Guiding

[jaygpoo]

I need some help as I am getting no where at present. I am using a celestron c9.25 and my sw 80 ed apo as a guide scope with a QHY5 11 camera with PHD software.  When I switch phd on and select the asom camera as I have been told to do all I get when I loop is a almost white screem. The brightness slider at the bottom makes little difference and when selecting the ascom camer option you can adjust the gain there but again not that much  help. I select a loop time of 5 sec . I think I see stars on the sceen and lock on to one to begin PHD but my images are streakly stars. When I move to another area of the sky the stars I think I am seeing appear to be in the same place?  As I am unable to get a clear star view I dont know what I am getting. In the brain option in PHD are there some boxes that I can adjust to help at all? As I have never seen anyone setting one up or using one I am in the complete dark as to how or what to do. Any help would be great . Jay

[Sam]

Hi Jay,

Try the exposure setting at 1 sec and see if that darkens it up a bit. Have you tried focusing on a bright star?

The streaks might be natural star movement over about 5 secs when your mount is not on tracking. Might be worth checking your polar alignment and the tracking settings.

[gary1968]

The slider at the bottom is display contrast..... as said, sec the exp to 1 sec, click the loop button and set the slider until you get the desired contrast.

[jgs001]

As well as the shorted exposures, with the QHY5v, it's worth capturing darks (one of the PHD options along the bottom) as this does make quite a difference to the noise displayed on screen.

[IanL]

Try the gain in the Ascom driver at 90 or 95% and an exposure of 1 to 2 seconds to start with.  It may seem counter-intuitive, but if you reduce the driver gain you can actually end up with a whited out image in PHD.  I'm not sure if it is the camera, the driver or PHD's screen stretch but I have seen than happen on mine at the default gain of 50% (which is way too low). Something (probably PHD) is applying a stretch to ensure the stars become visible, but if the whole image is basically black it seems to end up stretching the background so it turns white.

Put the PHD brightness slider at around halfway.  Tweak the slider until you up with a dark grey screen (not black or bright white).  You should then have a few stars visible if you are in focus; might be a good idea to check the rough focus position on a distant object during the day.  If still don't get anything then try increasing the exposure length to 2s or 3s.  With the ED80 you should be able to get stars pretty much anywhere in the sky once you are at 3s.

You may well get lots of horizontal streaking; this is pretty normal with the QHY5's due to the rolling shutter.  It doesn't affect guiding performance.  Using the 'Take Dark' option in PHD will clean the image up a bit, but remember to re-take it if you change exposure length.  If you're really struggling, try something big and obvious like the moon to test the camera settings.

[jaygpoo]

Thanks so much for all your inputs I will take it all on board and try again on the next clear night.  With regards guide focusing. If the image is being taken every 3sec then its not like just focusing the telescope on a star as the image I have been seeing is not something you can focus. I take it that I need to aim at say vega and foucs the camera there before I go anywhere else?

[IanL]

Thanks so much for all your inputs I will take it all on board and try again on the next clear night.  With regards guide focusing. If the image is being taken every 3sec then its not like just focusing the telescope on a star as the image I have been seeing is not something you can focus. I take it that I need to aim at say vega and foucs the camera there before I go anywhere else?

Yes start by focussing on a bright star and use a short exposure time like 1s so you get feedback as you adjust.  Focus on the guider is not as critical as for the imaging scope; just make small adjustments and wait for the next update to check - usually the best thing is to go past focus and then come back again.  Once you know the focus position, you can make a focus measure (a bit of plastic or metal strip) that fits between the focuser body and the front of the camera adaptor.  You just slot it in, adjust until the measure is touching front and back and you should be close enough to focus that you only need to tweak it once on a star.

[jaygpoo]

Ah yes the old plastic strip trick , heard that one before . As soon as I have tried thgis I will report back to the WISE ONES !!!!!!!!!!

[jaygpoo]

So I set up and using advise given I got a screen with stars on it that were moving.  Now I pressed the take dark button and placed the lens cover on. Pressed ok and small pause and another window asking me to remove cover. Press ok . Now the diaglogue box is red and its asking me to redo dark?  I am lost . So what have I done wrong or what do I do next?

[jgs001]

That's normal. Phd would then subtract the darks from the image on screen reducing noise. Once the darks are done, just carry on with guiding.

[IanL]

I don't know if you have read this:

http://stargazerslounge.com/topic/188777-phd-guiding-basic-use-and-troubleshooting/

It covers the whole process from start to finish, and may help.

[jaygpoo]

That was some guide, Great reading and a massive help in many directions. I now have my phd working fine and guiding. Its is at present guiding but I am getting a sound from my laptop lke a warning buzz every so often ? Thanks again for all your help. Jay

[jaygpoo]

yes that noise. the bottom of the phd screen with the boxes is all flashing dark red with this noise alert. the words Mass  00000 vs 000 appear ? any ideas. 

[sharkmelley]

The flashing and noise alert means it cant find the guide star any more within the search box.

Did the star disappear behind a cloud?

Did the star drift outside the search box?

Did the guidescope mist up?

Mark