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Update - the 73A flattener arrived today and as it was cloudy, raining, cold I thought I'd adjust the flattener to WO's specs (11.4 on the barrel scale), put a full frame DSLR (Nikon 800E) focus on an effectively infinite chimney, point said scope at the cloud base and take a look at the results. There are two images attached. One is as-is camera set to auto. The second is the same frame but given a mild stretch in Lightroom. Mottling in the frame area is I think from variations in the 'greys' of the cloud base. What I was really interested in was the corner vignettes. I'm pleased as that amount of 'corner' would likely be lost in stacking alignments or taken out with flats.

A few photos to show my concerns over the balance point: Images 1 - 4 show the balance point as it was last night - very near the end of the dovetail bar. Image 4 shows the locking screw's position blocking further movement of the dovetail bar. Image 5 shows the dovetail bar shifted back after removing the locking screw.

Miraculously it cleared late evening here, not brilliant but good enough to give the scope a quick test. I now know that I will need to be more careful with balance and to that end I will need another small weight on the counterweight bar and also shift the dovetail bar further under the focuser as I didn't feel the dovetail bar was fully supported across the Sky Adventurer's Dec plate. The built in Bahtinov mask worked brilliantly making focusing a simple task. There was some trailing to images but the fall-off in image quality from centre to edge of my DX (APS-C) size sensor is quite marked. The trailing I'm putting down to the balance issues and the dovetail bar position making the mounts axles non orthogonal. Smaller sensors using the centre of the fov will be fine. I've added an overlay to one of last nights images showing the sensor sizes I have. For me as this was bought for imaging - it looks like I'm going to have to get the dedicated field flattener at some stage. Whilst not unexpected I was expecting better. On a more positive note before packing everything away last night I put a star diagonal (2 inch) and my ES 68° and 82° eyepieces on the scope and had a quick look around. As with looking at the tree yesterday when unpacking the scope, stars were crisp with good contrast, focusing was very precise - a nice ending to a new scopes first day. So next I'll move the dovetail bar further back (focus lock screw will have to go to do this), make a small additional weight for the Star Adventurer to better control the overall balance... Image is 5x90 sec 1600 iso aligned and integrated in PI with a histogram stretch. TBC

This scope arrived this afternoon so this is a first impression of the scope. William Optics ZenithStar 73mm APO – Purchased from First Light Optics, Exeter, UK. March 2019. Why a William Optics 73mm ZenithStar APO There are loads of this sized telescope around, rebadged, trinkets added, paint jobs. So Why a WO ZS 73 APO ? Originally, I started looking at the WO ZS 61 APO to go on my Sky Watcher, Sky Adventurer Pro pack mount. I’d been using the mount with various camera lenses coupled to either of my Nikon cameras (D5100 or D800E). I especially liked the image fov's from lenses in the 400 – 600mm focal lengths. The mount handled them well and unguided subs of 100 – 300 seconds using an intervalometer show very little signs of star trails even with the occasional 600 second sub (due to faulty cable connection). The WO ZS 61 APO’s focal length at 360mm was just that bit shorter than my 400 -600 ideal range so here enter a WO ZS 73 APO. With a 430mm focal length it crept into my ideal range. At f5.9 it was fast enough (photographically), it came with a variety of goodies and it was not too heavy for the rated loading of the Star Adventurer (less than one of my camera lenses). I looked at longer focal lengths too but their weight didn’t suit the mount when camera, finder etc were all taken into account. So, I placed my order with FLO and it arrived very promptly (along with the clouds). It arrived double boxed with semi ridged black foam inserts protecting the contents extremely well. In the box and assembly: The WO ZS 73 APO OTA with two finder scope rings (attached – but removable) A vixen profile dovetail bar anodised gold (matching the finder rings and the scope’s trim) A 2 inch to 1¼ inch reducer. End caps, the front-end cap hides a clear Bahtinov mask feature. The 2018 version has a thermometer fitted in the end of a 1:1 focuser knob. The focuser has a helical rack-n-pinion adjustable with 1:1 and 10:1 motion control’s Putting it together meant nothing more than adding the finder scope adjustment screws to the finder scope rings, respacing the OTA rings along the dovetail (if required) – job done. Visual impressions: The body has that clean medical exactness about appearance. It’s there to do a job and it intends to do it. The coloured trim adds colour in a not too subtle way. Overall clean, minimalistic and functional. Other impressions: I’ll start with the vixen style dovetail bar. What I like about it is the asymmetric hole layout along it’s length, allowing it to be switched 180° to better achieve a balance point* and still retain adjustment on the tube ring positions. It’s 2 inch helical rack and pinion focuser is smooth in operation and I can feel no play even when extended fully with an APS-C DSLR mounted. Focus knobs are large enough for gloved hands when used on colder nights. *The focus lock screw on the underside of the focuser to me is poorly positioned as it hinders the positioning of the dovetail bar if you put a heavy camera or eyepiece assembly in the focuser. The dovetail bar can’t extend backwards far enough for balance unless this screw is removed. There are three knurled screws holding accessories in the focuser, these press onto a compression ring to secure diagonals, extension tubes etc. I’ve put a 2 inch diagonal and 24mm ES 68° eyepiece in and looked at a tree coming into leaf and I have to say very impressed with the contrast and detail. I was a little disappointed to find that to put my DSLR on I needed a 35mm extension tube to get the scope to focus. Considering how prominent astro imaging is spoken about in the blurb a suitable extension tube should I feel have been included. Looking down the interior of the OTA from the focuser there are numerous baffle rings along the focuser’ draw tube. Tube rings have comfortably sized knobs with nylon washers which either secure or release the tube easily. It’s lens shade/hood slides easily but with enough resistance to prevent it sliding back if viewing near the zenith. There is a small knurled screw supplied to fit into the lens hood but on mine there’s swarf or a bad thread form and my screw doesn’t tighten and secure the hood. The supplied finder rings are very sturdy and will do the job of securing and adjusting the finder scope well. What I can’t understand is the size and proportion of the adjustment screws for the finder scope. They’re way over sized – especially if you look at the size of knurled screws used to secure equipment in the focuser. Looking forward to using this in anger under the stars Once I have some results to share I’ll post them to this review. Francis

Remember you do not need to level an EQ mount before doing a PA. If you're having problems with bolt adjustment then raise or lower one of the tripod legs to compensate and keep the bolt within a useable section of the thread. I had to with my NEQ6 Pro.

I did spend quite some time after getting the SA aligning the reticule on as distant an object as I could. Took quite a lot of very small adjustments before I was happy that rotating the mount whilst looking through the polar scope showed absolute minimal movement of the central cross hair. If your using a phone app to locate where Polaris should be placed make sure you have the correct settings in the app. Mine has a visual setting and a telescope setting - one being 180° from the other.

Yes, just the polar scope. Used a phone app to locate where Polaris should be and set the mount accordingly.

Hi Graham, The subs were circa 100s, that's determined by the mount's firmware. I'm using the original firmware which when I connect the camera to the 'snap' socket on the mount gives - fits header says 99.4s. Note: the bloating round the stars is caused by primarily two things: the condition of the lens and the full spectrum mod on the camera making it more sensitive to IR/UV which doesn't focus to the same point as the visual spectrum.

I decided last night to try my S.A. with an old 400mm Tokina 400mm f5.6 lens on a Nikon D5100 mono modified body. Although I have the Pro version of the mount I decided to just mount the camera/lens on a ball head rather than the the dec shaft and counter weight. I pointed the lens at M51, focused by zooming the image on the camera's live-view screen. I set the iso at 1600, shutter to bulb, connected a shutter release cable to the 'snap' socket on the mount which gave me circa 100s sub frames. There is a firmware update which allows other variations but I'm using as supplied at present. The image is a central crop of the frame. 45 frames were shot and 34 selected via PI's blink viewer taking out frames with aircraft/satellites etc. No darks, bias or flats have been added. No DBE to even the background. Frames integrated and histogram adjusted. Will try again with the lens/camera mounted on the dec shaft with everything balanced out.

Just bought a CEM60 standard and tri-pier (where's that postman...) ?

Steve - responded to your message - thanks. Francis

Will you be getting the CEM 60 standard model in - approx. when please Francis

I'm using a TS 80mm guide scope with a Lodestar with no problems. Rather than using the short rail that came with the TS guide scope I took the rings off and put them as far apart as a could on the main OTA. That took out all the vibrations coming from the single stalk under the supplied guide scope rail. I've also added a pale yellow filter (a UV/IR cut filter would be better) before the Lodestar to reduce and focus difference between the red/blue which helps slightly in sharpening up the guide star.

Looking very Tudor - black woodwork?

If your saving the sono tube then yes it would be difficult, might do it adding multiple layers as poly sheet will slide against itself quite easily, or put a cloth layer round the sono, then a poly layer...

Wrap the sono in polythene tightly first that will give you a smooth barrier between the sono and the CF. Or I think TS do a CF tube for 10 inch optics. https://www.teleskop-express.de/shop/product_info.php/info/p10113_TS-Optics-Carbon-Composite-Tube-Upgrade-for-GSO-254-1250-mm-Newtonian.html They do others

A telescope is computed to operate at infinity only - therefore in general that's it at it's best . Camera lenses are computed to work over a range and therefore not at best at any distance. Go with a scope everytime

Welcome to SGL. Great start and 3 M's in the 1st photo ?

Look at the Canon EOS M100 too

Managed to get a short run with the Lodestar installed last night (need to look at SharpCap settings!), anyway sequence of 50 frames shot with a gap of 4 secs between frames. I've stacked the first and last frames in Photoshop CS3 with an image of M1 to approx. same scale (not my image). The arrow shows the drift in 4 mins 7 sec (from timestamp). Drift is mainly due to poor north alignment. I made no adjustments later when viewing M1 at x62 (1250 fl with 20mm ep) for 5 mins. So need to sort the north alignment and fine tune the tracking speed (Oh and remember to re-set the platform when it ends a run... ?)

Thanks ALL. Out again briefly, again rain stopped play but at least I was able to confirm the variable drive rates through an eyepiece. When (and if!) there's a longer spell of clear stuff I'll pop my Lodestar in and capture a short animation. Biggest problem I think is going to be getting a good north when I put the platform down. Might try and make a little jig to take the right-angle finder, or a wooden tripod to fit the rocker-box foot holes with a finder on top... Life would be so much simpler if I didn't keep thinking up things to do!

New controller arrived today and installed. Works fine, from mega slow to see it rotating! ? Soon as I could see a couple of stars I set the platform up, rotated to Vega being the brightest to get a initial speed indication. Let it drift then pull it back in with the controller. Adjust the controller to give me a tracking speed. Kept Mars in the centre of fov for a good while at x180 - strated to rain so further test will need to wait... ?

Just run some calcs on the controller - it's giving me x1.3 the correct PWM pulse width required for sidereal motion whether set to max or min potentiometer settings... Kaput I think. It was a cheapie of the bay. Just ordered something more substantial. TBC.

It cleared for a while and things started well @ circa x180 (14mm + x2 barlow & 1250 mm fl) I started making pot adjustments, turning drive off then back on, increasing speed to recentre stars, adjust down to track ? - then there was this distinct 'POP' from the PWM controller ? speed output went to max regardless of the pot's position. Mmmm back to *bay for another controller or something better? TBC...