Avalon Linear Mount at low latitudes

[arjv]

Hi everyone, I am interested in buying the Avalon Linear Fast Reverse mount. I live at a very low latitude (19 degrees N) so am not sure how this mount will perform here. While going through the Manual I saw some alarming photos of the adjustments to be made for operating at this latitude. See below phot from the user manual showing the adjustment. Basically the front altitude adjustment bolt has to be replaced with a small hex head bolt to avoid clashing with the mount body. 

 

Since this forum has the most number of Avalon Linear users, just wanted to get their opinion on how difficult it will be for polar alignment and whether there is a chance that the CW shaft will hit the tripod. The other mount that I was considering is the Losmandy G11G in which this issue is not there with the RA extension kit that they supply. However I was really impressed with the Avalon Linear's all belt drive system and guiding accuracy of <0.5 arcsec total RMS (based on reviews I read online). I intend to use whichever mount I get with Avalon's TPOD-110 tripod which I am also very impressed by. Any advice would be much appreciated. Thanks.

[sonnymoon]

Hello,

I have an Uno not a linear, but just wanted to say that Avalon's customer support is excellent and so it may be worth emailing to see what they say.

I did notice on their website that they have a new Mzero designed for low latitude, although whether that's suitable will depend on your payload.....

[AngryDonkey]

Hello!

I operate my Linear at 22 degrees north. Removing the adjustment knob and replacing it with the screw is no issue at all. Yes, adjusting altitude gets a bit more fiddly but I find that I can always adjust the hex screw by hand without any tools even when fully loaded at 19kg (balanced). As it only needs to be done once per night it doesn't bother me at all.

At my latitude I find that I can just about get away with the standard tripod (but its close), so depending on where your weights are you might struggle. In any case I would definitely recommend getting the Avalon tripod extension. This will not only give you more room to clear the weights but also allow you to image past the meridian.

I love my linear, hasn't let me down yet... 🙂

Kind Regards,

Mike

Edited April 13, 2020 by AngryDonkey
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[arjv]

Hi Mike thanks for the info, I'm guessing you also have to rotate the RA axis out of the way everytime to get to that hex bolt because there's barely any gap (2-3mm) from the photo. I use polemaster to polar align and one problem I have with my current NEQ6 is when I tighten the altitude adjustment bolts after achieving P, the alignment goes off slightly. And then I have to try again to bring it back to alignment while simultaneously tightening. Have you faced this issue with the linear? Can you get away with just finger tightening the bolts?

Yes I definitely am considering the tripod extension but only issue is its too expensive (200 Euros) and I'm already at the limit of my budget. I'll just try to DIY the extension and if that doesn't work out then I can always buy it later. 

How is your typical guiding with this mount , are you able to get around 0.5 arcsec total RMS regularly? I've read some reviews that say that wind can be a major issue with this mount. What scopes do you typically use with the mount? Since you said you're loading 19 kg on it I'm guessing a big Newtonian or SCT. 

Arjun

[arjv]

And yeah Sonny I will reach out to Avalon as well, I've read multiple places that their customer support is great (one of the reasons I'm seriously considering this mount). Also yes the MZero would not suit my needs as I intend to get an 8" newt or SCT in the future. I currently have just an 80 mm APO.

[AngryDonkey]

15 hours ago, arjv said:

Hi Mike thanks for the info, I'm guessing you also have to rotate the RA axis out of the way everytime to get to that hex bolt because there's barely any gap (2-3mm) from the photo. I use polemaster to polar align and one problem I have with my current NEQ6 is when I tighten the altitude adjustment bolts after achieving P, the alignment goes off slightly. And then I have to try again to bring it back to alignment while simultaneously tightening. Have you faced this issue with the linear? Can you get away with just finger tightening the bolts?

Yes I definitely am considering the tripod extension but only issue is its too expensive (200 Euros) and I'm already at the limit of my budget. I'll just try to DIY the extension and if that doesn't work out then I can always buy it later. 

How is your typical guiding with this mount , are you able to get around 0.5 arcsec total RMS regularly? I've read some reviews that say that wind can be a major issue with this mount. What scopes do you typically use with the mount? Since you said you're loading 19 kg on it I'm guessing a big Newtonian or SCT. 

Arjun

Hi Arjun,

At my latitude I don't actually have to move the axis out of the way as fingers just fit into the gap (but I have slim fingers 🙂). For me the trick to slightly overdo the adjustment on the hex screw (with fingers) and then tighten it up with the knob from the other side going back the other way. I also have the polemaster and this works well.

Please be aware that there are various versions of the polemaster adapter for the Linear. The latest one is correct but you need to remove the carry handle to fit it. Previous version only allowed the polemaster to be fitted with the cable coming out of the bottom which is incorrect. The USB cable must come out the left side looking from the front to ensure the the atmospheric refraction compensation is applied in the correct way. And at your latitude that's going to be important.

Yes I would say the mount is susceptible to wind but can't quantify how that compares with other mounts. I use an astro tent around it when it gets windy which works well. For me the guide performance using a guide scope is anywhere around 0.4 to 0.8 arcsec RMS usually. But regardless of the values I haven't had any issues with loosing subs due to guiding.

I'm using a dual scope setup 2xFSQ85 on the mount (the images are still with the WO71):

Hope this helps.

Mike

Edited April 14, 2020 by AngryDonkey
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[arjv]

Thanks a lot Mike, the photos definitely help. Your cable management is on point, I really need to get to your level on this! I'll definitely make sure I get the latest polemaster adapter if I end up buying this mount. 

[AngryDonkey]

I took a while to get it there 🤣 but time well spent...

In terms of easily portable mounts I think the Avalon hits the (expensive) sweet spot for me and as I have no prospect of a permanent setup just now it's just what I need. 

[Skipper Billy]

I ran 17kgs on my Avalon and it never missed a beat.

A few things I did notice were ....

It likes short aggressive corrections from the guiding system

It is quite sensitive to balance - it needs to be good

Its quite easy to get total RMS down to 0.5" but very hard to get it any better

Roundness and tightness of stars is almost always better than the guide graph would suggest (belt elasticity?)

A few photos about a third of the way down this page https://www.davidbanksastro.com/equipment

Great mount - you will love it when you get it dialled in.