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SkyMax 127 Focuser


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Can anyone help...?

I've recently purchased a SkyMax 127 with the SynScan AZ GOTO 127mm Maksutov-Cassegrain. all works really well and i'm happy with my purchase. i'm pretty new to all this and i'm hoping to venture out from the enclosure of my back garden. but i would like to get a bit more associated and comfortable with using the scope and motor settings, which i have to say is pretty easy to use and set up.....apart from one thing....... there's always something.!!!!

The Focuser on the scope is proving to be a bit tricky to use. Its heavy to turn, The scope shakes when trying to focusing which means its difficult to actualy focus on something if anything.

Can anyone suggest any alternative focusers for this scope or any advice on how i can make life simpler with this focuser? i'd be appriciative on any advice.

Also, i'm based in Toddington Bedfordshire. i there anyone on here that knows of or lives local that knows of some good spots to view the night sky.

thanks for your time guys

mark

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There are a number of approaches you can take, including at least a couple that happened to have turned up in other threads in the last day or two, oddly enough.

A common mod for the Mak focuser is to get a plastic lid from a jar (Nutella and peanut butter are apparently favourites) and cut a hole out of the centre to match the focuser knob. The lid can then be fitted over the top of the knob to allow better control of the focuser.

An even lower tech version of the same thing is to use a spring clothes peg clipped onto the focuser knob. The plus side of this is that it's then a single finger "push" to move the focuser either way, but the negative side is that you need to get the focus close before adding the peg because it will foul the visual back. I used to do this, partly because I don't eat Nutella and I can't stand peanut butter :) It worked ok.

Another option is to motorise the focuser. I modded the standard Skywatcher motor focuser to work:

http://stargazerslounge.com/topic/135260-127-mak-motor-drive-focuser/

(or http://www.tanstaafl.co.uk/2012/02/skywatcher-127-mak-focuser-motor-drive-conversion/ if you want a few more images). I'm very happy with this solution. It can be a bit slow when large amounts of travel are required, in which case I slip the drive belt off and spin the gear by hand. If you're interested in imaging then a motorised focuser is a joy to have.

Perhaps the most expensive option is to buy a converter to fit to the back of the baffle tube to take it up to an SCT thread and then buy an external crayford or rack and pinion focuser with an SCT fitting. You can then use the standard focuser control to get close and the external focuser for fine control. Because of the way Maks (and SCTs) work, using the external focuser alone may not work in all cases. The potential down-side of this approach is that it can make framing more awkward for imaging because the focal length of the Mak increases the further away from the back of the OTA the focus point is. That means, for example, that whilst I can just fit a solar or lunar image onto the sensor of my 450D if I put the camera directly on the visual back, the image is too large if I move the camera further away as would probably be the case if I had an external focuser. If you've no intention of imaging then this isn't likely to be an issue, nor is it for imaging objects with much smaller angular dimensions.

James

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Hi!

Sorry i can't help you, but you can always ask a Mod to move this thread into the beginners Help And Advice section then you'll get more answers to your queries.

Good luck! :smiley:

Edited by saturn4me
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I have just bought one of these myself as a "quick set up for a gap in the clouds" scope

I agree that the focuser does seem stiff - (much stiffer tham the one on my C8) and as the mount is not the most sturdy it can cause problems when trying to acheive focus. Maybe it will loosen off over time .

Maybe someone who has had one for more than 3 days can enlighten us :grin:

In the meantime it's off to Tesco for some Nutella

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thanks all for your comments.

look like i'll be purchasing some Peanut butter. good excuse to get some if anything.

i might look into the motor option as eventually i would like to get into the photography side.

i'll keep you posted how it turns out.

thanks

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I take the budget option and take a large pair of pliers out with me to grip the focuser with. These give good leverage for fine focus adjustments and result in far less wobble from the tripod.

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i think i may have to play around with both options here. see what works best.

seems to be abit of an after thought when designing this scope, seems odd that they would supply such a cumbersome focuser.

oh well onwards and upwards.

i did find this alternative for mead scopes and wondered if anyone has used or modified the same design for the Skymax 127.

http://stargazerslounge.com/topic/164407-skymax-127-focuser/

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I'd have thought one of those shouldn't be too hard to make up. I think the plastic lid or clothes peg would work better though, as they significantly increase the radius of the "control surface", making fine adjustment much easier.

If, for example, you effectively increase the radius of the knob by five times by adding a lid or peg then that requires five times the movement at the edge to move the focusing system by the same amount, or, looking at it another way, the same amount of movement generates only one fifth of the focuser movement when applied on the larger control surface than the standard knob.

James

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Do you not still get a shaky scope when you touch the dial?

i think that was my main issue was as soon as i lay my hands on the dial it seems like i was trying to look at something while standing at the epicentre of an earthquake.

i'll definatly give the jar lid and peg a go though. seems the easiest and most approved option.

thanks

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Not to mention cheaper :)

I found there was very little wobble when using the clothes peg, even when imaging at focal lengths you'd never dream of using for visual with that scope so hopefully that will be fine.

James

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The great thing about the 'peg' system is that you can focus by just pushing it with your finger tip rather than gripping the focuser which means you'll not shake the setup anything like as easily.

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Do you not still get a shaky scope when you touch the dial?

i think that was my main issue was as soon as i lay my hands on the dial it seems like i was trying to look at something while standing at the epicentre of an earthquake.

thanks

I agree with this. Maybe the problem is not only the movement of the mirror to focus, but due to the instability of arm mount. I have not problem while using the telescope for visual but when imaging it,s quite difficult not only to focus but to keep the planet at the screen if you touch the focuser.

nobody is using a cryford or motor focuser with the mak?

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Hanging weight from the tripod or putting it in the tray can help with the stability of the mount. I don't tend to use the eyepiece tray on my EQ3-2, so I often put a couple of decent size stones in it.

As regards the motorised focuser, see the links in my first posting in this thread.

James

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I agree with this. Maybe the problem is not only the movement of the mirror to focus, but due to the instability of arm mount. I have not problem while using the telescope for visual but when imaging it,s quite difficult not only to focus but to keep the planet at the screen if you touch the focuser.

nobody is using a cryford or motor focuser with the mak?

I have a crayford fitted to my 180 pro mak, and i still get lots of wobble at high mags, i could do with a bigger mount than the EQ5/CG5 combo, but that will have to wait

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ive been fiddling with my 127 during the day and not extending the legs fully, and a few kilo sandbag made a difference.

i suppose you could knock up some sort of brace for the legs too ..

credit to the weight idea from james as i tried it on an auto trak mount with with my frac and it helped there ...

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