SCT Telescope Collimation (With NO fancy tools)

[@DylanODonnell]

Thanks for watching! And thanks also to @MarkusSchierz and @jesuspineiro1622 for reminding me that if you want to dial collimation in perfectly, you should recenter the star as well after each adjustment. Lots of love for Bob's Knobs too which I understand .. it's a great product. I found they didn't hold collimation for as long as the factory screws in the past and local stockists didn't have the zinc plated options I need in this case. Also .. you should loosen opposite screws first and then tighten target screw. I do this a bit in the video but don’t say so explicitly. And yes.. do be careful waving your PP around the scope glass in the dark :)

[@aperturedriven]

I think Bob's Knobs seem to lose collimation more often or more easily because the amount of torque actually applied to a fastener when it feels like you've tightened it fairly well is going to be different depending on the tool and even the size of the tool used. For example; try using your fingers, a short handle screw driver, and a long handle screw driver to screw a sheetrock screw into the wall. The more torque a tool can applied raised the psi required to "feel" tight. For this reason using a small plier or 3D printed level that attaches to Bob's Knobs would increase the torque necessary to feel properly tightened down and thus would most likely hold collimation much more consistently. I replaced my philips screws with allen head screws to avoid accidental stripping or slipping of the screw driver with my remote C11 Edge. Cheers!!

[@AmatureAstronomer]

Thanks for extra instruction. 🙂

[@paths1111]

Thanks for the video! I replaced the Philips head screws on my EdgeHD secondary holder with M3 hex head screws, as I find that the long arm of the hex wrench makes it much easier to reliably make small adjustments, rather than aiming a pointed screwdriver towards my corrector plate and trying to guess how much I turned it the round grip. Much less prone to slip as well. One additional note is that collimation on a defocused secondary shadow is still relatively rough collimation, and is more an indicator of mechanical centering of the secondary mirror relative to the primary optical axis. However, because the SCT secondary is spherical and therefore has no optical axis of its own, centering is actually neither required nor sufficient for exact collimation (centering is extremely important for Hyperstar however, as it has a very strong optical axis). To dial in exact collimation, it is still desirable to actually examine the Airy disk and rings of an exactly focused, centered star. This after all is what the image is composed of, but the problem is that seeing often makes this difficult. I've found that the best solution for me is to use Metaguide (free) - its live stacking and high frame rate make examination of the Airy disk and first ring feasible under most reasonable seeing conditions, and the coma detection feature is much more sensitive than I can detect by eye. Lucky imaging on planets is where you'll really see the difference, as the scope is then (hopefully) diffraction limited rather than seeing limited and typically much more highly sampled. I'd be interested to hear your thoughts on it if you decide to give it a try!

[@DylanODonnell]

What a great comment .. thanks for the thorough exegesis !

[@k-d-n]

Instead of a star, I always use a powerful flashlight covered in tinfoil, with the smallest hole you can possible make with a needle. This way you don't need the mount, and you can collimate your telescope indoors.

[@lwizzit]

I’ve been wondering how I might do this. It’s been cloudy here for weeks so I don’t want to lose any time if it ever clears up again. Trying this tomorrow! Thanks!

[@JK-gn9qi]

and on what distance?

[@k-d-n]

@@JK-gn9qi I my case, it's about 9 meters.

[@OnceShy_TwiceBitten]

@@k-d-n how do you calculate that?

[@Cakebattered]

9m? Congrats, you have a large home.

[@robertlowenthal689]

This video was a lifesaver for my C9.25 Edge HD. I replaced the stock screws with Bob’s Knobs and messed up the collimation to the point where I had no idea where the secondary was pointing (my fault, not Bob’s). I felt hopeless and had no idea how to fix it. After watching your video, I removed the secondary mirror and adjusted it using a screwdriver shaft as a feeler gauge. I got it close enough that I was able to collimate the telescope in about 5 minutes. I hadn’t realized that I only needed to move the screws by a fraction to adjust collimation. Thank you!!!

[@Macro-Astro]

A great video about the secondary mirror, adjusting bolts and the collimation process. This is probably the only detailed video about dismantling the secondary mirror on the Celestron C11 telescope. Thank you very much, everything was very informative!

[@DylanODonnell]

Thanks! I like this one too !

[@joedenisco6033]

Dylan, That was priceless. The thin side needs to be tightened to PUSH it away from edge. Very easy to remember! Thank You, and I really appreciate all the advice you give to the community. Joe D

[@ChrisAguilar504]

But it depends on which side you defocus. If you defocus a star in one direction, you need to tighten. If you defocus the star in the opposite direction, you'll need to loosen.

[@rosscayley8773]

Nice Dylan. Another really quick and easy way Ive found for 'roughing in' an SCT collimation thats way off (especially easy with Bobs knobs) is to view the symmetry of the secondary vs the primary (and vs the baffle tube) by looking directly down the optical axis from the objective side, in daylight. By adjusting the viewing distance you can vary the relative size of the secondary and its obstruction of the primary, so that any asymmetry becomes obvious as an uneven 'ring' of primary mirror showing around the secondary. Its really easy and intuitive to adjust until it looks even, and you can do it during the day. It works so well that, in my experience, the subsequent star test becomes more a confirmation of good collimation than an additional step.

[@DylanODonnell]

Excellent tip!

[@ABCMO-bl5pi]

This is such a basic question that I’m embarrassed to ask it. Nevertheless, I want to make sure I’m following the details of this method correctly. My understanding is that the primary mirror is considered the objective in an SCT. As such, this means one should be looking through the visual back end of the telescope, not the corrector plate at the front end. Is this correct?

[@rosscayley8773]

Both ways work- obviously the conventional star test is the most accurate way to achieve perfect collimation, but since 'collimation' is basically just achieving the alignment of all the optical elements, and you can clearly see the relative alignments of these from the corrector plate end, assessing and adjusting from the front end also works well to quickly identify and correct major misalignments....its also easier, and you can do it in daylight too.

[@ABCMO-bl5pi]

@@rosscayley8773 Thank you!

[@steppen57]

I am so scared of collimating my C8. I checked the collimation just a couple of nights ago, and it looked fine. But I will likely come back to this video. You make it look so darn easy. Thank you for this very instructional video. Love the closing as usual.

[@dovthiessen]

I spent a lot of time initially calibrating my scope, understanding how it all works. I took the corrector plate off, cleaned it carefully. Replaced the screws with Bob’s knobs. I’ve found that the collimation needs to be checked and calibrated regularly. Similar to having to fine tune a guitar from time to time. Initially I bought a laser but the method in this video is the way to go. Bobs knobs make it simple to do this. Also , you can get that little donut image calibrated well enough so you can see many perfect concentric circles. It makes stars into perfect pinpoints. Worth the effort. I should note, I don’t have a computer hooked up to the scope, so I just adjust by trial and error and looking in the eyepiece.

[@billallen275]

Man, took the corrector plate off my old C8, and forgot to mark it! It's old, so maybe there's a mark on the plate. Then the collimating fun! It is scary... but now in my case, it's not working, so bring on the challenge. Think I'm gonna try a laser pointer and pinhole first. Made new leg clamps, too.

[@billallen275]

​@dovthiessen I bought thumb screws at the hardware. Zinc plated, might have to watch it. But they are too tall and the lens cap doesn't fit.

[@brandonrunyon]

I fixed my collimation by buying an esprit. Also, happy to see your kid out and about.

[@Photomanguru]

Thank you so much for taking the time to make this top quality instructional video, I stopped looking for answers after I saw this. Keep up the GREAT work!

[@MarkusSchierz]

Great video. However i think you forgot to recenter the star after your adjustments. For my c8 that makes a difference.

[@jesuspineiro1622]

It is right. To perform a correct collimation, the star must be kept centered in the field and recalibrate. In SC, off-axis stars may appear out of collimation, but on-center ones are perfect.

[@davidlittle3427]

Thanks for this video Dylan. Collimation is the one thing that still gives me the collywobbles! Anything to make it easier I took my Celestron apart to give it a clean (after taking a few very deep breaths) and set up the secondary mirror by eye as you did and then replaced it. I have got the Ocal collimator and I checked the collimation....I just had to turn one screw by a tenth of a turn and I was in. When I checked with a defocused star (Sirius) the next night the collimation was the best I had ever managed. The Ocal collimator is a great piece of kit and the one thing it has done is make me a little more confident to fiddle with the collimator screws. Getting the secondary just about trued in by eye with your trick, made it so much easier Thanks again for your pragmatic and practical approach to astronomy.

[@dwbattag5847]

My man you have upped your game! Every detail is so well covered and annotated watching everything that’s happening live at your point of the conversation is so helpful like you I will forget this until I look back at this particular. Saved KZbin video. Thank you so so much.

[@MakeAMark]

Hey Dylan -- one of the most useful videos out there for SCT users. Thanks for digging in on this. I know there are a lot more subtleties to collimation, as pointed out in some comments, but this video really is helpful.

[@DylanODonnell]

Thx Mate!

[@wooddogg8]

Thanks Dylan, all this time collimation has had me afraid to buy that SCT I've had my eye on. Didn't realize all I needed was my pp. I've got pp. in fact I've got multiple pps in a large range of sizes and shapes, even 90 degree pps for that tight work without much space. Thanks, I've been subscribed for years but came here through the link in the High point scientific write up about you. Good stuff mate!!!!

[@DylanODonnell]

Bro thanks so much ! That was very kind of them to post that write up!

[@allenbaylus3378]

got stuck before - bobs knobs - on my Meade 8 inch SCT. The star kept on moving out of the view on my ASIAIR - I will try again - I only wish it wasn't winter temps outside now. It's always inspiring to see other people do this with success.

[@deep_space_dave]

Ah I miss those days when I had an SCT as collimation was so easy. Now I'm a masochist with a RASA and it's dredded tilt 🙂 One piece of advice though, after getting your out of focus star, do a counter clockwise turn of the focuser to level out the mirror as it likes to flop around. Collimation will be more accurate that way. This was the most clear and complete video on SCT collimation, so well done Dylan! BTW Bob's Knobs are cool but I heard that the regular screws hold collimation better. Thanks for the video and clear skies!

[@DylanODonnell]

Oh man I agree with everything you’ve said here!

[@tubedude54]

Screws are screws whether they are regular philips head or Bobs knobs... I think what you find is people are afraid they are over tightening with the knobs as opposed to regular screws so they end up with loose Bobs knobs.

[@deep_space_dave]

@@tubedude54 Personally I like the knobs better so I don't have a screwdriver near my corrector plate 🙂

[@tubedude54]

@@deep_space_dave I agree... trying to use that little screwdriver in the dark is a nightmare! You have to constantly shine a light to make sure you find the screwhead and you end up losing your dark vision. With the knobs you just use your fingers and feel them!

[@robertsipes7391]

First off, I think it is great that no matter what string of short clips you use in the intro to Star Stuff, that you include the one where you chuck the can toward the observatory dome. I must say, from the beginning days of your channel, that one has always been my favorite. I have said that the day Dylan O'Donnell leaves that clip out of his intro, that will be the day he has lost his soul for astrophotography. Oh well, I have a 2008 Celestron CPC1100 that needs collimation. Thanks for sharing and thanks for being Dylan. I hope your family is doing well also.

[@Oamaruastro]

I'm really pleased that the neural implant I had my minions install in your cerebral cortex has worked flawlessly--as a new SCT owner, I was wanting you to do a tutorial on collimation, and within a very short few days after sending that message you produced this! Huzzah!

[@DylanODonnell]

Yes it’s all your fault ;)

[@aaronwmorris]

Meade SCTs are a bit different. Celestron secondary mirrors pivot on the central axis bump as you showed, but Meade secondaries use springs for tension instead of the central axis. A Meade SCT can be returned to the flat collimation by finger tightening all 3 screws all the way in (per the manual).

[@philiphood8194]

Thanks Dylan. Love your videos. This one has inspired me to set up my Meade Lx90 after months of dormancy just to check the collimation. Years ago I used a small bead hanging from a tree about 30 meters away and adjusted with bobs knobs fitted. ( C8)

[@DylanODonnell]

Nice! Yes, do it !

[@meadmaker4525]

Great video, but I kinda feel like Celestron needs to maybe go back to the drawing board and design a better mounting plate for that secondary mirror. No reason they can't machine a plate that mounts the mirror at perfect "zero" once the screws are installed, without mirror flop or lopsided attachment. As it stands, it's EXTREMELY fiddly and more than a little delicate. Can't understand why they left it the way it is, but maybe there's something I don't know.

[@davidleejenkins]

Great video! I recently discovered how to collimate my SCT with a Tri-Bahtinov mask. Wow! It made it so much easier and more accurate too!

[@fredhaggerty3969]

Super helpful. Just replaced all my screws and was needing this kind of help. Thanks for a great video.

[@DylanODonnell]

Thanks! I just rewatched it myself to help with the new scope!

[@denniswilde2013]

One additional step I would do is to mark the edge of the secondary at the notch so when you’re assemble them the mirror will be in the same orientation to the primary when reinstalled.

[@DylanODonnell]

Interesting .. in theory it should matter thought right? If the mirror is perfectly symmetrical anyway?

[@denniswilde2013]

@@DylanODonnell Celestron usually matches the corrector and the primary rotation to produce the best figure, so I would logically presume they would include the secondary to produce the best image possible from the set.

[@erykmozejko3329]

80’s I worked at the UK Celestron dealership: Astro Systems At that time Celestrons were very symmetrical but did have a “tipex”/“white out” dot on the corrector and the corrector cell to get them aligned. Although very symmetrical there would be a prime orientation for best results. The C11 and C14 would be less symmetrical and more critical as to the positioning of the corrector plate and secondary. We started selling Meade and found there was slightly more astigmatism on the 8” OTA’s so you could get a bigger drop in image quality if the corrector wasn’t in the optimal position. The 10” OMG those were a pain to tune. We checked and tuned every imported scope (we made our own newt’s) Our collimation bench was a 12” parabolic mirror in a wood frame. At the focus was a 1/16” ball bearing mounted on a vane. Off axis a light which was focused on the ball bearing. We had 2 pence pieces with a bore hole to mimic a star or pairs of bore holes to mimic a close pair of stars to see the resolving power. Looking through a scope I could see the ball bearing fill the field of view and the whole room reflected with the main light on. Lights out and the artificial star viewed at a minimum of 500x magnification we would look at the Airy disc and diffraction rings to get collimation and fine tune the scope. Looking at the Airy disc is the ultimate way of collimating a scope and judging it’s performance. The main downside of our set up was it was all set up horizontally. We should have got round to tilting the whole apparatus at 45° so the scope would flex and slump (including the optics) in a position that more accurately represented its typical position in use

[@erykmozejko3329]

I have to add this demo is excellent, including the key point of backing off/tightening the opposing screws so balancing the pressure on the cell. Next step would be to fully focus the star and for once Dylan you’ll have to get an eyepiece out, and the most uncomfortable one at around 4mm and look at the Airy Disk and diffraction rings formed by a starts image and see how concentric and clean the image is Bearing in mind you will also be limited by every tiny slight atmospheric distortion your local conditions will throw up. The collimation rig I mentioned we used. I could tell from the vibrations if that was road traffic. Train at the nearby station or someone walking past the shop. Even though we had our collimation bench in the most thermally stable location. I could still see the rippling and eddies of air moving round in the room

[@johnadastra1754]

While I've had my Meade LX200 secondary apart, I have never tried it with my C925 EdgeHD. Meade used to have an ultra-thin flat spring washer between mirror and secondary holder to take up any wiggle room. It's very surprising Celestron has no mechanism that stops the secondary from flopping about during adjustments.

[@robshaw6844]

@johnadastra1754 I thought the same thing when I took my 5SE SCT apart a year ago (after I spent 30 minutes on hands and knees searching the floor for one, assuming I'd not seen it drop to the floor). It makes perfect sense to a non-expert that a small, lightly sprung spring would help immensely.

[@derekregan6926]

A great basic way of doing collimation, you can use several other tools and tricks to get it highly accurate.. collimation isn't to be scared of and will be needed to do at some stage to any sct

[@billbean5912]

Best collimation video I’ve ever seen. Thank you.

[@gsevere2073]

This is a timely video for me as I've been reading the manual for my 9.25 thinking about how to cullimate it, something I didn't have to think about with my refractors even though one of them said you could if it needed it. Whew, thanks and it helps keep us busy during our Summer months when the night is short and seeing sucks.

[@sandragayle7866]

Thank you! Thank you! It works! My Celestron 6se telescope was completely out of focus and I carefully followed your instructions and it works! I did this on my Newtonian telescope a few years ago. But not on my SCT. Thanks😅

[@DylanODonnell]

Great to hear ! I rewatched it recently to do new scope too ! :)

[@amritseecharan848]

One of your best videos so far. Very very clear instructions. I image from Trinidad, and would like to share my images with you. Jupiter and Saturn are looking better every passing day

[@DylanODonnell]

Thanks so much !

[@NevadaDesertSkies]

One trick you can do if you are doing this manually with NINA is turn the bullseye overlay on, then using your mount fine movements, center the bright donut star directly in the center and you can adjust the focus and magnification so that the star is the same size as the bullseye overlay. It's then super easy to tell when your dark center is dead-on.

[@martynh5410]

Excellent and well explained! Having moved my SCT over 2,000 miles from Ohio to California, I should probably check and adjust collimation first!!

[@drunk_astronomy]

Thank you for the video Dylan. Your videos always cheer me up when I’m feeling down.

[@clearskiesastro1028]

It was my understanding and experience that every adjustment would push the target star out of the center of the frame...and on my C9.25 (non HD) if the star was off center, the shape would change in terms of how bad it looked in regards to collimation. So I'd have to adjust the screws, recenter the star, and then decide if I keep going...rinse and repeat. The star centering on a 2350mm FL scope is a pain in the PP.

[@JarrodMcKitterick]

Had just gone through this with my NexStar 5SE. Excellent advice about pointing at a starfield! I had used a single star and spent a lot of my time star chasing with every adjustment. I also was using a thin PP. Perhaps next time I will use a thick PP for more control while I am screwing. Great video as always. Thank you Dylan!

[@DylanODonnell]

Thanks!

[@astrojudebob]

Thank you for the video. Perfect timing. I was going to collimate on the next clear night.

[@DylanODonnell]

I hope it helps .. good luck !

[@kevinburke8608]

In your pinned comment you stated that Bob's knobs don't hold collimation as long. I noticed in your old videos with the C9.25 that the "knobs" were really loose and wobbly. I'm curious if your old knobs were slightly undersized. I use them on my C9.25 and the knobs aren't loose at all and were the same size screw that came with the scope. They seem to hold collimation pretty well. I'm shocked that Celestron used a regular zinc screw instead of all three being black oxide. Must have been late Friday for someone in the assembly portion of the factory just before a weekend! Think they should give you a RASA 36 as compensation for your troubles :)

[@PATTACAT72]

You’re the best!!! Hope you never stop being here for us.

[@DylanODonnell]

Thanks !

[@rtpman1953]

Great video, Dylan, and I never knew it could be so easy by just letting my p p do the work. Likewise, I'll be saving your video so I can tackle my 11 Celestron SCT should we ever get a clear sky, hopefully before I get too old.

[@DylanODonnell]

I trust your PP will do just fine.

[@Xanthus723]

Hey these are the lessons I learned over the winter. I noticed the secondary mirror was flopping. I got everything tightened back down but couldn't achieve collimation for shit. Took the secondary mirror out and it was not even close to flat.

[@StarlancerAstro]

why not add some small springs between the cap and the mirror to keep pressure so there will not be flop, I am actually surprised there isn't I have not taking my secondary apart.

[@Michael.Chapman]

Love your observatory and the fantastic 3 minute collimation-awesome :-) When screwing the secondary holder back onto the secondary mirror assembly, did you ensure the secrondary’s rotational orientation was in its original factory position? I understand that my vintage 1970s/ 80s Celestrons were set-up at the factory for optimal rotational matching between corrector, secondary and primary to obtain best possible wave performance.

[@DylanODonnell]

Thanks! There is a groove so there is only one orientation possible to get it back in :)

[@DylanODonnell]

Not sure about vintage though sorry!

[@martinlagrange8821]

Until this film, I never quite understood 'Mirror Flop' as it affects SCT's. I'm making a Frankenscope out of the best parts of two broken C8's, which (by their powers combined) will make a classic retromod Southern Hemisphere clock-driven orange tube. All descriptions I had for mirro flop were vague - but seeing it 'in action' was a great treat. Very much appreciated, from Auckland.

[@DylanODonnell]

Thanks Martin!

[@landspide]

Suggestion... Get a box of black nitrile gloves from Bunnings 🙂👍 They're dual purpose for late night moon walks, shamown...

[@DylanODonnell]

Heeee heeeee!

[@yobb89]

my meade has the same thing, random screws used, diy washer from factory, they just slap these things together cheaply once they get the parts made and ready for assembly

[@ABCMO-bl5pi]

Absolutely great video! And you’re a braver man than I am because I don’t think I would ever have the nerve as part of the process to remove the secondary mirror from my C6.

[@DylanODonnell]

Thanks !

[@douglasfleming1]

Hi Dylan Returned to this video to recall how to collinate my C11"xlt SCT. Thx again! A question if I may in case you are still monitoring the comments for this one: what is the backfocus change for the C11 when you add a hyperstar? Is it the same (77mm I believe) for a 6.1 reducer? Just bought one. As always: thx! Doug

[@zaphus]

Great to see this video - really good to see the real-time adjustments! Going to give my knobs a fiddle when I next get some clear sky. When collimating an SCT is it normal for the stars out to the edges to be non-circular when unfocused or should they also be nice donuts? All the pictures I can find only show what is happening with the central star, so it is hard to know if I've got other problems in my system or if it is normal to see squashed donuts towards the edges.

[@DylanODonnell]

When the stars are different at the edges that’s not collimation .. it’s usually optics or back focal distance being off. Collimate for a central star. Then fix the rest :)

[@jesuspineiro1622]

To perform a correct collimation, the star must be kept centered in the field and recalibrate. In SC, off-axis stars may appear out of collimation, but on-center ones are perfect.

[@virgill8502]

Great video! As far as collimating an SCT; couldn’t you measure the gap between the two halves of the secondary with a feeler gauge (gap gauge), and make sure the gap is the same all the way around? Then collimate on a defocused star to do any needed tweaking.

[@DylanODonnell]

In theory, yep! In fact just eyeballing it that way get's it basically close enough, then tweak the rest.

[@michael.a.covington]

Excellent -- useful information -- especially the shadow-of-the-hand trick.

[@10intexas]

Is it possible to make a collimation "band" to put around the mirror and the cap as a fixed spacer to make it impossible to screw the mirror to the cap out of alignment.

[@JAG9100]

i might have to do this on my C8, ive noticed weird stars after the summer temperature change.

[@frankbraker]

Don't know if you mentioned using a ball bearing in the video (because I have a Newtonian), but yeah. If you're inside and don't want to fiddle pointing at real stars, you can cover a flashlight with some foil, put a pinhole in it, and point that toward a tiny ball bearing and point the scope at the ball bearing to simulate a teeny tiny star for doing collimation indoors.

[@DylanODonnell]

That sounds like a lot of work :)

[@gspinin]

By far the best collimation video! Thank you, Dylan. Ps. Can you do a video on the easiest way to fix tilt. I’m debating on purchasing the asi2600mc but the dreaded stories about tilt is causing me to stick with the 533mc pro.

[@deathstrokeTT]

What's the sweet spot for optimal zoom/focus for the star? If I make the star too large its a bit difficult to see the centering. Too small and its difficult to make fine adjustments.

[@DylanODonnell]

I go back and forth until it’s good at sizes

[@skygazerII]

Thank you for another great video! I have an older C8, if it ever clears off here in the Northeastern USA I will collimate it.

[@tamsoncat2358]

Sweet I just got my edgeHD 11 off Celestron this really helped out with my CGX-l

[@DylanODonnell]

Oh great !

[@Opceedee]

Awesome video! I’d love to see one on how you pair your camera and oag on that edge. I’ve been struggling to get the spacing right on mine.

[@cyberblitz]

Did you need to have your mirror orientation the same as before you unscrewed it, having the screw holes aligned the same as before you removed the mirror? I'm not sure, but i believe when this mirror is fitted in the factory, it is carefully calibrated and orientated. This is why you have the notch, so when you place it back in, it is orientated exactly where the manufacturer had it, giving you maximum collimation to start with before you even touch the screws for fine tuning. But then again, i could be wrong on this

[@aperturedriven]

Nice smooth process there! Good tips as well. Is there any importance regarding rotational orientation of the secondary to the primary and corrector? I know the corrector has an indicator mark for it's proper orientation to the primary but don't recall if that applies to the secondary as well.

[@poisonpen26]

My faststar slider is abit stuck and wont rotate to expose the collimation screws what should I do?

[@thierrymartin8378]

This is not really collimation but for one position of primary mirror . Collimation means the axis of the mirrors are indentical Here it is not the case. For a SCT every time you change the focal lenght yoy have to check the qualite of the stars .

[@NightSkySurferAstro]

so, why did you take the secondary mirror assembly apart anyway? Did you suspect there may be bad screws or did you just want to OWN the thing and start it from scratch? I understand both reasons... just wondering which it may be.

[@DylanODonnell]

Understanding. I have 100% confidence in the screws. Celestron screws are great. I've only got a dud one once, which was a weird manufacturing error. If they're black they're good.

[@brianschumacher1922]

Great video! I really like the step one procedure with the secondary mirror for rough in. I see that you're not too concerned about the scope angle being vertical during the star process. Second I track while collimation to keep the star somewhat target centered. As I get really close I'll auto recenter between each adjustment. (Maybe overkill) I'll also collimate on both sides of focus (thoughts?). I've tried to use the Ocal Columation tool and collimation during the day using an artificial star. With both processes I was disappointed for my C/8 Seems the eyes are still the best. Thank you again for the video!

[@janitkumar5234]

Appreciate your hard work , I am here after the ch3 amazing clip , what a shot that was

[@DylanODonnell]

Oh hey! Thanks for watching mate! 🇮🇳

[@dagriz]

best collimation vid that I have found, i think ill be able to see Uranus perfectly now even from up here in the northern hemisphere :P

[@philiphood8194]

You inspired me to check my collimation. A celestron EdgeHD is not like my meade LX90! The principal is the same but for a start the manual tells you to adjust the WRONG screws.( meade did fix) . Your process worked great. Allen wrench not philips head.Thanks.😂😂

[@DylanODonnell]

Excellent :)

[@duke227]

Question? After the center star is collimated, should expect all or most stars to also look collimated?

[@DylanODonnell]

unless your scope has a super flat field, you'll always notice coma around the corners.

[@skyscope7795]

Hi This is Omar from Bangladesh. I've got a Meade Lx200 GPS 8" telescope. I need to collimate my telescope. How may I do without camera settings? I mean manually. Thanks in advance.

[@ezza2fly]

Can you test for mirror flop once finished?

[@kajouman]

i always thought that you need to centre the star again after making adjustments,i see in your video that your star is going from centre to bottom right area. but i need to do it myself tonight too,so i will test it out myself. good video ,just in time for planet season. greetings .

[@DylanODonnell]

Yes you should do that .. I pinned a comment .. in practice though I think this is close to perfect anyway.

[@matthewbaker7513]

I have never looked through a collimated SCT. Every SCT owner seems to think they don't need it, but the views are always terrible. Curious.

[@AmatureAstronomer]

Can collimate my Newtonians in less than one minuter. Have been trying for 8 months to collimate my SCT. Even when it looks collimated using my artificial star, all stars still have bad coma.

[@Skyman82]

Love your videos! I have an edge hd and was wondering if it matters if you collimate with or without the .7x reducer.

[@DylanODonnell]

Shouldn’t matter.. collimation affects the front, not the back. But in theory I guess you could eyeball it in better if you collimated without the reducer.

[@Skyman82]

@@DylanODonnell I ended up collimating at the native focal without the reducer and with the tri-batinov mask and got the best collimation. I think it’s better than the factory collimation.

[@mr.d.8121]

Thank you Dylan. Nicely done. Very much appreciated.

[@douglasfleming1]

D: are you using an HD 11"? Or ( like me) are you using an older C11 SCT? And: are you using a fast star step up? Hyper star? If so: worth it? Thx

[@DylanODonnell]

C11" Edge HD (Fastar Enabled) .. I used to use hyperstar on a c9.25" .. it's great!

[@ronlundgren4391]

Thanks Dylan, I’ve had my C8 for over 30 years and collimation has always been a mystery to me. There’s no removing the secondary on my model so I don’t know that I can get to a good starting point as you did? And after so long of tweaking it I’m sure it needs that reset. Anyone have any advice?

[@DylanODonnell]

Not sure .. hopefully someone can chime in!

[@Zealor365]

That video inspired me with a confidence to give it a shot on my own.

[@helthuismartin]

You need a camera for collimation.Without camera collimation is a total nightmare..I had a Celstron C14 and it took me hours to get the collimation very good..

[@Oxfire95965]

Do you think some type of foam washer would help with taken up the slack

[@DylanODonnell]

Not needed I think!

[@GrundleStiltSkin]

i was thinking the same thing, some strong foam to keep the neutral position.

[@Oxfire95965]

If so RTV silicone would probably be the cheapest easiest to use

[@scblue01]

Great vid, all I need now is to find that long lost bottle of brave pills. A question, did you focus beyond infinity or closer? Just wondered if where you out of focus position is makes any difference. Thanks.

[@DylanODonnell]

Can’t remember .. but focussing the other way would just mean the adjustments are reversed .. I think!

[@The13rannon]

What are your thoughts on bobs knobs?

[@wbehrens62]

I put spring tensioners on my secondary screws "to stop the flop".

[@pigeond]

So who should I contact in Australia to get those secondary mirror screws? I actually want to get some new screws for my 2nd hand C6 too.

[@DylanODonnell]

Here's where I got my handful! www.boltandnut.com.au/m3-x-0-50p-coarse-black-zinc-pan-phillips-ph1-machine-screws

[@ExoPhotography1]

You can do better by almost focusing a star, move it around where it looks best and center it, make a few itterations and you Will be blown away with how much better the collimation can get!

[@bofblog]

Great video...I read somewhere of AlsCollimationAid a free software collimation program..

[@avt_astro206]

Nice video! Any tips on actually cleaning a telescope Mirror?, How often would You do it for a Newtonian?, Like every 3 years. Or Should Not worry about it? Thanks For your great Work man! Keep it up! 👍🏻

[@DylanODonnell]

I've not come to that point yet. When I do I'm sure I'll film it :)

[@jasonpatterson8091]

It is entirely possible (and likely, even) that you won't be able to adjust a single screw and the opposite pair equally. If you notice that the thin part of the ring is biased to one side of a screw, you just loosen the screw opposite that bias a bit more than the other one when you're giving yourself space to tighten the screw you're focusing on. Of course you can also just get close to center, realize you're going to miss, and repeat the hand shadow trick to figure out which screw is closest to the thin side of the ring to repeat the cycle.

[@DylanODonnell]

Good point!

[@roymedina638]

Great stuff but my PP stopping working years ago and I now play with my knobs for satisfaction. Thanks anyway Mate!

[@DylanODonnell]

Haha I don’t mind the knobs but they don’t hold collimation for as long as the normal screws and some don’t come with the zinc plating.

[@roymedina638]

Well maybe I should start playing with my PP again and see if it still works. I’ll let you know Brother!

[@terrance_huang]

why not just replace them with SUS304 stainless steel screws?

[@C40V15]

Hopefully, the cool kids and their cool videos won't quit youtube!

[@BennyColyn]

I may be old-fashioned, but I still get the absolute willies using a tool like a screwdriver in the dark near the corrector plate. If I'm going to replace the collimation screws on an SCT anyway I'm still going to replace them with Bob's Knobs so I can continue tool-free. Sorry but I rather not use your PP Dylan.

[@DylanODonnell]

Sad PP

[@BennyColyn]

@@DylanODonnell I'm guessing Bob's happy though 🤣

[@alainmaury5941]

A couple of comments. If you have an old (non fastar compatible) don't ever touch the secondary mirror, you will use its position (you might rotate it), and might never get good images anymore. Same, if you insist on dismounting the secondary, mark with a felt pencil so that you remount the secondary correctly (not with a 120 or 240 degrees rotation). The optics are aligned in factory and their position in rotation is quite important. What is described here is correct for a pre-collimation. Apart from this, this video is correct but incomplete. When you have arrived to the point where the image look symetric (like at the end of this video), get closer and closer to focus. And keep adjusting by smaller and smaller adjustments. You may have something that looks good when completely out of focus, but as you get closer and closer to focus you might see that the star images are asymetric, more light on one side than on the other, like a comatic images. Also, find a star high in the sky, not like in the video, you want to avoid atmospheric turbulence as much as possible. Adjust till, when you get to the sharpest focus, the image falls symetrically into a point. Any asymetry needs to be removed. This is the type of collimation you need if you want to make nice high resolution images. You can also google "thierry legault collimation"

[@tmrdarkstar85]

Dylan I have always used an artificial star , then checked on Polaris , not sure what you southern guys would use. I also removed those stupid AF #1 Philips head screws out of my Secondary and replaced them with Hex head bolts of the same thread type , nothing like stripping a #1 Phillips head while collimating. Why the hell Celestron ever thought that was a good idea to use them is beyond me. Edit: I want to note , since replacing the screws with hex head, I have not had to collimate my C8 in years now, Granted it does spend most of its time in the pelican case because I cant find someone to make me the 5mm m42 threaded adapter with the bolt holes to attach it to my 268m and filter wheel. The M42/m48 ring adapter from ZWO doesnt work because the threads dont stop and the camera spins as the scope slews. Which we all know is a NO NO for many reasons.

[@DylanODonnell]

Great idea !

[@TheAngryAstronomer]

It would be cool if NINA had some concentric rings you can move around the screen and resize to aid with this.

[@DylanODonnell]

True !

[@Rob_1472]

I think Al’s collimation aid is still available. I used it on my 9.25 3 months ago. Yesterday I 3D printed a tri-bahtinov mask and it’s still in collimation…with bobs knobs 😉

[@GrundleStiltSkin]

sharpcap does

[@ScottDavies]

Brilliant video 👍

[@sakuntharanaweera2457]

Woooooooowwwwwwww... THANK YOU SOOOOOOO MUCH and I really love this..❤ great, clear instructions and demonstrations.. ❤👌🤘

[@DylanODonnell]

You’re welcome I hope it helps !

[@psegre]

Got it, thanks, I’m ready to collimate my edge 9.25, like right now, bye.

[@dinomonaco2665]

Another brilliant video.