Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Rocket_the_Raccoon

Members
  • Content Count

    103
  • Joined

  • Last visited

Posts posted by Rocket_the_Raccoon


  1. 13 hours ago, SIDO said:

    Those are some nice upgrades, I have made a ton of mods to my favorite achromatic refractor and its still ongoing, like the new rings and dovetail...now your ready for most any mount you come across.

    Thanks, I personally is a fan of refractors, especially for slow ones like this. It is unfortunate that they are not made any more (at least not in large enough volumes to be affordable). And yes, the new rings and dovetails made balancing possible on any mount. The original fixed dovetail is so limited but it does act effectively as a balance weight in this particular setup.

    • Like 1

  2. 14 hours ago, Demonperformer said:

    Great improvements.

    How do you find the tripod? From the pics it looks very similar to the one that comes with the 102, which I always found to be a very weak point of the system. I found it was improved greatly by rigging a means of hanging a weight from the centre of the tray, lowering the centre of gravity.

    Thanks. As for the tripod, which 102 are you referring to? This particular one comes with the scope and has a design flaw that the metal rod/handle sits above the altitude axis, making the setup almost always back-heavy. This was mentioned in my review of the scope in an earlier post. For this reason, the dovetail and tube rings were used so that I can balance the OTA. Lastly, hanging a weight from the tray centre is indeed a good way to stabilize the whole setup but as currently, vibrations pretty much die down within 2 seconds even at 112x, I had simply skipped this step. 



  3. 20181004_121410-01.jpeg.c3cfb7018997db3c63479eb23ffa2dfa.jpeg     20181004_121524-02.jpeg.017e8ce5bc24b87b4f6309f61cac3721.jpeg     

    A little more than a year ago, I acquired this 70mm f/13 long refractor for merely $40CAD and wrote a quick review on it
    https://stargazerslounge.com/topic/295880-celestron-astromaster-70az-review-and-improvements/?tab=comments#comment-3239177

    Recently I have made some further improvements on the scope to create a quick and lazy observing setup for me :
    - dovetails and tube rings for balancing the OTA, note that the tube is smaller than the standard 76mm ID tube rings and thus requires ~2 layers of felt pads for a tight fit.
    - Celestron prism star diagonal replacing the low-quality and stopped down Amici prism
    - 6x30 finderscope replacing the hard-to-use star-pointer, also better suited for a light-polluted sky, finderscope base was super-glued to the OTA instead of drilling holes.
    - because of the f/13 ratio, the stock 20mm and 10mm both perform very well
    - added a Meade 12.4mm Plossl for nights with only fair seeing
    - added a 1st generation 8mm Brandon for nights with good seeing
    - added a homemade 33mm for DSO's, TFOV 1.6 degrees (stock 20mm gives 1.27 degrees), please see https://stargazerslounge.com/topic/314649-diy-6-element-33mm-eyepiece/?tab=comments#comment-3441384
    - added a Skywatcher Crystalview Moon filter for obersving the full moon with the stock 20mm, also for slightly enhanced views of bright nebulas.

     20180930_201828-01.jpeg.79e87aa1c8e197c74674d719e9e993bc.jpeg

     

     

    • Like 3

  4. 9 hours ago, happy-kat said:

    Have you tried mounting the telescope like the below image. It crudely separates azimuth from altitude adjustment rather than rolling the ball head around. 

    That's indeed a good idea. I should give it a try once the night sky clears up. Unfortunately, rainy season just started over here in south western Canada.


  5. 20180905_121843-01.thumb.jpeg.a27fa8555a0149f5219cbd2951f7e6d5.jpeg      20180905_122716-01.thumb.jpeg.a03c1a1d145fb59ceb53465f83f12e76.jpeg      20180905_122221-01.thumb.jpeg.03c9b1c846bbef9932e065ca0afc9b1a.jpeg

    About 4 months ago, I brought a $20 trash scope (50mm f/7) back to a usable state at minimal cost, it was posted here : https://stargazerslounge.com/topic/315129-removing-the-trash-from-a-trash-scope-trash-panda/. Recently, I made two "improvements" on it. First of all, I added a "screw eye" on the hood to align with the L-bracket on the tube to make the "finder" more accurate. The adjustment/alignment is done but rotating the hood and screw eye itself. Next, I replaced the 45-degree hybrid-diagonal, which I found to be extremely difficult to use for astronomy, with a .965" 90-degree mirror diagonal that I scavenged from a $5 toy telescope (single-element objective, a "real" toy). I then use the .965"-1.25" adapter that was included with the 50mm in order to use 1.25" eyepieces with a .965" diagonal. Note that both the .965" mirror diagonal and the .965"-1.25" adapter have a 20mm opening instead of a full 24.5mm. Thus, my TFOV will be limited to 3.18 degrees. Fortunately, my Celestron 20mm eyepiece has a field lens of the same diameter so no field is wasted.

    The result, despite the mirror diagonal coming from a toy scope, is pretty good. No light-scattering is visible and the mirror seems to be well-aligned. Images are just as bright as the prism and of course, a 90-degree viewing angle is certainly more comfortable to use than the 45-degree one. Well, now I have an ultra portable carry-along or ever-ready-in-the-trunk scope.

       

    • Like 2

  6. If I have not mistaken, the Firstscope 80 is a 80mm f/11 and the ST80 is a 80mm f/5. Are you doing traditional manual guiding with a cross-hair eyepiece? or going digital guiding? The Firstscope 80 being a long refractor puts more load on your mount and you would need more effort to balance the whole imaing scope and guide scope setup. However, its long focal length is a plus for high magnification if you are using visual manual guiding,


  7. On 03/08/2018 at 04:47, Alex_o0 said:

    Would this be a suitable first telescope , I hope to be able to make out the rings of Saturn using stock the Eyepiece.

    Or would this be considered overkill and something like the Celestron 21035 70mm Travel Scope be more suitable.

    Hi! Alex, both can show you the ring of Saturn but at 40x (10mm EP with the Travelscope 70), Saturn will be a bit tiny. 65x (10mm EP wtih the Heritage 130) is more appropriate.

    Also, the Travelscope 70 comes with a photo trpod that would have problem supporting even a small point-and-shoot camera. It also comes with a non-achromatic 5x24mm finderscope and a 45-degree diagonal that is not intended/suitable for astronomy use. The Heritage 130 is a clear winner.

    Despite that, I am a proud user of Travelscope 70. The quality of its little 70mm objective lens is amazing for the price.  However, I use it with a red-dot finder, a 90-degree diagonal, and an heavy duty (for this scope) equatorial mount.

    • Like 1
    • Thanks 1

  8. 20180617_171248-01.thumb.jpeg.5bfbda2fbdcdf5fd078728403d9f0171.jpeg

    One of the two .965" eyepieces that I still have (the other being a Circle-V K40mm). Both of them I enjoyed using on my 60mm f/15 refractor with .965" focuser which I no longer have.

    3~4 years ago I made a temporary modification for this eyepiece so that I can use it on my current scopes with 1.25" focuser. However, it was kind of ugly and the eyecup was too long for the eye relieft of this 6mm Orthoscopic. So I took my .965" eyepiece projection adapter and a 1.25" eyepiece barrel from a H20mm to make this .965" to 1.25" adapter. 

    20180617_171323-01.thumb.jpeg.eda6f532fc43faa9f5bdc428ea78ab16.jpeg

    • Like 2

  9. 1 hour ago, cuivenion said:

    Nice post. Regarding the baffles could it not be on attempt to limit reflections. From my admittedly meagre knowledge of optics the cone of light will narrow as it travels down the tube, so the baffles you mentioned may not be necessarily limiting it's aperture. It would depend on the placement of the baffles of course, and the size of the light cone at the baffle points.

    Thank you, Cuivenion. You are right about the baffles. It is just an individual case that the two baffles of this scope has a severe "side effect" of limiting its aperture while not doing a much a job in limiting internal reflections. Of course, to be sure, one needs to do a trace diagram of the objective lens. ?

    • Like 1

  10. 20180527_222832-02.jpeg.b4795f5a88316aa62ad7d72c4d518ee8.jpeg

    I bought this Celestron Travelscope 50 for $20CAD, primarily for the two 1.25" eyepiece barrels that I can scavenge for my DIY eyepiece projects. I have seen and used "bad" telescopes before but it was never as bad as this one. Though a 50mm f/7 achromatic objective should show minimal to undetectable chromatic aberrations (CA) according to the 1.22D rule, Celestron still put a ~30mm baffle in the tube and worst, a ~5mm baffle inside the focuser! One can almost call this a CA-phobic scope. To make this "trash scope" usable, first thing to do is of course removing the two baffles. The one in the telescope tube is easy to deal with and I would suggest removing the focuser to get access to this baffle instead of removing the lens cell (to avoid possible mis-collimation). The removal will leave some bare metal marks and they need to be repainted with flat black paint (I uses Tamiya XF-1 acrylic model paint). The focuser baffle seems to be moulded as one piece with the focuser itself but it is not. It is just a very tight fit and can be removed by "force" but one needs to remove the focuser first. This also exposes the roots of the two finder bracket retaining screws and thus serves as a good time for any finder modification. After that, the inside of the focuser barrel MUST be painted flat black as it is unusably shiny. To improve image contrast, the objective lens can be removed then have its edge darkened by a black marker. This can be done by taking out the hood and unscrewing the retaining ring without the need of removing the whole lens cell. As the objective lens is not exactly tight fit (horizontally) inside the cell, a narrow piece of chalkboard sticker can be placed between the lens and the cell wall to fill the gap. Finally, when putting back the objective lens into the cell, the 3 spacers between the two lens elements of the achromatic objective should be aligned with the 3 screws that hold the lens cell and the tube together. At this point, the scope has become much more usable than its stock form but there are other improvements that can be done.

    20180527_222705-01-01.jpeg.9a478ceba0ede07164392b9191feeeee.jpeg     20180528_151035-01.jpeg.5dea5b94e7e716641bd14ac60d154f2b.jpeg     20180527_225430-01.jpeg.0595d82c8c74a25bc53bf6708241c96a.jpeg

    The stock finder is basically useless. It is even worse than a 5x24. I have a DIY 21mm achromatic finder but unfortunately the bracket is too tiny to fit it. Given I have an extra Vixen-style dovetail finder bracket, I might just put it on the tube and borrow a finder from my other scopes but I don’t so I simply use a L-shape corner brace (left image above) to make a peep-hole. It is of course far from accurate but it is usable at very low power, with which the 360mm focal length of the scope and my DIY 33mm eyepiece (middle image above) can give. I have two other DIY eyepieces (right image above) and they are both good companions with this little 50mm. One is an 18mm “traditional” Kellner scavenged from an old pair of 10x50 binoculars. I think it is based on the original optical formula because it has pretty tight eye-relief for an 18mm and a relatively narrow field (still way wider than the two stock Huygens, of course). Another one is a 10mm 1-2 König scavenged from a pair of 10x25. I have another post written for this nice little eyepiece here:

    With the above additional modifications on finder and eyepieces, the scope has now been improved to a point that any further advancement would require a new purchase. However, I just love the extreme portability of this scope so I might buy a cheap 1.25" star diagonal (as the scope includes a .965"-1.25" adapter, I do not have to buy a hybrid) just for it as I found the stock 45 degree hybrid, though not bad in quality, gives very odd viewing angles for anything 30 degrees above the horizon. Finally, to make an “one and for all” decisive improvement for this scope is to replace its .965” focuser to a 1.25” one. The AFOV of my 33mm eyepiece is not just now limited by the .965” focuser but also the 20mm opening of the hybrid diagonal. Having a 1.25” focuser and a full aperture star diagonal, the 33mm eyepiece would give a spacious 4 degrees of field.

    20180527_225407-01.jpeg.d76b8e3bf7a6ab945dcdfe4107fa7f90.jpeg     20180527_223359-01.jpeg.8e4cc99cd82b50dee3816b00f6e9a568.jpeg

    As for the "mount", I replaced the included super filmsy tripod with my portable photo tripod. Because the scope is extremely light, the ball head tension can be tightened to point that it gives smooth motions. At 40x, it takes only ~2 seconds for image to stop vibrating. Below is a handheld cellphone photo of the moon taken through this scope using the 10mm 1-2 König.

    20180524_204728-01-01-01.thumb.jpeg.9c8897cfbbea0d360ccda1a9edd63efb.jpeg

    • Like 2

  11. 16 hours ago, kingbo37 said:

    I had thought of spending a little more and getting a zoom lens, but wasn't sure how good they were across the ranges,

    The Skywatcher 8-24mm is pretty good according to 

    http://astro-okulare.de/English/indexe.htm

    I believe it is the same as the Celestron and Orion 8-24mm. It might even be under other brand names too. The drawback of course, as stated, is the narrow field of view at the 24mm end but you have a 25mm anyway. 

    16 hours ago, kingbo37 said:

    Initially I will stick to planetary, but obviously want to see some deep sky stuff too.

    If you are into DIY and can obtain old compact binoculars at very low price (e.g. charity shops, items that collecting dusts at home, ...), you might want to consider making a 33mm eyepiece like what I did in:

     


  12. 23 hours ago, Alan64 said:

    The EQ-1 is too small, however, to carry about a 70mm f/13 achromat.  Instead, I'll be placing my vintage 50mm f/12 achromat on it, and what I call "The Floating Achromat"...

    large.IMG-20170821-WA0022-01.jpeg.87af2182104af5285b62fd4bee885c1a.jpeg   I place my 70mm f/13 (also an Astromaster) on an Orion version of CG-4...and I used the Astromaster AZ mount with my 70mm f/5.7 as a grab-and-go combo.

    23 hours ago, Alan64 said:

    Sears(Towa) #4-6340 50mm f/12, Sears(Tanzutsu) 60mm f/15

    My first telescope is a 50mm f/12 but it is a Tasco and I used to have a 60mm f/15 which gave superb views even at 150x. I loves long refractors, too bad they are not made (as least not within my budget) anymore.

    • Like 1

  13. Greetings, kingbo37.

    Your next purchase on eyepieces really depends on what are your intended observation targets. For planets, you needs on-axis sharpness, contrast, and brightness more than edge performance and field width. Thus, you could save some money by buying short focal length eyepieces of simpler designs (e.g. Abbe Ortho, Plossl, or even a Kellner). In fact, I strongly suggest you patiently wait for the best seeing (atmospheric condition) and try out your 10mm stock eyepiece, which I assume is 

     If you don't mind the risk of disassembling it, darkening the lens edges should help enhancing the contrast which is essential in planetary viewing. On the other hand, a good 2x barlow is also a good investment for a short focal length telescope like yours.

    If you want a wider field than your 25mm can give to hunt for deep sky objects and to do wide field scanning, then you can go for a 32mm Plossl which gives you a field of ~0.45 degrees wider without spending a lot. The edge performance (sharpness, distortion, etc.) from a Plossl won't be first-class as you have a fast f/5 objective mirror. To get a wider field than this, you will need to go for a 2" eyepiece (I believe your scope has a 2" focuser) and it will be much more expensive. One thing worth noting is as your Newtonian has a central obstruction from the secondary mirror, there is a limit on the longest focal length eyepiece you can use but I do not know how to calculate this.

    Finally, enjoy your telescope and wishing you clear skies! 


  14. 5b02436026cf4_ScreenShot2018-05-09at12_24_10AM.png.95bc10c925928c2fd16703b0f45ac6e5.png

    Béla Szentmártoni (1931-88) was a Hungarian amateur astronomer and telescope maker. He founded the Albireo Amateur Astronomy Club in 1971 and have made one hundred mirrors ranging from 4" to 10". On the August 1967 issue of Sky and Telescope (http://alpha.dfmk.hu/~albireo/szm/skylap.gif), he published his making of a 6" rich-field Newtonian with an eyepiece design of his own, giving a TFOV of 1.5 degrees. The original Szentmártoni eyepiece formula consisted of 3 doublets, all with a focal length of 65mm. The spacing of the field group elements is 2mm while the spacing between the field group and the eye lens is 4mm. The modified version above retains the basic orientation of the 3 doublets and spacing ratio of 1:2. However, the focal lengths and actual spacings are different (as shown in the diagram). 
    ( Further Info : https://hu.wikipedia.org/wiki/Szentmártoni_Béla , http://alpha.dfmk.hu/~albireo/szm/atm.htm )

    Using the 3-lens formula from http://www.astronomyboy.com/eyepieces/ep_calc.shtml, the EFL of this modified version is 33mm. The TFOV is calculated by (field stop / objective focal length) x 57.3, which is then used to obtained the AFOV based on the EFL, AFOV = TFOV x (objective focal length / EFL of eyepiece). Finally, eye relief is calculated based on AFOV and the 7mm human pupil size using the formula from http://www.mira.org/ascc/pages/lectures/fabform.htm.

    For a 1.25" 33mm eyepiece, an AFOV of 43 degree is not considered wide in today's standard. However, one have to note that the AFOV of any eyepiece is limited by the size of its field stop and many 1.25"  eyepieces in the 30~32mm range have smaller AFOVs than specified. For example, Baader Classic Plossl 32mm has an AFOV of ~47 degrees (https://stargazerslounge.com/topic/179005-baader-classic-32mm-plossl-meets-vixen-30mm-npl-plossl/) and the Skywatcher Super Plossl 32mm has an AFOV of 43 degree (http://astro-okulare.de/English/skysp32e.htm).

    As for image quality, this 33mm Modified Szentmártoni is not just sharp but also sharp to the edge without distortion on my f/5.7 refractor. I believe it will pretty much replace my veteran Omcon 25mm Plossl (Celestron silver-top equivalent. fully coated only) as a great finder eyepiece and an indispensable accessory to enjoy rich star fields.

    20180509_191025-01.jpeg.9b6e6f30ecf74048ee2c36ca8afb07ba.jpeg20180315_210337-01-01.jpeg.2d391d566e5b8384e081e3b9b9eba951.jpeg20180324_192747-01.thumb.jpg.08b421f657e950fd9f522c1b28695445.jpg

    Ingredients :
    - two 25mm doublets with focal lengths of 100mm scavenged from a pair of 10x25mm compact binoculars
    - one 21mm doublet with focal length of 80mm scavenged from a pair of 8x21mm compact binoculars
    - plastic objective retention ring from the 10x25mm binoculars as the spacer of the two 25mm doublets (field group)
    - plastic part from the eyepiece of an old 10x50mm binoculars as the eyepiece top that holds the 21mm doublet (eye lens)
    - 1" copper pipe coupler as eyepiece outer barrel
    - metal ring from the StarPointer of a Celestron Astromaster 70AZ (intended to be the field stop, not used)
    - rubber eyecup from another eyepiece (not used)
    - rubber eyecup from an old pair of 10x50mm binoculars
    - chalkboard stickers to make the inner barrel of the eyepiece and for fitting elements with different diameters
    - E6000 crafting glue 
    - black marker pen for darkening the edges of the doublets


    20180322_201322-01.jpeg.e14750baa8b2aece9df2e54c0a7c8e08.jpeg20180322_201441-01.jpeg.651f29575a59ea99b5cf1a4c2e0b43f9.jpeg20180322_224934-01.jpeg.180ec5de60b75c411012ba9454702e4b.jpeg20180326_121458-01.jpeg.9016f5e27c670a586ed78ca6c1acbe35.jpeg

    Lessons Learned :
    - Though the total time needed to build the eyepiece is less than an hour, I spilt it up to several days in order to let the E6000 glue fully dried.
    - When glueing a lens to a plastic part, the glue should be put on the edge of the lens, not the plastic, to avoid excessive glue spreading onto the lens surface.
    - The use of an internal eyepiece barrel enables more precise placement of the field group and avoids the mess of glueing the field group to the copper barrel.
    - The chalkboard sticker, which was rolled up to make the internal barrel, took out the need of painting the inside of the eyepiece with flat-black paint.


    20180509_191012-01.jpeg.97a9aa2c9bfc876fac9bfd66ac58a388.jpeg   My DIY Eyepiece Set : 33mm, 18mm, and 10mm

     

    • Like 5

  15. 18 hours ago, Krisko said:

    Thanks,Ph

    Thank you !

    Last night i go out , and tried to watch Jupiter. I found it , but the problem was i was not able to see it with types of colors. I only see Jupiter in one color. Also when i looked at the moon, my eye start hurts , the light was really irritating my eye , and i could not see details on moon , only irritating eye and nothing more... :/

    Just like LukeSkywatcher said, you need a moon filter for viewing the moon comfortably.

    As for Jupiter, I believe it was just bad "seeing"  (atmospheric condition). Bad seeing can make planetary images blurry and featureless even on a telescope larger than yours. A few nights ago. I saw the clearest and sharpest view I have ever seen with my 70m at 111x. About half an hour before that, Jupiter was featureless at the same magnification. 

    • Like 1

  16. On 2018-05-09 at 13:49, Krisko said:

    Thank you, but i bought Astro Master 90eq , hope its better :p

    Congratulation! Your equatorial mount (a Celestron version of EQ-2) will give you far better slow motion capability than the Astromaster AZ mount.

    FYI, if you ever find the high power view from your 10mm eyepiece unsatisfactory, it might very possibly be the "ball-shape" diagonal to blame, not the eyepiece.

    I have a review on the Astromaster 70AZ which talks about this issue:

     

    • Like 2

  17. On 2018-05-12 at 02:40, domstar said:

    Actually, the 3x Barlow was usable on Jupiter with my 70mm scope and H20 eyepiece. I even saw the bands. Not the best views I've ever seen but at the time it (literally :happy11:) knocked my socks off.

    It could be the barlow has increased the focal ratio of the telescope to a point that the H 20mm performed obviously better than on its own. When Christiaan Huygens designed his eyepiece in 1662, telescopes had far slower focal ratios than the f/10~f/15 of today's long archomatic refractors.


  18. No matter you are going for the "one scope for all" or "two scopes" appproach, I would suggest go for a portable short refractor (the ED80 mentioned in the replies) first. My point of view is a 80mm that got used a lot is better than an 8" sitting at home indoor. 

    I have a short (f/5.7) refractor, a long (f/13) refractor, a light-weight alt-azimuth mount and an entry-level imaging equatorial mount. I found myself, using the short refractor more mainly because of its portability and ease of setup. For ocassional high magnification with the short refractor, I uses a Meade 3x barlow with my 10mm Plossl.


  19. 7 hours ago, John said:

    Good stuff Rocket

    Thank you!

    7 hours ago, John said:

    Way back when I had my 1960's Tasco 60mm refractor I realised that the stock hygens 1 inch eyepieces were pretty limited and I wanted a wider field so I nicked the eyepiece from our family pair of 8x30 binoculars. A bit of tape around the barrell to make it fit the diagonal socket and I had a Kellner or Achromatic Ramsden (never sure which it was) of around 17mm focal length but with no field stop fitted so an apparent field of around 60 degrees I guess. At last I could see clusters, the Orion Nebula etc in a decently wide field. The Tasco was F/13.3 so the edges of the FoV were not too bad...

    Almost all long 60mm refractors have above average objective lenses. I used to own a f/15 and I still remembered the view of the Trapezium at the heart of M42 at 150x with a 6mm Ortho.

    Also, I have a similar DIY ~18mm eyepiece like yours, scavanged from an old 10x50mm binoculars but mine is not wide field, possibly a Kellner. It actually has better edge sharpness than my Celestron 3-element 20mm (1-2 modified König) on my f/5.7 refractor.

    20180509_191214-01.thumb.jpeg.ef5b0be5351043687314d3c399fcba16.jpeg


  20. 8 hours ago, timwetherell said:

    Great to see someone experimenting with optics! It's a lot of fun and can yield some surprisingly good results :) 

    Thanks and yes, I was surprised how well the eyepiece performs given its cost. I have also made a DIY 33mm but instead of scavanged from binoculars eyepiece, it was built from scratch with binoculars objective lenses. I am in the process of some final performance testing and will write up a post once it is done.

    8 hours ago, timwetherell said:

    I have an old Erfle 20mm scavenged from something like a gun sight? Back when I had my little 60mm refractor...

    I think some of the wide -field binculars use Erfle eyepieces too.

    8 hours ago, timwetherell said:

    My Erfle isn't particularly brilliant optically compared to modern offerings but it has a high nostalgia value!

    Indeed! I treasure my DIY eyepieces despite their costs, it is the efforts and accomplishments that matter.

    • Like 1
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.