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pregulla

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Posts posted by pregulla

  1. I would think it won't make much of a difference. Shorter focal length will allow you to reach lower magnifications and wider field. It will make the object brighter but also the sky background, so no much help on visibility. For most object optimal magnification will be within range of your SCT.

    Smaller central obstruction of reflector over SCT may help somewhat with contrast, then F/6 or slower should theoretically have better contrast, but I am not sure how noticeable will it be in practice.

    • Thanks 1
  2. On 23/01/2021 at 20:08, Sluke321 said:

    Are you sure they were genuine items? 
     

     

    I was able to register them on ES site.  They also perform optically as you would expect from ES eyepieces - sharp almost to the edge and have perfect fit and finish. The astronomy market is too small to set up a line for fake ES eyepieces that would not be obviously fake. 

    Bottom line -  I am sure these are genuine.

  3. I have bought quite a lot of stuff from them. Including few ES eyepieces and some miscellaneous stuff. I had a good luck for the most part. One ES eyepiece had a spec on field lens that didn't seem to impact performance and I got a 30% partial refund. Another eyepiece had optical defect and I returned it for a full refund, AliExpress paid the shipping. 

    So there is a risk of getting a QC reject for ES stuff, but on some items the price difference makes up for the risk (some eyepieces I got for less than half of what I would have cost me from EU/US stores). I would first look for sellers that offer free return, not all of them do, then if item is not good you just return it and all you have lost is time.

  4. It all depends on your budget, preferences, observing targets etc. There is no single answer on what should you get.

    2" eyepieces offer larger field of view at longer focal lengths, there is no difference in performance in shorter ones.

    I would suggest adding 2" eyepiece in 30mm+ range, for wide filed low power view and as a finder eyepiece. It also quite different experience compared to stock plossls. There are a lot of options depending on your budget from Panaviews to Naglers.

    When you don't know what to buy, a zoom + 2x barlow is a good option. It gets you covered until you figure out what your preferences are.

  5. I started by purchasing a low power 2" eyepiece, a zoom and a 2x barlow. That had my needs covered for a while and I didn't feel the urge to add anything else until I figured out what my preferences are.

    I would recommend something in the 30mm+ range, like PanaView or Aero ED and Hyperflex 7.2-21.5mm zoom. I would also highly recommend getting a red dot (or Rigel/Telrad) + RACI finder. Makes starhopping much more comfortable. 

    • Like 1
  6. Only above certain focal length 2" eyepieces offer larger field of view. For example if you want 82 degrees apparent field of view than for eyepieces with longer focal length than about 17mm you will need 2", if you want 70 degrees - than roughly above 24mm you need 2". At shorter focal lengths 2" or 1.25" by itself doesn't make a difference. 

    • Like 1
  7. If only one I would pick a zoom eyepiece. For lunar and planets you want to be able to select magnification based on atmospheric conditions, if you can't have multiple eyepieces zoom would be the best (even if you can, some people still prefer zoom). I use Hyperflex 7.2 - 21.5mm + 2x Barlow for Moon and planets.

  8. I wouldn't recommend either of these 2. 82mm Lightbridge has very fast shperical mirror - which mean it has not so great optical qualitry and very large central obstruction (secondary mirror covering large part of the aperture). CELESTRON SCTW-80 is very short achromatic refractor, it will show a lot of chromatic aberration at higher powers. The Moon will probably be bearable, but the planets will be colorful disks. It also seems to come on photo tripod - winch will make it very shaky and frustrating to use for anything other than lowest powers.

    If you want to spend minimum amount of money possible I would recommend 70mm F/10 achromat. It will have very little chromatic aberration and will perform much  better than the two you have suggested. If you can stretch you budget a little more I would highly recommend getting something like SkyWatcher Heritage 130p or other 130mm table top dob.

    • Like 2
  9. I have the 35mm Aero ED and very happy with it in my F/5 scopes. It is not perfect, but for given size and weight (350g) I don't think you can get any better. It is a compromise I am willing to make. I also own ES82 30mm and even though it's better corrected and offers wider AFoV I just don't use it that often because of it's size and weight (over 1kg - almost exactly 3x Aero ED weight) . Another 2" eyepiece in that range I have owned was SW SWA70 32mm and it performed significantly worse at 8" F/6 (what I had back then).

    • Like 3
  10. There isn't much of a choice for under £30. I would suggest getting HyperFlex 7.2-21.5mm zoom. It costs more than £30, but covers entire range. At higher powers you get wider field of view, at the 21m end it is going to be a little narrower than a plossl. I would also add 32mm plossl for the widest field. 

    A little more expensive option for a bit wider field would be StarGuider series.

  11. Just got MaxVision 6.7mm from AliExpress. The build quality seems to be the same as my ES eyepieces. After a quick look in 8" f/6 dob I didn't see any optical faws either. The stars are sharp almost to the edge.

    As far as I can tell these are the budget version of ES82. Not sealed and with undercuts rather than taper.

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  12. The advantages of 102mm Mak would be that it's more light and compact, suitable for terrestrial observing, and because of slower focal ratio will perform better with simpler eyepieces. If small size and daytime use are high priority, than it is probably a better choice.

    For 130mm newt goes larger aperture, and much wider maximum field of view , because of it's shorter focal length and 2" focuser (4.1 degress max TFOV vs 1.2 degrees for 102mm Mak). So it would be a better choice for astronomy. If the person decides to upgrade later it can be a nice complimentary scope to a larger DOB for low power views and quick grab and go.

    Zooms can be as good as separate eyepieces, depends on price point both. I would say that Celestron/Svbony/Hyperflex zoom is a good alternative to plossls or stock eyepieces that come with scopes. Main drawback is narrower field of view at higher focal length end. I still prefer zoom for moon and planets.
    If you can only afford one eyepiece I agree that Starguider/SW UWA can be a good choice. I would go for something like 5mm, to get that extra magnification for planets.

  13. 2 minutes ago, Neil H said:

     I was told that the 7 to 21 is not a good zoom to get the 8 to 24 is the better one my works well thats why they cost more no one gets the 7 to 21  i use my with a bst  x2 barlow never has a problem with image always sharp focus

    Celestron 7-21 is indeed worse than 8-24mm, but there are other 7-21 zoom eyepieces that are fine. I was talking about Hyperflex 7.1-21.5, shorter focal length will allow some extra magnification without using a barlow.

    • Like 1
  14. I guess the problem is the switch from dob to 70mm refractor. Everything is going to look small or dim or both in comparison.

    The barlow that came with the scope is probably of poor quality. Pair it with not the best eyepieces and high powers and you won't see much.

    4mm is too much magnification for that scope as well.

    32mm plossl and 7.1-21.5mm zoom should be a good starting set, and may be everything you need.

     

  15. I use 40mm long 2" extension tube + low profile 2" to 1.25" adapter, about 10mm tall. All my 2" and 1.25" come to focus, 35mm would work too, 50mm is too much.

    BTW brass compression ring doesn't help to center the eyepiece, it just prevents the screw from leaving marks on the barrel, it even may hold some eyepieces with undercuts worse than just a screw

  16. An update after using it for a while. For my purposes (low power wide field) AZ3 was solid enough to carry the 120mm. I added an angled arm with removable counterweight - that solved the diving near zenith issue and made the mount pretty usable, but I still needed to move the tube when going from lower to higher altitudes. 

    Still I am glad I didn't go for AZ4 or AZ5 as I recently scored a used Berlebach Uni17 with GR-III head for comparable price - this thing is super smooth and solid and a pleasure to use.

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