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ronin

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ronin last won the day on November 16 2012

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About ronin

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  1. ronin

    My wife wanted to buy me a Jacket

    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. ronin

    effect of colour filters

    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 eyeball side of the filter. At a guess/estimate you would need say a white led 10x brighter then the red led to "see" about the same at the eye. As the red filter should pass all the red led output but block the blue and green and assorted other bits of the output from the white led, so reducing the final apparent "red" brightness.
  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 or 4 of). If the idea is simply to dabble at the initial AP stage then EQ5+70+bits will be fine. Many do as all they want is to get some images but not win AP of the year. You can get the EQ5 add a visual scope say a 102 Bresser and go looking then later buy a small imaging scope for imaging. Or buy a bigger mount now HEQ5 in preparation for the future. Pure visual will depend on you, a simple 150P or 200P dobsonian will do visual but before you get ideas forget any AP with one. It is simply the wrong scope on the wrong mount for any AP. The minute people ass AP into it as a factor that one aspet causes complications. Add a location, there are clubs around, just no idea of where you are, nearby town is adaquate. Suggest a town as a county means you could at a county border so have access to clubs in the next one. Also do not get a nice big sounding visual package and expect it to do AP, very little cross over in reality. An 8SE on its mount is again not really suited to AP (wrong scope and wrong mount) but it is a good visual one. I would say EQ5+102 Bresser (achro) or 150P reflector, and later buy a small 70ED for a bit of AP. So in effect 1 mount and 2 scopes eventually.
  4. ronin

    Televue plossls

    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 plastic moulding and the optics as a tube assembly are inserted into this kind of makes sense. Watch the costs as even the Vixen NPLs are getting to match the BST's, and the BST's may lose out on overall sharpness and clarity but they are close and they are comfoprable easy to get along with eyepieces. It will depend on what you want, and it may not be simple. Also may take a few eyepieces to come to a conclusion.
  5. ronin

    Magnification advise please

    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 looking through a telescope for an hour or so when a convenient clear night appears magically over the horizon.
  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 will do some to the R so possibly making the banding worse. What is the result without any NB filters, just simple OSC use ? I do wonder if getting a DSLR, modifing it, swapping filters and then debayering it and still it is uncooled and remains a DSLR with whatever limitations is really more economic then just buying a ZWO or Atik that is built for the purpose.
  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 about 400% relevant to virewing and 1000% relevant to AP. Dump the packages you list, all packages are aimed at visual, although I will say have a look at the ETX for another reason. I would say go get a good mount, equitorial and goto. Not sure whose however. Get a mount equal to the Sky Watcher HEQ5 - not sure of the equivalent in the US. Scope - if ES do a 102ED (triplet) then consider one of those. The FCD models are good the FCD-100's are better. Think ES do a 125 ED FCD-100 but cost leaps but it has had excellent reviews. With the mount you have the option to use mount and say a less costly Achro for visual, Bresser 102 or 120 maybe, and later get a smaller AP scope - ES 80ED maybe. That way you spread the purchasing cost and can do either. The ETX 125: I read somewhere that the OTA can be removed easily and so another put in its place. Must be a design change as on the old models this was not simple. If this is possible then you could use the supplied scope for visual and planetary imaging and then swap to, say, a 72mm ED for some AP. A lot will depend on how serious the AP will get. But the HEQ5 match should cover about it all for a long time. Other mounts are the iOptron, but their reviews are mixed. Add a location as I guess you are US based and people will point you at UK retailers and equipment.
  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 the right and leave the rest. So I suggest you ignore the previous and just use trial and error. Half an hours playtime. So whichever of the 2 imaging options will give you an AVI file for processing would be best, and I suspect that will be the webcam.
  12. ronin

    My new APO 80mm

    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 the strange properties of the incoming collimated light is in effect the sprad of the "data" - it's everywhere. Add a location as there is another mirror coater in the N. London area - Vacuum Coatings I think. All depends on where you are. Galvoptics (Essex) used to coat mirrors but I think they have pulled out, however may be worth an email enquiring. Half guess they still have the equipment and so may do one. The other aspect is find out the complete cost of it all, trhinking that if the coating is penetrated then the mirror may need a minor regrind to remove any significant pitting. There is the possibility that a new mirror may actually cost less - TS optics sell the GSO range of mirrors.
  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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