Trouble with planet focusing.

[Altocumulus]

Hi all,

Does anyone have tips on focusing - imaging purposes only?

Mak 180 pro f15.

Zwo 174mm - did L R G B 3 min subs at around 107 fps. That alone suggests focus wasn't settled when I pushed through pipp and astrosurface. ADC in the image train, though all targets high enough in the sky, but it did show a difference.

Pegasus focuser on Crayford focuser.

Main target yesterday evening was Jupiter, popping over to Mars and Uranus - but on none of them could I get a sweetspot in focus. Seeing looked reasonable there was minimal wobble in the image. Not even a Jupiter moon helped. I tried fwhm on Uranus, edge detection on Jupiter with a try with fourier detail. None showed any sensible sweetspot - I could clearly see out of focus both ways - but not the middle point, or even any sensible sharpness enough to process.

A bahintov mask on the mak turned out possibly too faint in the image to be useful.

I'm not a night man, usually only image on the 'easy' sun.... This is my third evening in the dark.....

[admin]

Hi,

there is quite a bit of discussion of similar problems in this thread that might be worth a read : viewtopic.php?t=5956 - I am still trying to understand why under some circumstances the focus detection works well and in others can give poor results.

Some things to be aware of though...

* When using one of the planet focus tools (contrast detection, contrast range detection, fourier detail), consider using image stabilization to keep the planet from shifting and try to put the selection box *entirely* within the planet rather than including off the edge

* Make sure you have the noise reduction setting turned up to at least 1.5 to 2 in contrast detection, otherwise a very noisy image can give no signal

* Consider using binning when focusing to further reduce noise

* Try using the SharpCap 4.1 beta to see if that helps as there are some improvements (see beta testing forum)

* Feel free to record a focus scan into SER format (ie start capturing to SER at the start of the scan) and share with me along with the SharpCap log - I can then investigate exactly how the calculations were applied and try to work out what went wrong. Please do this with SharpCap 4.1 beta, which has more logging to allow me to track which frames from the video were analysed for focus data.

cheers,

Robin

[Altocumulus]

Thanks for the reply Robin.

Ps the stabilising option works amazingly well!

Weather's now causing problems.

If you can consider a cloud pass filter - I think you'd be on a certain winner

[Altocumulus]

Thanks for the link - interesting though most way over my head. Wish I could get a Jupiter even half as good!

Not, yet, managed to auto focus with Pegasus Ultimate and focuser. Box has no switch off for the focuser other than a full disconnect when it's needed for important stuff such as dew strap! If the box has the focuser, Sharpcap can't connect . Grrr.

[admin]

Hi,

I'm still trying to get the cloud dispersal feature to work - it's just not reliable yet!

I've seen a few mentions of issues with the pegasus focusers failing to connect - try using it via the ASCOM Device hub to see if that fixes things (select device hub as your focuser in SharpCap, then select the pegasus inside the device hub setup).

cheers,

Robin

[Altocumulus]

Chuckles!

I've tried the hub option, posting results elsewhere on here. It says it connects, and says it moves the focuser - but doesn't.

Geoff

[admin]

Hi Geoff,

ahh, gotcha - sometimes I don't manage to link up different threads to the same person the way I should

With the focuser movement, most ASCOM drivers have a way to turn on logging of the commands they receive - hopefully the pegasus has that, in which case it would be worth turning that on and seeing if it is receiving move commands from SharpCap. If it is then the best bet would be to talk to the pegasus folks to see what might be going wrong. If it's not receiving commands from SharpCap then come back to me and we will dig into the SharpCap side a bit more.

cheers,

Robin