Let’s move the primary mirror inside of an Orion XT8 or similar telescope (to focus a DSLR)
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- čas přidán 11. 09. 2024
- As you know you can’t reach focus with a dslr on the original Orion ST8 Dobsonian. Like many reflector telescopes the problem is that the focuser runs out of travel. In a previous video I demonstrated ways to get around this problem. I mentioned moving the primary mirror forward as one of those ways. I show how I performed this on the XT8 and the required hardware. Many other model reflector telescopes will be very similar. Even if you don’t have an XT8 you should be able to see what’s needed for your particular model. I hope to illustrate the idea across those various models. This process is fully reversible should you wish to return it back to its stock position. Upon modification you will be able to focus with your dslr prime through the telescope. Eyepieces will also still work but require extension tubes. Why go to the trouble? The increased field of view offered by larger dslr sensors has advantages. Clear skies.
![How To Clean A Telescope Mirror: The Step By Step Guide [ 8" Reflector Telescope ] by Reflactor](http://i.ytimg.com/vi/wtc53Br_96g/mqdefault.jpg)
Question, would this same method work on an Orion StarSeeker IV?
I just Googled for “images”. From what I can see it has a fixed mirror cell. I may be wrong but from the best photos I can find it doesn’t look adjustable. I’ll pin this in hopes someone knows. I’ll keep my eyes open for one so I can look it over. Try Cloudy Nights and start a thread. Someone will know.
Great and helpful mod! Best part was seeing the kid take it out for observing! 😀
Thank you. That’s my personal assistant. If little fry can wheel it around I suspect nobody has an excuse.
A very ingenious method indeed. Always bringing ideas that apply to those of us on a budget. Thanks
Thank you for supporting my channel. The community is all I care about. Clear skies.
Nice! I had this same issue with a Celestron Newtonian, but was afraid to move the mirror.
Thanks for stopping by Chuck. I hope this helps a lot of people.
Another informative video Garnett. Folks if you have the skywatcher 200p dob you don't need to do this. Just remove the eyepiece adapter to achieve focus.
Exactly the kind of info I hoped to get on the comments. Pinned for others.
Teamwork mate. Thanks again for your help with my finder. Clear skies Vic
i just learnt something new today, thankyou so much Garnett 👊🔭👍
That’s a win. Thank you for watching. My goal is to do the same. Clear skies friend.
If you have a sky watcher truss type telescope, all you have to do is determine the distance were you can achieve focus with the camera. Do this by retracting the truss tubes until you find the spot and locking the scope there. Mark the spot for next time. For visual observation, extend the tubes all the way like normal.
Glad i found this, was about to cut the tube on my xt8 and 3d print extensions for visual observation
Great tips. Thank you. Happy new year.
Nice job! Hope you have fun with it Garnett :) I'm guessing the plan is to keep objects in the FOV for longer using the larger sensor?
You’re absolutely correct in your assessment. Buying object acquisition time. It’s easily reversible. My dslr told me no on focus. Cloudy Nights said can’t. I don’t like either word personally. I arrived here. Lol.
Very interesting solution great video showing process
Thank you Ollie. I look forward to your next adventure.
Very Cool !! Thats Clever Tip for Getting A DSLR into Focus..I might Have 2 Try Out My Self !! Clear Skies🔭
I tested. The very common 2” adapter is enough. For the XT8 this places the focus just outside of racked in by approximately 1/2”. I tried with 2” bolts also. They were not long enough. I prefer prime to ep projection to avoid the c.a. from my cheaper eyepieces lol. Ultimately I just like having the option if needed. Thanks for watching. Clear skies.
“2” extension” I meant. For eyepieces
Neat! You have the best instructional videos Garnett!
Thank you. I try to be helpful
Thank you, this was just what I needed! Careful about them bolts people, they're tight and will strip and snap off! I had to drill out two of them, not pretty work but I got the job done.
Also, is there a specific extension tube or length of tube you use with this set up to allow you to achieve focus with a telescope lens?
Easier and cheaper to cut the tube by 2 cm instead. When you want to go visual just use an extra extender at the eyepiece and the focal length doesn't change.
Wouldn't it be easier (and cheaper) to saw off 1/2" (an estimate) from the end of the tube? (edit: you won't get a wider FOV btw. The Focal length is determined by the primary mirror and doesn't change, your 'hack' moves the primary mirror closer to the secondary mirror. This moves the focal point up higher into the focuser but it does not change the focal lenght -> FOV is unchanged. Add a Focal reducer for a wider FOV.)
I know someone who had the same problem and the way he got round it was to replace the focuser with one that had a lower draw tube
That works in many cases. It was a gamble I didn’t want to chance. Thanks for sharing
Hello. I have an Orion 12" Skyquest. The primary mirror springs have always anoyed me because not enough tension. Do replacement springs have to be precise or can I just go to Home Depot and get anything similar?
It doesn’t have to be exact. You just want enough tension, that when compressed, doesn’t allow the mirror to slop around. Too rigid of a spring will obviously make it really hard to adjust. Too little resistance and you end up with a mirror mount flexing under its own weight. It’s definitely not something you can’t replace with a little judgement. I personally like replacement springs that have a touch more rigidity. I feel like it’s easier to collimate than the stock ones on the majority of the scopes I’ve used. Find something about the same length in a thicker material or slightly longer in about the same. No need to be overly critical. You might only opt for coated springs or stainless to avoid rust from weathering. That’s a good precaution. I hope you find what makes it easier and more enjoyable. Clear skies.
@@GarnettLeary H.Depot didn't have much. I found some nuts that fitted over the bolts and that in effect acted like a spacer for the existing springs. Turned out much better than before!
@patindaytona glad you improved on it. It’s always great to hear a success story. I don’t know why there’s not people pushing to improve what they sell. We get tired reiterations of the same old thing more often than not.
Where would you recommend getting these parts and how do I go about getting the right ones. I need this modification but I’m worried about getting the wrong stuff or messing it up.
Lowe’s or Home Depot. Take the original stuff there and ask them for similar parts. Springs that are a little longer and roughly the same size will do. It doesn’t have to be super exact. Have them match the thread pitch of the bolts. There should be someone in the store that can help.
What are your recommendations on how to remove the collimating bolts without stripping the threads?
Correct tool and bit size would have avoided that issue. Patience. A spray lubricant such as WD-40. In short don’t be a caveman and it will be fine. I set a bad example there.
That's my problem that I can't get focus with my Orion XT8 Plus Dobsonian using a Canon T3. Thanks for giving an idea of trying to fix this focus problem. 👍🏻🔭
Then, how I mesure the new focal length ?
Mine is 1200mm
Find the point where it comes to focus and measure that length. Alternatively you could use plate solve software and it will give you a very exact number.
@@GarnettLeary ok thanks
Before moving the mirror, if you only need an additional 8mm of infocus, considering getting a low profile canon t-ring, they make some that are only 2 mm thick and shave off 8 to 10 mm of back focus requirements. Another solution is adding a coma corrector that increases back-focus which some do, I believe that GSO 2” corrector does that… that gives you sharper stars to the edge which you need with a DSLR anyway, plus you can use it during observing.
@@stevenmiller5452 thanks, I had thought that, a comma corrector👍🏻
Garnett I have just bought stronger springs for my primary mirror on my 8” Dobsonian (Stella Lyra) which is basically the Zhumell. Can I just insert the springs one at a time from the bottom after I remove a collimation screw completely? Or do I need to strip the entire mirror and assembly out? Thanks mate 👍
That’s a good question and I’ve never considered it. I think you can get away with it if you can twist the springs into place. Let me know.
Although I have no Newtonian / Dobsonian I watched because your work is interesting. I suspect that now more people will undertake the project and that your method becomes known as the Leary Method. ((-:
Ha ha. Unfortunately I did not invent this clever trick. I just felt I had to dig too hard to find information about it. I published my results so I can confirm to others what works. Owners of XT8’s can copy. Folks with slightly different scopes can easily gauge off of this one. We live in 2021. Information at our fingertips and still it seems there are many holes. You sir are filling in the gaps too. I love sharing information. I love solving problems. Mostly I love helping people. Somewhere out there a person will type: “How can I use my dslr with my XT8.” Now they have an answer. I don’t much care if it’s only one person. It was worth the effort. They’re worth the effort. I love your bees. I don’t much know anything about bees other than their extreme importance in nature. Somewhere someone researching found you. Likely you solved a problem for them. That’s magnificent. If I ever were lucky enough to have a method named after me I’d hope it regarded generosity. The world would be amazing if we all treated questions as if their were no stupid ones. I hate seeing people ridiculed for curiosity. It’s foolish and only causes harm. I can’t even fit in the Grand Canyon what I don’t know about astronomy. I can easily overflow it with the gifts of knowledge from others tho. I just keep it up because somewhere someone is listening. I leave the entertainment to the clowns lol.
Although I do find it odd nobody commented on my Conan joke. If only people knew how clumsy I truly am... likely I’d never be given a camera to fix again. Lol
@@GarnettLeary Your outlook is admirable. Thanks for all the work you do making videos. You managed to do that of which I often fail. I get my elbows in the way. ((-:
I see your Conan comment as I type. At first I had the idea to joking call you "Conan" Leary, but the quality of your video made me forget to make that joke.
@@GarnettLeary ((-: At first I had the idea to jokingly call you "Conan" Leary, but the quality of your video made me forget to make that joke.
There's days I feel like I have a fist full of thumbs and that they're much too fat. If it wasn't for proofreading and the backspace key no one could read what I write.
Maybe you'll eventually graduate from fixing cameras to repairing wrist watches.
Lol!!!
Nice video! I made a similar modification on a small skywatcher reflector, but I skipped the addition of springs (the tube didn't have any from the beginning). That fact made collimation a real headache, so now I am going to buy and add some springs. Do you know if the springs need to match some kind of stiffness specification? Please forgive my english.
Greetings from Chile!
From my experience just get ones that have enough tension to push outwards. If they’re too tight the adjustments you make will just be smaller. It’s not overly critical. Good luck and let us know how it goes.
@@GarnettLeary thanks! I will give it a try
Don’t be overly critical with it. There seriously isn’t anything involved passed just getting a feel for the amount of tension you like. Warning: should you decide to cut springs down to size... do it with caution. I almost lost an eye to a small one. That’s a physics lesson nobody should learn the hard way.
my screws are so tight I feel like I'm going to strip them...wth?!
Great video and what's the first soundtrack that you played like the one at 0:51
Final Draw - Cushy. Epidemic Sound. Thank you.
czcams.com/video/JP1KTpRldWk/video.html
How do you remove the screws mine seem glued in place.
They typically are. You’ll have to put a good deal of inward force as you turn them. I stripped one of mine. I’ve heard of people using an alcohol based solution to dissolve the glue.
@@GarnettLeary I’m going to try that it’s very frustrating
Also what drill bit size did you use for the screw you stripped
I believe it was 11/32. Sorry I don’t remember. Alternatively you could use an easy out tool. I didn’t have one but definitely easier.
Would this work on a starblast 6?
Absolutely
@@GarnettLeary Hey, I'm looking for some springs, would a 1.6 inch tall spring and 0.23 inch wide spring work?
I’m not sure what size bolts are in the Starblast. 0.23 sounds fine. You need to fit it to the bolt.
@@GarnettLeary Ah OK thanks! That makes sense, Also I just wanna get the dimensions of the screws right, so the Diameter is 10, the thread type is 32, and the length is 3 inches?