Double Glazing?

[LouisB]

Double Glazing.

Strange effect I have noticed finding my way around various lenses fitted to CPC 800. I live on the UK south coast and the balcony of my flat overlooks a bay with a town about two miles away on the opposite side to myself. Tinkering around with various lenses and Barlows to see the differences in sharpnes/contrast etc and as it was cold I was looking through the d.glazing on my balcony - yes I know but this was tinkering On opening the window to get a clearer view I found that the result was more 'murky' with less defined edges and worse contrast - focusing did not improve matters. On closing the window the murkiness was vastly reduced and the ability to focus properly was restored. I find that this is contraindicative and strange.

LouisB

[AndyH]

It's to do with the vast differences in temperatures inside and out, I think. The air currents are going crazy at the open window.

There have been times, when I've had a really bad dose of the cold, I've pointed the scope through the double glazing for low power quick looks. Not even slightly ideal ,but it's either that or nothing. Tried both fully closed, on the latch and fully open. The former gives as good as you're going to get.

[LouisB]

@ AndyH.

Thanks for that Andy - I think you have got it in one. I dragged the scope into another (unheated) room in the flat and tried again. I found that although there was a temperature shimmer it was nowhere near that experienced from the balcony window. Although I have a fair history in photography I am on a fast learning curve with astronomical equipment.

Thanks again,

Louis.