Re: Is there something wrong with my optics
English is not my native language and I'm afraid, by the time I
received the reply, that it came from Taiwan, so maybe the exact
meaning is a little bit confusing.
Anyway I understood same idea as in your re-wording but I'm still
wondering why this effect is not so apparent in other air-spaced
triplets also designed by TMB, like APM/TMB. Maybe screws in FLT110
design protrude some more in the light path than other brands
designs. Also I don't understand reason to use screws as spacers
instead of rings as usually we could find in eyepieces. Do you have
An aperture mask could be a good solution to get rid of this effect.
What's your opinion? I'm anxiously waiting for WO commentaries on
--- In William-Optics@yahoogroups.com, Kurt Friedrich
> I am not sure I exactly understand this quote from WO.
> Please see if my re-wording is correct.
> The spikes are from the edges of two sets of 3
> adjustment screws. (total of 6 screws). Unlike oil
> based triplets, where the spacing between the 3 lenses
> is maintained correctly by the thin film of oil, with
> air space triplets, the spacing between the lenses
> must be set precisely, and this is done with the two
> sets of adjustment screws in the lens cell, and they
> are spaced at 120 degree around the lens cell. The tip
> of each of these 6 screws projects very slightly
> between 2 lens surfaces, to set and maintain their
> If I got that right, it explains why we have seen this
> effect in other brands of scopes, and why it is not
> there with some famous oil spaced scopes such as from
> AP and TEC. I know the current designs from AP are
> air spaced, I will ask Roland how he maintains the
> --- Julio César Monje <JULIO__CESAR@...>
> > I've just received reply from WO technical support
> > about "dark
> > spikes" as follows:
> > quote
> > The spikes is from the 3 edge of 120 degree per. two
> > adjustment
> > screws (the reflection of tip on 6 screws) the
> > design is not like the
> > oil spaced without any reflection in between 3
> > lenses, our design is
> > air spaced, we have 2 space reflection in between 3
> > lenses (total 6
> > surface coating on lens in cell).
> > it's not defective, all new FLT 110 are the same,
> > for maximum
> > performance of color correction it can not be
> > changed without dark
> > spikes on the bright star.
> > unquote
> > As I suspected, there's no defective optics but some
> > effect caused by
> > optical design. It seems to be located in the
> > triplet air-spacing but
> > I've never seen this effect in pictures of other
> > brand scopes. What's
> > your opinion? Should I return my scope or keep it? I
> > like a lot
> > visual performance.
> > Thanks everybody for the help.
> Don't pick lemons.
> See all the new 2007 cars at Yahoo! Autos.
- The turned edge would not cause the "dark lanes", but it would make
them clearly visible by causing the bright smear of light around the
bright star. Were the star a perfect airey disk, the only visible
effect of the spacers would be faint diffraction spikes. I'm not
saying that this is or isn't a problem on any or all FLT-132's.
--- In William-Optics@yahoogroups.com, <danjanos@...> wrote:
> It seems the cause of the dark lanes is mechanical whether spacers
screws in the optical path. When you stretch an image the dark lanes
become more prominent as do a brightness on the sides of each of the
dark lanes. This brightening is symptomatic of something in the
path similar to a reflector and it's diffraction spike caused from
> a turned edge will not cause a dark lane . It creates an uneven
brightness around stars and is especially notable on brighter stars.
> I look forward to your rationale.