131 replies to this topic

[Tom Gwilym]

I'll keep this short since I'm tired of explaining everything again, but I'm suffering the common problem of collinating a 16 inch Ritchey Chretien.  Need I say more?

 

I've been researching other ideas for this. 

- Takahashi collimating scope

- Autocollimating eyepiece

 

Scope:

GSO 16 inch Ritchey Chretien - our club has had this over a year, I've probably spent more than 20 hours struggling with it, and getting nowhere.  Still haven't taken any images that I'm happy with.

 

Have :

- Howie Glatter 2 inch with the Grid pattern (can't find any info on this type, but it's easier to find than the round type.  Where are the instructions on using this?)

- Cheshire eyepiece with the reflective surface with the hole.

 

Time wasted on this:

- 20+

 

Frustration:

- 95% (I haven't given up yet, but insanity is getting closer).

 

Question:

- What should I try next?  Takahashi collimating scope?  Autocollimating eyepiece (I've just discovered this from another discussion and reading more about this idea).

- If I can get something that will let me collimate this in 2 hours rather than 20 and making zero progress, I'd be thrilled!

 

Help!

 

Tom

Edited by Tom Gwilym, 22 April 2020 - 12:54 PM.

[mlrtime99]

On my shopping list so tagging along.  Good luck!

[Tom Gwilym]

I'm not even sure what to put on my shopping list anymore.  

 

On my shopping list so tagging along.  Good luck!

[Testgear]

Have you sen this video? Does it help?

 

Youtube

 

https://www.youtube....h?v=ynyT-Zyfbls

[Lead_Weight]

I've been collecting collimating resources, and collimating my 8" RC. Principals will be the same between the 8 and 16.

 

I have the Takahashi scope. It's not perfect. In fact, between the lasers, and Takahashi scope, none of these options are going to provide perfect collimation. They will all get you close.  Part of the reason is that the ways you attach the Takahashi scope and the lasers are through the eye piece holder with compression rings. These things aren't perfect, and often the device rocks a tiny bit even when tightening down. I find with the collimation scope that even the focus barrel of the collimation scope moves slightly, making your collimation look off. This plainly sucks because you would be collimating for something that's off axis. You could attach the Takahashi collimation scope with a threaded adapter, but it doesn't fix the fact that the focus barrel of that scope wobbles slightly.

 

You also need to adjust your focuser to have no tilt, separate from your scope. Another challenge. The laser I have moves even when locked down tight, and the reflection of the laser moves all over the place.

 

Here's the information I've picked up from all over the place.

 

RC8 Collimation instructions PDF. (the best I've used so far) requires a TAK collimation scope.

https://www.dropbox....AkKUZ1dL4a?dl=0

 

Using a bahtinov mask to collimate and adjust primary mirror:

https://deepspacepla...rccollimate.php

 

Some more collimation tips:

https://www.cloudyni...e-reset-method/

 

Another method projecting a laser and reflection on to the wall (non pattern laser):

http://www.hnsky.org...collimation.htm

 

Also there are options like CCDInspector that will show you tilt of your primary, and offers a collimation feature to collimate the secondary. I've never used this but am interested in checking it out to make final tweaks.

 

Lastly, there is ASTAP, which can also do what CCDInspector does, but it's free! It has it's own CCD inspector feature (I've tried this with images I took) and it will show you primary or sensor tilt. 

 

None of these options have resulted in perfect collimation for me. Largely due to imperfections in the hardware or focus mechanisms used to attach the collimation equipment to the scope. But I have got collimation close using the first method. But it does have to be refined with something like CCDInspector or ASTAP with a live star (actually field of stars), because you need a lot of stars in your field of view to properly check tilt of the primary.

[Tom Gwilym]

Thanks for taking the time to write all this. Very helpful!  I like that first link to the .pdf file, I haven't seen that and looks like a lot of good info in that one. 

I'll probably be going with the Takahashi scope with the 2 inch adapter which should be what I need to connect to the 16 inch RC.  I don't really expect to get this monster 100% perfect, but if I can get at least 89% close I think I'll be happy.  Just some stars that look round (or very close) would be such and improvement over the mess I dug myself into.

Yeah, I know the part about focuser wiggle, I've come across that.  I get it all centered, then work on primary/secondary and then check focuser again and see it's off. Fix that, then it's all a mess again.   If the Tak scope will cut this process down to a few hours I'd be thrilled.  I've got over 20 hours into messing with this. Galaxy season is here, and I really want to get this thing running well so we can do some public (at least virtual for now!) outreach viewing and imaging. 

 

Thanks for the info!

Tom

 

I've been collecting collimating resources, and collimating my 8" RC. Principals will be the same between the 8 and 16.

 

I have the Takahashi scope. It's not perfect. In fact, between the lasers, and Takahashi scope, none of these options are going to provide perfect collimation. They will all get you close.  Part of the reason is that the ways you attach the Takahashi scope and the lasers are through the eye piece holder with compression rings. These things aren't perfect, and often the device rocks a tiny bit even when tightening down. I find with the collimation scope that even the focus barrel of the collimation scope moves slightly, making your collimation look off. This plainly sucks because you would be collimating for something that's off axis. You could attach the Takahashi collimation scope with a threaded adapter, but it doesn't fix the fact that the focus barrel of that scope wobbles slightly.

 

You also need to adjust your focuser to have no tilt, separate from your scope. Another challenge. The laser I have moves even when locked down tight, and the reflection of the laser moves all over the place.

 

Here's the information I've picked up from all over the place.

 

RC8 Collimation instructions PDF. (the best I've used so far) requires a TAK collimation scope.

https://www.dropbox....AkKUZ1dL4a?dl=0

 

Using a bahtinov mask to collimate and adjust primary mirror:

https://deepspacepla...rccollimate.php

 

Some more collimation tips:

https://www.cloudyni...e-reset-method/

 

Another method projecting a laser and reflection on to the wall (non pattern laser):

http://www.hnsky.org...collimation.htm

 

Also there are options like CCDInspector that will show you tilt of your primary, and offers a collimation feature to collimate the secondary. I've never used this but am interested in checking it out to make final tweaks.

 

Lastly, there is ASTAP, which can also do what CCDInspector does, but it's free! It has it's own CCD inspector feature (I've tried this with images I took) and it will show you primary or sensor tilt. 

 

None of these options have resulted in perfect collimation for me. Largely due to imperfections in the hardware or focus mechanisms used to attach the collimation equipment to the scope. But I have got collimation close using the first method. But it does have to be refined with something like CCDInspector or ASTAP with a live star (actually field of stars), because you need a lot of stars in your field of view to properly check tilt of the primary.

[Lead_Weight]

One other thing with the software. It's not perfect either thanks to imperfect seeing conditions! This can make it appear you have tilt where there is none. If you read any of the forums on this software, there are people complaining left and right about it throwing out numbers that seem to regularly deviate form each other without adjusting anything. The software itself is sound. But you need to take lots of images (20 or so) under good seeing conditions to average together, of a rich star field (lots of stars) to adequately average out seeing conditions and understand the actual tilt of your primary mirror.

 

Just some more food for thought.

[Lead_Weight]

Also, save those PDFs to your computer! You never know when those links will go down.

 

Almost forgot the DSI collimation method to use a defocused star to visually gauge uniform brightness and adjust the primary. I've had mixed results with this method, because I can't actually tell if the light is uniform. But in anycase some have had luck with this method.

 

http://www.deepskyin...ure_Ver_1.0.pdf

[Tom Gwilym]

I did try the DSI method the last time I was there a few nights ago.  I messed with the primary trying to move the bright side of the star as mentioned.  I didn't see anything change at all.  Looking through the Cheshire just confirmed it was a mess since it was all skewed again. 

 

 

Also, save those PDFs to your computer! You never know when those links will go down.

 

Almost forgot the DSI collimation method to use a defocused star to visually gauge uniform brightness and adjust the primary. I've had mixed results with this method, because I can't actually tell if the light is uniform. But in anycase some have had luck with this method.

 

http://www.deepskyin...ure_Ver_1.0.pdf

[Lead_Weight]

I did try the DSI method the last time I was there a few nights ago.  I messed with the primary trying to move the bright side of the star as mentioned.  I didn't see anything change at all.  Looking through the Cheshire just confirmed it was a mess since it was all skewed again. 

Yeah, this was my same experience. I think if you were starting from very closely aligned, then it might work better. But if you were grossly misaligned and tried this method you would probably only make it worse. Because the changes in brightness were most likely due to atmospheric diffraction and not uniform illumination. Which was the case for me.

 

I just realigned over the last 2 days with my Takahashi scope indoors, and noticed something I had not seen before, which is that when you look through it, you can see the primary and secondary reflecting off each other, but in the very center (changing focus of the Tak scope some) you can see a third reflection even smaller of the same thing. I never noticed this before, and if all reflections are not perfectly center, then you are still off collimation. So, I'm hoping tonight I get under the stars and have it nailed down. I didn't realize previously I only had alignment of the first reflection, meaning that collimation was off just enough that the "hall of mirrors" wasn't aligned, so it had been off axis slightly. 

[Tom Gwilym]

Sounds like what I was reading about how the autocollimater works where the hall of mirrors has to stack up.  I think that effect will be helpful actually then I would know when I have both mirrors nicely squared up.   I know that most likely had the primary in the wrong place when I tried the DSI method.  I found it interesting that it says to work on the primary first, but then I'm guessing that this DSI method may be best when things are only slightly off in the first place.

I'm hoping I can use the Tak in daylight with a sky background through the open dome.  Seems that this will work without removing the scope from the mount, a 16 inch isn't easy to remove with social distancing these days! 

 

Yeah, this was my same experience. I think if you were starting from very closely aligned, then it might work better. But if you were grossly misaligned and tried this method you would probably only make it worse. Because the changes in brightness were most likely due to atmospheric diffraction and not uniform illumination. Which was the case for me.

 

I just realigned over the last 2 days with my Takahashi scope indoors, and noticed something I had not seen before, which is that when you look through it, you can see the primary and secondary reflecting off each other, but in the very center (changing focus of the Tak scope some) you can see a third reflection even smaller of the same thing. I never noticed this before, and if all reflections are not perfectly center, then you are still off collimation. So, I'm hoping tonight I get under the stars and have it nailed down. I didn't realize previously I only had alignment of the first reflection, meaning that collimation was off just enough that the "hall of mirrors" wasn't aligned, so it had been off axis slightly. 

[Lead_Weight]

Sounds like what I was reading about how the autocollimater works where the hall of mirrors has to stack up.  I think that effect will be helpful actually then I would know when I have both mirrors nicely squared up.   I know that most likely had the primary in the wrong place when I tried the DSI method.  I found it interesting that it says to work on the primary first, but then I'm guessing that this DSI method may be best when things are only slightly off in the first place.

I'm hoping I can use the Tak in daylight with a sky background through the open dome.  Seems that this will work without removing the scope from the mount, a 16 inch isn't easy to remove with social distancing these days! 

Yeah, you can use the sky. You do need some light. I set up my illuminated flat panel in front of my scope since I'm indoors in order to see the secondary vane alignment through the Takahashi scope. You'll also need a small LED flashlight to shine into the Tak scope on the side of it, as this illuminates the reflections inside the scope when looking through it.

[jmiller1001]

I used the following method to collimate my RC10:

 

1. Start with a mechanical alignment using a Takahashi Collimating scope and cheshire

2. Tweak optical alignment with an artificial star

3. Finalize the collimation with the DSI method/pdf

4. Confirm collimation with CCD Inspector

 

And, it was a learning process along the way.  There is a 3-part video on Youtube that looks useful as well.

[Tom Gwilym]

Thanks!  I can see using the DSI method later for the final star adjustments.

 

I put in an order for what seemed to be the last Takahashi around, OPT had one left (and the 2 inch ring).  Hopefully it arrives soon, then I can hook it up and ask more questions. 

 

I used the following method to collimate my RC10:

 

1. Start with a mechanical alignment using a Takahashi Collimating scope and cheshire

2. Tweak optical alignment with an artificial star

3. Finalize the collimation with the DSI method/pdf

4. Confirm collimation with CCD Inspector

 

And, it was a learning process along the way.  There is a 3-part video on Youtube that looks useful as well.

[Lead_Weight]

Well, this didn't work out for me. I seemed to get it somewhat close. But running CCDInspector showed a lot of tilt still, so I tried the DSI method, and seemed to get uniform illumination on the defocused star. Then Flipped to collimating the secondary, and took some images, and now it's way off again. And terrible. Ugh, I hate this telescope. Haha.

[Lead_Weight]

I spent about 5 hours outside tonight trying to get collimation fixed. It's impossible to tell what I was doing. First off, I have almost no visible open clusters in my night sky, which didn't help. The more stars the better CCD inspector works. Where I seemed to get the most progress was just watching the corner stars and how they were affected by adjusting the primary mirror. A few hours of moving things around seemed to get them in pretty good shape. Then I went to collimate the secondary and it threw it all out of whack again, so all I can think is that the axis is way tilted in one direction. I'll have to get out in the day time with the collimation scope and re-center everything again to try one more night. 

 

Will probably forgo the RC if I can't get this worked out, or I'll have to call in some professional help. Taking out my CCDT67 compressor would likely help me sort this out at the native focal length. So that's an option for me too. I have less issues with my Edge 11, and no issues with any of my refractors. Getting tired of messing with this scope. 

 

I actually had zero issues on my 6" RC collimating with the Tak. Everything worked great. I sold it, and bought the 8" used, and it was messed up when I got it. I might even have to consider taking it fully apart, and resetting the secondary distance, and primary back to the starting point where the push pull screws are even.

[Tom Gwilym]

Ouch. I know the pain of many hours in the dark messing things up. I hope my discussion didn't encourage you to go out and tweak your collimation! 

I was hoping to find some videos on YouTube specifically about the Takahashi scope use. Just the 3 part video and a couple other of the popular ones.  At least with your 8 you can probably reach around the front to adjust the secondary. I'm up and down the ladder to reach the secondary on ours. Maybe I can hook a camera on it somehow and look at the computer screen. 

I'm looking forward (and dreading) the arrival of the Takahashi stuff. I don't need research quality, just pretty images that are relativity sharp. 

Keep me posted on your progress. 

 

Tom

I spent about 5 hours outside tonight trying to get collimation fixed. It's impossible to tell what I was doing. First off, I have almost no visible open clusters in my night sky, which didn't help. The more stars the better CCD inspector works. Where I seemed to get the most progress was just watching the corner stars and how they were affected by adjusting the primary mirror. A few hours of moving things around seemed to get them in pretty good shape. Then I went to collimate the secondary and it threw it all out of whack again, so all I can think is that the axis is way tilted in one direction. I'll have to get out in the day time with the collimation scope and re-center everything again to try one more night. 

 

Will probably forgo the RC if I can't get this worked out, or I'll have to call in some professional help. Taking out my CCDT67 compressor would likely help me sort this out at the native focal length. So that's an option for me too. I have less issues with my Edge 11, and no issues with any of my refractors. Getting tired of messing with this scope. 

 

I actually had zero issues on my 6" RC collimating with the Tak. Everything worked great. I sold it, and bought the 8" used, and it was messed up when I got it. I might even have to consider taking it fully apart, and resetting the secondary distance, and primary back to the starting point where the push pull screws are even.

[Lead_Weight]

I've never had perfect collimation on this scope, so I've adjusted it every time, trying different tweaks to see if I can get it properly set. But I've yet to achieve good collimation with it. So still trying to figure out what works and what doesn't. 

 

Looking through the Tak scope this morning, I can easily see that I destroyed the collimation of both the primary and secondary last night. So not doing that again...Haha.

Edited by Lead_Weight, 24 April 2020 - 09:15 AM.

[Tom Gwilym]

I'm starting to get more nervous about all this, but at least I have the Tak on the way while I read more horror stories.  I also bought the 2 inch attachment to fit the focuser.  The focuser seems to be a good solid one when I lock it in place.  I'm hoping I can roll it all the way in and just add/remove the spacing rings between it and the scope.   Also that first article you shared sad you need collimate without the focuser and remove the primary baffle tube - but leave it in the scope since it can't come out easily?  Do you leave your baffle in and just attempt collimation through the focuser?

At least unless I whack something, there isn't any permanent damage I can do to this thing, mainly my sanity is at risk!

Tom

 

I've never had perfect collimation on this scope, so I've adjusted it every time, trying different tweaks to see if I can get it properly set. But I've yet to achieve good collimation with it. So still trying to figure out what works and what doesn't. 

 

Looking through the Tak scope this morning, I can easily see that I destroyed the collimation of both the primary and secondary last night. So not doing that again...Haha.

[Lead_Weight]

So yesterday, I did not take the focuser off. I tried to collimate it with the focuser attached, and used a two inch nose piece attachment for the Takahashi to attach it with compression rings on the focuser tube. This is not the recommended way to do this. And I used that method thinking I could adjust for any tilt In the focuser. But no. Taking images with it last night showed a lot of tilt still. I believe this isn't because the method is unsound, but because you can't reliably attach anything to the focuser tube with a compression ring. Any amount of compression from any single screw introduces some tilt. I did it anyway, and that proved to be a problem under the stars, which I made worse by tweaking the primary, then adjusting the secondary after.

 

Today, I have a rear cell adapter with my TAK scope (which by the way comes with no adapters, both the nose piece and this rear cell adapter I purchased separately), and I attached the scope to the back of the primary this way. Exactly how it looks in those instructions on the RC8 collimation. I adjusted everything back into perfect alignment, including the third/fourth mirror reflections in the 'hall of mirrors' directly in the center. The only other time I noticed these second and third reflections was yesterday when collimating through my focuser. So, I'm hoping that today I nailed it, and that tonight I'm going to see perfect stars. 

 

You do have to take out the baffle, or you can't see the secondary vanes to line up the primary mirror properly. Just follow those directions in that PDF. It will get you back to square one. You have to center the primary by aligning the vanes (through adjusting the primary screws), then collimate the secondary to it by adjusting the three hex bolts on the front of the scope to move the secondary's black center dot towards the center of the reflection. Then check how off the primary is again since you just adjusted the secondary. You just keep going back and forth between adjusting the primary and secondary as you slowly move them both into perfect collimation/alignment again.

 

It helps to have a second person adjusting the secondary, while you adjust the primary, but it can be done by yourself, it's just a slow process with some trial an error to see what directions things move when you make adjustments yourself, especially if you have to walk around to the front of the scope, then go back to the rear and look through the TAK. I had my daughter stand at the front of the scope, while I told her which bolt to adjust, and she would try both directions until we got the correct alignment direction down. This speeds up the process a bunch.

[Tom Gwilym]

I'm thinking I probably need to find one of these plates also to connect without the focuser.  They aren't as easy to find as the Tak scope, but a few places seem to have it.  I'm thinking the one for a 10 inch GSO RC is the one that would fit since they probably don't get bigger than that one.   It's about $50 so not as horrible cost.  We do have a 14 inch Celestron SCT  - I haven't looked at it yet, but I'm almost tempted to swap that out with the RC so we have something to use then I can work on the RC on a table. That one was sent back to Celestron for a tune up so we could sell it.  I can see all the spider vanes with the Cheshire eyepiece, but when I put the Tak on there, I can see that it would narrow the view down so the baffle would have to come off.   Yeah....I think this thing will have to come off the mount.

Any ideas how to use the Howie Glatter grid pattern laser?  We have that one but I can't find any info on that, just the discontinued round pattern version.

 

...and with the pandemic 6 foot rule, no help on this thing for now. 

 

 

So yesterday, I did not take the focuser off. I tried to collimate it with the focuser attached, and used a two inch nose piece attachment for the Takahashi to attach it with compression rings on the focuser tube. This is not the recommended way to do this. And I used that method thinking I could adjust for any tilt In the focuser. But no. Taking images with it last night showed a lot of tilt still. I believe this isn't because the method is unsound, but because you can't reliably attach anything to the focuser tube with a compression ring. Any amount of compression from any single screw introduces some tilt. I did it anyway, and that proved to be a problem under the stars, which I made worse by tweaking the primary, then adjusting the secondary after.

 

Today, I have a rear cell adapter with my TAK scope (which by the way comes with no adapters, both the nose piece and this rear cell adapter I purchased separately), and I attached the scope to the back of the primary this way. Exactly how it looks in those instructions on the RC8 collimation. I adjusted everything back into perfect alignment, including the third/fourth mirror reflections in the 'hall of mirrors' directly in the center. The only other time I noticed these second and third reflections was yesterday when collimating through my focuser. So, I'm hoping that today I nailed it, and that tonight I'm going to see perfect stars. 

 

You do have to take out the baffle, or you can't see the secondary vanes to line up the primary mirror properly. Just follow those directions in that PDF. It will get you back to square one. You have to center the primary by aligning the vanes (through adjusting the primary screws), then collimate the secondary to it by adjusting the three hex bolts on the front of the scope to move the secondary's black center dot towards the center of the reflection. Then check how off the primary is again since you just adjusted the secondary. You just keep going back and forth between adjusting the primary and secondary as you slowly move them both into perfect collimation/alignment again.

 

It helps to have a second person adjusting the secondary, while you adjust the primary, but it can be done by yourself, it's just a slow process with some trial an error to see what directions things move when you make adjustments yourself, especially if you have to walk around to the front of the scope, then go back to the rear and look through the TAK. I had my daughter stand at the front of the scope, while I told her which bolt to adjust, and she would try both directions until we got the correct alignment direction down. This speeds up the process a bunch.

 

[Lead_Weight]

I haven't used the Howie Glatter, and don't own one. I have thought about purchasing one, but didn't know they got rid of circular pattern. The Tak scope will get you aligned without it.

 

There's also two more tools that work with alignment of RCs that I didn't mention, and also don't own.

 

The Hotech Advanced Laser Collimator

I've read several nightmare stories about this one. It has very unclear instructions. Some have been able to get it to work but only after hours of frustrations. I just read a good thread on it here on cloudy nights.

 

TS-Optics R.E.E.E.G.O. LED collimator for RC scopes

I've only read one report on this here on cloudy nights. And the person had success with this tool. I think you have to order it overseas, though not sure if anyone sells it here now, as it's been some time.

[Tom Gwilym]

I heard the circular pattern isn't made anymore since Howie passed away. There are a small handful of dealers that still have some.  Either pattern, they will have to be shined on a wall perpendicular to the scope, so this again will need us to remove the beast from the mount.  I just don't find anything about using the grid version.

 

I have seen the Hotech in person once.  It was at the Advanced Imaging Conference I attended in San Jose, CA a few years ago.  They showed it on a SCT scope, which if I can just twist my Bob's Knobs on the secondary, I'm collimated good enough for my standards in just a few minutes. 

I haven't seen that other thing, yet.  I'll have to read up on that.

 

Clear here tonight, but I'll just pass on going over there tonight until I get the Tak scope. Seems it's shipped already, so early next week it should arrive.  The removing the baffle part stresses me out now that I see that part in the article you posted.

 

Tom

I haven't used the Howie Glatter, and don't own one. I have thought about purchasing one, but didn't know they got rid of circular pattern. The Tak scope will get you aligned without it.

 

There's also two more tools that work with alignment of RCs that I didn't mention, and also don't own.

 

The Hotech Advanced Laser Collimator

I've read several nightmare stories about this one. It has very unclear instructions. Some have been able to get it to work but only after hours of frustrations. I just read a good thread on it here on cloudy nights.

 

TS-Optics R.E.E.E.G.O. LED collimator for RC scopes

I've only read one report on this here on cloudy nights. And the person had success with this tool. I think you have to order it overseas, though not sure if anyone sells it here now, as it's been some time.

 

[Lead_Weight]

Removing the baffle is super easy. It just twists off. I'm imaging right now on my 8RC. I got collimation perfect with the Tak, but under the sky, it's obvious it's not quite perfect. Problems in every corner. Center is good, the rest is an issue. I am using a fairly large sensor APSc for this telescope reducer combination. And my reducer isn't a corrector, so no flat field, plus it exaggerates the edges where it compresses most. But I would think I should at least have uniform problems, but each corner is different.

 

Anyhow, I've given up on this mess with trying to get it perfect. I ordered the TS-Optics collimator. Shipping was costly as it's coming from Germany. I looked in US stores and it's no where to be found. I'll try it out when it arrives, and I also have a reducer/flattener on order for the RC8 as well. I hope that fixes the edge issues. I plan on using the TS optics collimator on my other scopes, as it apparently does SCTs and refractors. Interested to see how it works, and if it might be able to fix any issues the Tak can't fix.

[Tom Gwilym]

Oh, it just twists off?  I wonder if it's the same on the 16 inch?  The article says that it's left inside the truss since I guess it can't come out around the truss or something.  I'll read that again and look at ours. I hate the idea of it resting in there near the mirror since I hope to make some adjustments on the mount if possible. 

 

So you got yours looking good in the middle, is there enough good image to crop the crud on the edges and get a decent image?  I did get a reducer for ours, but I didn't have the right attachment for it (I do on my scope, but only have one of those rings, otherwise I'd loan it to the club scope!) cheap $20-ish part, but I'll get back to that later. We have another lens that came with the other camera (Mallincam), I'm not sure if it's a reducer or a flattener though.  

Looking at the tracking, the Tak should arrive Monday!

 

 

Removing the baffle is super easy. It just twists off. I'm imaging right now on my 8RC. I got collimation perfect with the Tak, but under the sky, it's obvious it's not quite perfect. Problems in every corner. Center is good, the rest is an issue. I am using a fairly large sensor APSc for this telescope reducer combination. And my reducer isn't a corrector, so no flat field, plus it exaggerates the edges where it compresses most. But I would think I should at least have uniform problems, but each corner is different.

 

Anyhow, I've given up on this mess with trying to get it perfect. I ordered the TS-Optics collimator. Shipping was costly as it's coming from Germany. I looked in US stores and it's no where to be found. I'll try it out when it arrives, and I also have a reducer/flattener on order for the RC8 as well. I hope that fixes the edge issues. I plan on using the TS optics collimator on my other scopes, as it apparently does SCTs and refractors. Interested to see how it works, and if it might be able to fix any issues the Tak can't fix.