Baader Diamond Steeltrak from a Visual Observer’s Perspective

Captain Scarlet · January 17, 2020

As per the “What did the Postman bring?” thread mid December, I recently got myself a Baader Diamond Steeltrak focuser for my beloved Ireland-based 12” newt. It was a mid-December birthday present to myself. But I’d forgotten I’d added it to my ongoing present sinking-fund-style wish-list, and GCHQ got me a second one for Christmas! Rather than return it, I decided to fit it to my “practise-horse” 8” based in London! Furthermore, I also acquired an SCT-fit Diamond Steeltrak off SGL, for use on my Maks.

So within a very short period I found myself in possession of 3 Diamond Steeltraks!

It seems that all Steeltraks come as two main pieces: the main focuser unit itself and a mounting arrangement for whichever type of scope you’re attaching it to. In all cases the one attaches to the other very securely via a circular dovetail. You might deduce therefore that the focus-unit itself is common to all scope-types, and all that varies is the attachment adapter. But you’d be wrong. The main focuser-unit is subtly different for each of the newt, refractor and SCT versions. The depths of the securing-dovetail are different in each case, and the focus-tube itself is much longer for the refractor than for the other two.

Most of the discussion here relates to the Newtonian version of the Diamond Steeltrak. The mounting plate which attaches to the OTA for this version is called by Baader “Versaplate”.

Fitting it was tricky, as Versaplate’s “rough-guide” holes are not the same as the Skywatcher’s OEM fitment holes, contradicting Baader’s own installation video which uses an 8” Skywatcher as an example. Baader specifically recommends using the existing SW holes to loosely attach the plate to the tube for lining-up and new-hole marking purposes. Which is odd.

Nonetheless the whole look and feel is of beautiful engineering. In fact it feels over-engineered, which is good because it suggests that, say, a 1kg eyepiece won’t trouble it unduly, and in the event, it doesn’t. The SW focuser looks and feels tinny and lightweight by comparison, which it is.

For example, the Steeltrak’s actual focus-tube looks more “pipe” than “tube”, and is held in its orientation by big roller bearings. The tube is completely micro-adjustable laterally and angularly, though the instructions strongly recommend you don’t touch these adjustments unless you really know what you’re doing.

One more thing: for the Steeltrak as supplied at the price advertised, at least for my SW 300p and 200p newts (145mm outside-tube distance of 143mm) my TeleVue eyepieces didn’t come to focus. More distance was needed. Luckily I had a 2” 47mm Baader extender which did the job. Baader’s site suggests that people often buy in addition the S58 focus-tube endpiece clamp which they say gives an extra 16mm over the standard. I’m not sure that would be enough though. In short, if you have a SW newt like my ones, you’ll need to spend extra money to allow eyepieces to get focus.

It would also be good if they sold the Versaplate as a separate item in its own right, but it seems they don’t. They do, however, sell an alternative flat plate to fit to an existing flat base-plate. Again, odd.

Fitting

As per the introductory paragraph above, I’ve now fitted 3 Steeltraks: 2 to Newtonians and one to a Mak.

The Mak fitting was trivial: it simply screwed on to the SCT “back” on my Mak. Fitting to the Newts, though, was altogether different, and involved carefully drawing out and making up drilling templates, and actually drilling new holes into my Newtonian tubes.

The account that follows is a hybrid of my experiences fitting the Steeltrak to 2 Newts, my 12” one and my 8”.

To begin with, I needed to separate the Steeltrak’s two pieces, the focus unit and the mounting plate, and attach the latter to the OTA. The instructions say:

1. Remove the old focuser, keeping aside the SW attachment bolts;

2. Present the Versaplate to the OTA and use the original bolts and holes to loosely hold it in place through 4 holes in the Versaplate, drilled to match SW ones (they didn’t, as discussed);

3. Move the Versaplate around in its looseness until it’s in the right position, tighten down a little more and mark where the proper main attachment holes require drilling;

4. Remove the plate and drill 4 x 5mm holes where they’ve been marked;

5. Attach the plate using the new holes and the special cylindrical nuts.

However, as others have discovered before me, step 2 wasn’t that easy – the Versaplate’s holes did not match the SW ones, not even close. In the end, for the 12”, I used tape to hold the plate in place, and dotted my drilling points in situ with a Sharpie. For the 8”, later on, I went as far as to draw and cut out a cardboard drilling template (see photos at the end).

A little thought made me realise that as long as the Versaplate’s “big hole” roughly matched the SW tube’s big hole, and as long as the “rails” of the Versaplate were flat to the OTA tube, and therefore parallel to it, it mostly didn’t really matter where the Versaplate went. Why? Because there was lots (i.e. more than 10mm) of up-and-down-the-main-tube adjustment available, and the secondary mirror could simply be rotated to accommodate any around-the-tube difference between before and after. The important thing was to ensure that each pair of new “along-the-OTA” holes was properly aligned along the main OTA, and that the alignments were the right distance apart (around the tube) to match the Versaplate. This is where Baader could make the job so much easier if they actually supplied printed drilling templates, or even just specified the circumferential distance they needed to be, for a given diameter tube. In fact the instruction booklet does contain technical engineering drawings of the units, but the only (to me) truly useful dimension, this circumference-distance, is not included in the diagram.

For each scope, taking care, I drilled the holes, starting at 1.5mm diameter, gradually moving up to 5mm. I fitted the Versaplate, centred its main hole within the OTA hole, and tightened the 4 bolts down. But it wasn’t quite as easy as that. Again, Baader’s instructions proved simply wrong. The Versaplate comes with a pair of shims, which they say are needed only if you’re fitting it to a tube of less than 8” diameter. For my 12” scope, I didn’t need the shims. But for my 8” tube, despite being told they weren’t necessary, I found that they most certainly were, and I did use them – see the photos at the end.

After fitting and tightening the Versaplate down, I was finally in a position to fit the focuser itself and I locked it in place with the 8 grubs. At this point, all the difficultly was over, and the sailing thereafter was plain. Mostly.

Re-Collimation of Secondary

Obviously the new focuser was likely in a slightly different place from the old one, so the secondary definitely needed re-collimation. I’d removed it anyway whilst drilling holes in the OTA.

For secondary collimation I use a so-called Concenter, a sight-tube with a peep-hole at one end and a transparent disc etched with concentric circles at the other, and my process is as follows:

1. Attach a piece of white A4 up the OTA to illuminate the whole secondary

2. Place the Concenter’s sight-hole/eye at focal point

3. Move the secondary mirror up/down the OTA using the spider centre screw until its fore/aft position is centred in the concentric circles of the sight-tube, and roughly rotate and tilt it by hand until it’s quite round within those circles

4. Loosely tighten the 3 adjustment screws down to preserve the secondary in more or less that position

5. Remove the A4 paper to reveal the reflection of the primary – ideally it should already be quite close to centred: the 3 grubscrews should only need a tiny further adjustment to make the 3 mirror clips concentric to the Concenter’s circles.

Unfortunately in my case, with the 12”, when I did the big “mirror-reveal”, step 5, the reflection of the primary’s mirror-clips was MILES OUT. I was confused, it should have been rather close. Using the 3 grubs I wrestled the secondary’s orientation to centre the mirror-clips’ view, but that put the secondary seriously off-round through the concentric circles. It was like “whack-a-mole”: I couldn’t get both a round secondary and a concentric set of primary mirror-clips at the same time, just one or the other. I was frustrated, and it was bed-time on day 2. It actually caused me to not sleep.

Day 3. I decided to start more or less from scratch. I removed the focuser unit from the Versaplate, completely loosened the plate itself on the OTA, loosened all 3 secondary grubscrews and randomly screwed the spider central screw to ensure everything was in completely the wrong place.

After tightening the Versaplate back down to where I thought it should be, using the above logic, and re-attaching the main unit, I re-traced my way through steps 1-5.

This time, everything was perfect. The paper-removal revealed the primary mirror to be almost spot on. I replaced the Concenter with my laser and its spot was within 2-3mm of the primary’s centre doughnut. Bingo. The tiniest little tweak to the 3 grubs to perfectly centre the laser spot, and the secondary was done. Thank God. I can only think first time around I’d inadvertently got a random shim stuck under one of the corners of the Versaplate, perhaps a drillhole-burr.

The same process on my 8” went without problems, it was more or less spot on first time around.

Diamond Steeltrak in Use

To begin with, for the 12”, it looked very much as though all this set up was to be in vain. With only 2 days left in Ireland, and a forecast for solid cloud until departure time, an actual account of what the focuser was like “in the field” was going to be unlikely. Or so I thought…

Luckily, Friday 3^rd Jan started as a beautiful clear morning, and it held out until after 9pm. During the afternoon I set up mounts, lined up finders, and as soon as Polaris appeared I was off.

The whole evening’s experience, a really rewarding one in the end, was a combination of new focuser and improved collimation (as a result of fitting said focuser). And that experience was my best so far from this dark site with this (12”) scope, despite the paucity of targets and bright Moon. I think superb seeing and good transparency also helped. Only the occasional band of cloud and eventual cloud-inundation put a downer.

I don’t have that much to say about the focuser in use, except that “it simply works”. You turn the knob. It goes there. There’s no doubt about when focus is achieved. Even just using the coarse knob is satisfying, though it could be a bit lighter-feeling for my taste. It’s much better than the single-speed OEM one, and better than the Lacerta upgrade I applied to it (though that is good, actually). On my Mak with its Diamond Steeltrak, the verdict was similar. Best focus was just as easily found despite the much narrower f/15 light-cone, albeit in daylight looking across the vista at number-plates etc. I didn’t get to use the Mak at night because cloud crept in around 9pm as I was changing OTAs to it.

Best of all, though, is that the flexure/droop problem that I found with the OEM and other SW-based focusers on my Newts is entirely absent with this. In other words, the tall, heavy stack of tubes and paraphernalia sticking up away from the OTA stays on-axis even with my big 35mm Panoptic attached.

If I could make one change, it would be for the fine-focus knob to be a little less low-geared, i.e. just a bit more gearing/resistance, and for the coarse focus to be a little lighter-geared, but I’m only mildly griping.

To round off (before the photo-medley), I thought it might also be useful to qualitatively compare my experiences of the various focusers I’ve now used over the last couple of years:

- SW OEM single-speed (on both my 200p and 300p as I first received them)

There’s nothing really badly wrong with the original SW single-speed focusers, with knobs that look to me like miniature Lamborghini Countach wheels. However, and this applies equally to the next two entries in this list, if you have a heavy and tall column to support outside the tube, the focuser (or the tube itself) is not strong or stiff enough to stop the whole column from tilting, sending secondary collimation to the dustbin. In my case, a 47mm Baader extension tube and a TeleVue Delos 6mm eyepiece was more than enough to cause this. It’s simply not heavy-duty enough either in its attachment to the OTA or in the build of the focus unit itself to support all this properly. Also, the amount of droop varied with the OTA’s inclination.

- Lacerta 1:10 upgrade to the SW OEM single-speed

Aside from the “droop” problem mentioned above, the dual-focus upgrade definitely made for a better, finer experience of actually finding focus. “Quite nice” is how I’d describe it.

- SW dual speed, as fitted to their “PDS” type scopes (lent to me by a friend for a few months)

The actual knobs are chunky and smooth in use, similar-feeling to the Lacerta-upgraded focuser, and give the whole thing a feel of being more substantial, but in reality it suffers from exactly the same unit/tube flexure column-droop as the first item in this list.

- TS-Optic 2” Monorail SCT focuser

I bought this to put on the back of my SW Mak 180, and also used it briefly when I had a Mak 127. I absolutely hated it, and quickly reverted to using the Mak’s main focus-knob. The whole feel of the thing was of “softness”, including its coarse-focus knobs. Its fine focus knob was unusable, so springy and so indirect that being confident in focus proved impossible. I love adjusting mechanical things, and am good at it, but no amount of adjustment made this anything other than horrid. My final attempt to adjust it to satisfaction ended up with me actually destroying it. Good riddance.

- Baader Diamond Steeltrak, newt and SCT versions

As indicated above, I find these very good indeed, it all stays stiff and in-collimation even with heavy tall loads. Focusing is very satisfying.

- Feathertouch, as fitted to my APM-LZOS 105/650 refractor

I’m lucky enough to have one of these as a supposedly “best in class” comparator. Everyhting I’ve said about the Steeltrak’s “just goes there”, directness and ease-of-finding-focus applies to the Feathertouch, but the FT is that bit more excellent and a delight to use. However it’s gratifying that the Steeltraks I own don’t feel that much different from it.

- Moonlite

Dunno, I didn't go into Burger King.

Finally, I’ve attached a slew of pictures (in the next post below) to illustrate various points of this journey…

If you’ve managed to read this far and stay awake, thank you.

Cheers, Magnus

Edited January 17, 2020 by Captain Magenta