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By Gary Shaw
Hi All I’m considering purchasing an 8”aperture, f3.8 newtonian ( primarily for EAA) from Orion UK and would appreciate any input or feedback from anyone familiar with the product, the company or the purchasing process - and how to assess the compatibility with my current cameras.
This is would be a step up from my current equipment and entails selecting components that I’ve never used and know little about such as a rack and pinion focuser and components (ACU-3L), and coma corrector (Wynne Corrector). I’ve added links to these items below. I’m also feeling unsure of how to mate up my Zwo 178 and 294 cameras to the 3” focuser and whether there will be an acceptable match between the scope optics and my sensors.
I’m sure the folks at Orion UK will assist with all this but I’d sure welcome input from the Stargazer's Lounge community before starting the dialog with Orion UK.
thank you in advance for any help you can provide!
ACU-3L Focuser selection Info: https://www.orionopt...sers.html#ACU3L
Wynne Corrector selection Info: https://www.orionopt...torsfittin.html
Hope someone with more experience than I, which basically means anyone that has successfully collimated a Newtonian, can answer a couple of compound questions I have based on my first and only attempt at secondary collimation of my SkyWatcher Flextube 250.
1) All three of my secondary collimation screws were extremely snug before I did anything and I was only able to comfortably turn them counter-clockwise. Is this normal? Do I need to loosen all three screws first before I can properly start collimation? Should I be turning any screw beyond "snug"?
2) Before collimating, I placed a yellow sheet inside my OTA opposite my focuser tube and I placed a red sheet between my secondary and primary. The view this gave through my focuser tube was of a red circle surrounded by a partial yellow ring (the secondary mirror stalk blocking a portion of this yellow annulus). While independently turning each of the secondary collimation screws counter-clockwise I looked down the focuser tube (both with and without a sight tube installed) expecting to see some change in the shape of the red area (more or less circular) and/or the yellow area (less or more even thickness). I turned the screws no more that 2 complete revolutions. I did not perceive any appreciable difference in what I saw and I turned each screw back (clockwise) to their original tightness before working with another of the screws. Does it make sense that I didn't perceive any change? Should I have turned the screws more revolutions? Should I have loosened more than one at a time?
Very confused and looking for your help. Thanks
Hi! I am very new to SGL (just signed up a couple of mins earlier) and to astronomy as well, though I have been facinated with celestial bodies since I can remember. I recently purchased a Celestron Powerseeker 127EQ but now I’m having troubles using it and I can’t seem to see anything through it. I also have a Celestron collimating eyepiece but I still can’t seem to make it work. Anyone here who has experience with the same scope? Would appreciate if we could chat a bit as I would be really interested in your experience and how you ultimately made it work!
I recently had to move from my residence and amongst the items in my store was the first telescope I had ever used. It as a Celestron FirstScope 114 that is no longer in production, a 4.5 inch f8 classic newtonian. Unlike the current model PowerSeeker 114, it has a EQ2 mount rather than an EQ1, and a red dot finder instead of the unusable 6X30 plastic unit on the PowerSeeker. So after probably a dozen years since last using it I decided it might be interesting to put it through its paces. I fondly recall seeing things like the polar ice cap on Mars at opposition, the GRS spot on Jupiter, the Cassini Division on Saturn and some deep sky objects like M7, the Double Cluster, the M81 M82 pair and a lot of more with this scope. After using a CPC 1100 almost exclusively since, I wanted to confirm to myself that I had really seen those object through the scope.
The carton it was packed in was not completely sealed so it was covered with a great deal of dust. Looking down at the primary I could see some dark smudges - I didn't know if it was dirt or deterioration of the aluminum coating but luckily very little dust. I decided I would try the scope out before attempting to dismantle and do anything with the mirror.
I cleaned it up the best I could and assembled it with more difficulty than I recalled having in the past. I used to keep it fully assembled with the latitude set at 9 degrees, the counterweight midway between two of the tripod legs and set it down with the polar axis roughly pointing North. I found that this way a could track an object with the RA slow motion control with only occasionally having to adjust the Declination. I tried to do the same this time but was constrained by having to set up on a narrow balcony rather than on the open ground.
After having to wait a few day for the unseasonal clouds to clear (It looks like the bad weather issue also applies when you resurrect an old scope?) first target (Drum roll!!!) Albireo which was high up in the eavening sky. I had difficulty finding the target - I guess it was too much to hope that the battery in the red dot finder would still be alive after a dozen years. Using a 20mm eyepiece that came with a Celestron 102SLT I anxiously searched around and after a few minutes located the unmistakable colorful pair. Encouraged I switched to a 9mm eyepiece from the Celestron Eyepiece and Filter kit - and I must say I was pleased. At 100X the image was sharp and somewhat surprisingly, the collimation seemed very decent.
The big difficulty was the stability of the mount. A touch of the slow motion controls would start it shaking, taking maybe 5 to 7 seconds to settle. Focusing was the real challenge. I would make a tiny adjustment to the focus wait for it to settle then try again till I felt I had achieved the best possible.
That was all I had time for the first evening and packed up not too disappointed.
A couple of days later I had the scope out again. I first tried Jupiter low down in the SW. The seeing was bad but I could clearly see the two equatorial bands and three moons. In the past I had used the 4mm eyepiece from the above mentioned kit for a magnification of 225X. There is a 2X barlow in the kit but I had wanted to use the minimum amount of glass possible. This time I used the barlow with the 9mm eyepiece from the same kit for a magnification of 200X but with a more comfortable eyepoint. When the seeing was more steady for brief moments I though I could see some structure in the belts. My next target was Epsilon Lyrae - the double double. After some difficulty finding the pair and battling with the focuser, I had a rewarding view with both pairs clearly separated at 200X - nice airy discs (almost points) with some hints of diffraction rings.
And finally for the pièce de résistance, I turned my scope to Saturn about 50 degrees above the horizon. With the 32mm eyepiece the rings were obvious. I carefully changed to the 9mm barlow assembly and frankly was amazed! The Cassini Division was in your face visible - no challenge at all. I felt the coloring of the bands on the planet was move vivid that through the CPC 1100. I could clearly see the shadow of the planet on the rings. Titan was visible with direct vision. The view was crisp to the extent that I thought it could take more magnification. With the CPC 1100 I once had the magnification up to 400X and though I could see the Enke gap as a darkening in the outer ring - but the FirstScope does not break your budget or your back!
In conclusion I remember reading a review of a 4.5 inch newtonian (I think in was the Orion XT4.5 Dobsonian) and the reviewer mentioning the apo like views given by the diffraction limited spherical f8 primary. Having never had the chance to look through an apo refractor I can't confirm either way but clearly these cheap reflectors are nothing to sneeze at. Were it not for the unsteady mount I would have loved to continue using this scope. I imagine this scope but on a good quality altazimuth mount would make a very good beginner instrument. Hopefully I can pass it on to a youth who is passionate enough about astronomy to tolerate its quirks as I did and put it to good use.
Thanks for reading!
I purchased a GSO 6" f/4 Newtonian "Astrograph" late last year and eventually found that stars on one corner were egg shaped while taking images. I narrowed it down to improper centering of secondary mirror from the factory and resulting tilt.
Long story short, after numerous iterations, I used the Advanced Newtonian collimation technique by Astro Shed guy and ended up with the below pic of the optics. Does it look ok or do I need to do more? I will be checking with a Howie this weekend too.