Just a gentle question...

[Andrew*]

I know I'm not meant to be thinking about this (was a train of thought that went down the wrong tunnel) but I was contemplating the benefits of the new BO 91mm Triplet and wondered how it compares pricewise to similar products. I came to the Megrez 90 - a hugely popular refractor AFAIK. I stopped and suddenly wondered, comparing these specs, why would you opt for the WO?

BO - 91mm FPL53 triplet, f/6.6, dual speed crayford, supplied with 40mm Paragon, finder, tube rings and dovetail for £649.

WO - 90mm FPL53 airspaced doublet, f/6.9, dual speed crayford, supplied with aluminium case only, for £695.

Clearly the Burgess offers a little more?!? Triplet over doublet, more supplied extras, and a better price? Any opinions?

Andrew

[Jamie]

Andrew i don't really have the answer for you on this one.

Here is my take on these two doublets and triplets though.

BO had to put 3 bits of glass (not including the eyepiece) on front of your eye to get the desired colour correction. WO only had to use 2 and i doubt if anyone could tell the difference without using some sort of machine to measure any differences.

Triplets are usually better than doublets but not always.

Just as an example most of Takahshi's refractors are doublets, not triplets (and they cost a mint)

I think it will have a lot to do with QC being the reason for the triplet being cheaper than the doublet.

Then again i could be wrong.... :rolleyes:

[Andrew*]

some good points there, the WO stresses the QC thing "Each scope undergoes rigorous testing for both mechanical and optical performance, including a high-power star test.".

However, I would imagine the BO gives you a pretty good run for your money. As you say, you would need more than a good pair of eyes to notice the optical differences between them, I reckon.

Perhaps there is a minor loss of light throughput due to the extra lens, perhaps the WO gives a bit more welly cosmetically and possibly optically, but when push came to shove, I would opt for the BO. Also because it works out of the box. With WO kit, you have to buy their rings, dovetails and finder before you can actually use it.

I do have one issue with the BO though - the included eyepiece. Yes, it may be a cracking eyepiece, but can I not choose my own eyepieces? It's an extra £180. I would much rather get the scope without the eyepiece for say £500. And why an eyepiece before a diagonal?

You see, I've got this idea in my head. If I changed my ED80 for one of these, and my SW200 for an 8" Orion Optics, and my HEQ5 for an EQ6 Pro, and put it all on the Orion pedestal.... What would I have? 8)

cheers

Andrew

P.S. and don't say "less money!"

[Whippy]

An 8" Orion Optics what??

You could look at it this way...

As far as I know, Burgess Optical is run by Bill Burgess and his wife Tammy. It's a really small operation. Bill's got less overheads and therefore can (and does) pass on the savings onto the consumer. Go and look at their site and his phrase is 'making the awsome affordable'.

William Optics is run by the William brothers and is a far larger operation. They still offer good value but their overheads are far greater than BO's and that glorious finish and ally case don't come cheap...

Are you thinking of purchasing one of the said scopes Andrew? I don't think they'd be much in it between them performance-wise BUT Burgess' scopes are made in small quantities, what if it's a Lemon? That could mean a trip for it all the way back to the States. The WO would most likely be replaced. Saying that, if the BO was around at the time I picked up my WO, I would have most likely had one!

Tony..

[Andrew*]

some more good points...

Are you thinking of purchasing one of the said scopes Andrew?

Just contemplating, really. Once (if) I get the hang of imaging and I can still afford it, I will certainly do some upgrading. I was thinking this particular scope cause it has the same fl as the ED80 but with a faster f/ratio for imaging, and more aperture for visual. Also, I reckon there will be some excellent S/H deals for this scope in about year.

An 8" Orion Optics what??

Just a newt.... Well, it'd be an "allwhite" set-up, wouldn't it?

cheers

Andrew

[Whippy]

Just a newt.... Well, it'd be an "allwhite" set-up, wouldn't it?

There's no need for any Michael Barrymore impressions is there?

If you want White, you could look into the Russian scopes, all their stuff is (ahem) 'all White'.

Tony..

[radioactive]

Just a newt.... Well, it'd be an "allwhite" set-up, wouldn't it?

There's no need for any Michael Barrymore impressions is there?

If you want White, you could look into the Russian scopes, all their stuff is (ahem) 'all White'.

Vixen? all white ish kind of :?

Tony..

[darditti]

Well, Andrew, you are not exactly comparing like with like here, because the triplet is f6.6 and the doublet is f6.9. These small differences are quite significant in the world of refractor colour-correction. The reason the ED80 is so good is because it is a doublet at f7.5: quite long, and therefore easy to make work well. To get equal quality at f6.9 with a doublet you have to try rather harder. And when you go lower than 6.9 you really need a triplet, or the chromatic aberration will start to become bad.

Jamie says:

BO had to put 3 bits of glass (not including the eyepiece) on front of your eye to get the desired colour correction. WO only had to use 2 and i doubt if anyone could tell the difference without using some sort of machine to measure any differences.

BUT if you had an f6.6 doublet and compared it with an f6.6 triplet of the same glasses (which you don't), I think you would see the difference rather easily. The point about expensive Takahashi doublets - well, what glasses are they using, what f ratios? You have to look at everything.

So the question which remains is: why is the BO so attractively priced for a triplet? I don't know, not having seen it, how the quality of the rest of the scope compares to other brands. Maybe they just are excellent value.

By the way, Orion Optics Newts are not well-made mechanically, and I wouldn't recommend them.

David

[Andrew*]

David, thank you for what seems an explanation coming from someone very experienced in this field, which I clearly am not.

I didn't think the difference in focal ratios was at all significant in this case - it probably explains a lot, especially when it comes to Synta products...

As I said, it was just a gentle question! I could anticipate this kind of banter before I even started the topic. VERY interesting

By the way, Orion Optics Newts are not well-made mechanically, and I wouldn't recommend them.

I am aware of that. As I say, I was just speculating...

Another "by the way": I'm enjoying that camera of yours, though I haven't had a great deal of success with it thus far... It's good to see you on SGL - welcome!

Cheers

Andrew

[John]

..... The reason the ED80 is so good is because it is a doublet at f7.5: quite long, and therefore easy to make work well. To get equal quality at f6.9 with a doublet you have to try rather harder. And when you go lower than 6.9 you really need a triplet, or the chromatic aberration will start to become bad....

My experience matches David's point here - My WO Megrez 90 had very sharp and well corrected optics but no better IMHO than my ED80 other than the impact that the additional 10mm of aperture delivered.

It's also why the ED100's have a good reputation - they work at F9 and are very well corrected despite their relatively low price.

In mechanical quality and finish though the WO scopes are ahead of the ED's of course and that can make a difference - I have heard of ED owners resorting to shims at the focuser end of the scope to collimate the optics whereas the WO Megrez 90 that I used to own and the Vixen ED102SS that I own now need no such measures as the accuracy of the machining is very good.

John

[MartinB]

A scope's only any good if you can get to look through it which seems to be the stumbling block with the Burgess, they seem to be a bit hard to get hold of. The BO would/will definitely get my vote

[iancandler]

And when you go lower than 6.9 you really need a triplet, or the chromatic aberration will start to become bad.

I used to think the same.. My ZS66ED cured me of that.. its only F5.9 but I'm hard pushed to find any CA in it.

[darditti]

Quote

And when you go lower than 6.9 you really need a triplet, or the chromatic aberration will start to become bad.

I used to think the same.. My ZS66ED cured me of that.. its only F5.9 but I'm hard pushed to find any CA in it.

No - the point is we were talking about 80-90mm scopes. The mathematics of of chromatic aberration are highly dependent on aperture as well as focal ratio. An f5.9 66mm ED scope does have little detectable CA, but a 90mm of the same design would have a lot. There is a square law involved if my memory serves right. That's why the focal ratios change as you change aperture for the same brands of telescopes. That's why WO make the ZS66 at f5.9, but the ZS80II at f6.8, and why Skywatcher make the ED80 at f7.5, but the ED100 at f9. They would make them shorter if they could (it would be more convenient), but they have found these are the focal ratios at which the results are acceptable for these lens designs at these apertures.

Another "by the way": I'm enjoying that camera of yours, though I haven't had a great deal of success with it thus far... It's good to see you on SGL - welcome!

Thanks Andrew. We have had terrible seeing mostly in December and Jan so far...

Also by the way, I sympathise with the problem of trying to get the telescopes on one mount to match up in colour. With a Celestron it is a problem, as few refractors are made in grey, and white doesn't look good alongside.

David

[PhilM]

You see, I've got this idea in my head. If I changed my ED80 for one of these, and my SW200 for an 8" Orion Optics, and my HEQ5 for an EQ6 Pro, and put it all on the Orion pedestal.... What would I have? 8)

Hopefully a very nice setup...

When the BO finally clears UK customs I will have the triplet along with my 8" OO reflector on a Losmandy headed EQ6 Pro, oh and I am looking at getting a pedestal Unfortunately I see you live in Aberdeen which would be a bit far away from Hampshire to have a play with them...

I did consider the WO as their reputation is excellent but went for the BO. It is interesting that some people are using scopes like the Stellarvue SV90 as a comparison, which is of course twice the price of the BO. We'll have to wait and see but there has been some considerable excitement about this scope from people who have used one. So far I'm feeling fortunate to have one on pre-order, there is some scepticism around as to whether these will became widely available long term or not.

Tony makes some good points about Bill Burgess, indeed some have argued he would be better charging more for his scopes as it would be less of a problem when events happen like the dodgy batch of focussers that was initially supplied to him for the triplet.

As regards getting a lemon - I'm hoping not (need a praying smiley). I am somewhat reassured that each scope is individually checked by Bill himself and reports from those in the states who have received their scope are extremely positive indeed.

I'd generally agree with David's comments on OO scopes, I'm sure he has a much wider knowledge of people's experiences than me. I think the usual comment applies, some people have had mechanical probs, others haven't, overall almost everyone agrees the optics are great. I bought the OO for the optics which I'm chuffed with and took a chance with the mechanics (which on mine are fine). I am mystified why OO can't just get the mechanics up to the consistent high standards of their optics. They could also improve their customer service...

All IMHO of course,

Phil.