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beka

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Everything posted by beka

  1. I was thinking it could also be like when you put a heavy load on a pack animal... then sometimes it has to go!
  2. Hi sonicninja, My twopence, I used a 114mm f8 reflector (Celestron FirstScope 114) on a manual mount for a long time with inexpensive eyepieces from an eyepiece and filter kit. I used these eyepieces later for another length of time with my CPC 1100 (11 inch SCT) before getting some Baader Hyperions. I will just say that on the CPC 1100 I am still not sure if the more expensive eyepieces actually showed me more detail on the planets. They are on the other hand more comfortable to use (with a higher exit pupil) and have a more satisfying build quality. Just saying that the differences between eyepieces - near the center of the field of view on planets, will be very subtle. I think you can go a long time with just the eyepieces you have and the 2X Barlow. The 3X Barlow is probably not useful. Best!
  3. Hi All, Was just wondering about SVBONY eyepieces. Browsing their site, they don't seem to have specific lines of eyepiece products like other companies. They also seem to use designs like Plossl freely without regard to the actual design. For example here they have 4, 5 and 6 element different arrangement eyepieces all called "Plossl". Then some SVBONY eyepieces on Amazon like here don't seem to exist on their own web site. Finally all the eyepieces are very inexpensive and generally are seen favorably by users on this forum. So are they actual manufacturers or are they scavenging surplus eyepieces from elsewhere and reselling? Do the likes of Stellarvue and Baader have to be worried? Best!
  4. Hi ChevyFan, Checking the link, the eyepiece specifications are a little strange. Specified as Kelner aspheric with 62 degrees field of view - conventional Kelner eyepieces or even Plossls which are considered better, don't have such a wide field. Aspheric elements are found in more expensive eyepieces so three different eyepieces as this price needs further looking into (strangely could not find these items on the Svbony site). If you and your wife are just beginning astronomy it would really be better if you just use the eyepieces that came with the scope for a while. The difference in the views between these and more expensive eyepieces is quite subtle near the center of the field of view. An inexpensive 2X Barlow will allow you to expand the range of magnification. Once you know what types of objects your wife is interested in you can plan the next items you purchase accordingly. Cheers!
  5. This is the kind of calculation I attempted - I assumed the eye to have a resolution of about 0.2mm for near objects and came up with numbers closer to the lower end of the ranges you mentioned. Thanks
  6. Hi All, It has been suggested that the maximum useful magnification of a telescope is about 50X for every inch of aperture. So for a 4 inch for example it would be 200X. I was wondering what the basis for this is? On Celestron's site, the magnifications they give for their scopes seem to be higher. For the NexStar 130 SLT it is 307X but it should be about 250X (5" X 50) from the rule above. I tried some calculation based on the image scale of the telescope and the resolution of the human eye but did not really get numbers close to these. Does anyone know how these numbers are arrived at? Best
  7. Hi ChevyFan, I have been using this scope over the last few months. If I recall the scope comes with 9mm and 25mm eyepieces. If you are completely new to astronomy I would not buy any more eyepieces just yet. You should get an inexpensive 2X Barlow for a maximum of 144X magnification. In times of good seeing this will show quite a bit of detail on the big planets. Jupiter's red spot and the Cassini division on Saturn are possible. The 25mm will give you excellent wide field views and many star clusters will be nice. Like has been stated by others, magnifications much higher than above will be hard to use because the mount's instability will make focusing and tracking difficult. You will also need to learn how to collimate the scope. I have found this important to get decent views. Have Fun!
  8. I managed to borrow this scope from a friend. Initially I was interested in using it for DSLR astrophotography, thinking it would be better than the 102 SLT refractor I had because it would be free of chromatic aberration. However I learned that DSLRs would not come to focus even before I tried - without modifying the OTA or using a barlow. I then wondered if it might be good on planets. On Jupiter using a 8mm to 24mm Celestron zoom eyepiece and 2X barlow (162.5 time magnification) the view was quite good. I could see details in the bands and it was free of CA. However I could tell from the moons that collimation was not prefect. I had tried some time back but was never fully satisfied with the result. Saturn was more disappointing. I could barely make out the Cassini division and some banding. I didn’t try to see its moons but I think I would have noticed them if they were obvious. I did not try any deep sky objects on this night but some months back I had tried to view the Orion Nebula and the stars of the Trapezium. Four stars were crisp but I could see no sign or the E and F stars. I will continue to check this scope for deep sky but I already reached some conclusions. Visually on planets my old FirstScope 114 900mm FL f8 is better. The longer focal length makes it easier to get higher magnifications and I guess the f8 focal ratio makes it easier to collimate. The 130 SLT scope does track but for me the manual FirstScope slow motion controls were better at high magnification. Visual deep sky - of course my CPC 1100 is vastly superior except for wide fields. Star fields in Orion and Southern Cross were very pleasant in the 130 SLT. So for wide field low magnification visual, this scope is better than the either of these two. Casual astrophotography I can do with the 102 SLT refractor without any modification. CA is prominent but it can be reduced in processing. The 130 SLT has the potential to be better but I would need to buy a dedicated astro camera (but somewhere I read that mirrorless cameras can come to focus without modification). My final thought is that it is a decent scope to have - if you have other scopes! Good for grab and go for quick wide field views. I would not recommend it as a good all rounder for a beginner. For that my opinion would be a 4.5 inch f8 reflector on a good manual mount – I don’t know how well a dob will track at 200x mag, but why does no one make these on a good equatorial or alt-az mount? Thanks for reading!
  9. Exciting yes, and also some serious nail biting and restless nights for all that have been looking forward to this!
  10. The Powerseeker 50AZ eyepieces are 0.96" so the usual 1.25" will not fit...
  11. Stellarium will help on the planets as well - use the search feature on the left of the screen. Cheers!
  12. The light pollution will not affect your views of the planets. You should even be able to glimpse Uranus and Neptune as a tiny dots with no detail using this scope. You can also try some of the brighter deep sky objects like star clusters for example the Beehive Custer, and some people like observing double stars - you can try Mizar. Happy Observing!
  13. Venus is close to the Sun now so you can't see it presently. You will be able to see it in the evening a few months from now - the scope will be able to show you the phases like the moon. Actually most other backyard scopes won't show much more. If you have not used it so far Stellarium is a very good planetarium program that will allow you to plan your observing sessions. I would suggest that you avoid the image erecting eyepiece and Barlow, and that you hold of buying any accessories (filters, eyepieces) for a while. You can decide later after using the scope for a while and you know more about what kind of observing you are more interested in. All the best!
  14. It's of course not a stupid mistake but I imagine no one on Stargazers Lounge would have thought of that! It is a better scope than Galileo had when he changed humanities view of the cosmos - so have fun! Best
  15. Hi All, In principle as the corrector plate is correcting spherical aberration, then some refraction is taking place at the surfaces and therefore there will be chromatic aberration (it effectively is a very weak over corrected lens). It must be that it is too little to significantly affect the final image. Best
  16. Hi Mike, you have to fit the steeltrack focuser in place of the standard visual back adapter. You will then need a 2 inch to SCT adapter to fit the 6.3 flattener/reducer. Best!
  17. The maths in the article we had to review was not covered anywhere in the course but in retrospect I think it is a rather specialized area that is probably not covered in general undergraduate courses. It was to do with Velocity Ellipsoids and digging into that takes you into deeper mathematics like Tensors also not covered in the course. But it is stated that for Level 5 modules some independent work will be needed - I personally don't think this should put you off. For the "Energy Matter and the Universe" course the maths and physics required is covered in the course materials. My favorite course is tough to say. I liked "Introduction to Cosmology" and next probably "Energy Matter and the Universe". Even "Sun Earth and Climate" which I was initially lukewarm towards because I thought it was least astronomy related, I ended up enjoying. All the best.
  18. Well, regarding how much physics and math you end up getting from the 'Energy, Matter and the Universe' course, while I am unfamiliar with the A level I have seen some of the International Baccalaureate (IB) courses my daughter had been doing which I understand are of a similar level. So the physics will be at the same kind of level as the IB Higher Level (there is also standard level), The mathematics though I believe might be on a slightly lower level than the IB Higher Level mathematics. In the 'Milky Way' course we had to review some papers and the mathematics in some of them was beyond the levels I had encountered in any of the courses. On the texts books I can't say much as I did not use them. I mostly used the course notes and resources on the Internet as it is not very strait forward accessing them or purchasing them where I am. In fact I ended up purchasing the recommended texts only for the first two courses. Some of the others were available online in the UCLAN library, otherwise I made do with the course notes and other Internet resources - though it might not be ideal. My own opinion would be that some mathematics beyond that covered by the above course would be a great advantage - for example differential equations, probability and statistics etc. Finally in 'Investigations in Astronomy' you choose one from five or six topics to write up. I would agree that it gives a good foundation in scientific writing and research skill, my reservation was that you learn what your mistakes were when you receive your graded feedback and there is no further chance to correct these in a subsequent assignment - which might be significant if you are concerned about getting good grades. Three courses a year is okay I think if you are not in a demanding full time job. I hope this information is helpful. Best
  19. Hi Newbiestargazer, If you are completely new to astronomy I am not sure it is a good idea to dive strait into astro-photography. It might be better to do some visual astronomy even with a pair of medium binoculars to familiarize yourself with the night sky and the objects that will be of interest to you. The gear you use for astrophotography is different for planets and so called deep sky objects for example, or if you want to do wide field vs galaxies or globular clusters. Also if you already have a DSLR and all you want to do is wide field stuff you may not even need a telescope - you might be happy with a tracking mount like the Star Adventurer with a suitable lens. Welcome to the hobby!
  20. I have completed 8 courses, currently on my ninth. Here is the list... Introduction to Astronomy, Introduction to Cosmology, IT for Astronomy, Energy Matter and the Universe, Investigations in Astronomy, Sun Earth and Climate, Introduction to Astrobiology, The Milky Way and finally Ultraviolet, Optical and Infrared Astronomy. The last which I am currently doing. Some of them require the first two as a prerequisite. I have really enjoyed all them - the course materials are fantastic. The instructors when needed are responsive on the forums. I intend to go as far as I can to the extent my time and resources allow. Best
  21. Hi Kadersin, While I have no experience with the NexStar 6SE, I have used the PowerSeeker 127 and I have no doubt that it would be a worthwhile upgrade. Just the stability and goto features of the mount will give a much improved observing experience. You will need to factor in getting better eyepieces though if all you have are those that came with the PowerSeeker. Cheers!
  22. That is strange isn't it? H-alpha is red so they should work best at that wavelength.
  23. I was thinking, does an apo produce better images than an achromatic refractor for narrow band imaging? Chromatic aberration should not be an issue for NB but I read somewhere that for apo's spherical aberration is corrected for two wavelengths vs one for achromats. Cheers!
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