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Skymax 127 mak - Fine Focus


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I put one of these on mine-

https://www.amazon.co.uk/Svbony-Finderscope-Astronomical-Photography-Observation/dp/B0852TP9R5

I had the older version of the mak so had to get an adaptor to take the thread to the sct one -

https://www.rothervalleyoptics.co.uk/antares-mak-sct-thread-adaptor.html

The focus locking screw makes a good index guide to allow you to make fine adjustments around a position. I wind it about half way out focus with the normal mak adjuster then tweak with the helical focusser.

You can of course add a handle to the normal focus knob, I think some people have used something as simple as a clip that looks like a large clothes line clip.

Edited by Toltec
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Initially I also struggled with focus on the Skymax 127 as the focus knob is VERY sensitive.

I tried using a Baader Helical Focuser (https://www.firstlightoptics.com/adapters/baader-t-thread-to-125-helical-focuser.html) but turning this caused the whole scope to wobble and when used with a zoom eyepiece the focuser turned when I changed the zoom!

I considered an electronic focus control but there is no off the shelf kit for the Skymax 127 and the DIY options are all rather Heath Robinson and unsatisfactory I felt.

Many people use a clothes peg (the spring loaded type) to get fine focus adjustment on the Skymax 127. Initially I though this seemed a bit basic but it actually works really well and a modified clothes peg is now an essential part of my kit.

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Not only does it allow very fine focus adjustment, but if you just gently nudge the tip of the clothes peg then you can change focus without causing the scope to wobble.

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Knew I'd seen the clothes peg somewhere Peter, just after I had ordered the Svbony focusser iirc. That focusser does not rotate so the diagonal stays where it should.

I've just swapped from an Allview to a AZ-EQ5GT and I'll admit it does still wobble when focussing, it settles within a couple of seconds even with an 8mm eyepiece though and it isn't like the wobble is large. If looking at Trapezium in Orion the wobble is 1/4 to a 1/3 of the diameter of the cluster on my setup.

I still like your lowcost solution though, minimal and elegant.

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1 hour ago, Zermelo said:

The cheapest option (apart from the peg) is possibly one of these : https://www.ebay.co.uk/itm/185060378222?hash=item2b1675466e:g:AZYAAOSw4J5hR8Li

@Zermelo I thought you had modified the visual back of your MAK to 2" as I have. With mine I have a Baader 2" ClickLock clamp on the visual back now and that doesn't leave much room around the focus knob. Does the fine focus wheel you mention still fit with a 2" visual back?

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2 hours ago, PeterC65 said:

@Zermelo I thought you had modified the visual back of your MAK to 2" as I have. With mine I have a Baader 2" ClickLock clamp on the visual back now and that doesn't leave much room around the focus knob. Does the fine focus wheel you mention still fit with a 2" visual back?

Well spotted, Peter!
I bought the knob first, but it doesn't fit with the larger visul back in place.
At some point I will think about grinding it down a bit and see if I can still use it.

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I fitted a diy focuser motor to my 127mak and it is the best mod I have done because you don’t have to touch the focuser which negates any vibration. Here are some pics.

B91E5413-F17F-4D22-928F-55B68B6EE550.jpeg

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This 1.25” crayford will fit the Skymax perfectly.  Unfortunately the focuser to scope adaptor has to be custom made at €84.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11734_TS-Optics-1-25----T2-Crayford-Focuser-for-Refractors--Cassegrains-----.html

https://www.teleskop-express.de/shop/product_info.php/info/p9286_TS-Optics-custom-made-Adapter.html

Here’s a pic of one I had fitted to my Omegon 127 mak.

04AB76D1-4266-438F-8285-6F64E0B7D51D.jpeg

Edited by johninderby
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Since the rubber grip on the focuser shaft of my used 127 Mak split and immediately fell off of it anyway (this was not disclosed by the seller, grrrr), I wrapped it in racquet grip tape and then shoved a cut down bicycle foam grip over that.  Both were sourced from ebay for $1 each.  With so much foam between my finger and the shaft, I don't get much shake during focusing.  There is still a gap next to the 2" visual back as seen in the photos below.  I also keep Sorbothane pads under each tripod foot to cut settling time from 3 seconds to 1/2 second.IMG_7467.thumb.JPG.fbda1b69365ac8495d36b23ba0102b0a.JPGIMG_7468.thumb.JPG.7251a219d4fc170dc3fba5ac1a176f70.JPG

 

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20 minutes ago, banjaxed said:

I fitted a diy focuser motor to my 127mak and it is the best mod I have done because you don’t have to touch the focuser which negates any vibration.

What exactly do you use for a controller since it isn't shown?  I'm presuming a home-brew box with buttons or a switch and batteries?

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17 minutes ago, banjaxed said:

I fitted a diy focuser motor to my 127mak and it is the best mod I have done because you don’t have to touch the focuser which negates any vibration. Here are some pics.

If you make this mod, be very careful to keep the tube objective lens upwards when you remove the focus knob as I understand that without the knob there is nothing to stop the whole mirror and focus mechanism from disappearing inside the tube! When I was planning a similar mod, my plan was to leave the focus knob in place as the ribs around it are exactly 6mm apart and so will mesh with a 3mm pitch belt drive.

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35 minutes ago, Yubnub said:

Will the SW 127 Mak take a crayford fine focuser? ...looks like there could be possible clash to the main focus knob. 

This adapter from FLO will convert the non-standard visual back thread of the Skymax 127 to SCT, then you should be able to fit an SCT focuser. The distance from the centre of the scope to the near edge of the existing focus knob is 39mm, so for an SCT focuser to fit it would need to be less than 78mm in diameter. I have a Baader 2" Clicklock clamp on my SCT adapted visual back and that takes up most of the space.

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And even the new ones can be converted back to the old Mak thread size by simply unscrewing the included SCT adapter ring.  The 127 Mak I bought for my daughter came this way.

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51 minutes ago, Louis D said:

What exactly do you use for a controller since it isn't shown?  I'm presuming a home-brew box with buttons or a switch and batteries?

Sorry I missed it.

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4BD996CA-33A2-4C24-914D-7C627D4AE8D6.jpeg

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15 minutes ago, johninderby said:

The Skymax127 comes with one of two thread sizes. The old non standard thread and the SCT thread. You would need to check to see which one.

The non-standard thread is 45mm in diameter, an SCT thread is 50mm. My Skymax 127 is less than a year old and was from a new shipment but it has the non-standard thread so I'm not sure the thread type is age related.

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54 minutes ago, PeterC65 said:

If you make this mod, be very careful to keep the tube objective lens upwards when you remove the focus knob as I understand that without the knob there is nothing to stop the whole mirror and focus mechanism from disappearing inside the tube! When I was planning a similar mod, my plan was to leave the focus knob in place as the ribs around it are exactly 6mm apart and so will mesh with a 3mm pitch belt drive.

Which is exactly what I did, fortunately standing the OTA the opposite way up everything slid back in to place and I was relieved to find it hadn’t done any damage. I had to buy 2 drive pulleys which fit perfectly on the focuser shaft so I have a spare one if anyone wants it at cost.

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3 hours ago, PeterC65 said:

If you make this mod, be very careful to keep the tube objective lens upwards when you remove the focus knob as I understand that without the knob there is nothing to stop the whole mirror and focus mechanism from disappearing inside the tube! When I was planning a similar mod, my plan was to leave the focus knob in place as the ribs around it are exactly 6mm apart and so will mesh with a 3mm pitch belt drive.

I don't believe this is true. The focus knob can be safely removed if the baffle-tube O-ring is in place (yellow added later). The baffle tubes and the primary mirror (which sits on the outer baffle tube) are supported and held in place by the three bolts whose heads appear on the back of the rear cell of the OTA, and are locked in place by the three smaller bolts also at the rear end of the tube. Undoing those three big ones is what will cause the primary to crash around inside the tube.

See my link here for pictures (and lots and lots of words! sorry!) of how my skymax 180 works inside: the skymax 127 will be similar although the metal tube itself is attached in a slightly different way (127 tube threads on to the rear cell).

Cheers, Magnus

Edit: on thinking more about this, I see what you mean. You mean that the outer baffle tube )with the primary mirror on it) can slide down and off the inner baffle tube without the focus knob on the threaded rod to retain it. There should be an O-ring sitting in a recessed trench on the outer baffle tube preventing this. If that O-ring is missing, and it's likely rubber and may have perished, then yes you are right. So I agree, best keep the scope horizontal or corrector-plate up when removing the focus knob from the threaded rod. And beware the evil black grease that coats the rod!

Edited by Captain Scarlet
PeterC65 was right :)
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6 hours ago, Zermelo said:

Well spotted, Peter!
I bought the knob first, but it doesn't fit with the larger visul back in place.
At some point I will think about grinding it down a bit and see if I can still use it.

How did you find it worked before you changed the visual back ? 

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