Vic individually star tests each and every telescope that he makes. A question was asked about what happens when a telescope does not pass the star test. This is his answer. I think it also answers the question about the price difference between some 'APOS' and others.
Quote:
This really depends on the lens in question. For example, we do twice
as many tests on the 90T Fluorite as the others. But when one of
these does not pass muster it is often disassembled and we sometimes
must do some refiguring. That is why these are wait listed. We want
each one to be as good as the last.
To date, I have had great luck with Lomo lenses. We have only
returned four. These lenses come mounted in the cell so the following
two paragraphs will not apply to these.
In terms of our other lenses, some of the ed doublets and the dual
fluoro triplets are computer matched. My designer developed a program
long ago that allows him to match each numbered element to its mate
to get optimal performance. On these few lenses, this saves a lot of
time. It takes little time to match but saves a great deal of time
during lens assembly and does increase the spec.
Now with all non Lomo or LZOS lenses, the two or three elements are
mounted in an adjustable cell and bench tested to make sure they are
properly aligned and optimally rotated in relation to each other. We
have a test device here helps us do this. It is not alien technology
or anything, certainly actual lens makers get what this is, but it
certainly saves time and increases spec again over randomly assembled
lens sets. When we have an issue at this step, the lens set is
disassembled and used with other mates but this never happens with
the computer matched lenses.
The lens cell is then mounted in the ota and bench tested for system
alignment. It is then star tested. I star test to get perfect
alignment and do a final check for spherical and color issues. A very
small percentage of these do not pass. This is usually an alignment
issue which means only going back one step. But not always.
A low percentage of telescopes fail the star test. I assume it is a
glass issue. These are the achromats that are accurately figured and
yet, they do not meet our spec. Many years ago I learned to just
forget about these. When we find an offending achromatic element we
literally throw it away. Trying to do anything else with this would
not be cost effective. Also, be advised, I will not sell these
individual elements. I make sure they are destroyed. The world does
not need more mediocre lenses floating around out there.
This is hard to answer specifically since each lens has a slightly
different procedure. But I hope this helps.
The easy answer is that lenses that do not pass muster get either
realigned, slightly refigured or in the case of the achromats -
dumped. We write these off and keep the ones that work.
Recently someone asked a well respected USA apo lens manufacturer why
his lenses cost more than the new wave of cheaper telescopes hitting
the market. I knew how much better his telescopes were, I knew the
cost difference and so I knew why his were a bit more expensive. I
felt his simple answer said it all. "You get what you pay for." The
time it takes to get it perfect is not small and this does add
considerably to the cost. If we randomly assembled lens elements and
did not take the care we do in every step, we could drop our prices
considerably. But then we would not have consistency. Apo triplets
are hard to make, very hard. The high end name brand telescope
companies offer an alternative that is only slightly more expensive
than some others but in my opinion, the difference is significant.
The simple motto here is, "no excuses." I am proud to be among those
who take the time needed to produce what is certainly the finest
production refractors the world has ever seen. Seeing is believing.
Best regards
Vic Maris
End Quote.
Are there any SV scopes in Singapore? IMHO, they will join the ranks of AP soon. I'll be getting a SV90T (90mm triplet Fluorite) to compare to a TMB 90mm Signature Series to replace my TV76.
Vincent
Why some 'APOS' are $500 and others are $2000
I saw the website in more detail this time. There was some mention of the source of the lens cells. 
Last edited by mrngbss on Sun May 06, 2007 8:47 am, edited 1 time in total.
Wee Nghee the Pooh
http://tech.groups.yahoo.com/group/Stel ... sage/68157
The 80S. 80L and SV4 lens cells are from LOMO. The bigger lenses are from LZOS. But they didn't mention the source of the 90T and SV5.
Anat
The 80S. 80L and SV4 lens cells are from LOMO. The bigger lenses are from LZOS. But they didn't mention the source of the 90T and SV5.
Anat
Arief,
ALL SV scopes get the same treatment. Testing is the same for all the scopes. Standards are the same for all the scopes.
The only difference is that SV doesn't make the lenses in house. They are sub contracted to LZOs or LOMO or whatever. But SV does the final testing and any apo lens that doesn't meet their standards get returned. In fact, if you read the post, any achro element that doesn't pass the tests gets DESTROYED!!
The plus side to not having to make your own lens is that the wait is much much shorter since they are made by a company that does nothing but make lens.
Only time will tell of course. But I do believe that if they don't reach the same stature of AP, they will be a very very close second.
Vincent
ALL SV scopes get the same treatment. Testing is the same for all the scopes. Standards are the same for all the scopes.
The only difference is that SV doesn't make the lenses in house. They are sub contracted to LZOs or LOMO or whatever. But SV does the final testing and any apo lens that doesn't meet their standards get returned. In fact, if you read the post, any achro element that doesn't pass the tests gets DESTROYED!!
The plus side to not having to make your own lens is that the wait is much much shorter since they are made by a company that does nothing but make lens.
Only time will tell of course. But I do believe that if they don't reach the same stature of AP, they will be a very very close second.
Vincent
Hmm.. I tot you said "STOP"?rcj wrote:good post, vincent. would wonder how they go about conducting the testing... am thinking about the SV102ED at this point in time, but would not expect the colour correction to be zeroed. neveretheless, it is of good value considering the favourable exchange rate now.
Wee Nghee the Pooh