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ronin

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Everything posted by ronin

  1. 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.
  2. 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.
  3. A 1200mm scope will give a prime image that is dependant on the focal length (1200) and the subtended angle of the object. It is not a magnification simply a size in mm. It is not "magnified" the image is simply 14x bigger in mm then the iimage is for a 50mm lens or mirror. But that is not a magnification. What is this 1x on a camera? You say 50mm lens on a 35mm film but the DSLR's are not 35mm, so is a DSLR bigger or smaller in terms of this "magnification"? From the arguemnet it reads that a 50mm lens on a 35mm film or full frame DSLR give a different "magnification" against an APS size DSLR whereas the lens will produce exactly the same size image.
  4. Not arrived yet Another item is now 3 days late, beginning to suspect that has been lost in the post.
  5. For the basic intention then the Nikon is fine. The basic beinng that you take say 20 exposures of say 20 seconds each then head off and stack them in DSS. Might be a little simplistic but Canon were recommended initially as Canon supplied software for their cameras whereas others did not. How much you will or might use this software is a question. Assuming no use then no great difference. One internal difference is the IR filter, on a Canon their filter will pass about 23% of the incoming Ha and on a Nikon it is lower at around 15-18% - the curves I have are a bit out of date. Main reason for problems is likely to be settings on the Nikon. The whole thing needs to be in Manual, so you set the exposure length, the ISO and the focus. You also have to turn off the Noise Reduction. Sure they is something else in there that needs doing. Assuming you have an intervalometer (you will need one) then you need to set the Mode to "B" for Bulb (old photography term that got carried over), then the exposure length is determined by the intervalometer and after the exposure set a Wait time to allow the DSLR to perform all the required post exposure functions. Do not just get on taking the next exposure, there needs to be a time period for things like writing the data to the memory card. One thing to remember is that a DSLR was not intended for AP the exposures are too long and this causes problems, also AP tends to go for RAW files which are big. They will manage AP to an extent but you have to work with them. For stacking you will need say 20 or 30 good exposures and if possible 10-15 (say half as many) darks. Darks are "easy" same setting as the exposures, set the number of exposures to say half as many and press the Go button on the intervalometer then put the whole lot in a fridge and close the door, Make a coffee and at the end you will have Darks. Stick with just those for the early stages. If I recall DSS will stack jpegs so you could just collect standard images initially to get going and learn what is involved with the DSS options. It is a bit less involved at the start. You will have to track down all the setting for manual operation, they do tend to hide the things and occasionally in odd places.
  6. No magnification, you need an eyepiece and an eyeball for magnifiv=cation. What youy get is an image size, defined by the tangent of the angle subtended by the object multiplied by the scope focal length. If you put a 2x barlow in then the object size is doubled. So moon = 0.5 degrees, scope appears to be 700mm so the image is: S = tan(0.5)*700 = 6.1mm.
  7. All I can think of is the secondary. First thought was the collimation may be off sufficent that not all the light cone is hitting the sceondary and so half of it is lost off the edge. Next is that someone has replaced the secondary with a smaller one and again not all the light is getting sent to the focuser. Third did you clean the secondary as well as the primary. First should result in pretty awful shaped stars. I wouldn't use a solar filter for the sun on it. Basically even if the film attenuates by 100,000 you are still collecting a lot of light, and IR and UV. Basically you will be getting 7000x a eyeful which I agree is then filtered so about 14% of naked eye, and I am uncomfortable with those amounts. Just me I suspect but it is different cutting back what goes into a 70mm comapred to what goes into a 250mm. Clubs in case you need to locate one: http://www.astronomyclubs.co.uk/
  8. Around the 150x mark. Little use for anything more, that covers Saturn and Mars when it appears next year will required values that realistically mine would find difficult, the scope collection tends to be on the smaller size. Will say I want a good image, a 300x blur is of no interest to me. However as Mars interests me little also (seems a bit odd) then I am content at around the 150x area and that covers just about everything other then Mars.
  9. Slight concern of the TS Imaging Star 71 is that it basically has to be a clone of the WO Star 71, and it is a copy of the original 5 element one which was gpod but the optical alignment/collimation of the many elements really needed to be done - FLO went to Ed Reid for this and that improved matters considerably. TS cannot do that. As it already has a reducer in place you will have to live with how it comes. Don't know about the TS Photoline, they appear good however seems not many get mentioned as in use, probably worth asking in the Imaging specific section about either of these. Why not f/6 out of interest. Fast causes other problems as the spherical surfaces are less ideal the faster the lens. Usually the faster the objective the greater the problems that get mentioned, both mirrors and lens. There is the WO ZS1, that is £400 and the Flatenner another £150. Doublet only but reports appear good.
  10. The Tal 100RS were always well regarded but don't think they have been produeced for some time now so one would be used. After that on the new side it would be one of the Vixen's. The problem is that there are several Flint glasses and several Crown glasses so one achro can/will change from another simply by the glass used and the resultant combination. That is likely the difference between a good Achro and a mediocre Achro. If the Crown component (I think it is Crown) has an Abbe numbers between a cheap Crown and FPL-51 then you still have an Achro but likely a good one. One question it all leads to is: "What is an ED glass?" We talk of FPL-51 and FPL-53 but what about FSL-5 or BSL-7 (maybe BSL-7 is the Ohara equivalent of BK7). Looking at the Ohara chart it half looks like ED glass is an Abbe number of 80 and above, or maybe 75. Basically no specific definition - as best I know. If you want a good achro you are likely looking at f/8 or slower and a make in which there is a degree of confidence that the glass used is as originally considered in the initial design. The ES offering seem good and as they are seperated doublets there is better flexibility to design the 2 lens to operate better. On a cemented one two of the faces have to be the same radaii. Equally the ES ones seem to cost more, Bresser make very similar but they made cemented dioublets so R2=R3. If I were to buy one (but I have a Tal100 anyway) then for cost the Bresser 102/1000, £212. I see that ES do not make an equivalent.
  11. Dig out a few globular clusters M13, M92 (Hercules), M10, M12, M14 (Ophiuchus).
  12. Did you look at the Kernow Astonomers webpage, well the one before it on that link? I noticed that it had to be written by someone that was unaware of the meaning of Kernow, it said: Address: Kernow, Cornwall. So it is at Cornwall, in Cornwall. Someone should notify the club list maintainers that the location is St Columb Major. I see they have a public viewing night on Sept 2nd. Seems it could be worth a visit to get a feel for them and ask a few questions. A bit like yourself I am always a bit puzzled why clubs meet for the observing during the week, one club around here have applied thought and arrange theirs for a Friday and/or Saturday. Their thinking being Friday if clear otherwise hope Saturday is better. The remainder pick Mondays and Wednesdays which is when people have work commitments the next day.
  13. http://www.astronomyclubs.co.uk/Clubs/Default.aspx?CountyId=18 Looks like Callington has ceased. The Roseland one check out how they operate seem to think it is not quite as a "normal" club. The Tolcarn one looks different.
  14. Harry, any chance of getting your hands on Roger Griffins 36" one clear night? Will say there is a well known saying that includes "snowflake" and "hell" that comes to mind. As it has just been refurbished - I think I heard they had redone the mirror also. Nice shiny mirror, nice clean observatory, only problem is talking Roger in to it.
  15. Not sure about the not need the goto aspect. Someome once did ask "At night how do I find the moon?"
  16. From pots the mount does beter with more then 12v BUT not too high as there is little or no voltage protection in them, also they need a reasonable current to back up the voltage. People have said the better voltage for these so maybe ask seperately for that. But I suspect the answer will be 12.6 to 13.2 volt and at least 2 amp but preferably 5. Batteries will drop voltage rapidly and not sure of the current they can actually supply. A Li-Ion discharge curve shows a drop below 12v in about 10 minutes. In just about everything the manufacturers quote the best most ideal situation. Many years ago on a very critical item I recall it said "2 years life", what was failed to get mentioned was 2 years in it's packet on a shelf in a temperature controlled room. Take it out of it's packaging, put it in the equipment and use it outside and failure in 3 months and often less. So expect a 12v battery to be 12v for say a few minutes only, same for 6v items. Isn't the flashing LED a sign of under votage or under power? Which would correspond to what is seen. Must ask: 4 batteries is an odd number as that makes 6 volts if the "normal" 1.5v items and I only know of the simple RA/Dec motors that use that.
  17. Very difficult, may be a case of what budget overall is there, big one will be the time available to you. Mono will give the better results, as in effect for each "colour" all the pixels will be used. So a 10Mp camera uses all 10M on Red, then all on Green and then all 10M on Blue. So more data and a better final result. The negatives are that you will need the camera, then you will need a filter wheel, then you will need the filters. None of which are exactly inexpensive. The next problem is you need time. You need to collect the Red data, then you need to collect the Green data, then you need to collect the Blue data. So doing it "simply" you have to have 3 imaging sessions. What is the weather like in Swansea ? Lots of good clear nights ? With a colour camera you basically lose the number of pixels, the mask means you have 3 colours at once so on a 10Mp camera I think about 30% are Red, 30% Blue and he rest Green - there is a bias towards Green on a DLR not sure if the same on a dedicated AP camera, have sort of assumed there still is. So for Red and Blue you have about 3Mp, not the 10Mp of a mono. That is a big decrease. Where you "gain" is initially not needing a filter wheel and you gain on time. You get the whole lot in 1 session. So maybe simplistic that is where the choices lie. On a colour camera the "key" bit seems to be the "O" in OSC = One. Budget is simply the filter wheel and filters that you will need, but ultimately (not immediatly) you should get better images, in some instance much better but the "much" better may be a case of 5 to 10 years learning all the data collection and processing skills required. They do not appear overnight. I for one do not have the patience for mono. Very likely it should be a progression of colour to mono, meaning both at some time. So you start on colour, learn all you can and when you cannot progress much further you enter the world of mono. Myself I have already marked up the ASI 178 camera as a candidate for when I want to lose the DSLR and maybe try an AP camera, likely for convenience to be colour.
  18. I guess that the term "good all round scope" can be misinterrpreted. Eventually it seems people take it to mean excellent at everything, maybe it more means bad at nothing. The old phase "Jack of all trades, master of none" is I guess more appropriate. It is after al a scope of just under 5" aperture, 127mm is 5", were you thinking 5" at purchase or 120mm at purchase? The light gather of a standard 200P is close to 2.75 more. It is I believe a doublet at the end of the day. May have a nice bit of ED glass in it but still doublet I believe. Unlessthe definition of APO is changed and redefined that has to be kept in mind. Suppose the question is "Would I have one?" Actually not sure, nice and a reasonable aperture but enough questions to me to make me hesitate, think I would opt for a slightly smaller ES triplet at the end of the day.
  19. As a minor point on the coatings mentioned earlier, they should not be seen, in an ideal case. They are antireflection, so if they do their job and do not reflect any wavelength then everything goes into the lens and you see nothing. If you see the classic purple it is because the the AR coating is designed for the green wavelength and so reflect a small amount or red and blue so appear purple. The "best" would be a sort of totally absorbtive surface so black. Only seen one even close and that was down at NPL on a lens they had. Nothing came off that lens surface - beauitiful. In effect looking for colour and seeing any means some wavelength is being reflected, not the purpose of multilayer antireflection coatings.
  20. I would ignore collimation until you can at least see things in some manner, there is a greater chance of making it worse rather then better. The almost standard way is to check with a star test and as you seem not to be able to get a star in sharp focus then a star test is pretty pointless. Collimation on an SCT is not really something to do without a fair degree of research first and a reasonable amount of preparation. Have you changed the data ? I assume here that there is no GPS on the scope, and even if there is it is a good idea to set your own. GPS can take some time to get a location and other data. Simple one are you telling it DST = On ? If you want an eyepiece then get a 32mm plossl or a 40mm plossl, at this time get the widest field of view you can, especially with the focal length of the LX90. Alignment is usually easy but again with the focal length and reduced field of view North has to be North and level has to be Level. A compass is not accurate enough for North. And as Polaris is off true North about the same as a compass is then neither is aiming it at Polaris. The Meade "Level and North" is relatively easy to get going with but it does all rely on the scope and mount being fairly accurately level and North as the initial start position. Spend 5 to 10 minutes getting it so. One other aspect is if there was/is old data in there then you may be better resetting the handset and entering all aspects again yourself. Sometime they just need it doing - half convinced that old data lingers around and so upsets things. Aligning finder and main scope is a daytime exercise on a distant object, distant = about 2 miles, not the ariel on the roof over the road. By the way forget an erecting prism, little point in one with that scope, when you get it going.
  21. You can get an Alt/Az mount that removes the fun/frustrations of an EQ. However a reasonable spotting scope is a fair idea, not overly sure about the zoom aspect - I have a small Bushnell and I have the idea that the zoom bit is the weak aspect. Equally the whole scope was not costly. So will depend on how much you intend to pay. Always the main aspect. Should be fine for astronomy within reason/limittions, lets face it we use binoculars a lot and I use the same for general sky viewing as I use for walking round an RSPB reserve. Main concern is what they will show. They will not be up to the rings of Saturn, doubt that Jupiters bands will appear either. Reason is simple = they were not designed for that purpose, sparrow 50 yards away Yes, Jupiter a few million miles away No. I picked up a Bresser 102S, nice wide scope that may be an alternative scope but that means buying one to find out, also means getting an Alt/Az mount (although they may come with one from a retailer). ANy clubs to visit? Someone may have something that is still an astronomical scope but fits what you want. http://www.astronomyclubs.co.uk/
  22. Likely worth adding in the description that for anyone who has an interest in astromony or simply observing the skies by eye or with binoculars it is in a good dark sky location with the milky way easily observable. However I guess more then that is likely to be a bit irrelevant as I would say that only about 1 in a 1000 people actually do anything resembling observing, and less actually own a scope.
  23. Thanks for the model, located the manual and there is no Eq mode of operation specified in it. Also looking at the mount it would appear that placing it on an Eq wedge would be difficult. Seems that it is dedicated to being Alt/Az only in operation. Any work round will therefore be exactly that and may not be overly accurate. From reading through the 6SE it, and I presume the others, have an EQ South and an EQ North option, so they can be set to operate on a wedge, actually the manual shows them on a wedge as well. Somewhat annoyingly the SE mount unit looks somewhat similar to the 127 AZ unit, just guess they did not put the Eq option in the firmware. That sort of ties in with the memory of the Eq going from one (Nexstar SE scopes) then being put back. But it occurred some years back.
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