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Single Arm Fork Mount Chirality - Left or Right?

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#1 abe


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Posted 24 January 2014 - 12:19 PM


In reviewing various single arm fork mounts, I was a bit perplexed as to why there doesn't seem to be any consistency as to whether the fork should go on the left or the right.

As a right handed person, it seems to me that the fork should go on the left so you can move the scope/diagonal with the right hand while loosening the clutch with the left. This is why the friction controls on the well designed fork mounts of the C8 / Meade 2080 have the clutch on the left. However, for the single arm fork mounts that have cropped up over the past few years, most have the fork on the right although there seems to be no clear consensus:

Left hand forks:
- Astrotech Voyager
- Meade LS Goto Series
- Celestron C90 (70s vintage)
- Celestron C5+ (80s vintage)
- Meade 2044
- Tecnosky AltAz / Binomount

Right hand forks:
- Vixen Porta
- Celestron SLT Goto Series
- Celestron SE Goto Series
- Borg/Hutech Oasis
- Kenko Alt-Az (can go either way)
- Takahashi Teegul
- Quantum Q4/Q6
- Half Hitch Series

I don't get it. Is there any logic is behind these design choices?

In some ways, it seems that the old 70s era Celestron/Meade designers had it right decades ago and since then many designs seem, shall we say, less than inspired.


#2 Sorny


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Posted 24 January 2014 - 01:35 PM

Nexstar SE scopes, when looking through the eyepiece should have the fork to the left. You also don't move an SE series scope without power if you want it to work for long.

#3 LTE



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Posted 24 January 2014 - 05:41 PM

Both the Celestron SE and the Meade LS/LT series telescopes have the fork (in the sense of the upright arm) on the left. Neither can be moved without power. I am right handed and preferred the practice of placing the HC in a recess in the right hand arm, as was done on the Celestron GPS series, whereas the SE necessarily has it on the left. I generally keep the HC there, avoiding seeing the display while observing faint objects, and finding the motion buttons by feel. I have nonetheless come to appreciate the location of the handset on the Meade, flat on the base, as less tiring to use, and it is also easier to replace the HC in this rest position than in the vertical socket on the SE after using it loose.


#4 abe


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Posted 24 January 2014 - 06:16 PM

I stand corrected on the SE mounts, which have the fork on the left like the Meade LS scopes. However, the SLT mounts and Meade DS2000 have the fork on the right. Also, the non-Goto mounts are split about 50/50. So it's still not very consistent or sensical.


#5 Manny Myles

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Posted 24 January 2014 - 08:16 PM

Abe, The Voyager goes both ways and I did not see the ES TwilightI mentioned and that goes right or left too.

#6 abe


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Posted 25 January 2014 - 03:39 PM


Thanks, yes, good point about the Voyager. The left-handed verses right-handed issue with these single arm mounts relates to the fact that they do not provide a good place to grab and in general, they have poor ergonomics. I have a Voyager, which is ok, not great, but a slight improvement on the Porta, which I also had for a time.

On the Voyager, the slow motion controls work well but it still has a fair amount of stiction, no bearings (all bushings and sleeves with some sort of gummy lubricant), no setting circles, it's gratuitously heavy in the wrong places, has poor ergonomics (no comfortable places to grab), doesn't lock very well (tiny screws that are easily lost instead of nice levers) and doesn't move as smoothly or generally work as well with a 5" scope as the fork mount of my 40 year old 2080 does with an 8" scope. I ended up replacing the Voyager head with a custom made aluminum fork mount which moves better and has better balance (anyone want a Voyager head/fork?):

I've been looking for / trying out mounts for small 5-6" scopes and just haven't been that impressed. Next up, I'm waiting for a Kenko Alt-Az. Still, I sometimes get the feeling that I'd be better off trying to find an old Celestron C5 mount from the 1970s or 1980s. What would be ideal is an all metal "push-to" mount with built-in encoders that would communicate wirelessly to a mobile app, blending the build quality of past decades with the benefits of modern tech without all of the cheezy plastic construction, motors, batteries, and goofy hand controllers of the GOTO world.

With the dwindling market and insignificant margins on astronomy products, you can't blame the manufacturers but the mechanics of a lot of the gear on the market today seems pretty inferior (although modern optics are excellent and inexpensive).


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