Have I got a dodgy EP??

[Skipper Billy]

Just been outside with my new 200pds to make sure I can achieve focus both visually and with my SLR attached and first popped in a 25mm EP and focused on a trig point about a mile away - pop - pin sharp.

Dropped in a 9mm X-Cel LX and the sharpest focus is very 'woolly' - turning the focuser in or out makes it worse so it is passing through the focuspoint. I tried adding a 2x Barlow and that made it twice as bad.

Went back to the 25mm and pop - sharp again.

Might it be a dodgy EP ?? I have never tried it in the daylight before!!  Or might it be that the mountain top I am focusing on is bathed in sunshine creating really poor daytime seeing????

[Avocette]

You got it right first time.......

........the mountain top I am focusing on is bathed in sunshine creating really poor daytime seeing????

[Avocette]

But seriously - daytime testing of astronomical equipment can be very helpful in showing just how the seeing is influenced by a mile or two of turbulent air and also illustrate why in my case (some floaters which are not obvious in normal binocular vision) I sometimes struggle with the view in the eyepiece in the dark.

[Skipper Billy]

Wow - now I understand about poor seeing - the view now through the 25mm and the OTA its self is very warm is like viewing something at the bottom of a swimming pool - I didn't realise it made such a dramatic difference !!

Thanks Avocette - I have learnt something today!

I guess we just aren't used to this bright warm thing in the sky.

[Peter Drew]

I've been testing a few telescopes for collimation over the last couple of days using the reflection of the Sun on a grid pylon a couple of hundred metres away. The insulators provide a very bright "star" image for rough tuning and small reflective specks of something or other on the paintwork produce superb faint star images with perfect Airy discs and first diffraction ring. I have a Vixen 102mm Flourite as a "control" telescope to monitor the conditions, daytime observations can often be very helpfull.