Low Profile Focusers

[ShOrEbReAk (Troy)]

Hi all

I know this has come up before and I have searched and read the tutorials on cutting down the tube etc. Will a low profile crayford focuser fix my problems? can anyone suggest a good focuser as the one that came with my OTA is a crappy here you go to start job .

My OTA is a sky watcher Newtonian with D=130mm F=1000mm.

cheers
Troy

[Retrograde (Pete)]

What sort of issues are you having in particular?

Moonlight are always good (not cheap however).
Have a look at their page for some good info on sizing etc.https://focuser.com/newtonianinstall.php

[ShOrEbReAk (Troy)]

Hi

Just cant get my dslr to focus on any stars even with the T-ring setup and just the camera adaptor onto the focuser alone. I can get the moon to work but anything smaller i cant.

just lacks the amount of focus needed to get stars or other objects i would like to shoot in focus.

Thanks will look into the moonlites

Troy

[Wavytone]

Originally Posted by ShOrEbReAk

I can get the moon to work

Er... if you can focus on the moon everything else will be at the same focus. No adjustment needed !

Are you sure you know what you're doing ? With a 130mm scope and a fairly ordinary DSLR there's a good chance it won't show any stars in the viewfinder, unless you happen to be pointing it at the really brightest ones - Sirius, Canopus, Rigel; or Venus/Jupiter.

Focus on these, lock the focus and then go point it where you like. This is a rough start, there are better ways but it sounds like you have a lot to learn and a rather small scope.

[Tropo-Bob (Bob)]

Try using the scope on a distant object during the daytime. Also take the time to align any finder with your scope.

If this works, U can be assured that U can see stars ok.

[Retrograde (Pete)]

Yes as Wavytone said if the Moon focuses then stars should as well & it's very hard to see any stars other than the very brightest with a DLSR - even using live-view. Try focusing on Sirius, Canopus or Alpha Centauri & see if you can get focus using them before investing in a new focuser.

[ShOrEbReAk (Troy)]

Originally Posted by Wavytone

Er... if you can focus on the moon everything else will be at the same focus. No adjustment needed !

Are you sure you know what you're doing ? With a 130mm scope and a fairly ordinary DSLR there's a good chance it won't show any stars in the viewfinder, unless you happen to be pointing it at the really brightest ones - Sirius, Canopus, Rigel; or Venus/Jupiter.

Focus on these, lock the focus and then go point it where you like. This is a rough start, there are better ways but it sounds like you have a lot to learn and a rather small scope.

Wavytone

I am not a dim wit! I have tried this with the obvious brightest stars you mentioned and still nothing!

I have a Canon 70D camera, so fairly ordinary of sorts i think. This camera has no problems locking onto stars and seeing them in live view with a lens less competent than a bigger lens in the OTA. also how do I LOCK my focus with the OTA? no focus lock on that! i have taken test pictures trying the live view getting it to where i can see an image of some sort and adjusting the focuser either way after getting there. I also tried with just adjusting the focuser manually. I can not get an image other than a blur. I also shoot the milk way regularly and know how to get my focus right and set for the night. As for the small scope and alot to learn, Isn't that why we ask questions on here. Its not a pissing contest for who has the biggest scope! I would like to use what i have available to me and is why I asked the question. If you cant be bothered helping then don't reply no skin of anyone's nose either way! Let mte guess your a 60yr old man who sits in his shed all night and run a star club cause you know everything? everyone starts out somewhere even you did if you can remember that far!


Before I use the scope at night I focus on a distant object to adjust my scope and finder before I polar allign my setup.

I dunno beats me!

[Retrograde (Pete)]

If you are getting your stars focused OK in live-view but the resulting images are blurry then it could possibly be focuser slip caused by the weight of the camera which is relatively common (& causes many headaches). A quality after-market focuser should have a focus lock/tension adjustment knob.

If you aren't able to achieve focus through live-view then it's likely you need more inward focus & a low-profile focuser as you originally suggested might help. Getting the correct sized one will be critical however to ensure you can achieve focus both using the camera as well as with an eyepiece for visual.

Good luck.

[multiweb (Marc)]

I had a simlar scope but f/5. At the time GSO provided a cheap low profile focuser. From memory the barrel height was under 50mm for a 2' diameter.
You said you can focus on the moon. Are you full travel on the focuser at this stage or do you still have a bit to go in? Because if you can focus on the moon then the stars are really pretty close as well. What you could do is take any adaptor off the camera, hold if flush to the focuser barrel fully racked in then point the scope to the moon and check live view to see if you are focused. With a bit of luck you might have to rack your focuser out. If you have let's say 10 to 15mm of travel to focus then you might get away with a very thin adapter to hold your camera. Your scope is 1000mm FL so unfortunately I doubt you'll see any stars in live view at that FL even at high ISO. If you're still out of focus then the easiest way would be to get a x1.5 barlow. Otherwise chop 10mm off the bottom of the tube to get the primary cell closer to the secondary.

[ShOrEbReAk (Troy)]

Pete and marc

Thanks for the replies. I think the generic focuser doesnt like the weight as suggested and is another reason why i asked abiut the low profile focuser.

I think the focuser was racked out to achieve focus on the moon by memory. I cant get anything in focus on live view except the moon when the camera is attached.

I will try the suggestion of taking everything of the camera and measuring as you said. Last and worst case scenario i will cut the tube down a little.

Would a better primary mirror be any help? Or is it just the size of the scope that is limiting my capabilities of getting some nice photos.

Cheers
Troy

[multiweb (Marc)]

Originally Posted by ShOrEbReAk

Pete and marc

Thanks for the replies. I think the generic focuser doesnt like the weight as suggested and is another reason why i asked abiut the low profile focuser.

I think the focuser was racked out to achieve focus on the moon by memory. I cant get anything in focus on live view except the moon when the camera is attached.

I will try the suggestion of taking everything of the camera and measuring as you said. Last and worst case scenario i will cut the tube down a little.

Would a better primary mirror be any help? Or is it just the size of the scope that is limiting my capabilities of getting some nice photos.

Cheers
Troy

If you're racked out then all you need is an extension tube, maybe 50mm and rack the focuser back in accordingly. Maybe try day time on the horizon to get an idea.
Your primary is likely to be more than adequate. I wouldn't worry about the optics. All you need to do is work out your focuser travel and how far from the tube your camera comes into focus. If you wish to upgrade to a better focuser in future and are worried about slippage then I'd recommend a moonlite. They're the best value for money, simple and beautifully engineered. For the aperture, your scope is a little slow but that's ok if you're guiding. I reckon you can get a lot out of it before you move on. 1000mm is a good FL. Plenty to do.

[ShOrEbReAk (Troy)]

Marc

cheers again. I will try it out again this weekend to see how it goes again. I would like to use this scope for a while yet as I would rather drop more money on a good mount first than a new scope as I have the eq2 which is barely usable. It came with the clock work motor but I have noticed it tends to skip a gear or what sounds like, when I have he camera on there.

at least if i get the moonlite I can just buy the mounting plates for the new scope in the distant future!

Troy