I have a Celestron C5 spotting scope, that came with a 45* erect image diagonal and a 25mm, 1.25 eyepiece. It's my first scope and I'm trying to figure it out. I have a few questions regarding filters.
1- Do planetary filters help in focusing? In other words, if I'm viewing Neptune and it's blurry, no matter how much I focus, is there a filter that helps?
2- I love using my scope for long distance nature watching. Sometimes when it's hot, really sunny or when I'm looking over a body of water, my view has a little atmosphere/heat aberration. Is there a filter to help with terrestrial viewing?
3- Lastly, I currently have a stock 25mm Celestron Plossl, a Celestron 8-24 zoom ep, and ES 82* 14mm wide view ep. Will all 1.25 filters work with my set up? Or could someone recommend a set of filters for what I have?
You've gotten good answers. I have little to add.
1) Terrestrial viewing will be between 20x and 60x, and the higher powers will not be usable after about 10am due to heat turbulence.
2) Atmospheric seeing conditions are ALWAYS the limit to power
3) for astronomical observations with your 125 (an excellent scope, BTW), ditch the 45° diagonal and replace it with a 90° star diagonal
for astronomy. Why?
--it is more convenient to use when the scope points up
--it has a much larger clear aperture, allowing you to use eyepieces with a wider apparent field and, hence, larger true field
--it will be optically more accurate, leading to sharper images.
Just be aware that magnifications will be limited by the atmosphere:
4-10x/inch (20-50x) low power for astronomy--images least damaged by atmospheric seeing.
10-20x/inch (50-100x) medium power for astronomical observations. Best for general use on nearly all deep sky objects.
20-30x/inch (100-150x) high power for astronomical observations--moon, planets, double stars, small star clusters. Affected by the atmosphere, be careful to apply a few rules:
--don't observe at high power directly over a roof top. Roofs bleed heat all night long and cause local air turbulence.
--don't use high powers immediately after taking the scope outside. Let the scope acclimate and cool down for at least an hour before attempting high power
--don't observe objects below 30° altitude. The air is too thick and there will be a LOT more turbulence and chromatic blur. If you have to (like a low planet), don't expect sharp images most of the time.
--look at the twinkling of the stars. They will appear steadier and display less turbulence in the scope when the atmosphere is calm. This often occurs a couple days AFTER a front has come through,
and the air may not be as transparent as it was. For sharp high power images, though, we want stable air.
30-50x/inch (150-250x) ultra high powers, mostly for the Moon and double stars. Not usable very often, but when you get a night where such magnifications are usable......magic!