0.90
#...
·
 |
|---|
|
Yes, good. i will try that using the Tool from sharpcap. CS Haakon |
0.90
#...
·
|
|---|
Jean-Baptiste: Hi Jean-Baptiste. When I had my first newtonian, I was watching some tutorials on how to check if the focuser needs adjusting. The guy took the secondary mirror out, measured the center of the focuser tube and put a mark on the inside of the telescope tube, perfectly opposite to the center of the focuser. Then with a laser, if the beam didn't fall on the spot, he adjusted the tilt until the focuser tube was perfectly aligned with the telescope tube. Emil |
0.00
#...
·
·
1
like
|
|---|
|
Hi Emil, Great idea you saw there. Do you remember which tutorials you have watched and where??? thanks! jens |
|
0.90
#...
·
·
1
like
|
|---|
Jens Leuteritz: This is the video https://youtu.be/3LbR1nIx-jw Around minute 27 Emil |
2.41
#...
·
·
1
like
|
|---|
Emil Andronic:Jean-Baptiste: * Hello Emil, I remenber this video ! And to be completely honest, I used to do the same when I came back to astronomy 4 years ago When I decided to buy a Lacerta, I asked Tommy Nawratil if such a mark could be made, I asked also where was the screws to manage the tilt of the focuser in order to have a focuser precisely squared to the tube ... I could not understand that I was buying a high end newtonian without this feature ! And Tommy explained me that they were useless. I decided then that I wanted to undertand precisely what I was doing during colimation, I spent some times in drawings and exchanges via MP on cloudy night with Vic Menard and Jason Kadder also. I discovered that there is this thinking among astronomers that for a newtonian, it is important to have a focuser precisely squared with the tube Of course, it is helpful for the first position, especially with the "classical offset" positionning of the secondary mirror. But I can guarantee you that there are absololutely no need to be precise and that you don't need to adjust the tilt of the focuser itself ^^ If you look carefully at : - the objectives in terms of optical alignement of the colimation / tilt issues : primary mirror / coma corrector lenses / camera sensor - the mechanical parts that are used for that : tube / primary and secondary holder / focuser / coma corrector holder / camera holder - the information that the various colimation tools are giving you - the various tuning tools that you have : screws at primary mirror / secondary mirror / possibly a tilt device such as ZWO tilt plate or gerd neumann CTU You will see that in the end the fine tuning comes from the tuning screws of the primary mirrors and that there is no need to manage the tilt at the focuser level. (In the same time, managing the tilt at the sensor level can be very important !) I discovered also there are no need to fight about that, at the end of the day, the colimation will be good in both case, with or without a tilt tuning at focuser ;-) At the same time you fill find : - product / people such as Lacerta that are provinding newtonian without this feature - SKywatcher which is providing this feature So no problem if you think that I am a fool, let's have fun with our passion, trying to reveal the beauty of our universe :-) Clear Skies Jean-Baptiste |
|
0.90
#...
·
·
1
like
|
|---|
Jean-Baptiste: *** Type your I don't think you're a fool at all, I really appreciate your comments and I hope that I can learn from them. I had newtonian telescopes before and I was never 100% pleased with them so I ended up selling them. Now I bought another one, an Orion Optics CT8 and I replaced the focuser with a moonlite but for the life of me, I can't get the collimation right. I'm thinking that I might have put it in the wrong position, not exactly how the stock focuser was. To be honest, I would prefer not to alter the tilt of the focuser because, in my opinion, it makes it weaker. Any suggestions would be much appreciated. Emil |
7.90
#...
·
|
|---|
| I assume you had an adapter made to fit the existing hole pattern on the CT tube so it should a relatively easier job to square the focuser to the optical axis (not the tube!) of the scope, if the offset is already set (assuming it was) and having the right tools for the job. At any rate is hard to pass suggestions without the real thing in your hands. Should you fancy a long drive I'm 120 miles north of you and always happy to help. |
0.00
#...
·
|
|---|
| Hi @Jean-Baptiste , I also used Ocal and I also noticed the center is slightly moving when rotating the camera. I do not understand when you explain that "it is normal to see a difference after a rotation". After centering circles against the tube, I would not expect my center to move when rotating. |
|
2.41
#...
·
·
1
like
|
|---|
Yann-Eric BOYEAU: Hello Yann-Eric My point was to say that it is normal to have a "small" difference because what you see is very precise : the game between the M42 tube and the focuser tube, the various flexion, how you are tightening the ocal in the focuser etc ... this is not the rotation by itself but all the others factors that have an impact If the OCAL is inserted without being tigthed, and you apply a smooth presure while turning the body of the OCAL, the center should remain still unless you have a "calibration" subject (see below) If you have a "big" difference such as the one that Emil showed, the most likely is that your OCAL is not properly "calibrated" : you must tell the software wich pixel of the sensor is at the center of M42 thread of the OCAL body : at a minimum with the settings adapted with your serial number, or with the "offset" tuning as I showed for example CS |
|
0.00
#...
·
·
1
like
|
|---|
|
Thank you Jean Baptiste for the clarification and your feedback on the ocal. Your contributions on calibration with newton are really helpful. |
