Can't get Saturn using a Barlow

[robbie c]

Hi I done my first imaging the other night and now I'm trying to image Saturn again using a Barlow and I'm having a problem trying to get it on the screen of my laptop if I take the Barlow out I get it on screen no problem I've let it drift across the screen without the Barlow then tried again with it but nothing could it be something to do with focusing. Robbie

[haitch]

You will need to adjust your focus when switching the barlow in and out. perhaps try with and without it visually and note the relative positions for the focuser to give you an idea of how much you need to alter it and in which direction when using the barlow - it will need fine focussing of course once you have switched.

Also bear in mind the fov with the barlow and a webcam is pretty small so it is easy to miss it (I think I heard it said that a webcam sensor give about the same fov as a 5mm plossl for a given scope).

HTH

[Steve Ward]

As above , and the Barlow will also dim down the image so start by pushing the Gain and Brightness settings right up in your capture software .

[Carl Reade]

Yep agree with above, gain up brightness up. The FOV is tiny, get the highest powered eyepiece in with barlow and centre it then gently replace with the cam. This is assuming you have a tracking mount. If not it is difficult to say the least. Even with tracking can be a task at times.

If you get it then bring down the gain and brightness and then focus.

Good luck.

Carl

[CSM]

If you have a reticule eyepiece that is even better for centering - something like a 12.5mm. It is surprising how far out you can be when trying to center without that aid and it makes a really big difference as to whether you actually get it on the computer screen or not. And yes, you will need to adjust the focus - it won't be the same as the visual focus - but do it gradually. It is very easy to go past the focus point without realising it. And upping the gain and brightness also helps.