The Fornax Lightrack 2 thread

[900SL]

If nobody objects, I'd like to start this as a repository of useless knowledge for the LT2 mount.

 

I've gone from shooting wide angle DSLR then an Omegon Lx3 (lasted two months before I sold it), a SW SA2 pro (6 months, had some issues but got me off to a good start) and recently a Fornax LT2 has taken its place. 

 

Honestly, it's worse than a coke habit is this game. So to stem the outflow of cash for a while I've decided to stick with the LT2 for a year. well, apart from the Redcat 51 I quite fancy.

I'm bowled over by its tracking ability and think I've worked out a few fixes to tackle its limitations, namely 110 mins tracking, counterbalancing and targeting. If you have a LT2 or just bright ideas feel free to contribute fixes, workarounds.

From this to this in just over a year:

     

[900SL]

1: Targeting:  I use an Astromania red dot sight. I collimate it before dark with the Nikon. Can't always see the stars through the mirrored glass but it works with the right technique of sighting. Helps I'm usually shooting in a B2 area

2:  Polar alignment: I went for a HEQ5 polarscope (I think its HEQ5..), the one with the graduated circular reticule, and because this is not usually accurately collimated with the RA axis when fitted into the radius arm outrigger I bought the adjustable collimator sleeve which means I can get it bang on line. I preset this in advance then mark the location with reflective tape so I can install it in the correct position when I set up

3: North orientation and level:  Sunway photo level and pan head. Usual Chinese quality, the locking arm is poorly toleranced so needs herculean strength to fix in position once leveled but once done it's good all night. I had to strip it to get the old duck pan grease out of there but now pretty smooth and saves a lot of time and effort setting up. 

4: Counterbalance: I use the SW SA counterbalance arm on a vixen clamp on a panorama head so can balance and set approximate RA and Dec. I'm in the process of changing this to a vixen rail and a slimmer pan head to reduce the offset weight as I'm at 24N so it hangs out a bit. Works great

5: L bracket and various clamps for the camera and guide scope. I'm not actually using the ASI Air Pro or scope at the moment as the guiding is first rate if accurately polar aligned but this is how I used to set it up.

6: Ram mount for Android tablet

7: Second ram mount for a smallrig magic arm. This thing is great, I can lock the counterbalance arm in position when the Fornax comes to the end of 110 minutes, release the pan head and rewind the Fornax without losing frame.      

[900SL]

V1.3

 

Being an Engineer I can't leave good enough alone

I bought a Vixen counterweight arm at a reasonable price. Changed the TS optics panorama head for something slimmer, a Novoflex pan head, fitted with a smaller TS Vixen clamp.

The TS pan head has been repurposed as an adjustable dec head.

This is solid with no lateral or axial play. The big advantage, apart from the improved stiffness is that the camera weight is now no longer as eccentric (not hanging off the front) and when balanced correctly is over the RA axis of the Fornax mount. At 21N the Fornax is not far off vertical so this really helps reduce eccentricity. I think I'm finally happy with this arrangement

Astrophotography. Synonymous with the accumulation of brackets, heads and adaptors.

   

[900SL]

OK, now we are cooking.

First numbers look good with the ASI and Fornax.  Wind was up a bit so the odd buffet to the mount but the tracking seems stellar. 

 

 

 

Edited September 14, 2021 by 900SL

[900SL]

GT71 arrived with a 0.8 reducer flattener. Polar aligned with ASI 120mm mini

Quick test at 1 minute exposures in the back garden show round stars (unguided) using the crop sensor D5600.

Set up seems quite sensitive to wind or vibration however, needs handling with kid gloves.

 

 

 

[900SL]

I need a sturdier tripod with a 100mm or thereabouts flat head, to suit the Fornax wedge...  3/8th inch thread preferably. 

 

Preferably not silly money but maybe something I could subsequently re-purpose with a future Equatorial mount?

 

 

[900SL]

Monologues R'Us 

Found that a couple of LT2 users has successfully repurposed a Bosch survey tripod BT170.

At a cost of $70 this seemed like a no brainer. Arrived yesterday, pretty substantial piece of kit.  It's a few years since I was a site setting out Engineer but it all came back to me

Solid as a rock. Had to change the 5/8" coarse thread coupler to a 3/8" x 16 TPI bolt set up to mount the Fornax 200 wedge. 

It's made a considerable difference when compared to the Benro I was using. There is ZERO wobble or movement. I shot 16 test frames yesterday evening, every one a keeper.  

 

I'll get some light chain to act as spread limiters at some point

Edited November 1, 2021 by 900SL

[900SL]

Guiding with the ASIAP.

I continue to be impressed by this tracker. I'll write a full review shortly, pros and cons. Mainly pros..

[DBT]

Brilliant solution! I have the Fornax and GT71 and have been struggling with a damped ball mount screwed onto the Fornax to hold the WO.  Copied your elegant design...

Edited April 15, 2022 by DBT

[900SL]

After buying a Vixen SXD2 GEM goto, the Fornax LT2 sat in a corner but I recently shipped the mount to Finland so I have put the Fornax back into use.

 

There's something to be said for a simple unguided tracker set up under dark skies. I managed to bag 80 minutes on Andromeda with the Redcat 51/D610  at 120s exposures, 80 minutes on the Pleiades (same set up), then 2 1/2 hours on the Witch head nebula with a Samyang 135mm / D5600 at 135s in succession.

The friends I went with didn't bag much due to guiding issues, software issues or a mount fault. Whilst my rig purred away I went over to commiserate

Collimate the polar scope over a 180 degree swing on a distant target in daylight. Set up facing north, get Polaris whilst it is still twilight, focus the scope, collimate the red dot finder

Rewind counterbalance arm, Focus, tape down, Red dot to target, intervalometer

It was a bit breezy so I expected a few throwaways but Not one duff sub out of 150+

Tracking is phenomenal if accurately polar aligned

Runs for 6 hours + on a small battery bank with a USB 5.5 to 12V converter

Here's the compressed Jpegs. Seeing was poorish due to dust with the breeze. and the odd high level haze. All are cropped

 

 

Edited October 23, 2022 by 900SL

[900SL]

And for anybody interested in this mount who has read the Peter Zelinka beat down on it:

 

The primary issues Peter had with the mount were due to operator ignorance or bias towards a favored brand in my opinion. I'm sorry Peter, but if you are going to review a mount at least take the time to find out how to use it

His criticisms are:

1: Expense:  True, it isn't as cheap as a cheap Chinese tracker so expect to pay for it. It will, however, do what it claims to do. You can Heath Robinson a balance arm and use a WO wedge. The Fornax base and counterbalance are expensive accessories but you can use alternatives. I typically shoot up to 320mm for up to three minutes with NO lost subs due to the accurate PE (or lack of, I should say). It's in a different league to the SWSA and iOptron trackers 

2: Restriction on exposure time: Peter was using a ball head so had trouble re-framing after 100 minutes of exposures. He obviously wasn't aware that you can reframe after adjustment by releasing the panoclamp on a ballhead or panohead on the RA axis and then reframing the target using the red dot finder. Takes me all of three minutes in the field, including shooting a test frame, focus check, then I'm good to go for another 50 frames. See above for demonstration in the field

3: 12V Power: I use a cheap as chips Anker battery pack with a 5.5V to 12V USB connector. Lasts for a couple of nights or more and can charge your phone etc as a bonus 

4: Polarscope: I use a standard circular graticule scope from an EQ mount. He also didn't seem to realise that you need to collimate the polar scope on the radius arm by swinging through 180 degrees on a distant target before use. Again takes 5 minutes

 

So, in conclusion, and if you know how to get the best out of it, the LT2 is a phenomenally accurate bit of kit. I've used it in pretty adverse conditions (Saudi desert mainly) and it continues to perform flawlessly. By way of contrast, the SWSA I had beforehand needed a complete strip down and rebuild before I could get anything like acceptable performance, and had significant PE in operation resulting in a rising reject rate on subs as focal length increased.

 

Totally recommended

 

Edited October 23, 2022 by 900SL