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vlaiv

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vlaiv last won the day on November 15 2022

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  1. That is a trick question, and like dear friend of mine once said - "I don't answer trick questions"
  2. I think you are right! Same thing is mentioned in the answer that I linked.
  3. I don't know much about this, but from what I've gathered, rated voltage of stepper is not important as it is used. This I've gathered from 3d printing forums as steppers are used to move the mechanics of 3d printers. In any case, stepper can be driven in two different ways, if I'm not mistaken, and most modern stepper drivers are current drivers. They just pump enough current (depending on settings) to get the motor running. I think that max voltage has something to do with holding torque in that case - if you want more holding torque (or is it max speed?) - you need to provide higher voltage. Some stepper drivers work with 48V - and you can use those drivers with 3.5V motors for example. With current drivers - you really don't care about declared voltage. See this answer for more details: https://electronics.stackexchange.com/questions/200324/how-to-interpret-the-stepper-motor-voltage-requirement
  4. You can use something like torch - one that focuses to tight beam to illuminate the ball bearing from the side. Use very small ball bearing to get small reflection.
  5. Yep, two more things might give a clue. AZ-EQ6 was in production before 0.9 degree steppers were common place, and this as well: EQ mod prerequisites page shows that worm is 180:1, then total reduction is 720:1 (belted part is 4:1). There is 51200 micro steps per worm revolution. That includes 4:1 belt reduction and steps from stepper motor. 51200 / 4 = 12800 micro steps AZ EQ6 uses 64 micro steps 12800 / 64 = 200 and that is of course 1.8 degrees since 360/200 = 1.8.
  6. +1 for artificial star. Small ball bearing or similar can be used to simulate it, or you can get commercial one. There is also a way to DIY one from optical fiber and white led with a bit of soldering. If you have a good small scope (even achromatic refractor if stopped down to F/10 or so while being slightly larger aperture than lens will do) - then you don't need a large distance. You can use scope as collimation lens for the beam to make it close to infinity.
  7. Don't waste money on replacement motor - just use 1.8 degree Nema 17 stepper. Any idea of how much current is delivered per stepper? What is total consumption of the mount? About 2A when slewing (I'm guessing). This means 1A per motor at most. Something like this should do the trick: https://www.omc-stepperonline.com/nema-17-bipolar-1-8deg-44ncm-62-3oz-in-0-85a-5-3v-42x42x48mm-4-wires-17hs19-0854s You can also measure length of body of stepper to narrow it down. I just guessed that it is 48mm, but looking at your image - it might be less like 34mm (at least it won't cost you much to try).
  8. If both are diffraction limited - Strehl >0.8, for imaging it won't.
  9. In imaging it is much more "black and white" than in visual. When observing - we can't exclude effects of seeing, nor can we increase contrast nor sharpen the image. We do all of that regularly when imaging and that sort of levels the playing field between different quality scopes. Of course, neither should be a lemon, but you'd be surprised what can be recorded with even moderate quality telescope. For example - this image was taken with 5" newtonian with spherical mirror (F/6.9): That is remarkable level of detail for such scope and visual on such scope won't come anywhere near, but take any Jupiter image taken with any 5inch scope and you'll see about the same level of detail
  10. There could be a number of reasons for that, but the fact is - if both scopes are diffraction limited (and I'm guessing they should be in 95% of cases) - C11 is simply better imaging platform. You can't beat the laws of physics, larger aperture allows for sharper image.
  11. I've been both really positively surprised and somewhat disappointed in flexible plastics. I think that TPU is great material given it's properties. It is very tough, very resistant, somewhat flexible (depending on type), but what I was disappointed about was that it does not have that rubbery feel to enhance grip. I considered it for ergonomic/grip surfaces of some parts. Then I ran into this: https://forward-am.com/material-portfolio/ultrafuse-filaments-for-fused-filaments-fabrication-fff/flexible-filaments/ultrafuse-tps-90a/ However, I haven't still had a chance to print with it. It looks like it has been specially designed for hta purpose.
  12. Or design in tolerances and features that makes use a bit flexible. Here is aperture mask I designed for someone once: It's a bit oversized - by 1 mm or so - just to make sure it will fit and I added 3 pockets for simple nuts so nylon tipped thumbscrews can be added to secure mask in place. They are also designed to be printed without supports with 45 degree overhang. One could also design holder separately and have just few aperture mask inserts printed along it - no need for several masks. Saves on material use and shipping (I guess this last bit).
  13. Here are some interesting points regarding exit pupil: - telescope can't make extended objects brighter, only dimmer. The brightest view is with our naked eye. Exit pupil matched to our "entrance" pupil will give the same brightness of extended object as when viewed with naked eye. Smaller exit pupils will dim the object brightness for extended objects. - Sky is also extended object. Contrast ratio, or ratio of target brightness to sky brightness can't be changed by a telescope. It is always the same. Only way to change this is by use of special filters (for example UHC filter if target is emission nebula). - Human vision is complex topic. Perceived contrast ratio depend on amount of light. It also depends on angular features of target - look at this image: Frequency changes from left to right and contrast from on Y axis. It shows that not all frequency components are perceived the same although they have the same physical contrast (ratio of dark and light). This even changes with amount of light and our night vision adoption. This is why we can "dial" in magnification for particular target and why larger scopes show faint fuzzies more easily - it is because of this combination of absolute levels of light + magnification. On physical level - small scope with exit pupil of 5mm delivers same amount of surface brightness as large scope with 5mm exit pupil.
  14. 5 at the moment. 8" F/6 Dob, 4" F/10 Achromatic refractor, 80mm F/6 APO triplet, 4" F/13 Maksutov, 8" F/8 RC Well, 5 1/4 I have 80mm F/7.5 achromat being lens in a cell at the moment and trying to grow into full fledged OTA (waiting for me to get aluminum tubing and to 3d print a focuser for it).
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