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May 10, 2001

 


----------------------------

#5423 May 10, 2001

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ap-ug@yahoogroups.com wrote:

> To UNSUBSCRIBE, or for general information on the ap-ug list

> see groups.yahoo.com/group/ap-ug

---------------

>

> There are 10 messages in this issue.

>

> Topics in this digest:

>

> 1. Re: 155 EDF and 180mm EDF

> From: dnovo@...

> 2. Re: Digest Number 386

> From: Joe Bergeron joe@...>

> 3. Re: Re: Ed Ting's Super Comparo - The Tak FS152 vs EDF155

> From: "John J. Kasianowicz" surpher@...>

> 4. Re: Re: 155 EDF and 180mm EDF

> From: "res00y6g" ca.lewis7@...>

> 5. Re: Re: 155 EDF and 180mm EDF

> From: "John J. Kasianowicz" surpher@...>

> 6. Re: Re: 155 EDF and 180mm EDF

> From: "John J. Kasianowicz" surpher@...>

> 7. Re: Re: 155 EDF and 180mm EDF

> From: "Patrick J. Madden" RevPJMadden@...>

> 8. Re: Color correction - not necessary?

> From: aries57us@...

> 9. Re: 155 EDF and 180mm EDF

> From: dnovo@...

> 10. Re: 155 EDF and 180mm EDF

> From: vahe@...

>

---------------

---------------

>

> Message: 1

> Date: Wed, 09 May 2001 02:04:44 -0000

> From: dnovo@...

> Subject: Re: 155 EDF and 180mm EDF

>

> Jeff: I am not an "expert" either and I suspect that there are too

> many self-styled experts out there. Let us start with this premise.

> I was as AstroFest last year. I listened to Roland and Tom talk

> optics. After an hour of listening, I decided that they were 1) both

> very gifted designers; 2) both speaking a language that few of us

> would understand (I sure didn't);and that 3) most of the self-styled

> pundits (you know, the ones who have read Suiter's book, claim to

> understand optical theory, and after they test a telescope by looking

> through it, opine that this sample was 1/8 wave and the other only

> 1/x wave and not fit for dog food) don't know what the hell they are

> talking about. As a result, I am careful to avoid making statements

> like that here or in a review.

>

> So I am not, and do not pretend to be an expert in optics. However,

> and Roland, I politely disagree with you to this extent, I ask if you

> really need to be an 'expert' to tell a Synta from a Vixen or Borg ED

> by looking through the ep. I don't think so. I also don't think it

> is any great feat to be able to then tell an ED doublet from an AP or

> a TMB by -- again -- looking through the ep. And that is, I think,

> Jeff's point

>

> The Synta refractors do serve a purpose. They are a good, cheap

> introduction to refractors. The next step up (which even a blind

> person can see in the ep) is the ED doublets such as the Vixen or the

> Borg. Again, you don't need to be an expert to tell that, nor to

> critique fit and finish on that or any other scope. The next rung up

> in color correction and optics are the triplets such as the AP and

> the TMB -- again something very clearly visible in the ep.

>

> So what is my point. I am one of 'those guys' who has praised

> the 'lesser' refractors such as the Borg EDs and yes, even feel that

> the lowly ST-80 has its place in the realm of

> price/performance/availability. And I have said so with the AP

> and/or TMB near at hand and often on the same side of the mount.

>

> Again, I am not nor do I claim to be an optical expert. But I am not

> blind, and the view through my 155 f/7 next to the 150ED Borg was

> such that only a blind person would say "that Borg kicked the AP's

> butt." Nor do I intend to do so in the review that I am writing nor

> did I denigrate the AP when I reviewed the 125 ED Borg even though I

> own a 130 f/6. No, the APs are clearly superior instruments for

> visual or photographic use, and no Rolond, color correction is not

> out of style. However, there is a niche in the market, IMHO, for

> lighter, modular scopes for travel and fast use. (The 150 Borg

> weighs in at under 12 pounds, and the 125 at a tad over 8. Both of

> them can be easily taken into sections for transport.) So please

> don't mistake praise for an improvement in view for ignoring obvious

> differences in performance. There are, as we all know, horses for

> courses, and as I said in my tests, these scopes are not a 'threat'

> to the better-corrected triplets, nor were they intended to be. They

> fit into a niche and fit there very well.

>

> But now lets turn to the middle ground. As you say, Jeff, the Synta

> refractors are cheap and easy to acquire. The Vixen 102 ED and the

> Borg 100 EDs cost more, but they are about half to two thirds the

> price of the AP and TMB scopes and more readily available. And, they

> are a significant optical improvement over the Synta products.

>

> Would even an optical dummy like me be capable of looking through a

> simple achromat and then being able to tell the difference in - and

> recognize the inherent improvement that is offered by -- the addition

> of an ED as far as color correction, ability to handle increased

> magnification, and offer better contrast (due in no small part to

> better coatings and baffling, to be sure)? Of course. Can the same

> be said about the improvement available in the AP or TMB? Sure.

>

> So, Roland and Jeff, the issue isn't 'rave reviews' but simply

> a 'rave' for what a good Borg or Vixen is in comparison to an

> achromat or as a specialized scope for quick use and travel. That

> does not mean that color correction or other aspects of optical

> performance is now out of style. No the ED doublets have their place

> and it is, as you say Jeff, one that is a step up (and a big step up)

> from the cheaper achromats. There is, however, a step up further,

> and that is what those of us fortunate enough to have owned or used

> the APs and the TMBs recognize and I trust will continue to recognize.

>

> Now, what I DON'T understand is the claims by some that there are

> some ED doublets out there that are the equal of the APs or the TMBs

> in color correction and other optical performance. However, as I

> became embroiled in at least one Holy War for saying that, I will

> pass for the present with the observation that Jeff, I agree with you

> and Roland, color correction and fine optics such as you and Tom

> produce are not passe nor are they likely to become so in the

> forseeable future. Dave Novoselsky

>

> --- In ap-ug@y..., "Jeffrey D. Gortatowsky" jgortatows@a...> wrote:

> >

> > ----- Original Message -----

> > From: chris1011@a...>

> > > In reading posts on other newsgroups, it seems almost that any

> kind of

> > lens,

> > > whether color corrected or not, will get rave reviews. Has color

> > correction

> > > gone out of style?

> > >

> > > Roland Christen

> >

> > Just my opinion, and I am not 'expert'...

> >

> > But no. It's not. I believe it's just the refractor is enjoying an

> enormous

> > comeback thanks to the affordable Chinese clones. So some people,

> new and

> > old alike, are 'rediscovering' the sharp contrasty views of a

> refractor as

> > compared to (please no flames - or in private) an 'average' SCT.

> IMO, and

> > only MO, it's that simple. People were so used to poorly performing

> > telescopes, that by comparison almost any 'decent' refractor is a

> revelation

> > for it's size. They more than likely have nothing (or very little)

> to

> > compare it to experience wise. Those that do, well, when your

> telescopes are

> > so hard to get, they are willing to see the best in what they can

> get a hold

> > of.

> >

> > For example, lets say you mean a Vixen ED. Pretty darn good color

> correction

> > if you are comparing it to the SkyWatcher 120 next door right? And

> the odds

> > of that person then having an AP APO sitting next to that to

> compare? Pretty

> > small.

> >

> > OTOH, I think some, like Tom Back's are very very good and deserve

> the high

> > marks they get. YMMV. But those are not exactly flooding the market

> either!

> > :)

> >

> > Clear skies!

> > Jeff

>

---------------

---------------

>

> Message: 2

> Date: Tue, 08 May 2001 19:47:41 -0700

> From: Joe Bergeron joe@...>

> Subject: Re: Digest Number 386

>

> on 5/8/2001 6:59 PM, ap-ug@yahoogroups.com at ap-ug@yahoogroups.com wrote:

>

> > In reading posts on other newsgroups, it seems almost that any kind of lens,

> > whether color corrected or not, will get rave reviews. Has color correction

> > gone out of style?

>

> Not with me it hasn't.

>

> --

>

> Joe Bergeron

>

> www.joebergeron.com

>

---------------

---------------

>

> Message: 3

> Date: Tue, 8 May 2001 23:00:29 -0400

> From: "John J. Kasianowicz" surpher@...>

> Subject: Re: Re: Ed Ting's Super Comparo - The Tak FS152 vs EDF155

>

> .. and I'm still waiting to see it!

>

> Arpad wrote:

> > Vahe, I picked one up (1995 version) within minutes of it being

> > posted on Astromart last year, and you're absolutely correct, it's a

> > phenomenal scope.

>

---------------

---------------

>

> Message: 4

> Date: Tue, 8 May 2001 22:00:36 -0500

> From: "res00y6g" ca.lewis7@...>

> Subject: Re: Re: 155 EDF and 180mm EDF

>

> Amen. Dave

>

> Charlie

> ----- Original Message -----

> From: dnovo@...>

> To: ap-ug@yahoogroups.com>

> Sent: Tuesday, May 08, 2001 9:04 PM

> Subject: [ap-ug] Re: 155 EDF and 180mm EDF

>

> > Jeff: I am not an "expert" either and I suspect that there are too

> > many self-styled experts out there. Let us start with this premise.

> > I was as AstroFest last year. I listened to Roland and Tom talk

> > optics. After an hour of listening, I decided that they were 1) both

> > very gifted designers; 2) both speaking a language that few of us

> > would understand (I sure didn't);and that 3) most of the self-styled

> > pundits (you know, the ones who have read Suiter's book, claim to

> > understand optical theory, and after they test a telescope by looking

> > through it, opine that this sample was 1/8 wave and the other only

> > 1/x wave and not fit for dog food) don't know what the hell they are

> > talking about. As a result, I am careful to avoid making statements

> > like that here or in a review.

> >

> > So I am not, and do not pretend to be an expert in optics. However,

> > and Roland, I politely disagree with you to this extent, I ask if you

> > really need to be an 'expert' to tell a Synta from a Vixen or Borg ED

> > by looking through the ep. I don't think so. I also don't think it

> > is any great feat to be able to then tell an ED doublet from an AP or

> > a TMB by -- again -- looking through the ep. And that is, I think,

> > Jeff's point

> >

> > The Synta refractors do serve a purpose. They are a good, cheap

> > introduction to refractors. The next step up (which even a blind

> > person can see in the ep) is the ED doublets such as the Vixen or the

> > Borg. Again, you don't need to be an expert to tell that, nor to

> > critique fit and finish on that or any other scope. The next rung up

> > in color correction and optics are the triplets such as the AP and

> > the TMB -- again something very clearly visible in the ep.

> >

> > So what is my point. I am one of 'those guys' who has praised

> > the 'lesser' refractors such as the Borg EDs and yes, even feel that

> > the lowly ST-80 has its place in the realm of

> > price/performance/availability. And I have said so with the AP

> > and/or TMB near at hand and often on the same side of the mount.

> >

> > Again, I am not nor do I claim to be an optical expert. But I am not

> > blind, and the view through my 155 f/7 next to the 150ED Borg was

> > such that only a blind person would say "that Borg kicked the AP's

> > butt." Nor do I intend to do so in the review that I am writing nor

> > did I denigrate the AP when I reviewed the 125 ED Borg even though I

> > own a 130 f/6. No, the APs are clearly superior instruments for

> > visual or photographic use, and no Rolond, color correction is not

> > out of style. However, there is a niche in the market, IMHO, for

> > lighter, modular scopes for travel and fast use. (The 150 Borg

> > weighs in at under 12 pounds, and the 125 at a tad over 8. Both of

> > them can be easily taken into sections for transport.) So please

> > don't mistake praise for an improvement in view for ignoring obvious

> > differences in performance. There are, as we all know, horses for

> > courses, and as I said in my tests, these scopes are not a 'threat'

> > to the better-corrected triplets, nor were they intended to be. They

> > fit into a niche and fit there very well.

> >

> > But now lets turn to the middle ground. As you say, Jeff, the Synta

> > refractors are cheap and easy to acquire. The Vixen 102 ED and the

> > Borg 100 EDs cost more, but they are about half to two thirds the

> > price of the AP and TMB scopes and more readily available. And, they

> > are a significant optical improvement over the Synta products.

> >

> > Would even an optical dummy like me be capable of looking through a

> > simple achromat and then being able to tell the difference in - and

> > recognize the inherent improvement that is offered by -- the addition

> > of an ED as far as color correction, ability to handle increased

> > magnification, and offer better contrast (due in no small part to

> > better coatings and baffling, to be sure)? Of course. Can the same

> > be said about the improvement available in the AP or TMB? Sure.

> >

> > So, Roland and Jeff, the issue isn't 'rave reviews' but simply

> > a 'rave' for what a good Borg or Vixen is in comparison to an

> > achromat or as a specialized scope for quick use and travel. That

> > does not mean that color correction or other aspects of optical

> > performance is now out of style. No the ED doublets have their place

> > and it is, as you say Jeff, one that is a step up (and a big step up)

> > from the cheaper achromats. There is, however, a step up further,

> > and that is what those of us fortunate enough to have owned or used

> > the APs and the TMBs recognize and I trust will continue to recognize.

> >

> > Now, what I DON'T understand is the claims by some that there are

> > some ED doublets out there that are the equal of the APs or the TMBs

> > in color correction and other optical performance. However, as I

> > became embroiled in at least one Holy War for saying that, I will

> > pass for the present with the observation that Jeff, I agree with you

> > and Roland, color correction and fine optics such as you and Tom

> > produce are not passe nor are they likely to become so in the

> > forseeable future. Dave Novoselsky

> >

> > --- In ap-ug@y..., "Jeffrey D. Gortatowsky" jgortatows@a...> wrote:

> > >

> > > ----- Original Message -----

> > > From: chris1011@a...>

> > > > In reading posts on other newsgroups, it seems almost that any

> > kind of

> > > lens,

> > > > whether color corrected or not, will get rave reviews. Has color

> > > correction

> > > > gone out of style?

> > > >

> > > > Roland Christen

> > >

> > > Just my opinion, and I am not 'expert'...

> > >

> > > But no. It's not. I believe it's just the refractor is enjoying an

> > enormous

> > > comeback thanks to the affordable Chinese clones. So some people,

> > new and

> > > old alike, are 'rediscovering' the sharp contrasty views of a

> > refractor as

> > > compared to (please no flames - or in private) an 'average' SCT.

> > IMO, and

> > > only MO, it's that simple. People were so used to poorly performing

> > > telescopes, that by comparison almost any 'decent' refractor is a

> > revelation

> > > for it's size. They more than likely have nothing (or very little)

> > to

> > > compare it to experience wise. Those that do, well, when your

> > telescopes are

> > > so hard to get, they are willing to see the best in what they can

> > get a hold

> > > of.

> > >

> > > For example, lets say you mean a Vixen ED. Pretty darn good color

> > correction

> > > if you are comparing it to the SkyWatcher 120 next door right? And

> > the odds

> > > of that person then having an AP APO sitting next to that to

> > compare? Pretty

> > > small.

> > >

> > > OTOH, I think some, like Tom Back's are very very good and deserve

> > the high

> > > marks they get. YMMV. But those are not exactly flooding the market

> > either!

> > > :)

> > >

> > > Clear skies!

> > > Jeff

> >

> >

> >

> > To UNSUBSCRIBE, or for general information on the ap-ug list

> > see groups.yahoo.com/group/ap-ug

> >

> > Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

> >

> >

>

---------------

---------------

>

> Message: 5

> Date: Tue, 8 May 2001 23:03:43 -0400

> From: "John J. Kasianowicz" surpher@...>

> Subject: Re: Re: 155 EDF and 180mm EDF

>

> If you're taking a vote, I would prefer a highly color corrected AP 180 over

> the 155 f/7.

>

> > Thanks Eric, I'll keep that in mind. I have been experimanting with a new

> > design with some glass made to my specs that will result in a very nice

> lens

> > at F8.8. But until I actually try it on the sky, I won't know whether it

> will

> > be a good product.

> >

> > In reading posts on other newsgroups, it seems almost that any kind of

> lens,

> > whether color corrected or not, will get rave reviews. Has color

> correction

> > gone out of style?

>

---------------

---------------

>

> Message: 6

> Date: Tue, 8 May 2001 23:17:36 -0400

> From: "John J. Kasianowicz" surpher@...>

> Subject: Re: Re: 155 EDF and 180mm EDF

>

> Hi Dave,

>

> I don't think it is a matter of questioning the relevance or need for lower

> cost refractors. It's a matter of having folks not overstating the

> performance of same.

>

> Suiter is not a good primer on optical theory or on instrumental optics. You

> might enjoy reading good optics books (e.g. Born & Wolf, Hecht & Zajac, C.J.

> Smith, Hardy & Perrin, etc.) or one on telescope optics (I think it's by

> Rutten & a coauthor, but I loaned that book to someone and can't verify

> their names).

>

> Clear and Dark Skies,

> John

>

> Dave Novo. wrote:

>

> > Jeff: I am not an "expert" either and I suspect that there are too

> > many self-styled experts out there. Let us start with this premise.

> [snip]

>

---------------

---------------

>

> Message: 7

> Date: Wed, 9 May 2001 01:45:26 -0500

> From: "Patrick J. Madden" RevPJMadden@...>

> Subject: Re: Re: 155 EDF and 180mm EDF

>

> Here's a question from a rank beginner as far as refractor optics are

> concerned (I've ground and polished a few Newtonians). I live in an area

> where there are not too many astronomy enthusiasts, so I don't get much

> chance to compare different scopes--although once at a star party over in

> Shreveport my home-ground 10" f/3.8 held its own against a 10" commercial

> SCT looking at Mars.

>

> Anyway, back to refractors: Synta, Vixen, AP & TMB. I hate to enter a

> "four-letter word" into this discussion. But where would "Mead" fit in this

> hierarchy? Somewhere below AP & TMB, I'm sure. Any refractor connosieurs

> out there who will enlighten me?

>

> Clear skies!

>

> Pat Madden

> Monroe, LA

>

---------------

---------------

>

> Message: 8

> Date: Wed, 09 May 2001 06:53:52 -0000

> From: aries57us@...

> Subject: Re: Color correction - not necessary?

>

> > From: dnovo@i...>

> > To: ap-ug@y...>

>

> > Now, what I DON'T understand is the claims by some that there are

> > some ED doublets out there that are the equal of the APs or the

> > TMBs in color correction and other optical performance.

> > Dave Novoselsky

>

> Dave,

>

> This is true to a some degree. If a doublet (fluorite

> combined with properly choosed second glass) has F/8 - F/9,

> it will equal to a best triplets in color performance for

> a human eye. However it will loss vs triplets for CCD

> applications. But for visual work it should be better for

> several reasons:

> 1. Less optical surfaces (less reflections, less scattering,

> better overal transmittion).

> 2. Less mass for cool down - faster stabilizing

> 3. Easier lenses centering (can be performed by amateur - like

> you did in your Borg).

>

> > From: chris1011@a...>

> > In reading posts on other newsgroups, it seems almost that any

> > kind of lens, whether color corrected or not, will get rave

> >reviews. Has color correction gone out of style?

> >

> >Roland Christen

>

> With your own help it does drifted already. Your own recent words,

> said against Chromacor, was that 6" F/12 achromat does not show

> false colors on Saturn etc. - is the best illustration to

> above thought about "color correction gone out of style".

>

> So, you don't have to be wonder. You self participate in this.

>

> And this was one of a reason of a "pseudo-APO" definition (he he)

> appearence - a simple achromat with "minus blue-voiolet" filter.

>

> The next natural step will be a "brain-tired APO", when a guy,

> with similar to "pseudo-APO" father mentality, will tell us -

> you don't need any APO, just keep your eyes for a minute in

> purple light and then immediately look in a telescope - and for

> a period your will see no any purple around objects.

> So, let see what will happens next.

>

> Valery Deryuzhin.

> ARIES.

>

---------------

---------------

>

> Message: 9

> Date: Wed, 09 May 2001 10:28:04 -0000

> From: dnovo@...

> Subject: Re: 155 EDF and 180mm EDF

>

> John: Thanks for the thought, but I have read a fair number of books

> on the subject, including some that you list. However, the point of

> what I was saying is not that reading those books was a waste of

> time. I just disagree with the idea that reading these books makes

> one an 'expert' in the sense that you can look through a telescope

> for three minutes (or less) at a star party and then walk away

> musing, "Too bad, only 1/x wave." I have heard/read/been subjected

> to e-mails regarding optical performance from a number of people who

> have read Suiter (a good book, and one I do not mean to pillory) and

> feel that -- based on their reading of that book and their ad hoc

> star testing -- they are now qualified to offer an 'expert' opinion

> on a telescope or its design just by a glance through it. I don't

> buy that. Dave

>

> --- In ap-ug@y..., "John J. Kasianowicz" surpher@e...> wrote:

> > Hi Dave,

> >

> > I don't think it is a matter of questioning the relevance or need

> for lower

> > cost refractors. It's a matter of having folks not overstating the

> > performance of same.

> >

> > Suiter is not a good primer on optical theory or on instrumental

> optics. You

> > might enjoy reading good optics books (e.g. Born & Wolf, Hecht &

> Zajac, C.J.

> > Smith, Hardy & Perrin, etc.) or one on telescope optics (I think

> it's by

> > Rutten & a coauthor, but I loaned that book to someone and can't

> verify

> > their names).

> >

> >

> > Clear and Dark Skies,

> > John

> >

> >

> > Dave Novo. wrote:

> >

> > > Jeff: I am not an "expert" either and I suspect that there are

> too

> > > many self-styled experts out there. Let us start with this

> premise.

> > [snip]

>

---------------

---------------

>

> Message: 10

> Date: Wed, 09 May 2001 12:48:09 -0000

> From: vahe@...

> Subject: Re: 155 EDF and 180mm EDF

>

> > Anyway, back to refractors: Synta, Vixen, AP & TMB. I hate to

> enter a

> > "four-letter word" into this discussion. But where would "Mead"

> fit in this

> > hierarchy? Somewhere below AP & TMB, I'm sure. Any refractor

> connosieurs

> > out there who will enlighten me?

>

> Just my opinion, worth two cents only, I would place and rate Meade

> ED's as better product than Synta but below Vixen apos, particularly

> in mechanical department, and all of this assumes one of their better

> ones in 4" to 5" sizes.

> As for AP & TMB, no contest there.

>

> Thanks,

> Vahe

>

---------------

---------------

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/







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