[reh321]

Do not understand the reflection comment. In reflection the angle of incidence is equal to the angle of reflection. I am talking about refraction not reflection. When light enters a substance like glass it is refracted (bent). This is dependent upon the refractive index of the glass. Different wavelengths refract differently. Hence the pretty colors you get when "white" light passes through a prism. It is like looking at fish in a pond. The fish is not actually where you see it.

The comment I responded to was

A new prism made form different materials is actually quite a challenge. The change in refractive index of the glass means the whole shape of the prism had to change too. Directing light is never easy when you have to pass it through a substance.

In a DSLR, the light reflects from a prism and never passes through it.

[MMVIII]

The comment I responded to was
In a DSLR, the light reflects from a prism and never passes through it.

? No. It is reflected from the surfaces inside on the inner side [edited to be clearer] of the pentaprism. Thus it has to enter it and passes through it. Here the refractive index of the glass comes into play.

[alfa75ts]

It is reflected from the surfaces inside of the pentaprism

As is clearly depicted in the drawings in the patent.

[TwoUptons]

The comment I responded to was
In a DSLR, the light reflects from a prism and never passes through it.

That sounds more like a pentamirror than a pentaprism.

I think some of the later model Pentax film SLRs used pentamirrors, and I don't know how long that persisted, but the higher end stuff always used prisms...

-Eric

[Kunzite]

That sounds more like a pentamirror than a pentaprism.

I think some of the later model Pentax film SLRs used pentamirrors, and I don't know how long that persisted, but the higher end stuff always used prisms...

-Eric

Yes, and they used pentamirrors on some cheap DSLRs, too. Was K-r the last?

[thibs]

I think so. Kr, Kx, Km, K100D, K200D, ist DL and variations were all pentamirrors AFAICT (0.85x, 96% coverage).

[gaweidert]

The comment I responded to was
In a DSLR, the light reflects from a prism and never passes through it.

Light does pass through the glass in a pentaprism but it does bounce around in there a bit first. From a Wikipedia article. In a prism angled interior surfaces act as mirrors.

[DagT]

Could that stacked sensor be something similar to the Sigma Foveon Sensor??

There is a bit more about the stacked sensor here:
Espacenet ? search results

Probably a dead end as they have not applied for corresponding patents outside Japan.

[ogl]

I don't understand how new prism could make OVF 10% brighter...

the loss of light on the prism is insignificant compared
to the loss in the lens, on a translucent mirror and frosted glass,
no matter how much the transparency of the pentaprism is increased,
the overall increase in brightness in the viewfinder will be just as insignificant.

[Cynog Ap Brychan]

? No. It is reflected from the surfaces inside on the inner side [edited to be clearer] of the pentaprism. Thus it has to enter it and passes through it. Here the refractive index of the glass comes into play.

The light enters and leaves the prism perpendicular to the surfaces, so in theory refraction does not take place. In practice, though, I imagine a small amount does take place. I am no expert, so please correct me if I am wrong.

[Kunzite]

I don't understand how new prism could make OVF 10% brighter...

the loss of light on the prism is insignificant compared
to the loss in the lens, on a translucent mirror and frosted glass,
no matter how much the transparency of the pentaprism is increased,
the overall increase in brightness in the viewfinder will be just as insignificant.

It is explained in the patent. Have you read and understand it? No? Then, you have no choice than to trust the professionals who tells you how it is.

Rather than, say, pretend you know better and they're liars.

[ogl]

It is explained in the patent. Have you read and understand it? No? Then, you have no choice than to trust the professionals who tells you how it is.

Rather than, say, pretend you know better and they're liars.

Your manner to discuss is rather insulting for me. You try to blame me for fictitious thoughts and doing wishful thinking.
I just want to get any explanation from the specialists, not to read your insult.

[Kunzite]

Your manner to discuss is rather insulting for me. You try to blame me for fictitious thoughts and doing wishful thinking.
I just want to get any explanation from the specialists, not to read your insult.

I pointed out exactly to where you can find an explanation from the specialists - linked to in the first post.
But you already rejected the words of Mr. Shigeru Wakashiro, explaining yourself how this cannot happen. You said: "the overall increase in brightness in the viewfinder will be just as insignificant" - which is not a question.
Perhaps it's a communication barrier, in which case I'd have to apologize for believing you're calling them liars, and also to ask you to make your questions a bit more obvious and less definite statements.

[Smolk]

Sorry but ogl did start with a question, kunzite. And he did not call anyone a liar. Let's keep this discussion a bit more relaxed.

[DagT]

The light enters and leaves the prism perpendicular to the surfaces, so in theory refraction does not take place. In practice, though, I imagine a small amount does take place. I am no expert, so please correct me if I am wrong.

No. The light entering the prism is not perpendicular to the surface. The light entering from the screen is scattered and a higher refractive index will make more use of the light scattered from the screen as more of it will be refracted sufficiently to be reflected by the internal surfaces in the prism. The ocular lenses are focused on the screen, receiving that light. The higher refractive index also makes the optical path length from the screen to the eye higher en then you need to ajust that part as well.

Think of the differences between the cheap pentaprisms that made small and dark finders, compared with the glass prisms of more expensive models.