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hunterknox

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  1. I prefer cotton wool but each to their own. Look for “Cotton wool BP” on the label in the UK. BP = British Pharmacopedia = medical grade Light touch is a given but I also try to rotate the cotton wool as I move it across the surface so the overall effect is lifting rather than polishing. One swipe per cotton wool ball then discard. Imagine you’re a nurse trying not to cross contaminate different parts of the mirror surface. There used to be a great video online of David Sinden cleaning a refractor lens with the proper technique but I’m not sure it’s available anymore. My worry is always dragging whatever’s on the surface over the surface. It’s not exactly analogous but next time there’s a sunny day look at the reflection of the sun on a car bonnet. What you’ll see is scratches in a circle around the reflection of the sun. That’s because there will be scratches in random directions all across the bonnet and it’s the ones in a circle around the solar reflection that bounce back to your eye. Why are there scratches in all directions on car bonnets? Because when cars get washed whatever’s on the bonnet usually gets dragged across it before it gets removed. There’s a huge difference between cars and telescopes but as a general principle if you assume whatever’s on the surface of your mirror and could be abrasive and think about your technique from that starting point you won’t go far wrong.
  2. Think about it like this: how much do you worry about your windows with all that intense sunlight bearing down on their massive surface area? Assuming you’ve got a standard refractor with the lenses at the front then the light and heat that hits the first lens is no more concentrated than it is on a window and on the second (or third) lens it’s slightly more so but not a big deal. As John implies: things aren’t getting too intense until closer to the eyepiece end and the Herschel wedge is designed to deal with the concentrated heat and excess light. The former doesn’t go round corners well and the latter is effectively filtered out using basic darkening (neutral density) filters once the heat’s been sapped away. Refractors with lenses at the back as well as the front (such as Petzval or Steinheil designs) might be more problematic but your Starwave should be just fine. Nice scope, by the way.
  3. Thanks Shimrod - that looks like a backup option. 2kg is not that heavy in normal terms but not ideal on top of my other gear. Should have said I’m carrying everything off the beaten track so the lighter the better but I realise a compromise might be in order somewhere.
  4. I’m looking for an easy way to power my portable setup, which just means powering an Astrotrac and a dew heater, but I can’t seem to find a stock, light-weight battery that will do both. All the astro power tank stuff seems to either have 12v cigar sockets, or a small DC outlet, but not both. Happy to buy a new dew controller if needed but the only ones designed to power a mount as well as dew strips are on the massive side. Any ideas from the Lounge?
  5. Seeing as it’s likely out of warranty it can’t hurt to take a look. The PST uses a 5-sided prism to bounce the light up to the eyepiece. One face should be parallel with the front on the scope, one with the eyepiece. When you’re turning the focuser you’re just screwing the prism holder back and forth within the black box. The holder isn’t a great design. The prism is “pinched”, if you will, at the slides (like a litter picking claw might pinch some rubbish). It’s not a great way of securing something so it’s not unknown for the prism to slip a little which puts the whole optical alignment out of kilter. Have a go at unbolting the hex bolts on the side of the black box and see what you find. They might be a bit stiff - I think mine were loctited. It could just be a case of manually adjusting the the prism so it’s facing the correct way in its cradle. Good luck.
  6. Good work that man. I love EQ platforms as a technology for the marriage of simplicity and sophistication. 20 mins at 350x is an achievement indeed.
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