Fornax Lightrack 2 Review

[900SL]

Blame Ollie, he suggested I do a review.

Or why you really don't need any other tracker than this masterpiece, for a portable set up.

 

I bought the LT2 after banging my head against a wall in trying to overcome the inherent failings in a Skywatcher Star Adventurer 2.

I won't go into details about that here, and I know several users are more than happy with the wobbly little pot metal box of poor tolerance gears and wheels, but I wanted something that would give better than 50% keepers on longer exposures and focal lengths, and wouldn't go out of polar alignment if I sneezed. Maybe I'm being too harsh. It worked sort of OK at shorter focal lengths and exposures, despite the apparent quality of manufacture. 

Better gears than my SWSA

 

So, my thoughts, impressions, and stream of consciousness ramblings on the LT2:

 

First up, it isn't cheap. Probably because it's well made and highly accurate. But that comes at a price. And the associated Fornax wedge is too expensive in my opinion, but it works. All in, for the money I've spent on the rig and accessories, I could have bought a HEQ 5 Pro, and had Go-to, but I travel out into the desert so need a relatively quick and portable set up. Plus my previous Skywatcher experience had put me off the idea of cheap Chinese mounts and tuning.

The LT2 uses a 30 degree sector arm to give the equivalent of a very large diameter drive hub, together with a friction drive wheel and electronic wizardry to track at a claimed 2 arc second PE or better. More on that later

It can rotate through ~ 30 degrees before it reaches the travel limit, which is just less than 2 hours of exposures. It also runs off a 12V supply.

These are frequently cited by paid product promoters sorry 'Youtube Astro Influencers' as drawbacks and reasons to place their free samples higher in the rankings, which is incorrect IMO.

 

The 12V is easy, either run from a 12V supply, an ASIAir or a 10,000 mA battery bank with a USB 5.5 -12V converter like I do (it draws very little current when tracking)  

The apparent time limitation on tracking is easily addressed with a 'small rig' outrigger arm and a panoramic head. As the LT2 approaches the tracking stop, turn it off, clamp the camera in position, release the pano head, reset the sector arm, re-tighten the pano head, release the small rig clamp, check framing, check focus, then start tracking for another 2 hrs. Takes 5 minutes or less  

 

 

Polar alignment.. well, i went through a few iterations before I got this nailed. I started with a polar scope and collimator adaptor. This worked fine but would take me 20 minutes to set up and dial in each time. I did consider a Polemaster but this required a PC, and I wanted to keep it simple. Plus the name 'Polemaster' sounds a bit like a strip-joint nightclub star, not that there's anything wrong with that I suppose   

I already had an ASI Air Pro but didn't realise that I could use the AAP software PA routine with the 30 degree rotation limit of the LT2. It asks for 60 degrees but guess what, I decided to give it a go one evening and it worked perfectly

Here's how:

Set up, level, +/- 5 degrees of north using a compass (the limit of the adjusters in the wedge)

With the tracker off, use the main camera for PA using the AAP plate solve process. Switch on, rotate 30 degrees, switch off, complete PA. It's that simple. I can get better than 1 arc minute every time, and because I am using the camera rotational axis rather than the polarscope outrigger, there's no cone error

 

I can use the LT2 two ways. For shorter focal length stuff on visible targets, Milky Way etc, get it polar aligned, don't bother with guiding, use a red dot finder, get to work. Rock solid tracking, every frame a keeper unless the conditions change.  

Targeting of DSO's at longer focal lengths was a bugbear though. Using a red dot sight, I would star hop, then fish around in the dark taking photos to see if I was on target, then mess around with the RA and Dec adjustment for a while trying to center the target in the frame, and just forget it for dim DSO's, it was like blind darts interspersed with occasional yelling at the sky.

 

BUT THEN EPIPHANY. the ASI plate solve and DSO annotation functions completely transformed my targeting. Get it roughly pointed, plate solve, enter the values in an android spreadsheet, rotate the RA and Dec pan heads the required angles, plate solve and find the target in frame. I now use a worm gear Dec head to allow fine adjustment to center targets. I can be on point in a few minutes.    

 

Counterbalancing. I've seen videos on youtube by Fornax users with the most ridiculous assemblages of ball heads, extension arms, DSLR's and 400mm photo lenses that must weigh 5 kilos mounted precariously above the center spindle. Accident waiting to happen is all I can say. As the mount tracks the center of mass will move away from the pivot and place increasing strain on the drive wheel and motor, resulting in poor guiding, stalling or slippage, and there's always a risk that the moment will 'unwind' the ball head at the mount screw and dump your gear off to one side

I'm a Structural Engineer. Trust me, this isn't a good idea 

Image courtesy of internet

   

More to follow when i can be arsed.

 

Where was I? Ah yes, counterbalancing. I baulked at the ridiculous pricing of the Fornax counterbalance, and then ended up spending more on alternative arrangements. Such are life's lessons in astrophotography

First up, I used a Star Aventurer dec head and counterbalance weight on a vixen clamp adaptor.  Works fine, need to shim the spacing to make sure the counterweight clears the LT2 controls. I like the worm gear Dec adjuster.

Not being one to leave things alone. I then upgraded to a Vixen Polarie counterbalance arm, assorted clamps, panorama heads and the like, to join my ever growing collection of 'stuff'. I might need to move to a larger place if this continues. The Vixen arm works really well, the rigidity is excellent.

I would strongly recommend a counterbalance arm if you are mounting anything more than a APS-C camera and short lens. Easier to target, track, balance.

Tripod:

The tracking capabilities of the LT2 are completely wasted if you plonk this on a photo tripod with a center pole. I saw the set up above, which uses a Bosch survey tripod, and thought 'now here's an opportunity to reduce the average spending to date'. I bought the heavy duty version for about 60 pounds.  You need to remove the center adaptor screw and fit a 3/8 x 16 bolt and plate to mount the wedge

It's rock solid. Way better than my Benro

So, what does this get us?

Here's an AAP screen shot:

 

Vixen counterbalance on the old Benro tripod. I've made a few adjustments since then, I'll post an up to date photo after I've moved   

 

 

 

 

 

 

Edited March 12, 2022 by 900SL

[900SL]

Final iteration (for now )

 

Using the new to me TS 72 APO with the Vixen counterbalance arm, scope and ancillaries around 3 kg. I've included a photo showing how the smallrig arm holds the counterbalance locked in position when you need to reset the LT2 after a couple of hours. After reset, I release the smallrig clamp and move it to the rear. Hope these are useful to LT2 owners out there