A Tale of Two Focusers (with apologies to Dickens)

[pmrid]

You could not get 2 pieces of equipment more different: On the one hand we have a brand new ED127 from North Group with what they describe AND SELL as an " advanced 2inch dual speed focuser for astro-photography". On the other hand a Moonlite "CFL 2.5 inch Large Format Crayford Refractor Focusers".

When the ED127 arrived, and I removed it from it's case, the focuser simply fell off. It was not attached to the OTA at all, but merely sitting in place. There are 3 grub-screws that had not been tightened in the least degree. So much for Quality Control and Presentation. But wait, there's more. When attached, the focuser that is supposed to suit the needs of astrophotographers proved unusable for any purpose. There is a locking bolt underneath the body. When fully engaged, the drawtube moved easily in and out and would not hold even a light DSLR. But worse still, the focuser flopped a good half-inch to left and right as well as up and down. Even when racked well inside the focus point for this scope, the drawtube waved around like a leat on a tree: and that with the locking bolt fully engaged. On looking inside, it was clear that there should be two rollers per side holding against the metail rails that centre and stabilise the drawtube. Only one roller per side was visible. There did not seem to be any second roller, so the whole drawtube was centered by two rollers in the front position. No wonder is flopped around.

By way of extreme contrast, Moonlite's focuser arrived promptly, fitted wthout a hitch and is firm, stable, accurate and does precisely what is says it will.

On describing the complaints I have with their focuser, the NG response was to ask for photos. I sent a short video instead but have had no reply from them to those. Even if they do reply, there is now no way this side of eternity that I will put anything they make onto this telescope.

What remains now to be done is to test the optics. The scope is sold as an APO. I am suspending judgment on that and may report back when I get a chance.

If you are contemplating buying an ED127, do so by all means, but do not have any expectations of a usable focuser as part of the package.

Peter.

[FlashDrive]

I recently purchased an ED127 .... WITHOUT ... any of your problems in place. In fact the Focuser was smooth to use .... fitted firmly in place ... and a joy to use. Sure .. there are better focuser's out there eg: FT and MoonLite if you want to " improve " your gear.

It is disappointing to hear you received yours in such a state. From reading what you say ... some one is negligent at the other end for not doing a " final " shipment check prior to dispatch.... and I understand your feelings on this matter.

I consider these Scopes to be " good value " for size and mine produced very nice views with "low " power eyepieces . ( wide field views )

I hope your new MoonLite Focuser and your opinion on the optics " drowns away " your unpleasant beginnings with your new Scope.

Flash :hi:

[h0ughy]

i never regretted fitting the moonlight to my 127, as for the optics sure its no TAK but it is pleasing for the money.

[pmrid]

The irony is that when I confirmed the order, I specifically asked that the collimation and assembly be fully checked before shipping.

And to be fair to NG, this is my second ED127. I alays regretted selling the first one that I bought 2 years ago. Like Colin's, it had a reasonably functional focuser.
As I said, I haven't tested the optics yet so that can wait for another day.

Peter

[adman]

Hi peter - good to hear you've bought another one! Have you got any pictures of the moonlite you got? I am going to order one for mine after Xmas. The focuser on mine is not held on by grub screws, but rather the whole focuser screws onto the end of the OTA, and i am wondering whether the good folks at moonlite can accommodate this...?

Adam

[scagman]

Hi Peter,

Sorry to hear you are having problems. I've only had mine out a couple of times and found the focuser to Ok. Having said that I havn't got anything else to compare it too. I also have a moonlite to go on but have to get the right size alan key.



Hi Adam I have the OTA with the focuser screwed onto the end. Rob from moonlite as the correct end for this setup. Just mention that to Rob and he will send the correct flange.

[pmrid]

Here are a couple of images of my Moonlte setup as requested by Adam. Not the best photos but you get the idea. The ED127 requires the large-format 2.5inch focuser and there is a specific flange that they make for the 127 - easy to order. Be sure to tell them that you have the aluminium OTA or the CF - the attachment method is different for each.

The upshot of these focuser issues has been that I have now disassembled the NG version and discovered what was wrong. I'll mention it here in case others find it useful.

Disassembly is not difficult. You remove the knob on the left side (without the 10:1 knob) and slide it off. There is a single grub-screw. That should allow you to slide the shaft part-way across and allow the drawtube to be removed. Fully slack off the tensioning bolt underneath of course.

The rollers on which the drawtube should slide are mounted in short 44mm long aluminium sections in which there are two rollers - one at each end. And the roller shaft is mounted just a bit above the midline so that the rollers sit slightly proud of the body - provided that body is inerted right-side-up. There are two of these assemblies - at the 2 o'clock and 10 oc'clock positions. As the pressure is applied from the tensioning bolt below, the drawtube is pressed upwards against these 4 rollers thereby providing both guidance and a degree of braking. There is no separate brake.
In order for these 2 aluminium assemblies to sit in the body of the focuser, their corners are slightly beveled (should that had 2 'l's) and these have the look of somethig that is done by hand because they are different and irregular. In my case, the bevels on the side required for proper orientation were too small so the constructor merely flipped one of the 2 assemblied upside-down to make it fit. The bevels on that side were sufficient to allow it to be seated properly but the result was that the rollers were not exposed and so there was nothing on that side to guide/control the drawtube.

A few minutes judicious use of the grinding wheel corrected the bevel and allowed me to correctly orient that roller section. Re-assembly was uneventful and the focuser now functions pretty much as the first one I bought in 2009 did - not great but sufficuent for visual and light DSLR use.

If anyone needs more guidance on the disassembly process, feel free to PM me.

Peter

[Terry B]

I have an early one of these with the stock focusser. It was OK but would slip with a heavy camera or spectrograph on it.
I pulled it apart and drilled 2 holes in the base at about 60deg. I then tapped these and inserted locking bolts. It now can be held absolutely rigidly with any weight you want on it for the princely sum of about 50cents worth of stainless bolts.

[pmrid]

I like the simplicity of that solution.
I've done the same with various adapters etc. I must say though that I'm finding the fully integrated temperature and stepper control of this new Moonlite an absolute delight - something the NG could not provide if it has to be locked down manually every time you want to change focus. But if you were working with OSC and not imaging over a period of likely temperature shift, it would be a darn good solution.

Peter

[adman]

thanks for the photos Peter - very nice. Looks like it will be in the new year sometime when I order mine. The stock focuser on mine works OK for the moment - but it is already started to grate on me. I think that I will just bite the bullet and get the full focus controller option. I miss the remote focusing I had on my newt.

Thanks also for the info on the flange scagman - that is good to know.

Cheers all
Adam

[marki]

Great focusers, they just do what Ron says they will, no if's, buts or anything else. Well worth the cash and Rons service and attention to detail are legendary.

Mark