9x50 straight through finder focal length

[IvanT]

Hi,

Tonight I was trying to get my finder focused with my QHY5 using QGVideo, apparently it's easier to foucs using QGVideo than with PHD. I couldn't get it to show any stars. Even tried focusing on the moon but no joy. I noticed the default focal length is set to 300, should I be changing that, if so, what should it be for the 9x50 finder and should it be in pixels or arcsec? I'm hoping that's the problem, or has that got nothing to do with it?

I centred on Vega and before connecting the camera, made sure that the finder scope was also centred and focused on the star but it wouldn't see it. I tried adjusting the finder's focus ring all the way out and back in again leaving time in between for QGVideo to settle down. I even tried backing the camera out from the finder a few mm.

Anyone had similar problems?

Thanks in advance.

[Glider]

On my finder guider the focal length is more like 175mm. I've unscrewed the objective completely, removed the locking ring and then that gives me about 5 to 10mm more 'in' focus when I screw the objective back on.

The focus is very fine, it's very easy to miss it.

[IvanT]

Interesting, I was expecting to see a donut as it approached focus, so it's either on or off and nothing in-between to indicate if you're close?

Sent from my iPhone using Tapatalk

[IvanT]

Still no joy with this. It's completely clouded over tonight so thought I'd try and focus in doors. If I point the guider at a something like an illuminated wall, should I get a picture of the target using say 8 sec exposures 0% gain using QGVideo?

The camera connects ok for both PHD & QGVideo, so I don't think it's a driver problem, I'm running Win 7 home premium 64 bit, any potential problems there?

[Glider]

The depth of focus is very narrow so you can go through it almost without seeing the donut come and go.

I found my approximate focus doing what you suggest, focused on the TV across the lounge.

[jgs001]

Something to bear in mind, the plane of sharp focus gets shallower the close the subject (the shorter the working distance)... so it may be that if the wall/TV is too close, you don't have enough fine control to focus it...

[Glider]

It is a very tight focus but it works. If you just aim at a light and wave your hand in front of the camera do you at least see shadows flickering?