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Hi, I've got a Skywatcher Heritage 130p reflector, and if i insert anything less than 10mm eyepiece, the image won't get crisp. I guess it's normal, but as I'm very new to astronomy, I'd like to know what the sharpness depends on exactly.
Is that the focal length (how fast the telescope is? ) or the size of the mirror and how much light it gathers? Or both affect it the same way?
Are things the same with refractors in this regard? Thanks.
I bought another 300 mm lens as an alternative to the Canon 300 mm L lens I already have. The main reason is to achive a lower vignetting. I have very positive experience from an earlier medium format lens. This is the Pentax 645 300 mm ED f/4 lens with good reputation. If I get some positive results from this lens I maybe replace my Canon 300 mm lens with this one.
Here is some photos and data about the lens:
I bought it mostly because I'm curious about it and want to test it. It's more than ten years older than the Canon lens.
Baader optical wonder solution is practically Isopropyl alcohol. Instead of £12 for a 70mL of it, buy a 1000 mL of Isopropyl alcohol for £22 (before pandemic it was only £5). They have also smaller bottles which will be cheaper of course. The Baader solution and Isopropyl alcohol don’t remove the toughest of fungi on optics, only a few of the less deep set ones can be treated with them. I have used both for cleaning eyepieces and on certain stage of cleaning several 8 to 12 inch mirrors. They both worked identical. When applied through an optical cleaning fabric, they remove ( dissolve) fatty oils and fingerprints on optical surfaces. I had cleaned a 12 inch mirror once which for some unknown reason had ice cream stain on it (cleaning followed standard operation procedure for cleaning coated aluminised mirrors).
So, I have been testing three different kind of lasers, each one is supposed to be the "best" in each category or what you want to call it, the hotech and HG is almost the same, but whit the difference in how you lock it down.
The Catseye is very different in how it works.
I made a Youtube video of my thoughts
What do you think? which one do you use?
A friend ask me about filter size, I already had a Excel sheet with that calculation. But I did a new web calculator.
It's the first version but it looks to calculate it correct, have a look:
It's not any high precision calculation, but gives knowledge enough I think.
Too small filter gives vignetting, too big filter empty the wallet.