to have made phd more complicated than necessary 😊) I found a post that says use on camera, but I may have my asi st4 cable mixed up with the one for the starshoot, would that matter??

Edited by Ozone
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"I found a post that says use on camera"

Try reading the PHD2 instructions ?

But On-Camera is correct.

"but I may have my asi st4 cable mixed up with the one for the starshoot, would that matter??"

The USB cables that came with the ASI and StarShoot probably have identical wiring.

But a sure way to fry your camera and mount is using the wrong cables.

Michael

 

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3 hours ago, Ozone said:

Thanks for the help. I switched to my starshoot autoguider and had a lot better luck. I still have one problem (may have been my alignment, or slight breeze). On PhD2, there is the connection box camera, mount, etc. Which one do I choose for mount? On-camera, GPINT 278, 378, 3BC, GPUSB, INDI mount, On-AO? (May just be old school, but they seem to have made phd more complicated than necessary 😊) I found a post that says use on camera, but I may have my asi st4 cable mixed up with the one for the starshoot, would that matter??

Fig 3b is an extract from the Starshoot auotguider manual, it uses a standard ST4 connection.

The other image shows ST4 compatibility across different mounts/manufacturers.

From this diagram SSAG and ZWO ASI have the same pinout (as you would expect) so your asi st4 cable and the SSAG cable should be the same and should work identically. Just be very sure the ST4 cable is plugged into the correct port on the mount.

ST4_SSAG.jpg.87ea8028b97a6efd6eefa64702247f62.jpgst4.jpg.c5f7fa4f992abc56c107d8a31ea0cb1f.jpg

 

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Would I be able to use an st4usb adapter with this setup? Using the ascom platform and appropriate cables? Guide Camera to computer USB, computer USB to st4 adapter, st4 to mount?

 

 

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11 minutes ago, Ozone said:

Would I be able to use an st4usb adapter with this setup? Using the ascom platform and appropriate cables? Guide Camera to computer USB, computer USB to st4 adapter, st4 to mount?

 

 

Do such adapters exist? The disadvantage with st4 is that phd isn't aware where the mount is pointing, and needs a new calibration for each new target. Far better to connect the mount to the computer that runs ascom and phd using an eqdir cable.

Windows: computer with ASCOM based software, cameras to usb, mount to eqdir/usb. No st4

Linux: computer with INDI based software, cameras to usb, mount to eqdir/usb. No st4

Edited by wimvb
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6 minutes ago, Ozone said:

Would I be able to use an st4usb adapter with this setup? Using the ascom platform and appropriate cables? Guide Camera to computer USB, computer USB to st4 adapter, st4 to mount?

 

 

You should be able to. Assume it's along the lines of - Guide Camera to computer USB to PHD2, PHD2 to computer USB to st4 adapter, st4 to mount.

But if your guide cam has an ST4 port then Guidecam (On-camera selection in PHD2) to mount ST4 would be simpler.

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On 16/06/2022 at 18:56, Ozone said:

First off, thanks for the help. Maybe I will use my Orion starshoot autoguider. It's one of the originals (maybe had it for 10 years?). The only problem is PhD2 asks me the unbinned pixel size in microns? I know the chip is larger and mono. Does anyone know where I can find that info or old files?

It's 5.2 x 5.2 micron (SSAG #52064)

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I had tried on camera last night (computer to guide cam, guide cam st4 to mount). Didn't seem like PhD2 was actually holding the guide star. May have been due to slight breeze off and on, or poor alignment. Going to make sure everything is square and level tonight if I get a chance.

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I went back to trying the asi224mc, and bingo! Seems like everything is working ok now. I see why they made PhD2 more complicated. After adjusting some of the binning settings and running the wizard (backlash routine) it seems to hold the star. They seem out of focus, though, look like a flame in the asi. (furthest object I can focus on during the day is only 3-500 ft away.) Yes I adjusted focus for star with a bahtinov. May just be the asi is not centered perfectly, or needs to be back further from the pick off prism, but I have no more outward travel on the OAG for the guide camera.

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