ZWO focuser advice

xelasnave · #1 18-10-2021, 11:47 AM

I had not contemplated getting a ZWO focuser so I do not know a thing, however I expect the RASA may be a pain to focus both because being F2.2 but also I realise for me just getting out of my chair to move a metre is really a pain..and if I am to get one the sooner one orders these days the better...

SO... Anyone have experience with the unit, what should I order and what software will I need so I can get started..I have watched one video on installation but not my scope and it seems simple enough.

OR any helpful links would be very much appreciated.

I would ring Bintel but my voice is so crook I doubt if I could be understood plus having become more adventurous buying on the net I am wondering if I would save time ordering direct...Bintels service against getting it sooner...mmm I need to think about it as I really prefer dealing with them..and if I could talk probably would have already spoken to John and placed an order...

Alex

The_bluester (Paul) · #2 18-10-2021, 05:36 PM

I have the superseded version which has a 12V input (The new ones have USB only plus an aux port for a temperature probe and hand controller, which I presume has a battery in it)

Mine has worked flawlessly for the couple of years I have had it. The only downside I can think of (Which was discussed on here some time back) is that on an SCT, and I presume this carries over to a RASA, the focuser can count steps for about 11 turns of the shaft and a Celestron SCT has about 40 turns of the focus knob. The fix is to get it ready to mount (With whatever mounting kit applies to the RASA) move the focus motor to the mid point of it's step count then rough focus the scope prior to fitting the focus motor, so best focus should be around the middle of the motors travel.

Nikolas (Nik) · #3 18-10-2021, 06:49 PM

I have the older version as well on my big refractor and swear by it. Gonna get another one for the 72mm as well

xelasnave · #4 18-10-2021, 08:01 PM

Thank you Paul and thank you Nik..
It is wonderful to have input from people you know and trust.
Alex

Startrek (Martin) · #5 18-10-2021, 10:45 PM

Alex,
6 months ago I fitted the ZWO EAF focuser to both my 6” and 8” newts ( had to make up a custom bracket etc.... to allow it to fit ( ZWO don’t have a focuser kit for GSO newts )
I opted for the hand controller and use my Capture software APT to perform fine focus. Works brilliantly !!
These ZWO EAF focusers are excellent compared to my old JMI Moto focusers which were painful to use and waisted so much time focusing.
The ZWO EAF hand controller has 2 modes, fast / slow and a focus in and out button.
Distance from my focuser to laptop table is 5m for both 6” and 8” newts
Power Supply -
5m USB2A to USB2B cable available anywhere ( power supply via a plug in USB2 charger from Bunnings)
Hand controller control cable ( 3m + 2m cables ) -
3m 3.5mm TRRS 4 pole Male to Male cable ( Avencore part no AVC - C5693 available from Cable Chick in Brisbane)
2m 3.5mm 4 position headset cable Male to Female ( Startech part no MUHSMF2M available from Mwave in Sydney)

Check to see if the ZWO EAF fits the RASA ok ?

You only need the EAF focuser software if your Capture software doesn’t have a focusing feature or focusing tool

Cheers
Martin

xelasnave · #6 19-10-2021, 02:07 AM

Thanks Martin I really appreciate having your input.
Alex

AdamJL · #7 19-10-2021, 08:58 AM

They’re known to have a lot of backlash. If you’re okay tuning them out, they should work fine, depending on the scope, with a bit of effort.
When I looked at it, for my Esprit I had to modify my scope to fit it and that didn’t seem good at all. That, plus the backlash meant I went with a Sesnto Senso 2 which is a very good unit. Highly recommended. Minimal backlash and easy to tune out with a gauge dial.

Startrek (Martin) · #8 19-10-2021, 10:01 AM

Quote:

Originally Posted by AdamJL

They’re known to have a lot of backlash. If you’re okay tuning them out, they should work fine, depending on the scope, with a bit of effort.
When I looked at it, for my Esprit I had to modify my scope to fit it and that didn’t seem good at all. That, plus the backlash meant I went with a Sesnto Senso 2 which is a very good unit. Highly recommended. Minimal backlash and easy to tune out with a gauge dial.

I don’t know about yours , but I have 2 on different scopes ( focal length 1000mm ) and focusing is so precise it’s ridiculous,the movement is Swiss watch stuff. If there is any backlash it’s negligible
I usually focus on a mag 2.0 to 3.0 star ( zoomed in 8x ) and the slow focus speed is actually too slow which means you have some tolerance in and out
I use my diffraction spikes to achieve tight focus , when they are sharp swords as sharp as I can visually achieve , I’m done.Never had an out of focus image at my focal length using the visual method. Pixel / centroid software methods are fine but at the end of the day your eyes ( or someone else’s eyes )have to be the final judge. Unless your imaging at 2500mm to 4000mm then software is definitely needed but eyes are still the final judge at the end of the day.

Cheers
Martin

Nikolas (Nik) · #9 19-10-2021, 10:32 AM

Quote:

Originally Posted by AdamJL

They’re known to have a lot of backlash. If you’re okay tuning them out, they should work fine, depending on the scope, with a bit of effort.
When I looked at it, for my Esprit I had to modify my scope to fit it and that didn’t seem good at all. That, plus the backlash meant I went with a Sesnto Senso 2 which is a very good unit. Highly recommended. Minimal backlash and easy to tune out with a gauge dial.

Did you actually own one?

xelasnave · #10 19-10-2021, 10:46 AM

Quote:

Originally Posted by AdamJL

They’re known to have a lot of backlash. If you’re okay tuning them out, they should work fine, depending on the scope, with a bit of effort.
When I looked at it, for my Esprit I had to modify my scope to fit it and that didn’t seem good at all. That, plus the backlash meant I went with a Sesnto Senso 2 which is a very good unit. Highly recommended. Minimal backlash and easy to tune out with a gauge dial.

I watched a video showing the installation on similar scope to the RASA and was happy to see that zwo sell a suitable braket as my experience with "cheap" units was that you ended up making something which these days is beyond my physical ability and indeed my mental tolerance.
Getting rid of back lash was covered and I may be able to pull it off as it seemed very easy to do.
Alex

The_bluester (Paul) · #11 19-10-2021, 11:22 AM

I would also say that the backlash on mine is minimal, far less than the Celestron focus motor I used to have on my SCT when I imaged with that scope. I keep seeing "They have lots of backlash" written about them but it is not my experience.

For visual use or manual imaging focus I would say that the backlash would be more or less irrelevant, and when used with imaging suites like SGP, Voyager or NINA (I can't comment on APT as I was not doing automated focus when I was using it) any sane amount of backlash is irrelevant and can be dialled out in software. There is no need to be precise, so long as your backlash compensation moves go the right way and are more steps than you have backlash combined in the focus motor and focuser, no problem.

AdamJL · #12 19-10-2021, 02:32 PM

Quote:

Originally Posted by Nikolas

Did you actually own one?

No, but is that relevant? I researched it and other options (SS2, Pegasus Astro) before I made my choice. I spoke to others on the NINA discord seeing as I’d be using NINA as my software platform and in the end decided on the SS2 based on my comments above

AdamJL · #13 19-10-2021, 02:40 PM

Quote:

Originally Posted by The_bluester

For visual use or manual imaging focus I would say that the backlash would be more or less irrelevant, and when used with imaging suites like SGP, Voyager or NINA (I can't comment on APT as I was not doing automated focus when I was using it) any sane amount of backlash is irrelevant and can be dialled out in software. There is no need to be precise, so long as your backlash compensation moves go the right way and are more steps than you have backlash combined in the focus motor and focuser, no problem.

Agreed. I used a fantastic method to measure my backlash accurately using a dial gauge, and added the necessary compensation into NINA based on that. Should be easily doable on any focuser.

The_bluester (Paul) · #14 19-10-2021, 02:49 PM

While I really like the SS2, from my experience the backlash in the ZWO is irrelevant in use. Some backlash compensation steps (I use 100 steps with my refractor) added to the focus setup and it functionally makes no difference in operation. I have used mine on three scopes, one with a crayford and two with R&P focusers with excellent results on all three.

I reckon there will be more to deal with inside the RASA than in the ZWO focus motor, unless Celestron have made the mirror behave a lot more predictably in the RASA 11 than in the regular SCT lineup.

The only thing I might say against it is that the internal temperature sensor reads consistently high, probably from being housed inside with the electronics, but temperature delta is what I use that for to trigger focus runs and it works fine in that regard.

evltoy (Wayne) · #15 19-10-2021, 04:43 PM

I'm an owner (2 month) of the 5 volt version and have it installed on my C8.

Very easy to install with the addition of the SCT bracket. Took me a few days to get my head around the fact the EAF will NOT travel through the OTA's entire focal range. You will need to find the middle of your working range with your equipment on the OTA and set that as the middle point in the EAF. For me that was 18-19 clockwise turns for my 0 point on the EAF. So far I have used a Barlow, reducer, DSLR (Full and APS-C), ASI camera, 40mm, 23mm, 12mm eye pieces and my EAF travel range has been within.

Yes backlash is evident, but you can tune this out by punching the values in the app you are using.

I'm currently using mine with the remote (no batteries required) and I find this very handy when doing visuals on planets on my Evolution mount. When imaging the planets I have it connected to FireCapture which shows you its current position point. The cool thing about this is if I change my equipment and know its position point for that setup, I can just enter the number in and "Bam" it goes right to it and I just have to do some minor focusing - no more hunting!

You dont have to have the EAF connected to your PC when using the Hand Controller. You just need a standard 5v USB and that is it. It will also retain its position point without the PC.

I also use APT for imaging with my DSLR. I have connected the EAF to it, it works but not using it in auto mode.

I have on order the ASIAIR plus which will work well together to automate my imaging nights.... cant wait! I think its a well worth item for me and will also be getting one for my ED80.

Cheers
Wayne

Sitt (Simon) · #16 19-10-2021, 05:12 PM

Quote:

Originally Posted by AdamJL

No, but is that relevant? I researched it and other options (SS2, Pegasus Astro) before I made my choice. I spoke to others on the NINA discord seeing as I’d be using NINA as my software platform and in the end decided on the SS2 based on my comments above

I own an Espirit 120 with a Sesto Senso 2 fitted to it but suffered slippage i.e. when you pull the focuser all the way in to the 0 position the Senso seldom managed to fully reach the 0 position leaving around 10-15mm left on the draw tube. I sent several emails off to SkyWatcher in the US and they recon my slippage was caused by the Senso being fitted to the micro-focuser side rather than the course side of the focuser. They recommended either the ZWO EAF or Optec SWX30. I went with the EAF which appears to have fixed my slippage issues. Just something to keep in mind with the Sesto.

evltoy (Wayne) · #17 19-10-2021, 05:21 PM

Correct me please.. The Espirit range and evostar 150DX uses a geared meshing system for the focuser as oppose to the evostar using a friction style setup. My ED80 did slip a little when loaded up with the SE 2x barlow and DSLR. To fix this I just slightly tighten the grub screw under the focuser to provide a little more force to grip.

The_bluester (Paul) · #18 19-10-2021, 05:37 PM

The ED80 has a Crayford style? In which case yes, there are tension screws to increase the tension of the focus shaft against the drawtube and improve friction, you might need have a good look as some have multiple screws for tension and most have lock screws which stop the drawtube from slipping in use but which will also stop the focus knobs from moving it too.

evltoy (Wayne) · #19 19-10-2021, 06:02 PM

Quote:

Originally Posted by The_bluester

The ED80 has a Crayford style? In which case yes, there are tension screws to increase the tension of the focus shaft against the drawtube and improve friction, you might need have a good look as some have multiple screws for tension and most have lock screws which stop the drawtube from slipping in use but which will also stop the focus knobs from moving it too.

Yes, I know of the lock screw to fix the draw tube in place after focus. I would expect this will need to be removed when using the EAF of auto focusing

My issue was slipping while trying to focus. Especially when pointing 70-90deg.

Drac0 (Mark) · #20 19-10-2021, 06:15 PM

Recently purchased the EAF (from Bintel, only a few days for delivery) but haven't had a chance to test it yet as it will be going onto the 102 refractor I have coming. I have the Celestron focuser on my C8 & very happy with it. While the Celestron version is more expensive than the ZWO EAF, it works out of the box and you don't have to spend another $60 for the special bracket.

Just a note on the Celestron focuser: if you are not connecting it through a Celestron mount but via USB to a pc/laptop, the Celestron unified driver on ASCOM does not work. You need to download the USB driver version direct from Celestron & use that instead.

Cheers