Do you believe in such a statement?

About BO's new 127mm F/8 achromatic refractor quality:

"I called BO on Monday 12:00 noon EST. Tammy answered and took a
message for Bill about my situation. Bill called me back 2 minutes
later and gave me a brief education on how the BO 1278 is made. I
enjoyed my call tremendously! Bill told me about my objective as he
had inspected and tested it himself. He told me that these objectives
are polished to 1/20th wave after the 3rd polish. That's how fine the
grit is that is used. Also that a good number of these objectives are
testing null, as well as approaching null! That explains the Star
test results with my Ronchi EP. Anyway in Bill's usual engaging
conversation he told me he had one other call that day about what
were thought to be scratches on the objectives. I can't say what the
out come of that call was. But mine I can and will."


1/20 wave? Yes? Did I understood you correctly?

Anybody else believe in such a statement?


V.D.

"ValeryD" wrote in message
om...
About BO's new 127mm F/8 achromatic refractor quality:

1/20 wave? Yes? Did I understood you correctly?

Anybody else believe in such a statement?


V.D.

Valery,
Good to have you back. How are the AP eyepieces coming along? 1/20th wave?
sounds like the marketing department doing the testing.

Regards,
Ed

Good to have you back.

No it's not. I wish Valery the jerk
would stay off s.a.a. permanently.
The only time he ever posts here
is to attack another company.
Like:
Stellarvue
TMB
Burgess
APM
Zambuto

So who gets the "honor" of
being next?

Dr. Evil:

No it's not. I wish Valery the jerk
would stay off s.a.a. permanently.
The only time he ever posts here
is to attack another company.
Like:
Stellarvue
TMB
Burgess
APM
Zambuto

So who gets the "honor" of
being next?

At least Valery has enough guts to sign his name to his posts.....


Me too

Jon Isaacs

"Edward" wrote in message thlink.net...

Valery,
Good to have you back. How are the AP eyepieces coming along? 1/20th wave?
sounds like the marketing department doing the testing.

Regards,
Ed

Ed,

These eyepieces are in progress in all focal lengths. Roland Christen
strictly tested several prototypes and we improved some sides.
He tested the most critical f.l. ones and was finally satisfied.
I should say, that it was far not easy to satisfy Roland's requirements
if consider them all together.

I hope, that all eyepieces in the very first serie will be 100% as
Roland required and then we will begin a full production run.


Valery Deryuzhin.

He told me that these objectives
are polished to 1/20th wave after the 3rd polish.

Well

Given that a REFRACTING surface effects the wavefront roughly 1/4 as strongly
as a mirror surface.....this means that any given refracting surface that hase
1/20 th wavefront error is roughly that of a 1/5 wavefront error mirror in
terms of absolute surface accuracy requirements.....and given moderate,
spherical surfaces.....the claims may be slightly exaggerated but the are not
neccessarily "astronomical"

Blll

(BllFs6) wrote in message ...
He told me that these objectives
are polished to 1/20th wave after the 3rd polish.

Well

Given that a REFRACTING surface effects the wavefront roughly 1/4 as strongly
as a mirror surface.....this means that any given refracting surface that hase
1/20 th wavefront error is roughly that of a 1/5 wavefront error mirror in
terms of absolute surface accuracy requirements.....and given moderate,
spherical surfaces.....the claims may be slightly exaggerated but the are not
neccessarily "astronomical"

Blll


Blll,

It is clear, that lenses were _polished_ to 1/20 wave (guess surface
accuracy). That mean, wave front for each lens is about 1/30 wave
P-V. Complete objective (if it is a doublet) will has about 1/25 wave
wave front P-V.

Ask any refractor manufacturers out here and there if they can make
such precision in 5" objective for... about $200 (dealer's profit included).
Ask them if they can support such quality in general.

I think, that they will only smile in answer.


Valery Deryuzhin.

Ask any refractor manufacturers out here and there if they can make
such precision in 5" objective for... about $200 (dealer's profit included).
Ask them if they can support such quality in general.

I think, that they will only smile in answer.


Valery Deryuzhin.







Is that 200 dollars of USA labor rates or starving chinese peasant labor rates?

A western paid optician could probably only spend a few hours getting a good,
smooth spherical surface.....a chinese peasant could spend a WEEK or 2 on
it...and you can be a peasant and STILL be a skilled optician .....at least in
some ways....

You ASKED about possible accuracy....my answer being that 1/20th wave refractor
wavefronts ARE ALOT easier to obtain than 1/20 wave reflecting wavefronts....

labor/cost is a whole other can of worms...

take care

Blll

(BllFs6) wrote in message ...

You ASKED about possible accuracy....my answer being that 1/20th wave refractor
wavefronts ARE ALOT easier to obtain than 1/20 wave reflecting wavefronts....

Blll

You forgot some things:

1. Refracting systems has such a factor as internal inhomogeneity,
which hurts wave front too and typically more than for 1/20 wave.

2. For highest wave front accuracy one should use highest rate glasses.
They are expensive regardless of country they were melted.

3. Refracting systems contains sveral surfaces - in any case 2x more,
then reflecting systems.

4. Reflecting systems can be made of zero-expansion substrate - this helps
a lot in manufacturing and testing - and such in reaching necessary
precision. in the same time glasses for objectives has rather large TEC
and very often _different_ TEC.


So, your statement is at least very questionable. But BO's statement about
their objectives quality on 1/20 wave level even more questionable.
We even don't know what the test method(s) was (were) used to prove such
precision.

V.D.

"ValeryD" wrote in message
om...
About BO's new 127mm F/8 achromatic refractor quality:

"I called BO on Monday 12:00 noon EST. Tammy answered and took a
message for Bill about my situation. Bill called me back 2 minutes
later and gave me a brief education on how the BO 1278 is made. I
enjoyed my call tremendously! Bill told me about my objective as he
had inspected and tested it himself. He told me that these objectives
are polished to 1/20th wave after the 3rd polish. That's how fine the
grit is that is used. Also that a good number of these objectives are
testing null, as well as approaching null! That explains the Star
test results with my Ronchi EP. Anyway in Bill's usual engaging
conversation he told me he had one other call that day about what
were thought to be scratches on the objectives. I can't say what the
out come of that call was. But mine I can and will."

1/20 wave? Yes? Did I understood you correctly?

Anybody else believe in such a statement?

V.D.

Greetings Valery,

I wonder if those values are determined with an interferometer or other test
method(s)?

In general, I think the properly conducted interferometer test results would
show lower values, but a bit more realistic values.

Dan McShane


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