Karl Theberge:
I couldn't help but to look. I've done this already and have the tools (lens caliper). Well, the 4 x2 plastic screws around were completely loose, which is ok as far as the lens shouldn't be too tight, but the lens still didn't move. There should be a small movement by shaking it, at least feel a tiny movement.
As it turns out, those screws won't make a difference whether they are loose or not, if the large retaining ring behind the second objective lens is ultra-tight via a retaining ring, squeezing the 2 lens together.
That's where the caliper came handy and I slightly loosened it, as it was extremely tight. Immediately I felt the pressure on the lens were gone, I'm talking about a small fraction of a turn on the retaining ring.
Then, I tightened the small plastic screws, to a point where they just barely making contact with the primary lens, so the lens have that fraction millimeter of space if they need to expand a bit.
The plastic screws are actually a good idea instead of metal, since it allows pressure without cracking the lens.
A few more things though. Looking the lens under light, I noticed smudges in the inside lens near the retaining ring, it looked like either glue or some sort of grease, I don't know. It might be the compound goop they use in the factory, to secure the retaining ring, preventing to get too loose. It's similar to Locktite you can buy in a hardware store.
I ended up using my sensor cleaner kit, and the swipes to get off the goop, carefully wiping with one that is soaked with sensor solvent and then wiping it dry with a dry swab. It has to be done carefully, not to damage or scratch the coating on the glass. It looks perfect now.
Now, I want to test it on a star, so hopefully tonight there will be some break among the clouds and see if my tweaks done any good (or bad).
I know my keyboard looks dusty, but it's a super bright light, I use it to inspect optical parts of my gear. It will reveal any dirt or dust, I use it to check my camera sensors too, when I notice too many dust motes in my images.
That's the retaining ring I'm talking about and if you notice that goop applied in the threads, that might have contaminated the lens on the edges inside that I managed to clean off.
Let me know when your test is done, I am curious and I will try it if your result are good.
And btw I think you (Original poster) and the other member that kinda "hijaked" your tread have the exact same issue.
And I do have the same issue as both of you. I have better star now, but noting is perfect so.
I also think it doesn't really matter, the AT72 and the WO73 are the same stuff with slightly different glasses and look. Both are probably produced at the same place by the same ppl.
Did you damage the lens ring (at the bottom)?
Please tag me in your answer if you dont mind so I get a notif.
KArl
No, there is no damage to the lens, you either seeing the reflection or glare or that sticky stuff on the retaining ring, I'm not sure what you're referring.
I did a few test shots last night, although it was semi clear only, there were a few minutes of clear between the clouds.
Unfortunately it doesn't look much better at all. I tried it with the original reducer/flattener as well as I tried my Svbony reducer/flattener too. Interestingly with the Svbony, the stars appeared better than the dedicated Astrotech reducer at the center, but it didn't correct the edges, with elongated stars and I tried with a few mm added and then removed.
With the dedicated flattener I have to say I have not noticed any improvement as far as star-size and shapes.
LOL, it's basically looks the same, like I did nothing to it.
I'm not sure what to blame anymore, if it's the lens, if it's the flattener or both. I'm gonna try the W.Optics flattener too, since I have it, but I don't have high hopes, since I've already tried that at 3 different backfocus settings. The backfocus settings only changes the corner stars a bit, it just never gets round, while the center stars are still bloating, just like with the original flattener.
I also tested for collimation, but that's fine. Centered a star and checked for roundness and the rings around the centroid. I'm pretty much convinced that there is absolutely no way to collimate these anyway, I noticed with my Zenithstar 61 also in the past. The plastic screws around the objective lens only keep the lens tightness, does not change the collimation. I tested this in the past with the Z61, turning the screws all over changed absolutely nothing. Not to mention, they were completely loose, I mean so loose that they weren't touching anything, they were just hanging in there.
Just knowing this, these telescopes are very cheaply made , including this and any other variation of them, including the William Optics series.
I shoot mainly with Newtonians for specifically for this reason, since any "budget" (That includes scopes with $600 price tag) refractors are not worth the money they are asking for. It's literally a lottery game now, whether you get a well corrected one or a complete junk. I see the ods of 1 out of 5 chance, that you eithe get a good one or bad one. I avoid buying W.O. and now I have to add Astrotech. In the future, I will probably get either Stellarvue or something more premium to avoid poor quality control.
This is my 4th short refractor and out of the 4, only one works as intended, so I start to advise beginners to avoid these telescopes to avoid these quality control issues. Basically don't buy a telescope under a $1000. Or buy a Newtonian and spend another $800 on accessories and upgrades to make it imaging-ready.. Sad, but true.
