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jetstream

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About jetstream

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    Boreal Forest

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  1. Hi Gerry.I will pack the 5 and 6mm and get a postage cost for Canada with a suitable discount adjustment for UK postage.

    I will get back to you tomorrow.

    Kindest regards.

    Martin

    1. jetstream

      jetstream

      Perfect!

      Thanks Martin,Gerry

  2. A bit of a delay because of the snow storm, but here is the view that the obsy will give. Like I said its going to take a while... this storm might set me back weeks.
  3. I'd like the 5mm and 6mm, can you pm me Martin?
  4. Can you post to Canada and do you take PayPal Grump?
  5. My vote:SLV.
  6. Hopefully this is the last white out (blizzard) of the year...

  7. John, you are more than welcome here, to observe and enjoy.
  8. Yes, I will by choice, thank you. I see you live in St Louis, the site of my '71 Vette's build. Has urban development affected the area you live in or observe? How dark are your skies? We keep our local, rural skies at 21.6 mag + and offer superb, zero light dome skies. Even our home lighting is muted by the tall pines...
  9. You guys have a great place, I love the trees and gravel road, it reminds me of here! I could feel at home in this place, fantastic report.
  10. Years ago a huge wind caused a bunch of blowdown on this property. While dealing with the blown over and uprooted white pine and balsams it took down with it I discovered a nice spot for an observatory. There is much frost cracked granite on this this ridge which we have to remove to get to the stable bedrock (Canadian Shield) underneath. This is phase 1 of my obsy (cabin) build. We use all of the branches, rotten wood etc for the road base and also this top layer of cracked granite. A buddy has a whole pile of Red and White pine young trees on his property (farm land) and has volunteered them to me for use to re plant this one. We plan to plant a couple of hundred trees, while respecting the forest balance ie poplar, pine, spruce and balsam. Its going to take me a while but here is phase 1.
  11. Great info Peter, understanding at least somewhat, how different scope designs work can be a benefit for us all I think. I still love newts
  12. No idea... personally if I buy one I'll ask Intes first if there is an optimum mirror spacing. I have wondered how some people get great views from SCT's in particular and I believe that there are a few things that can make or break the image. This one shows a big contributing factor to Shanes 150mm f11 performance (CO %) and allows some wiggle room to keep the .8 system Strehl.
  13. Sorry to go extremely off topic Shane. I hope its OK. As the thread opens up more questions and comments it might be relevant for Cass users to understand what this graph shows. If it were me I would find the optimum mirror spacing, leave the focal length lie where it be and focus by some other means. I might look at an Intes Micro, hence my own pursuit for some understanding. The reason why some Cass work so well is the same reason Shanes 150mm f11 works so well- they are at or above difraction limited performance as a system ie .8 overal Strehl. I also have a high respect for Horace Dall after learning a bit, the graph shows one of the reasons why.
  14. I hold the personal belief that the whole optical chain, including eyepieces and eyeballs can affect the MTF. Many educated people don't think eyepieces can however. Visual acuity with regard to viewing is another puzzling thing, for me anyway. https://www.cloudynights.com/topic/566542-visual-acuity/#entry7704523 I also believe that an excellent goal is to get a truly diffraction limited optical system.
  15. Modulation transfer function. Assuming the light containing the image we view is perfect we can only degrade the image and not improve it with optics (or seeing, thermals etc) ie Suiters filtering concept. The graphs tell the tale... and there are many.