Borg 77ED - First Light Review

[AndyUK]

This would seem to be quite an opportune time to post up a first light review of this scope as First Light Optics and Ian King are just about to become the UK stockists

Borg telescopes are made in Japan and seem to be pretty much an unmarketed brand - Even finding out information over the Internet doesn’t bear much fruit. There is a Yahoo! Group, but to be honest it’s not very active and membership appears to be fairly low., however, the main selling points are quality of optics and design and modularity - If you wish, you can basically literally build your own from all the separate parts.

I bought my 77ED Borg second hand about 5 weeks ago – At the time I had an Equinox 80 and whilst it was a very reasonable scope for imaging, especially with a TRF2008, I was disillusioned with Crayford focusers in general and couldn’t justify spending as much again on a new R&P focuser or quality Crayford. However, the real problem was regardless how much I spent on a new focuser, it would still attach to the Equinox via 3 radial screws, so ensuring true orthogonality and collimation would be pretty tricky. After looking about and talking to others, the familiar names of Takahashi and Televue were obviously on the list (too expensive for my pocket), as was the now-discontinued Pentax (almost as rare as rocking horse droppings on the second hand market)… and then there was Borg.

I therefore bought the Borg (as it was available and I could afford it) which came with a 0.85x reducer. The scope is native f6.5, but there are a couple of reducer/flatteners, one of which is 0.85x (giving a tad over f5.5) and the other of which is 0.6x (giving around f4). It’s ridiculously light (I think it came in at about 1.7Kg!), but aside from the front lens element the majority of the weight is on the back end, which is obviously a consideration for balancing.

I also received a Canon EOS adapter, which is exactly 11mm thick, thus ensuring that exactly 55m spacing is provided for – Exactly what the 0.85x reducer requires, so I now also have a very nice 425mm lens to play with too!

For imaging use though, I needed to fit my Atik MFW (T connection) to the reducer. So I needed an adapter… Well, actually, it turned out I needed two adapters, and I found it a real maze trying to work out which one(s) I needed. Fortunately someone on the Yahoo! Borg group pointed me to Ted Ishikawa (Hutech) who REALLY knows his stuff and he was able to give me the exact configuration / part numbers I needed as well as spacing information – There are literally dozens of adapters available! However, I’m sure FLO / IK will be able to come up with the answers in the future

On the subject of modularity, there’s an interesting thing about the 0.85x reducer in that it has 2 elements which can be unscrewed and you can then insert additional spacers (included with the reducer) in between, depending on which Borg scope you have (77ED, 101ED or 125ED). However, it may then be necessary to buy a shorter central tube as well. For me that’s not a downer, but just something to be aware of if wishing to upgrade to an f4 scope, but I doubt I shall be going down that route as I'm on a budget and I just spent it!

Similarly, if you fancy upgrading to the 101ED, you can actually buy just the lens element, which then screws into the top of the central tube. In other words, you can effectively have a second scope which is only about 8” long and sits in a small box… (No dear, that’s not a new scope – How could it be, it’s only 8” long!)

The “standard” Borg focuser configuration has TWO parts – One is a draw tube, for rough focusing, and the other is a non-rotating helical focuser (as you’d find on a camera lens). Everything attaches to the central tube by screwing the pieces into each other – There are no radial screws to attach the parts so everything is in alignment / collimation and orthogonal. Having said that, if the draw tube is pulled all the way out with a camera on the back end, it does drop a little but this is rectified by tightening two lock screws (which of course ARE radial). When rough focus has been achieved, you lock it off and then use the helical focuser to fine focus and then lock that off too - It has a total of 20mm travel. In my opinion, the radial lock screws are perhaps the weakest link of the design, but then almost all focusers with lock screws work in this way - Apparently there is a way of tightening it up by buying another one of the ubiquitous Borg adapters, but I haven't needed to do this (yet!)

A couple of other unexpected tasks was firstly having to drill out my dovetail – The tube ring bolts weren’t the normal width and were a bit wider… and I then found I had to pad out the dovetail as the tube ting bolts were slightly too long and were coming through the rings. Not a major problem, but unexpected none the less! The second task was fitting my finderguider, which I decided to fit on top of the forward tube ring to try and offset some of the back-end heaviness. Again, finding the right size/length bolts was a bit of a pain, but it's a one-off task and now it's sorted

Visually, the views appear pin sharp right to the edges (using a TV 32mm Plossl) and the scope shows very good contrast - I’m afraid that’s really all I can say about visual use as I only use an eyepiece for alignment...

Once aligned / on target, I then swapped out the eyepiece for the camera, filterwheel and reducer. I found using the drawtube fairly easy (you can also use it to rotate the camera a full 360 degrees if you need to) and the helical focuser is very smooth, but I can see it’s going to take me a little practice to ensure critical focus is achieved as it’s quite a bit different from using a “normal” Crayford or R&P focuser.

So on to the first night under the stars…

As the moon was up, I had to go with an Ha filter, and IC1805 was nicely placed to allow for a 7 hour run until a meridian flip would be required at about 0430. Unfortunately I didn’t get anywhere near that as the fog descended fairly suddenly about 0200! I wasn’t initially convinced I’d totally pegged the focus, but after some inspection of the subs, I now believe that it was the transparency / seeing that was hampering me, and not the focus after all. But it’s an area on which I’ll want to practice more. If I don’t get on with it though, there is a fallback option of a feathertouch focuser...

Being a pedant for round stars out to the corners, this is something very high on my list to watch out for… I’ll let the first light image speak for itself – This is 14x900s Ha taken with the Borg 77ED and 0.85x reducer. The spacing might be a tad out, but as I don’t have CCDInspector I can’t test it (if anyone has it and is happy to run one or two frames through, please let me know and I’ll email over a couple of fits files!).

In summary, I’m very happy I bought this scope, and although early days the optics appear as good as I was hoping and expecting with regards to flatness of field and star shapes. Obviously I would still like to take it out for an RGB image to test the colour correction, but I’d really like to get a night of OIII on IC1805 first so that I can sort of finish it off! As soon as the skies allow, I’ll see what it can do though – I have high hopes that even though this is “only” a reduced doublet, it will perform well.

[libraryman]

What a great reveiw Andy,very usefull.

Ray

[E621Keith]

Great review Andy. Glad to hear you've been assimilated and welcome to the Collective.

If you are worried about the draw tube set screw being radial screw, there is a gadget call Yeutsu-27g (Borg 9777) that will reduce the problem. It's an kingfisher blue anodised aluminium ring fitted between the draw tube holder and the draw tube that will greatly reduce the clearance between the drawtube and the holder. This will reduces the drawtube's deflection and also acts as a dust seal that will reduce dust ingestion (as it is claimed by the manufacturer).

I don't know if it is marketed outside Japan, because I haven't seen one fitted on a non Japanese Borg yet. However since First Light Optics is becoming a Borg dealer may be you should send them an e-mail if you find draw tube deflection a problem.

[AndyUK]

Cheers Ray... and also Keith - The draw tube issue isn't a problem I've come across as yet, but thanks for the info. I'll store that part number somewhere safe just in case. As you've noted I'm sure the FLO/IKI "partnership" will be able to sort it out if it should become an issue, but from the star shapes at the moment, I think everything's fine

[Gina]

Thanks very much for the review Andy I'm thinking of getting a Borg for my next scope - maybe in time for next winter if I can save up in time. I'm actually looking at the smallest Borg that FLO sell - the ED60 - as I want a wide-field fast scope to complement my Evostar 80 ED DS Pro. I'm hoping these scopes will be well corrected for CA as that is the problem with lenses. Most critical test is changing filters from Ha (or SII) to OIII. I have parfocal Astrodons and I don't need to refocus with the SW ED80 which makes things so much easier. I had a chance to try my best camera lens - an Asahi SMC Takumar 200mm f4 - the other night and I needed to refocus considerably. The little ED60 Borg gives 245mm FL which will do me nicely. Of course it does cost many many times the price of a camera lens but camera lenses are not designed to be used as astronomical telescopes or more correctly astrographs. The Borgs are described as astrographs and so far reports have been good.