Sky-Watcher Maksutov-Cassegrain: Skymax-102 OTA

Look | Look on Different Bases | Basic Data | First Photo Attempts | Preliminary Conclusions | Links

On this page, I present some information about my newest telescope (Maksutov-Cassegrain), a Sky-Watcher Skymax-102 OTA - 102 mm /1300 mm Maksutov-Cassegrain optical tube assembly (ordered on May 23, 2016, received on May 28 after collimation at the dealers'), which I also wanted to use at my Virtuoso base (in addition to the Heritage 114P Dobsonian tube that was delivered with the Virtuoso base). However, I returned the Virtuoso due to technical problems and got a refund. Therefore, I use the tube currently on the Heritage 100P base only.

The basic data was collected from the Teleskop-Spezialisten Website (in German), where I purchased the telescope.

Note: On a further page , I describe how I use the Skymax-102 on a simple Dobsonian table-top base (from Sky-Watcher Heritage 100P).

 

Look

Unpacking, Bag

Outer package

Ditto

Package dimensions :
Outer package: 57 cm x 25.5 cm x 24.5 cm
Innermost package: 53 cm x 21.5 cm x 21 cm

Gross weight : 4 kg, net weight: 3 kg (gross weight 4,5 kg according to DHL)

Ditto

Ditto

Outer package comparison with Sky-Watcher 114P Virtuoso

Ditto

In-between package

Ditto

Another box appears...

All packages on one photo!

Ditto

Opening the inner-most box reveals a bag...

Bag taken out of the box

Small box with accessories unpacked

Accessories unpacked

Telescope tube taken auf of the bag

Ditto, the screwdriver points to the diagonal mirror...

Ditto with Heritage 100P base

Bag opened, you can see the cover for the content

Bag and cover for the content opened

Bag with tube, which is wrapped in protective plastic

Accessories: 10mm and 25mm eyepieces, red dot finder, diagonal mirror, and more

Collimation

The 6 Allen screws for collimation at the rear end of the tube

  

The main mirror of the Sky-Watcher-102 OTA can be adjusted using 6 Allen screws, which are located at the rear end of the telescope. The small Allen screws are used for locking, the large ones for adjustment.

Instructions from Teleskop-Express (translated, original in German):

The collimation should be done directly at a star. Make it out of focus at a magnification of about 100 x. A dark shadow (the secondary mirror) should be exactly at the center. If it is not, you should adjust the telescope. Please proceed as follows:

  • First, loosen the (small) locking screws. The adjustment is not yet affected.
  • Then carefully adjust the primary mirror using the adjustment screws. Note that ¼ turn already has a clearly visible effect. Please adjust the mirror until the dark spot of the secondary mirror is exactly at the center.
  • Then fix the locking screws again.

The telescope is now collimated and will give you the best possible performance.

 

Look on Different Bases

Telescope Tube on Heritage 100P Base

Skymax-102 on Heritage 100P base

Ditto, front view

Ditto, front view, closer

Skymax-102 on Heritage 100P base, other side

Skymax-102 on Heritage 100P base, seen more from the back

Ditto, details (focuser, diagonal mirror)

The tube is mounted against the "official" view direction. The locking knob for the tube was orientened so that the knob hit one of the three holes in the prism rail.

Telescope Tube on Omegon Mini Dobson Basis

As an alternative to the Heritage 100P base, I also use the tube on a simple Omegon Mini Dobson base.

Skymax-102 on Omegon Mini Dobson Base

Ditto, front view

Ditto other side

 

Ditto, rear view

 

The diagonal mirror hits the ground plate. You cannot rotate the tube complete - not a real prroblem...

Ditto, detail

Ditto, detail

The locking knob for the tube was orientened so that the knob hit one of the three holes in the prism rail. However, I found out that, when using the Omegon base, it is better to orient the locking knob towards the side of the prism rain that does not have holes.

Teleskop-Tubus on Heritage P130 Base

Since the tube tembles too much for may taste on the two small bases, I also tried the base of the Heritage P130 for the Skymax-102 OTA. This base is slightly too big, but somewhat more stable than the two other bases and thus, trembles a little less. For home use, this base seems to be a good solution, but for travel purposes, it is too big and unwieldy.

Skymax-102 on Heritage P130 base, side view

Ditto, other side

Dtito, rear view, detail

Ditto, rear view

Ditto, rear view, tube vertical

Ditto, rear view, tube horizontal

Ditto, front view

Ditto, front view, tube vertical

Ditto, front view, tube horizontal

The tube is mounted against the "official" view direction. The locking knob for the tube was orientened so that the knob hit one of the three holes in the prism rail.

Telescope Tube on Star Discovery AZ GoTo Mount

Last, but not least, I also use the tube on my Star Discovery AZ GoTo mount, which regrettably results in an unusable position of the red dot finder.

Skymax-102 tube on mount (overall view)

Ditto (Detail)

Front view - you can easily see the unusable position of the red dot finder

Skymax-102 tube on mount, turned around (overall view)

Ditto (detail) - you can easily see the unusable position of the red dot finder

Rear view

 

Ditto (detail) - you can easily see the unusable position of the red dot finder

 

I will have to find a solution for the finder positioning problem...

 

Basic Data for Sky-Watcher Skymax-102 OTA (in Comparison)

Telescope
Meade
Sky-Watcher Skymax/Heritage
GSO
8" 10" 12" 16" ETX 90EC 102 76 100P 114P P130 GSD 680
Optical Design Newton
(Parabolic)
Newton
(Parabolic)
Newton
(Parabolic)
Newton
(Parabolic)
Maksutov-Cassegrain Maksutov-Cassegrain Newton (Spherical) Newton (Parabolic) Newton
(Parabolic)
Newton (Parabolic) Newton (Parabolic)
Primary Mirror Diameter 203 mm 254 mm 305 mm 406 mm 96 mm (90 mm) 102 mm 76 mm (3") 100 mm (4") 114 mm (4.5") 130 mm (5") 200 mm (8")
Focal Length, Focal Ratio 1219 mm
f/6
1270 mm
f/5
1524 mm
f/5
1829 mm
f/4.5
1250 mm
f/13.8
1300 mm
f/12.7
300 mm
f/3.95
400 mm
f/4
500 mm
f/4.38
650 mm
f/5
1200 mm
f/6
Resolving Power (arc secs) 0.56" 0.45" 0.38" 0.28" 1.3" 1.15" 1.51" 1.15" 1.01" 0.9" 0.58"
Limiting Visual Stellar Magnitude ca. 14 mag ca. 14.5 mag ca. 15 mag ca. 16 mag 11.7 mag 12.7 mag 11.2 mag 11.8 mag 12.1 mag 13.3 mag 14.5 mag
Maximum Practical Visual Power ca. 550 x ca. 600 x ca. 700 x ca. 900 x 325 x 204 x ca. 100 x (152 x) 150 x (200 x) 170 x (228 x) ca. 220 x (260 x) ca. 300 x (400 x)
Optical Tube Dimensions (diam. x length) 28 cm x 115 cm 35 cm x 119 cm 40 cm x 144 cm 51 cm x 170 cm 10.4 cm x 27.9 cm 10.4 cm x 27 cm n.a. 11.5 cm x 37 cm* n.a. Tube collapsed < 37 cm
(14.5") long
23 cm x 115 cm
Net Weight Basis 9 kg 12.2 kg 15 kg 24 kg 3.5 kg (complete) --- 1.75 kg (complete) 1.3 kg* 1.6 kg 3.1 kg* 11.2 kg
Net Weight Optical Tube 10.9 kg 17.2 kg 21.3 kg 33.6 kg 1.9 kg 1.2 kg*
(2.5*/2.8 kg complete)
3.7 kg
(5.3 kg complete)
3.25 kg*
(< 6.5 kg or 14 lbs. complete)
9.5 kg
(appr. 21 kg complete)

Dark Blue: Telescopes that I still own; italic and dark red: telescopes that I owned; black: for comparison; *) own measurement

 

First Photo Attempts

In preparation

 

Preliminary Conclusions

OTA

In preparation

Bases

I tried the Skymax-102 OTA on four different bases and came to somewhat different results than I had initially assumed. Since the Skymax 102 tube is significantly heavier than the Heritage 100P tube and also magifies more than three times more with the same focal length of the eyepiece, the trembling of the small bases is more noticeable with this tube. Therefore, whenever I want to do without GoTo, I will always use the more stable P130 base at home (even if it is still not free of trembling...).

On holidays, on the other hand, I would choose the 100P basis because of lack of space. The Omegon base is more or less superfluous, unless I take the Heritage 100P tube also with me.

If I want to use the tube with GoTo, the Star Discovery AZ GoTo mount comes into play. This will, however, only be the case at home...

 

Links

 

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gerd (at) waloszek (dot) de

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24.10.2016