Weight and cost is the reason we are developing oil spaced triplets.
With the oil spaced objective, you simply mount the lens in an
aluminum cell with cork lining. The nature of an oil spaced design
is much more forgiving in terms of coma than an air spaced design.
With large air spaced lenses, each element must be accurately
mounted in a steel cell. Steel has the same CTE (coefficient of
thermal expansion) as the fluoro glass. Using aluminum for a large
air spaced lens would not work. The aluminum would contract and
pinch the lens as the temperture drops. Now to shave off weight in
an air spaced design, titaniam may be used but this drives the cost
up astronomically. That is why only the SV190 uses titanium. We have
reduced weight by milling blind windows in our dual fluoro cells
(see the SV127 or SV135 pages). This helps but it is still a little
heavier than aluminum.

But how do each perform? The fact that Roland at Astro-physics is
switching from oil to air is telling here. With air spaced, you have
more design freedom to correct for a number of issues. Roland told
me he did the switch to air spaced to provide better correction for
increased demands by ccd imagers using the new big chip cameras.
This makes sense but the effort and cost is much greater with air
spaced designs. Also, there are ways to address issues seen in oil
spaced designs using correctors, aspherical surfaces, etc. Yes, it
adds to cost but it can improves things.

Oil spaced only has two coated surfaces so the coating spec can be
relaxed a little compared with air spaced. With air spaced, you have
six surfaces to coat and unless one uses an expensive broadband
coating that reduces reflections to nearly zero from 450 - 900nm,
ccd cameras will show reflections when pushed. Film is more
forgiving here but who uses film anymore? In addition, air spaced
lenses will show optical issues with each surface whereas oil spaced
lenses tend to hide any interior zonal issues. In this regard, an
oil spaced lens acts like a singlet.

Now if one wants to produce a Stellarvue Quality optic addressing
all of the issues and providing stunning visual and photographic
performance, the air spaced optic will cost much more than the oil
spaced. Much much more. Despite this, people always like to compare
aperture to aperture and do not take into account the differences
which are many. This is particularly true today with ccd cameras
pushing the envelope. New coating requirements are adding thousands
to the overall cost of the optic if one wants to ensure that
reflections are eliminated and this affects the air spaced optic
more, obviously.

Our SV155 project is designed to deliver a 6" + sized telescope that
is light in weight and reasonable in cost. It will have all of the
features people have come to expect with Stellarvue's big guns. This
includes the 3.5" Feather Touch Focuser, spherical baffles, cnc
mounting rings, retracting dewshield, aluminum tube that acts as a
heat sink, minimizing cool down time, exceptional super ed optic
with excellent broadband coatings. In addition, the new SV155 will
use a new thinner main tube and dewshield to cut tube weight in half
based on our tests. So it will be our lightweight lower cost apo
triplet.

We are aiming at an introductory price of about $6995 for the new
SV155. That is very low when you consider all that will go into the
telescope.

This does not mean we will not make our large air spaced apo
triplets. These projects are moving forward with LZOS on schedule.
These will constitute the pinnacle of perfection when it comes to an
apo refractor. We are making these to be the very best, bar none.
Many areas have been addressed with these new LZOS triplets:

1. More advanced glass than used in our former LZOS lenses resulting
in a design that reduces aberrations even more!
2. Much higher coating spec
3. Much higher polishing spec
4. Specially design lens cells to minimize weight without
compromising thermal characteristics
5. Edge blackened lens elements

So we are going over the top with these. We are making only a
limited run for next year of the following instruments:

SV127 Dual FLuoro (first to appear)
SV135 Dual Fluoro
SV145 apo triplet
SV165 apo triplet
SV190 apo triplet.

I realize that seeing is believing. Also, thanks to all of you, 2006
was our most successful year ever. For this reason, I will invest
what we have made this year to reduce the sale price for the first
of these large telescopes using the new LZOS super objectives. The
introductory sales price will truly be below my cost. I have enough
money to offset the cost for the 2007 LZOS production run only. Once
we have taken orders for a given telescope model that is equal to
the number objectives to be made in 2007, the price on that
telescope model will go back up. So this is truly an introductory
offer. Why? I want people like Tony Hallas, Bob Fera, Jon Talbot and
others to have the opportunity to use and image through these
telescopes. This will prove the performance of these exceptional
optics and make clear why we charge what we must. So starting this
weekend, you will see a significant introductory price reduction on
all of our new large telescopes using LZOS objectives. Here are the
specific price reductions for these models:

Apo Triplets:

SV145 - Reg $8690 - intro price $7990
SV165 - Reg $13990 - intro price $10,990
SV190 Titanium - Reg $22990 - intro price $18,990 (way below cost!)

Superfast Dual Fluoros

SV127 Reg $7990, intro price $6990
SV135 Reg $9800, intro price $7990 (way below cost!)

Again, once we have sold the number of telescopes that equal the
number of objectives we have coming in 2007, the price will go back
up. This is, in part, due to the rising cost of Russian optics. We
cannot predict our costs in 2008. However, it is also the extent of
funding I have to produce a limited number of large telescopes and
sell them below cost.

Why am I doing this? I honestly believe that nothing can touch these
telescopes. Once they hit the streets and people look and image
through these telescopes, each will prove itself.

So the Stellarvue line now includes three types of apo triplet
refractors:

1. Lower priced, lighter oil spaced triplets
2. Very high spec air spaced apo triplets
3. Very fast, high spec dual fluoro triplets.

Never has the amateur or professional had so many high end choices.

And again, I realize, it is all due to you. Without you, none of
this would be possible. As I look over this past year, the
incredible work we have done in bringing over one dozen new
telescopes to market, I am mindful that none of this would be
possible without your help. Thank you all for supporting Stellarvue
in 2006. I want to wish all of you a very happy and prosperous new
year. And I am deeply and sincerely happy to have all of you along
for the ride.

2007 is going to be a great year!

Vic Maris




n Stellarvue@yahoogroups.com, "albireo13" <polaris@...> wrote:
>
> I really wish SV could come up with lighter weight OTAs. I've
owned the SV105 and,
> frankly, the weight of the tube has scared me away from any larger
SV apos. I've owned a
> TOA130 and TEC140 as well. I found the TEC140 to be a very nice
compromise in scope
> "beef" vs. aperture.
>
> Rob
>
>
>
>
> --- In Stellarvue@yahoogroups.com, "thms_dll" <thms_dll@> wrote:
> >
> > Robert,
> >
> > Vic mentioned earlier that he was looking at a way to reduce the
> > weight of the SV5S. If you wanted to shave several lbs off the
> > weight, using an oil-spaced triplet in an aluminum cell would be
one
> > way to do it. I suspect that the use of the oil-spaced/aluminum
cell
> > is one of the reasons why the TEC 140 and AP 130EDFS are as
light as
> > they are for their size.
> >
> > Happy New Year to you,
> >
> > Tom D. in Fla.
> > SV105
> >
> > --- In Stellarvue@yahoogroups.com, "Robert" <pellet_masher@>
wrote:
> > >
> > > Vic,
> > > Looking at the lovely ad in the Feb. 2007 Sky&Tel, it
describes the
> > SV5
> > > and SV155 as oiled triplets. If I'm not mistaken these are the
> > first
> > > oil spaced SV's. Can you tell me what are the advantages and
> > > disadvantages of the oiled design and why you chose it ?? Will
the
> > > oiled design allow you to use an aluminum cell instead of
steel ??
> > and
> > > is it as good for correction of aberrations, as an air spaced
> > design at
> > > say f7 ??
> > >
> > > Always the student :?)
> > > Robert
> > >
> >
>