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Topics - Mark Richmond

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Weeks and weeks of clouds and not a single decent night. Either it is brightly lit by moon or it is cloudy. The new telescope curse is really getting on my nerve now. Any holy chants to calm down the curse or my nerve?

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I'm trying to image planets using my NexStar 8SE on an alt-az mount. After doing the SkyAlign the scope does a reasonable job of go-to i.e. the target appears in a 25mm eyepiece but is not quite centered. I then manually center the target in the eyepiece. Is this enough for tracking to work well, or will the initial non-centered go-to mean that the target will start to drift out of the FOV?

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Mounts Questions & Expirience / iOptron ZEQ25 payload limits
« on: December 30, 2017, 10:58:45 AM »
I have a used but spectacularly useful iOptron ZEQ25 mount that out performs just about any other EQ mount I have ever owned. With a nearly precise polar alignment using the included polar star finder, and one star alignment, I get nearly center of field goto's, especially when I am doing EAA and a Sync to Target alignment on a nearby star.

My question is, what can be a useful determination of actual payload weight of my mount. With my current setup or either an 80mm short tube refractor or my trusty Celestron C8, I never go above the 1/2 way mark of tube weight, included imaging accessories.

Now the total mount payload is 27 pounds, while Paul Chaisse said that it could take more than that weight in his opinion. What I want to know is, can I put a 25 pound 10" F/4 OTA on that mount and still gt good imaging results? The tube is only 38.6" long and weighs 25.5 lbs. Now, my imaging is more or less less than 5 minutes and I do mostly video camera imaging using SharpCap and Live Stacking. I never do an exposure more than 2-3 minutes worth and my planetary imaging is usually 60 seconds or less, maybe slightly more on the fainter planets using Firecapture.

I want to purchase a larger OTA, like the Orion 10" F/3.9 astrograph for video imaging but I am unsure about the weight limits.

Can I get away with that 25.5 lb weight on a 27 lb payload limit?

Your opinions will be greatly appreciated.

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ATM, Optics and DIY Forum / Mirror Cell Questions
« on: December 28, 2017, 11:59:05 PM »
(DISCLAIMER: I'm most likely completely incompetent and am thinking completely the wrong way)

On my first build, looking at a mirror cell. Why are springs on the pull bolts necessary? If the mirror is glued to the adjustment plate, and the pull bolts are attached to the adjustment plate, why do you need springs? What tension do they provide? Thanks in advance.

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ATM, Optics and DIY Forum / Texereau's Foucault apparatus question
« on: December 28, 2017, 05:27:24 AM »
Hey folks,
  I'm putting together a Foucault tester and following the design in Texereau's book, figure 31 which has a fixed source and moving knife edge. I have a question about one feature on the tester, though:

On the moving carriage, there's a small note for a "positive eyepiece on swing arm, for checking knife and image parallelism".

Could someone please elaborate on this feature, how its used and what, exactly, you're looking to learn/accomplish with it?

Thanks!

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Eyepieces Questions & Recommendations / 3.5mm Nagler
« on: December 25, 2017, 10:32:40 AM »
I'm considering a 3.5millimeter Nagler to go for my new 6 inch 750mm focal length reflector.  This eyepiece will give me 214x magnification.  Can it work ok using an f/5 scope without blackouts or kidney beaning?  I really don't need an eyepiece where eye position is overly critical.  Additionally, at $265, the Nagler is not affordable.

I have Siebert SS3 3.9mm and Agena Dual ED 3.2millimeter eyepieces, which provide me 192x and 234x.  These eyepieces appear to work just fine.  Plus, they have the benefit of already being paid for.  If it ain't broke, do not fix it?

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