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Help with PHD


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Hi over the last few weeks I have been trying to get PHD to work with my set up but I am still having problems getting it to keep locked on to a guide star.

My set up is

Synscan Pro upgrade kit with a HEQ5 mount

EVOSTAR 100ED Pro with a focal length 1000mm (Which I am using as a guide scope)

EQUINOX 80 (for imaging)

Opticstar AG-130M with shoestring GPUSB interface box

.I am using pole finder to get polar alignment

.Getting focus with the opticstar

.Selecting camera/mount

.Finding and selecting a guide star

.Going through the calibration process

.Starts guiding for about 10secs then star drifts quickly to the top right hand corner of the green box

.Box goes orange and says star lost but to the left it still says guiding and star seems move around very slightly with each frame for about 5mins until it leaves the orange box

I am using all the default setting in PHD

Thanks Dean

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I bought the AG130M + GPUSB from Opticstar and could not get it to work with PHD.

Eventually, I returned the AG130M for a refund and bought a DSI II which works fine with PHD in conjunction with the GPUSB. Since the only component that changed was the camera .... well, draw your own conclusions.

In essence, I do not think the AG130M is sensitive enough for other than the brightest of stars.


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Have you got DEC guiding set to "on" in the brain

Hi i have it on auto thanks to your post to dean watson at the begining of the month

Thanks for sharing your experience Mike . If cannot resolve this problem maybe I should think about putting some money by for a DSI II. While having a go at M16 I found it hard to find a guide star because I did not have enough adjustment in the guide scope rings. So may be with a DSI ll I would be able to pick out faint stars closer to the object that the AG-130M could not detect?

Thanks Dean

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There is no comparison between the AG130 and DSI II - the latter is vastly better and you'll have no problem finding a guide star.

DSIs occasionally pop up in the For Sale section - I really do not know the difference between a DSI I and a DSI II but suspect that for guiding the former would be perfectly OK .... but do seek opinions before spending any cash.


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I have had both the DSI 1 and DSI II (both pro models, mono).

My DSI 2 committed suicide but my mk1 is still going fine and is in constant use as my guide camera.

I never have any trouble finding guide stars, and never have to adjust scope orientation to find one.

PHD works with the DSI perfectly and I can heartily recommend the camera.

The DSI2 has a bigger chip, but you'll pay more for it.

If you're using a 100mm F10 scope for your guidescope, while imaging at a much shorter focal length, you may run into some trouble caused by the guidescope guiding on movements caused by seeing which your imaging scope won't register.

As a rule, you will be able to guide perfectly well with a guidescope FL of 1/3 to 1/2 of your imaging scope FL.

I use a 100mm F10 scope as a guider. It's guiding 1200mm and 555mm FL scopes, and I have a 0.5x antares focal reducer in the nosepiece of the camera, so the guidescope has a FL of 500mm.

Another thing to remember is that if the seeing is rough, and/or it's windy, make your guide exposures above 3 seconds to avoid trying to correct the seeing/wind.

Don't make your calibration exposures too short either, especially near the pole. I use about 1000ms.

Before you start the guiding calibration, using the hand controller, nudge the mount slightly to the north. PHD's first DEC command is to the north, and doing this will take up any backlash and make sure the gears are engaged.



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That's great Rob, you have really filled in the gaps for me there. It’s really cleared up some questions I have had for a while on using my set up for imaging.

Thanks Mike if I see a second hand DSI I think I may go for it.

Thanks again Dean

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