[nidi]

has this come up before:


how would you rate all glass lenses to hybrid ones?


all glass lenses are quite rare nowadays, right ?


my first projector was a limited Barco 701 which had all


glass lenses (Noritar) and had a 12lp/mm spec.


any advantage to hybrid ones ?


Thanks


Michael

 

[Graham Johnson]

While everyone says that all glass lenses are better. the fact is that even the best projectors still have plastic elements in their lenses.


All LC projectors have plastic C element. And beautiful HD-10 lenses have some plastic elements as well.


Designed correctly they are not always done to be cheaper. They plastic has a higher refractive index than glass and the lenses can be physically smaller and more tightly stacked inside.


Good lenses are good lenses regardless of whether they have plastic elements or not.


Funnily enough some all glass lenses have higher light losses than plastic ones.

 

[RoBro]

Aspheric glass lenses are VVEEERRRYYY expensive.

So they make only spheric glass lenses and everything that is aspheric is done in plastic.

If all elements are plastic, then they can be aspheric and you can get away with 3 lenses (1 power element and 2 field flatteners).

For color correction ad at least on additional lens with different dispersion.

for better thermal stability and better resolution make the power element (element group) of glass, and do just the correction of the aberrations in aspheric plastic.

for all glass lenses you need more elements as you can only make spheric ones.

With glass you get more resolution and less temperature drift, but as you need more elements you have more light loss...

Roland

 

[Graham Johnson]

Hey Roland what do you do for a job ??


I love finding out stuff like that. Very cool info. I know next to nothing about the reasons lenses are constructed as they are. I just observe the results we see.


Seems you know heaps.

 

[kschmit2]

IIRC the Sony HDIH series had all-glass Nikon Lenses with motorized focus adjustments.

I'm not too sure about the c-element, though I think it was also made of glass.

For 1080i these PJs offer the ultimate in performance.


Kai

 

[mikelyw]

I have asked similar question to the Barco technician when I was told Cine 9 has special made lenses (not all Glass as 1209s or 1200). To be simple, Barco guy told me the Pro and Con of All glass vs Hybrid lenses: All Glass is sharper and crystal clear, Hybrid has more light output (brigher), overall Glass element is usually more critical so it appears in most 9" or highend model. However, Barco last HT flagship model Cine 9 has exclusively made Glass+Hybrid compo lens to combine the best of both type. And its extra high 180Mhz RGB bandwidth make it two exceptional components to other HT 9"s.

 

[dav99]

The difference i see, is it seems the coatings are less quality as the lenses

get newer,

On the older all metal hd8's the coatings are as good as i have seen on quality telescopes "$2000+ class".

The latter hd8 rev b, and the sony lenses i have seen, the coatings look

like a candy coating, also the older lenses can be cleaned easily, but the

newer coatings come off with most cleaners.

 

[wonsug]

dav99, I actually have metal barrel hd8 lens.

I thought hd8 rev b has some revision and improvement, so I didn't swap it to my BG 1208/2.

can anyone explain the difference between hd8 and hd8 rev. b ?

3M site offers very little information about their products.

 

[techman707]

I think that the worst thing about plastic lenses is that they seem to scratch too easily. I wonder "why" they can't use some kind of scratch resistant coating on them like they "claim" to do with eye glasses. However, if given the choice, weight not withstanding, I will always choose glass.

 

[DaveInVA]

Just don't bother ever trying T07 all plastic lenses, they suck bigtime. No corner focus at all and you can easily tell HD10's have a better PQ. If I remember correctly they only rate the T07 at 5 lines/mm and HD10 are rated at 10 lines/mm I believe...


Dave

 

[RoBro]

but they are quite a bit brighter...

roland

 

[dav99]

It seems that it's the coating that scratches on the newer lenses,

Take a look at how thick the coating is.