At the risk of starting a fight.....Which Optical Supplier

[Moonshane]

Hi all

Many people have a favourite optical supplier and I love my OO UK Dobs.

I am starting to plan (financially and logistically) a larger dob (16" is currently edging ahead of 18" on the grounds of practicality) in late 2011 and need to get the mirror purchase right in terms of best value for money but I have always taken the view that a little more spent now loses impact in time as prices generally increase.

If you were me and about to make your own 16" dob which of the following optical suppliers would you choose and why?

I am sure all the mirrors will be very good quality and I am looking for something as good or better than the 1/6PV optics in my current 12" which I'll sell once I am sure the 16" is usable all the time and not just at darker sites. I know I can possibly get a good deal from USA etc but like the idea of a UK based purchase as I can see it first.

Option 1) Used Meade Lightbridge - standard/unmodded versions seem to go for £1000-1200 and use as it is eventually either refiguring or recoating the optics - I can do the usual mods myself at a modest spend.

The remaining options would mean that I would need to make my own dob - could be done at a reasonable cost - maybe £200-300.

Option 2) Orion Optics Research grade (1/8PV) or ultra grade optics only - would be expensive at £1900 plus build costs.

Option 3) Oldham Optical (1/10 PV) mirrors - would have the advantage of f5 and also costs around £1600 so a little bit less than OO.

Option 4) Nichol Optical (1/8 PV) mirrors. Seems to be a smaller business but personal attention to detail possibly a bit higher? Cost also less at £1250.

Option 5) I have seen some Hubble Optics 'lightweight sandwiched' mirrors which seem very reasonable - eg a 14" went for about US500 on ebay recently. Is it worth even thinking about one of these?

I realise this is a difficult question to answer really but if you can offer any comments about your own experiences it will be much appreciated.

Best wishes

Shane

[pete_l]

Hubble Optics 'lightweight sandwiched' mirrors which seem very reasonable

I wouldn't fancy putting a fragile and expensive mirror in the hands of a standard courier to bump its way across the atlantic. You'd probably find transport costs (incl. insurance) would almost double that price - if they'd even agree to do it at all.

[Moonshane]

apparently they triple box things and they do arrive intact over long distances - makes a nice change!

[Bizibilder]

Try:

Parabolic low expansion mirrors

These - I havn't used them but they are a longstanding UK company with a good reputation.

[Moonshane]

cheers Bizibuilder. I did speak with this firm a while back and they were not doing finished mirrors anymore - maybe that's changed - I'll ring them when I am ready to place an order.

[Capricorn]

The Galvoptics mirrors seem to match the Oldham ones in diameter and focal length. Bizibilder's post.

So may be a case of who's is the better cost.

[sixela]

If you were me and about to make your own 16" dob which of the following optical suppliers would you choose and why?

I already had a mirror, but most of the Dutch who've recently bought 12" and 16" mirrors went for Orion Optics Pro grade ("1/6th wave") mirrors and they were all good. They were also specifically requested to be thin, and that helps a lot (GSO 16" mirrors are THICK and those Lightbridges take ages to cool down even with fans.)

But especially for larger scopes (that are going to be seeing limited most of the time and used more for deep sky where a smooth mirror is also important) John Nichols is indeed also worth a look.

Hubble mirrors are quite frankly a gamble, I think. A couple of years ago they didn't have astigmatism under control, and they produced a umber of spectacularly bad mirrors (with so called "Strehl ratios" in the high .9s, but measured over only one diameter).

More recent users tend to say that they've since mended their ways, but it's really impossible for me to even guess at their QC or consistency (I've seen some recent Foucaultgrams that indicate a fairly good figure but a lot more roughness than you can expect from even GSO and Synta, let alone OO or John Nichol). Some people have indeed been pleased and the sandwich mirrors do cool quite fast.

But I'd only consider those if I had someone who could evaluate and refigure the mirror cheaply in my neck of the woods.

Personally, I think these are your best bets. I have a "1/10th wave" from Oldham that is actually quite good (excellent figure; although more than a bit rough, not enough to refigure), but I've seen others.

Personally, if I wanted a more-expensive-than-GSO-and-Synta and less-expensive-than-OO mirror, I'd tend to go with John Nichol, from having seen some mirrors, his web site, the way he talks about optics and the honest appraisal he makes of the mirrors he sells. But that's partly a matter of personal preference.

One other thing: it really does pay to get a really good secondary from Protostar or Antares Optics, especially if you get your primary from one of the cheaper vendors. You're assured the very best at a more or less reasonable cost.

[Moonshane]

cheers Sixella for this and all the advice by PM earlier - top man.

I am slowly chipping away the questions in my mind - might have got through all of them by the time I have the funds together for the mirror!

[sixela]

."l" eno ylno sekat ti os ,sdrawkcab delleps sixelA si alexiS

Also, the "ella" sounds a bit too feminine, does it not?

[Moonshane]

Ah, wondered where it came from! Sorry for the female inference!

Best wishes

enahS