164 replies to this topic

[rgsalinger]

If there's no light leak then there's no real reason why you couldn't set the back focus a tad short and then do as suggested. It would be interesting to see if that worked. However, if you use the ZWO device, you do not have to remove the camera from the system to do the adjustment. It's the same with some other tilt adjusters which could be used in the same way. Clever idea. 

 

Rgrds-Ross

[gpom]

I received my scope a few weeks ago and finally had some 5 consecutive clear nights this week. I set the back spacing at 56mm to account for my filter thickness. The scope definitely needs some more fine tuning as I also have the comet shaped stars in the corners with my 2600mm. The good news for me is that I am by no means a perfectionist and a few mis-shaped in the corners don't bother me. I'm sure I could have messed with the tilt adjuster and spacing a bit to get better stars, but I was more happy to have perfectly clear skies and no moon so I'll leave the fine tuning for the full moon.

 

Overall, I am happy with the scope. The f/3.8 is great in my light polluted back yard and will be even better when I take it to Cherry Springs this summer. I love shooting super wide fields and used my trusty Redcat 51 for years so this is a good upgrade for me. I totally understand how others would expect better performance out of this scope but for me it is good enough

 

Here is my first light with the scope. BXT was used to clean up the stars and a slight crop for stacking artifacts.

 

https://www.astrobin.com/jeyxbs/

 

[Oort Cloud]

That came out really nice, gpom!

[Oort Cloud]

If there's no light leak then there's no real reason why you couldn't set the back focus a tad short and then do as suggested. It would be interesting to see if that worked. However, if you use the ZWO device, you do not have to remove the camera from the system to do the adjustment. It's the same with some other tilt adjusters which could be used in the same way. Clever idea.

Rgrds-Ross

Ross, do you have your camera, EFW and OAG-L all bolted together? That's how I set up my 2600, which puts the tilt place between the flattener and OAG. I have access to all 6 screws on the tilt plate as a result and can adjust tilt without removing anything as a result.

[whwang]

Greg, That's a great shot.  Do you mind showing your corner stars before BXT?

[gpom]

Greg, That's a great shot.  Do you mind showing your corner stars before BXT?

Thanks! Here is the unedited master Red file (let me know if you can't download). Upper right corner is definitely the worst but for me overall, I think I can get it pretty close to dialed in with some fiddling.

 

https://drive.google...Po8?usp=sharing

[rgsalinger]

I do have the L-OAG etc bolted together. I don't see how I would be able to actually adjust it accurately while it's still on the scope. That may just be because I've gotten too old. I'll look at it more closely if we ever get clear skies. What I was thinking was to dig out the ZWO tilt adjuster that they sent me a while back "free" for some reason. I can attach that to the system (I think) and then it would be easier.

 

Still the claim is that the scope will cover a full frame camera. I can see the same problem that I had with mine in the corners. And, isn't that sub at least slightly cropped? I do get that you can process your way out of it, though. I'm happy to give it one more try and then use the RMA they sent me and see if they can't fix it. I do not think that you have tilt. What I'm seeing that sub is poor collimation or the design simply isn't as good as they claim. No surprise either way.

 

Rgrds-Ross

[Foobaria]

Foobaria. What size chip did you say you were using?

I’m using ASI585MC, so i think 11x 6mm (less than FF), something like 1/1.2. 

[Oort Cloud]

I do have the L-OAG etc bolted together. I don't see how I would be able to actually adjust it accurately while it's still on the scope. That may just be because I've gotten too old. I'll look at it more closely if we ever get clear skies. What I was thinking was to dig out the ZWO tilt adjuster that they sent me a while back "free" for some reason. I can attach that to the system (I think) and then it would be easier.

Still the claim is that the scope will cover a full frame camera. I can see the same problem that I had with mine in the corners. And, isn't that sub at least slightly cropped? I do get that you can process your way out of it, though. I'm happy to give it one more try and then use the RMA they sent me and see if they can't fix it. I do not think that you have tilt. What I'm seeing that sub is poor collimation or the design simply isn't as good as they claim. No surprise either way.

Rgrds-Ross

I guess it depends what the OTA attachment point looks like. Mine is a refractor flattener, so it's not much larger than the M48 connection. As a result, it does not block access to any of the screws when it's all put together. I'm at work now, but I'll send a pic when I get home which will show what I mean.

[gpom]

I do have the L-OAG etc bolted together. I don't see how I would be able to actually adjust it accurately while it's still on the scope. That may just be because I've gotten too old. I'll look at it more closely if we ever get clear skies. What I was thinking was to dig out the ZWO tilt adjuster that they sent me a while back "free" for some reason. I can attach that to the system (I think) and then it would be easier.

 

Still the claim is that the scope will cover a full frame camera. I can see the same problem that I had with mine in the corners. And, isn't that sub at least slightly cropped? I do get that you can process your way out of it, though. I'm happy to give it one more try and then use the RMA they sent me and see if they can't fix it. I do not think that you have tilt. What I'm seeing that sub is poor collimation or the design simply isn't as good as they claim. No surprise either way.

 

Rgrds-Ross

I was assuming a little tilt adjustment would help since the stars in the upper right are worse than the rest of the image, but maybe not. And as I said, I understand that the performance may not be as good as WO claims. For some, especially those with full frame cameras, it might be a deal breaker. For me, it'll get the job done. And I guess this kind of goes back to that BXT mega thread where someone asked why spend the money on super premium optics if you can process out the imperfections haha.

 

But that's not the point here. The point is that it's very likely that this scope can't cover a full frame sensor based on my results and others. I was just trying to show that you can still get decent images and maybe this scope is better for someone with a 533 size sensor or 2600 max.

[Oort Cloud]

If there's no light leak then there's no real reason why you couldn't set the back focus a tad short and then do as suggested. It would be interesting to see if that worked. However, if you use the ZWO device, you do not have to remove the camera from the system to do the adjustment. It's the same with some other tilt adjusters which could be used in the same way. Clever idea. 

 

Rgrds-Ross

Ross, this is what I was referring to. on my 'frac, all of the tilt screws can be reached without any disassembly.

Attached Thumbnails

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[rgsalinger]

OK. The adjustment screws that I'm seeing are on the OAG, not the camera which is what I thought you were referring to. I never looked to see if the L-OAG has tilt adjusment screws. I think I'm going to be able to go out on Saturday and I'll have a look at it. I have the OAG bolted to a spacer and then the spacer bolts to the 2600MC but it's otherwise the same. I'm not sure that I'm agile enough to be certain that all my adjustments are equal and the last thing I want is to introduce any tilt into what's already a good system in that regard. 

 

Rgrds-Ross

[rgsalinger]

I've been able to get a bit closer using 55.75mm of back focus. I was able to do this by using the threaded variable spacer on the back of the OTA. Unfortunately that technique has left me with extreme tilt rather than comets. I just heard that WO is going to be manufacturing a new flattener/reducer that replaces the one in my scope. Hopefully this will be the final answer. If so, then I'm glad that I never sent the scope back for repair. It's a long trip to Taiwan and back. 

 

Rgrds-Ross

[Beaverpond Astro]

I've been able to get a bit closer using 55.75mm of back focus. I was able to do this by using the threaded variable spacer on the back of the OTA. Unfortunately that technique has left me with extreme tilt rather than comets. I just heard that WO is going to be manufacturing a new flattener/reducer that replaces the one in my scope. Hopefully this will be the final answer. If so, then I'm glad that I never sent the scope back for repair. It's a long trip to Taiwan and back. 

 

Rgrds-Ross

Ross, do you know how that is going to work?  I assume one has to send the scope back to WO for a retrofit?  Or is it something that can be done by scope owners or dealers?

thanks for the heads up.

 

(I've been on vacation for 2 weeks and haven't been adjusting mine to see if I can get better stars)

[rgsalinger]

Contact WO and let them know that you have the comet problem with your scope. See what they say about the situation.