Collimating your Schmidt-Cassegrain telescope in just a few minutes
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- Опубліковано 13 гру 2011
- The A&NC's Ralph Bell shows you how to quickly collimate a Schmidt-Cassegrain telescope using an Astro Engineering Picostar artificial star collimating aid. Presented by Ralph Bell.
for The Astronomy and Nature Centre
Produced by DB Video Services for Astronomy and Nature TV - Наука та технологія
I watched so many before this and they made it soooo complicated. And This is the most simple tutorial ever! I wonder if others make it look more complicated just to act like they are geniuses . Thank you! Keep up the great tutorials
I've recently a nexstar 5se, the lovely bloke who sold me the scope recommended your channel for tips and guidance, I'm glad he suggested to check your videos out. Thanks for so many helpful videos. Clear skies!
Thank you, your video helped me a lot. Rest in peace Mr. Bell.
Oh damn it's such a calming and nice video and then I read this super sad comment - how sad is that =(
Very helpful especially the trick of placing the screwdriver out in front of the telescope to work out which of the 3 adjusting screws is closest to the small side of the image
Awesome video! Thank you for taking the time and effort to make this.
just the video iv been looking for...good work
Thanks a lot for making this video... despite being a scientist familiar with high-power microscope set-up processes, I remain a novice when it comes to collimating my SCTs...it frustrates me to remember the hours of tweaking screws I've spent outside at night, battling mosquitoes, cold and dew, never being certain I've actually reached an acceptable endpoint (I followed the Celestron Manual's technique where collimation starts with a defocused star at low magnification, progressing finally to in-focus tweaking using a high power eyepiece--awful. However, I've just bought an artificial star--when it arrives I hope I'll finally achieve fast, optimal, easy collimation using your very promising advice!
unless you are throwing your scope down the stairs...
Bravo.
Love this video thanks for posting.
Thanks for posting this video.
Thanks it gives the basic of what you need to do especially good for those that Macgivyr their needs as most amateurs do.
Excellent video, thanks a lot!
Thank you! I have exactly same telescope, so glad you made this video. Well done sir!
Excellent advice, thank you.
Me ajudou bastante, estava com uma imagem horrível e nunca havia realizado esse procedimento. Obrigado! Mr. Bell R.I.P.
Thank you! Helped me a lot.
Well, done. Very helpful.
Thank you very much! Helped alot!
Simple but effective training video. Thank you. However, I would say that collimation is the least of one's worries if the scope went down a stair well!!
Just bought one of these. Thanks!
Thanks so much. A very helpful video! :)
Fantastico! Muito obrigado pelo video! Greetings from Brazil
A million thanks!!! Very helpful to me indeed as I've the same telescope with me and collimation has been a nighmare for me... :) :) :)
Thank you sir. very helpful.
Thank you!
Great video. Made me laugh when you mentioned throwing it down the stairs.
Excellent video, having the same SCT it’s been a worry when the need arises to collimate it, I’m better suited to learning things when watching than reading from a book, hence why I subscribe to your channel. Sorry to hear the gentleman in the video is no longer with us.
amazing video,,, to be honest, after reading the telescope manual regarding the collimation I found it hard and complicated. But after watching this video..... is it that much easy !!. thank you sir
thanks for posting,
has helped me a great deal with what misalignment actually looks like - instruction manuals are so slapdash
Excellent! I would suggest 1 more step, to use a higher powered eyepiece and recheck and make more adjustments for even greater accuracy
I know this sounds stupid but when he “recenters” (the image) is that by pushing a digital imaging sensor on the keypad???
@@slopedouche5460 he’ll probably use a hand held controller to point the telescope up/down/left/right.
Thank you.
Thank you
Thank You :)
Question: What is the best magnification (eyepiece) to use to get the diffraction rings? How far out of focus should we have to go to get them? Thanks.
I do that in reverse, first move the scope so that the ring looks the best (doesn't need to be in center), then adjust screws to move the ring to the center of eyepiece..... repeat until the ring is round and center in eyepiece
also only loosen the screws one a time... that means if you loosen one, you tighten the two others
I have a cordless drill so I usually throw my scope down the stairs.
This comment made me laugh ! ....no idea why though
hahahahaha
BUAHAHAHAHA
@@mikegee9284 lmfao becouse as amateur we are all retarded here.
Question: How do you replace the factory adjustment screws with "Bob's Knobs" without de-collimating the scope completely?
I have a new 8" SCT on order and I want to verify that it is collimated after it's assembled and make fine adjustments if needed.
Wow, is it really that easy? That seems amazingly easy!
Very nice method for the basic collimation but you need the Airy disk technique to get the maximum out of a SC telescope. The artificial star thing looks really nice though, it prevents the sky turbulences and having to set up the mount before collimation. Do you think any white LED would do it?
Most of my SCT collimation issues result from driving down bumpy roads on the way to datk sky viewing sites, so I just make sure I take the same route back. In theory, this reversal will cure the issues, correct. 😀
Only if you drive backwards at the exact same speed that you drove forwards to get to the site.
Great video. You can get even more precise by examining the image IN FOCUS with a high power eyepiece. The "star"(Airy disk) should be surrounded by a ring or rings of light ( diffraction rings) . The Airy Disk should be in the center of the ring/rings The adjustment is the same, disk must be centered and the ring or rings round and concentric when in focus. Fine tuning at high magnification with the image in focus can make a big difference in image quality compared to rough collimation using an expanded out of focus disk.....especially Schmidt Casseagrains that are more sensitive to precise collimation than most telecopes. The closer to focus you can go , and the smaller the pattern the more precise are the results. In good seeing Polaris makes a good star to use for collimation since it is basically stationary
That's great advice thanks, I didn't know that. I have just purchased a 5" Schmidt Casseagrain so I will try that. Would a 10mm eyepiece be good enough?
@@koolkutz7 4mm
When you say to recenter the image what exactly do you turn? The focus knob?
nice!
ty
Hi, what do you mean by recenter the image? I don’t know how to do that.
My Celestron 8 was sitting on top of The Cat Pad. I picked up the cat which in turn Clung to the carpet. And The Cat Pad moved and the Celestron dropped 4 feet, landing on the tube and putting a nice ding in it. Is there hope?
Does anyone know which camera model he had attached to the Celestron?
Does this improve the object overall qualaty or just center the object?
What sized screwdriver should I use for this?
why i can only see the light. not the twirl like that?
i put a nikon camera and i only get a blur.
I think you're supposed to check both focus points in and out of focus. This may be geared toward the absolute beginner so I guess it's fine
I accidentally removed the secondary mirror of my cpc 1100 , i put it back but the images appear like a streak. I disturbed the collimation severely, Should i try the method you mentioned above (its going to take a long time) or is there any other way to collimate it?
You've probably wrecked your scope.
The secondary is designed to be removed, so no the scope isn't wrecked. He probably just didn't put it back in correctly, though I thought they could only go in one way.
Thanks for making video. The instructions that came with mine said to "move" the rings to the edge of the field of view and then adjust screw to make rings symmetric. Does it matter whether it's centered in the middle of the field of view?
It's been 4 years, so this is more of a contribution to the passing reader. Yes, it does matter if the airy disc (or star) is in the center of view. The light, being gathered from all points on the reflective mirror, should focus on the center point. If after your "best" collimation effort, you note odd shaped airy discs, bring your scope to a local Astronomy Club for a second night time look. A seasoned amateur could tell the difference between air turbulence, tube current or pinched or deformed optics. Without keeping the point of light in the middle, you might overlook an opportunity to diagnose spherical aberrations on the mirror. Pure astigmatisms can occur even in the best of telescopes, and collimation is almost always the cure. Clear Skies!
Re centre the image ???????
How do you centre the star accurately without a crosshair eyepiece? Or is it not that critical that it be absolutely centred?
Hello Scott, I have the same question! Unless you use a 4mm eyepiece or something, it's tough to really be sure you're centered. I do have two solutions, though. If you've got a camera that can put up an overlay, turn that on to pinpoint the center. Or, if you don't mind spending somewhere between maybe $40 and $100, there are some pretty cool illuminated wide field eyepieces with cross-hairs out there.
Great video, but please keep that screwdriver away from the optics! Replace the collimation screws with knobs that can be turned using clean hands. Fingerprints are far more forgiving than a fumbled metal tool. I couldn't stop from cringing every time the screwdriver passed in front of the telescope.
Hi Mr Johnson, thanks for your post. Whilst I don't like the idea of people flailing about with metal tools near critical optics any more than you do - it's as well to remember that if the folk who built your telescope in the first place followed your advice, you wouldn't have anything to look through! I don't think it helps anyone to instill an exaggerated fear of tools - the advice, I think, should be to use them with care. My friend Ralph Bell (RIP) in the video was a qualified telescope service engineer of long experience - just watch what he does and do it like he does it, and you can't go wrong. I agree collimation knobs (or Coll-U-Mates, as we used to call them in the far-off days when we [Astro Engineering] used to manufacture such things - still available BTW from www.astroboot.co.uk) - are a good idea and greatly simplify collimation of SCTs up to 10" (you can look and twiddle at the same time). But the advantage is not so obvious beyond that aperture other than that they are a bit quicker than using hex keys. Hex keys provide a great visual index of fractional movements - and are more precise than knobs in this respect I feel. Anyway, thanks for watching and for the constructive and useful post. KR RJD A&NTV.
i like those odds...
Is there anyway to collimate a Schmidt-Cassegrain telescope without going through all of the things that you do? What happens if nothing gets in focus when pointed at a star regardless of what is done? Mine is a nightmare , and the only thing that I see is a out of focus light. And where is the star or light at in relationship to the secondary mirror when looking through the eyepiece? Is it behind the secondary mirror or along side of it?
Joseph Wonderless This is an update to my last entry above. I got my scope to focus,but I had to turn the coarse focusing knob to the right with ( ready for this) a small wrench turning it clockwise until it loosened up. I must of turned it to far to the left and it wouldn't turn after that by hand. I also collimated it using the hex screws on the secondary. But I am going to get bob's knobs because the look like an safe easy way to collimate in the field during a observing session , or star party. Joel Baker I try not to throw my scope down the stairs (lol) Thank you for making this video.
You haven't focused your telescope. It is impossible for collimate on to be that bad just turn the knob at the back to bring the light into focus.
It's been two years since you collimated your scope, Joseph. If you haven't done so, already, get the scope out of the closet, and add a two inch tube to your crayford focuser. You probably needed to increase your focal length, and not wrench the knobs all the way out. Glad you learned how to adjust the secondary. Good video!
There is a 1 in 6 billion chance that the bumps will perfectly collimate your telescope. ;)
does this work on a mak-cas as well?
+A Thinker I have the C 4se. A mak-cass should stay perfectly collimated forever, unless maybe it gets dropped.
Johnfsu I see. Thank you!
I own a celestron 4SE this is one chore I hope I never have to perform.
The scope that you have doesn't have to be collimated. This video is only for a Schmidt-cassegrain. Yours is a Maksutov-cassegrain, which doesn't have to be collimated.
Very good video. Thank you! Could have a video building one artificial star?
I built one yrs ago when I ground a 12.5 in mirror for Foucault testing. Take a tin can from beans or peas and strip the label off and place a white christmas tree light in it after you drill a small hole in the side about 1/8th in in diameter and some vent holes in the can bottom (which now becomes the top of your pinhole device). Tape a piece of aluminum foil over the hole and now put a small hole in the foil with the tip of a needle. Could probably do the same with a flashlight putting the foil over it and sticking a hole in it.
can you use a normal star
Jack Lawrenson Any star will do, but it's easier if you pick a bright one. Just defocus it to get the doughnut effect and you're ready to go. I have just done it to my 8" SCT and it was dead easy, only difference is I plugged my camera into my laptop so I could see the changes on screen as I was making the adjustments. This tutorial is really good.
Polaris is excellent because it doesn't move (much). It's also best if the scope tube isn't level.
It would be more helpful to keep cutting to the shot of the telescope as you make each adjustment.
i have a 5se celestron.
I have a stupid 12" LX90-ACF GPS. The computer freezes up. I have to reboot and realign it to get it to work again. Headache. It started after I had it for 2 months. It's still under warrantee and Meade says they will fix it if I pay $400 for shipping! I will never buy another Meade product!
This isn't very helpful for the amateur. A,how do I attach a camera and B, where do I get an artificial star and C, how do I get the cap off to see the screws.
Amen
Hi Ray. I hope you don't mind, but I took I while to reply to this as I had other priorities. But, hey, 4 years is nothing astronomically speaking. A: You don't need a camera - we used one so that you - the viewer - could see what we were doing. To not use a camera would rather defeat the object of putting this material on UA-cam. B: You can get one from the artificial star shop - or failing that, have you heard of the 'Internet' - it's quite big over here. B: I can only suggest you do some basic research on your particular model of telescope and see if you can work this out for yourself. In short - try a bit harder. KR RJD A&NTV.
I have not done this yet - 2:47
The SCT is easy to collimate using a bright star and "Bobs knobs" plus some patience. Once it's perfectly collimated it's easily visible by the blue halo close to the star and the small narrow concentric rings just visible near the target star. My 8" Meade has stayed in collimation for over a year, despite a few minor knocks during setup etc.
This poor man was dead in five years after this video I remember watching this video when I first got into Astronomy 🔭 this is a lesson to us all yes there are other way to collimate this SCT like buy the cheap Baader laser collimater at least he tried and admit it he did help so long Ralph 👋
Unless you have thrown it down the stairs 😁
So you need this Picostar ? I doubt it, Surely you can do this in other ways
Hi Lance, and thanks for your message. Of course, the Picostar is just an artificial star. Just use a real star. You may have to wait for the clouds to comply, but on the plus side, real stars are cheap, available in a range of colours and magnitudes, and readily available at a participating sky near you. KR RJD A&NTV.
@@RocketPlanet How much real stars are priced these days? I heard that double stars are quite expensive.
"Something as simple as a screwdriver." How about that 20-30 meters in your house though?
Hi there Eddie. Well, yes it's true, not everyone has a warehouse to play in. So the choices are: 1) buy a bigger house, or 2), do the job outside. My sixpence is on number 2 as the best bet. KR RJD A&NTV
Just go outside at night and use a real star instead of a fake star....
One does not need to use a camera. Just look through the silly scope! Adjust. Look through scope. Adjust...look...adjust...look...adjust...looks good. Done. Duh!
Hi there. You might be overlooking the essential visual 'spirit' of UA-cam. Without a camera involved how can we show you what we are doing - finger shadows? The camera is just so we can easily show the viewer, in an engaging and easy to understand way, what we are doing to the instrument to collimate it. They will do the job with one of the readily available 'cameras' planted in the front of their skulls. And to continue the theme of unsolicited advice, in case you were wondering, the SOP of good comments is to first think, then write, review, review, think, and finally post - if and only if you still think it makes a useful contribution to the thread. KR RJD A&NTV
Also, it is easier to make adjustments with your phone set up like that, as you can see your adjustments in real-time (though I would only do that with Bob's Knobs installed).
very poor how to.. it doesnt say what settings the camera are, what is that star finder,
all I see when I put my camera into the scope is whatever its pointed at, like a sign..
I see No circle in my camera.
Hi there, it's hard to know where to start, but you may have mistaken our intent. We used a camera merely to show you, the viewer, what we were doing, and the method that Ralph was demonstrating only has any relevance for the telescope type (Schmidt-Cassegrain) shown in the video. I have a sneaking feeling that nothing I say at this stage is going to help you because I don't think either of us has a clue why you watched this video. If you have a problem with your telescope and you can formulate it into a question, I'll try to help. Meanwhile, thanks for watching. KR RJD A&NTV