RC8 focuser recommendations.

[Len1257]

I'm getting ready to pull the trigger on an RC8 for increased focal range over my WO GT-81 and SW 150PDS. It seems that the supplied focuser supplied with these scopes isn't the best for heavy image trains. I will be useing it with an ASI071 camera, filter drawer, ASI OAG, and ASI EAF and probably at some point a field flattener/reducer. So not particularly heavy but I would rather hit any likely focusing problems out of court if I can.

I have recently fitted a Baader Diamond Steeltrack to my 150PDS and found it strange to see a relatively large gap between the focus tube and housing. Not helpful when it comes to darks but as the 150PDS is an open tube not relevant to my other concern which is that of dust, moisture etc getting into the image train for a closed system. The Steeltrack is working well with an ASI EAF and seems to be fine with the same image train. But for the gap, which I would have expected to be shrouded, I would have automatically chosen another Steeltrack for the RC8.

I noticed another member of our community advocating the use of rack & pinion focusers for this application. I aleady have one on my GT-81 with another ASI EAF and that works just fine too. I see that FLO has a TS 2.5" Rack and Pinion Focuser M90 for £220 which I suspect may be the one Vlaiv uses? This is cheaper than the Steeltrack to boot. Any reasons not to go for this? 

Any other contenders out there? 

[Clarkey]

I put a Steeltrack on my RC8 (and I also have one on my 150mm TS Photon) and I think they are excellent. Yes, rack and pinion focusers are good for imaging as they won't slip, but they can have some backlash. The Baaders don't slip or have backlash - but it is at a price.

If it was me I would go for the Baader, but I think both would work.

[johninderby]

Have the TS focuser, an original Steeltrack and a Diamond steeltrack and have tested them all on my 8” CC. All are the refractor version.

The original Steeltrack draw tube is short enough to fit the focuser with no extensions.

With the Diamond Steeltrack an extension is needed as the drawtube is longer.

The TS has the longest drawtube and could be a problem due to limited infocus caused by the long drawtube.

The Steeltracks are noticeably smoother in operation and will lift as much weight as the TS. You can feel the difference in quality. Now the TS is good, just not as good ass the Steeltrack.

[Len1257]

Thanks both. Orders in! Any comment on the gap between the drawtube and the housing? I'm asking just in case mine has some shrouding/felt missing!

[bottletopburly]

1 hour ago, Len1257 said:

Thanks both. Orders in! Any comment on the gap between the drawtube and the housing? I'm asking just in case mine has some shrouding/felt missing!

I used the foam that the steeltrack came with in box and cut a small strip , a silly design error , there is also a solution here not sure if they have a 150pds one https://en.rbfocus.net/product-page/adaptador-200pds-para-enfocador-baader-diamond-steeltrack

 

Edited January 9, 2022 by bottletopburly

[Len1257]

2 hours ago, bottletopburly said:

I used the foam that the steeltrack came with in box and cut a small strip , a silly design error , there is also a solution here not sure if they have a 150pds one https://en.rbfocus.net/product-page/adaptador-200pds-para-enfocador-baader-diamond-steeltrack

This wasn't the gap I was referring too LOL! I've fixed that with some self-adhesive foam strip. I have a gap between the outer housing and the actual drawtube. It is a concentric gap around the moving focuser tube. It's not seen in John's image as the focuser is racked fully in. 

[johninderby]

There is a small but needed gap between the drawtube and the housing.. Pic of the Diamond Steeltrack on my 6” CC.