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martinl

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About martinl

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    Sweden
  1. 7x80 binoculars

    To expand on Charic’s answer; the exit pupil of an optic (binoculars or telescope) is the objective diameter divided by the magnification. If this exit pupil is larger than the dark-adapted pupil size of your eyes you will not be able to see all the light collected by the lens. For example, if your dark-adapted pupil is 6mm a pair of 7x80 binoculars would give you the same image brightness as a pair of 7x(6mm*7x)=7x42. Peoples’ dark-adapted pupils vary greatly and decrease with age, from about 7mm for teens to about 4mm for geriatrics. Here is one of the best studies available: https://homepages.uni-tuebingen.de//martin.adler/pup_age.html You can measure your dark-adapted pupil size in a number of ways (google it). The most accurate is probably to take a flash picture of your eyes and a ruler in a dark room and measure your pupil size on a computer screen.
  2. It is entirely possible, of course, but the eyepiece height will not be comfortable without an oversized rocker box or a riser. I had my 220mm f/5 (1089mm FL) on a dob mount initially and even that was low. I’m not aware of any commercial 6” dobs with reasonable EP height so you’re probably forced into diy territory.
  3. I have a flip-mirror on my TeleVue Starbeam red dot finder and I almost never use it. The field of view using the mirror is simply too small and you lose the main benefit of unit power finders, which is that you can look at the sky with both eyes. Much more natural for navigating. Dew/frost is often a problem with Telrads though, however I’ve found that a simple home made dew shield like Littleguy80 posted is usually sufficient. I made mine from 2mm foam from the local craft store and some self-adhesive Velcro. A side benefit is that the dew shield also cuts down on glare from street lights and other light sources.
  4. New EP delivered today!

    The magnification of standard barlows (not telecentrics like PowerMates etc) increases with the distance between the barlow element and the eyepiece focal plane. I’ve measured the magnification of the Celestron Ultima barlow to be X~2.2+0.02d, where d is the distance between the top of the barlow and the EP focal plane. If your binoviewer has an optical length of 100mm the resulting magnification would thus be about 4.2x. Placed between the binoviewer and EP it would be 2.2x if the EP focal plane is at the shoulder and about 2.07x with most TV EPs (d=-6.35)
  5. You may want to look into soft cases for musical instruments for the OTA. They come in a great variety of sizes so one should fit the bill. This site has a fair assortment (no affiliation). https://www.thomann.de/gb/index.html Also, camera bags can be useful. My Lowepro Flipside 500 backpack holds either my TV85 + eyepieces etc or my CG5 (~EQ5) Mount + accessories. Unfortunately I don’t think it would hold an ST120. I’ve never felt the need for a bag for the tripod. I do use a shoulder strap for carrying it, though.
  6. Jupiter and Mars imaging - help needed

    There is undoubtedly a learning curve with planetary imaging. Fortunately, there are people willing to help and once you get the basics you realise the learning curve is not as steep as you might have feared. I second everything Neil has already written. In addition, I cannot recommend the tutorials in the link below enough. They cover everything from equipment to processing in a very pedagogical way and got me off to a very good start. Hang in there. It’s worth it! http://planetaryimagingtutorials.com/
  7. Eyelash oils on eyepiece

    It is usually best to start with a q-tip or cloth dampened with some cleaning solution that cuts the eyelash oil and then use breath+microfiber to get rid of any streaks left by the solution.
  8. Eyelash oils on eyepiece

    Yes, isopropyl works or, better yet, a mixture of isopropyl and distilled water with a tiny drop of washing up liquid. Isopropyl by itself evaporates a bit too quickly.
  9. Eyelash oils on eyepiece

    Cleaning the eye lens of short eye relief eyepieces is something we all have to do quite frequently since, in contrast to the objective/mirror, any dirt on it will impact the view. As long as you’re careful (and it sounds as you are) it should be fine. The coating is more durable than you might think.
  10. This is what I have heard as well. The 24mm was apparently Paul Dellechiaie’s (of Ethos, Delos and DeLite fame) first design for TV. Compared to the rest of the Panoptic range the 24mm also has slightly shorter eye relief as a percentage of the focal length.
  11. 12v Power Connectors

    I’ve recently changed over to Anderson PowerPoles. They are small, secure, modular and hermaphroditic. So far they seem to work well. They do not, however, have any option for cable clamps, but so far I haven’t felt the need for any. Since they crimp on the cables rather than being soldered there is less risk of the cable snapping.
  12. Since I also have a lovely TV85 and have considered a 150/180 Mak for planetary/lunar I follow this thread with interest. One strategy for dealing with tube currents that hasn't yet been mentioned is to insulate the tube. As long as the optics and air in the OTA are at the same temperature it doesn't really matter if the scope is not fully cooled down. There is a long thread on CN discussing this approach at the moment, might be worth looking into.
  13. Veil Opinion Needed

    I also prefer the first one, but I agree with Allinthehead that the background seems to have a green tint. The second image on the other hand has a fairly strong red cast in the background that I would find more objectionable. Perhaps edit for a version a quarter or so of the way from the first to the second? Personally I would edit for a color balanced / neutral background and let the Veil fall where it does. I would also look out for areas with saturated reds / blues in the nebula as these areas can be ugly when printed.
  14. Not a rumor. If you’re happy with 62 degrees they’re hard to beat.
  15. Nagler T6, perhaps? I liked my 11mm, except for the 12mm ER. Alternative solution: Keep the 22LVW and 10XW. Get more LVWs / XWs / Deloses.
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