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ronin last won the day on November 16 2012

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About ronin

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  1. Should have bought the jacket. Simply you may think the world revolves around astronomy but I suspect your wife does not. Very likely she will think her gift was wasted. And there is SG Lite which is free.
  2. By rights if you put a blue filter in front of the red led nothing should get through, the filter should be blocking red and green and passing only blue. Same if you put a green filter in front as it should pass only green and block red and blue. It all depends on how good or narrow the filter is, the speactra passed tends to spread out a bit. Also depends on how pure the red wavelength is but an led tends to be narrow/pure. A red filter would pass the red led output and also pass the red component of the white led, so with a red filter you should get red light coming through on the
  3. The astrophotography side is the problem. To do both it first cost money - I would say the least expensive, but reasonable, AP option is around £1200. This would consist of a Goto EQ5 (£600), a small 70mm ED refractor (£400), flattener for the scope (£150) and some pennies for the assorted attachments. The mount needs to be equAtorial. Now that will get you going but at some time it will be a better scope, that means a better mount, guiding is extra cost and extra weight so a bigger mount, mono is very good but that is a dedicated camera, a filter wheel and nice £100+ filters (minimum 3 o
  4. The TV's are good, they do cost a bit new, and although used sounds nice I suggest you put a Wanted ad up. If you wait for someone to advertise some for sale you have to both wait and be the person that gets in there first. TV plossl's go down to 8mm, Al stopped there and I can half understand why, eye relief gets a problem below that and I suspect field curvature, at either the object or image plane, does also. Alternatives are likely the Vixen NPL's. Always reported as good - except for the outer housing which some compalin of feeling plasticky. Which as I suspect they are a hard p
  5. Why a focal reducer and a barlow, one reduces the focal length then you go adding a barlow to increase it. I would have expect the 2 item to not work overly well together, they were sort of not intended to, so anticipate a poorer image. Generally the less glass in there the better, they all add to the aberrations. I would forget the barlow and the 4mm, maybe a 10mm as you think or a 12mm.
  6. Taken from Wiki: The curve (2) is for a doublet - basically a parabola. The curve (3) is for a triplet (Cubic) The distances away from the ideal focal plane indicate the difference between a double and a triplet and the plot Agema give is that of a triplet not a doublet. Which gives me concern for the data supplied.
  7. Have Skysafari on a tablet and it has never caused a problem immaterial of the brightness of the screen. The tablet does "sense" the ambient light level and adjust accordingly. Think there is a night or red mode on it, tried it once or twice, but the detail and usability seems worse, so it is just left as normal. Half the reason is I want to be able to see and read it and the usual display is best for that. Doesn't seem to really destroy any night vison, or if it degrades it then it is for a few seconds. Sometimes think we take aspects too seriously, we are after all just hobbyists l
  8. Interesting chromatic focal shift, they seem to have fixed the focal plane for 3 seperate wavelength in the visible spectrum, Fraunhoffer G which is 430nm, e line of 546nm and around 680nm (guess B line of O2). Yet that requires 3 lens to accomplish as in a doublet design you can only work with 2 wavelengths. The plot is also not parabolic, which is the output of a doublet. Going to be interesting what people find with it, as they appear to have controlled 3 wavelengths with 2 lens.
  9. As it reads it is not debayered then the sensor+mask will be a row or RGRGRGRGRGRGRG, then a row of BGBGBGBGBGBGBG. With a Ha filter in then a row of BGBGBG gets in effect no illumination on it and would remain a dark band, even the RGRGRGRG gets just alternative pixels illuminated. Since it is still fundimentally a general purpose camera for holidays, landscapes, nature and sports shots it makes me wonder how the software of the camera gets around all this. One sort of option is that the internal software is just trying to boost the level to get the G and B row of pixels up but it w
  10. 1: Yes you are interested in DSO. Reason is there are 3 planets and they are not there all the time, what are you expecting to do when not there? The underside of the clouds are boring, eventually. 2: Immaterial of everything a good refractor will give the best planetary views. They are also likely the best for AP. AP requirements are differnt to visual. 3: Don't say that. A good refractor can be 5x the maximum you have indicated, and that is just the refractor. 4: No idea, 5: Goto you will require. It is very useful and it has tracking as a default and the tracking is abou
  11. The usual way for planetary imaging is to get a video of the offending planet, load the video into AS2 or Registax and then select the best 200 frames or something like that, then stack these and the do a little processing. Seems from comments that AS2 is a bit better at stacking and registax a bit better at the processing. The processing is faairly minor. For Registax I have heard 3 "options. First was move all the wavelet sliders to the centre, second was move the first a little, the second a bit more and so on all the way to the last, the other was slide No 3 or 6 all the way to t
  12. Is that a Red one or have WO added a Bronze ?? Didn't they used to have a thermometer on the focuser - close to totally useless but it was a talking point .
  13. They are presently unlikely to effect the view you get. If you think about it the modern telescopes are multi mirror construction and the gaps between them have no effect. I would take the mirror out, have a good look at it and probably give it a clean, you can ask how to do it properly on the forum. Then have another look. Some marks may get removed others reduced, some unchanged. What you are bothered about are ones that are oxidation of the aluminium layer as that means the SiO layer has been penetrated. Seriously suspect that you will find no degration of your view. One of t
  14. Long Perng do make an ED Doublet 90mm: http://www.longperng.com.tw/goods.php?act=view&no=7 Not going to guarantee the link going to the right page. Trouble is you need to find you imoports and sells them. They ahve a new one that is a 90mm Triplet and uses 2 bits of ED glass also.
  15. Only one I know of is the Primaluce Airy 90 which is a copy of the WO Megrez 90. You do not see many Megrez 90's for sale, no-one seems to let go of them. Myself included. Likely someone does make a 90mm but it maybe a triplet, wasn't there a Raptor 90 from either Astro Tech or Stellarvue think a triplet, and if the idea is imaging then get a triplet. An ED is good but still a doublet and people do report CA, and imaging is harder on the optics. WO have a 61 and a 73 now. Just wondering if the old 80 ED and then the Megrez 90 may make a reappearance . How about the new WO 73?
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