The challenge of the new Pentaprism

Smolk · 05-12-2021, 05:03 PM

Originally posted by Andrea K

A Canon user will never tell you that another brand has done something good

Let's ignore any others, any negativity, better to focus on the strengths, which are plentiful now, and always were, recognised as such or not.

One3rdEV · 05-12-2021, 05:37 PM

Originally posted by Andrea K

Mind that the improvement is "only" for APS-C shooters as FF shooters already have this kind of OVF experience.

True, but many Pentaxians are ANXIOUSLY awaiting the OVF experience that FF shooters will be enjoying in the future.

It will again be an opportunity for unique differentiation between Pentax and the FF competition.

**Serkevan** · 05-12-2021, 05:43 PM

Originally posted by Andrea K

A Canon user will never tell you that another brand has done something good

Nah, I know one or two Canonites and while both swear by L glass they know full well other brands do an excellent job as well...

**grahame** · 05-12-2021, 06:23 PM

Originally posted by Not a Number

The prism in the K-3iii is significantly larger than the one in the K-3ii.

But the mirror is not significantly larger. Pentax only put a magnifying glass between the focus screen and the pentaprism. So the amount of light reflected into the prism is similar, but the image is larger, so must be darker. Maybe Pentax made a new focusing screen to make prism brighter.

mtkeller · 05-12-2021, 07:35 PM

Originally posted by grahame

But the mirror is not significantly larger. Pentax only put a magnifying glass between the focus screen and the pentaprism. So the amount of light reflected into the prism is similar, but the image is larger, so must be darker. Maybe Pentax made a new focusing screen to make prism brighter.

I think every single one of us who has used the K-3 iii will tell you that, even if by some scientific measurement of bright/dark the OVF is now darker, the increase in size certainly makes it seem brighter. I feel like I read something about an adjustment to the focusing screen to improve clarity. I know sometimes under just the wrong light, my K-70 OVF would appear kind of textured. I haven’t run into that yet with the K-3 iii.

cfraz · 05-12-2021, 08:04 PM - **1 Like**

Originally posted by grahame

But the mirror is not significantly larger. Pentax only put a magnifying glass between the focus screen and the pentaprism. So the amount of light reflected into the prism is similar, but the image is larger, so must be darker. Maybe Pentax made a new focusing screen to make prism brighter.

According to Ricoh, the brighter viewfinder image is owing to, in part, a high refractive index glass with lower reflection losses than in conventional prism glass. See the link in post 1 of this thread and also the features page of PENTAX K-3 Mark III - Ricoh, where they state:

Quote:

This viewfinder also provides an almost 10-percent increase in brightness, thanks to the improved reflectance of the pentaprism, while also assuring a nearly 100-percent field of view.

**grahame** · 05-12-2021, 09:23 PM

Originally posted by cfraz

hanks to the improved reflectance of the pentaprism,

That must be a BIG improvement of reflection because there are only 2 interfaces in the pentaprism are mirror and others are total internal reflection and are 100%. The improvement makes OVF 10% brighter even after compensating the darken image caused by the magnifying lens .
I still believe some modification on focusing screen might be easier. Just a guess.

Don't take me wrong, I love MF lenses and love bigger viewfinder. I bought Fuji x-t1 over x-pro because the bigger EVF, and olympus em-1 over 5 or 10 mostly because the bigger finder.

**Serkevan** · 05-13-2021, 01:06 AM

Originally posted by grahame

That must be a BIG improvement of reflection because there are only 2 interfaces in the pentaprism are mirror and others are total internal reflection and are 100%. The improvement makes OVF 10% brighter even after compensating the darken image caused by the magnifying lens .
I still believe some modification on focusing screen might be easier. Just a guess.

Don't take me wrong, I love MF lenses and love bigger viewfinder. I bought Fuji x-t1 over x-pro because the bigger EVF, and olympus em-1 over 5 or 10 mostly because the bigger finder.

Two mirrored surfaces are enough to mess brightness up, look at the pentamirrors... (Aight, technically there are 3 surfaces for light rays outside from the center because of the prism being a roof-type, but potayto potahto).

They also removed the transparent LCD layer that shows the focus points. That increases brightness as well.

**RobA_Oz** · 05-13-2021, 02:16 PM

Originally posted by grahame

That must be a BIG improvement of reflection because there are only 2 interfaces in the pentaprism are mirror and others are total internal reflection and are 100%. The improvement makes OVF 10% brighter even after compensating the darken image caused by the magnifying lens .
I still believe some modification on focusing screen might be easier. Just a guess.

Don't take me wrong, I love MF lenses and love bigger viewfinder. I bought Fuji x-t1 over x-pro because the bigger EVF, and olympus em-1 over 5 or 10 mostly because the bigger finder.

Have a look at the image I included at post #90 above. The final mirrored surface before the eyepiece is no longer semi-silvered to provide for the viewfinder information, which is now introduced by the LCD panel on top of the focussing screen. While there will be some loss incurred by the LCD panel, I imagine that will be less than that from the semi-silvered mirror surface previously used.

You could be right about the focussing screen, too, nonetheless, even though they haven’t talked about it in Ricoh’s discussion about the new system. Reducing the light scatter from the screen is the key to improving the brightness there.

Smolk · 05-13-2021, 05:03 PM

Originally posted by MMVIII

That's fantastic. It's always good if someone can define his personal needs so well. Keep it up.

Indeed. All these reviews go for the everything a can can hold approach, whereas individuals have their own needs - and might wish their cameras to be geared towards them.
I like a good AF butI don't shoot formula 1.

**RobA_Oz** · 05-13-2021, 05:14 PM

Originally posted by Smolk

Indeed. All these reviews go for the everything a can can hold approach, whereas individuals have their own needs - and might wish their cameras to be geared towards them.
I like a good AF butI don't shoot formula 1.

My car has a reported top speed of 215 km/hr, although I mostly use it around town.

Some people relentlessly press the limitations of their requirements, and I have to wonder why saying it so many times seems to be needed. A camera maker has to satisfy a sufficiently broad range of needs to ensure a profit, but over time, and with competition from other makers, that range continues to expand, no matter how small our individual needs might appear after a while.

Smolk · 05-14-2021, 10:29 PM

Originally posted by RobA_Oz

My car has a reported top speed of 215 km/hr, although I mostly use it around town.

Some people relentlessly press the limitations of their requirements, and I have to wonder why saying it so many times seems to be needed. A camera maker has to satisfy a sufficiently broad range of needs to ensure a profit, but over time, and with competition from other makers, that range continues to expand, no matter how small our individual needs might appear after a while.

But sometimes more is less, and a tool’s clarity of purpose lost.
I always keep in mind what is indispensable to me and what might be a bonus and what a distraction.

**RobA_Oz** · 05-15-2021, 04:55 AM

Originally posted by Smolk

But sometimes more is less, and a tool’s clarity of purpose lost.
I always keep in mind what is indispensable to me and what might be a bonus and what a distraction.

I think I understand what you mean, but it’s only less if the greater portion interferes with what the photographer is trying to achieve. If you can ignore the distractions, then they don’t matter. That, of course, might be a big “if” for some.

Thus far, I haven’t had anything in my cameras that has detracted from my use of them, but I don’t have the latest in any of the three Pentax formats. Mind you, I keep finding useful things I didn’t know about with the ones I have, often thanks to these pages. Perhaps I’ll find out if/when I get a K-3iii.

Smolk · 05-15-2021, 10:58 PM

Originally posted by RobA_Oz

Mind you, I keep finding useful things I didn’t know about with the ones I have, often thanks to these pages.

That's true, I am expecting this myself. The only digital cameras I seriously used were the Sigma DP2 & 3 Merrills, great little things, but they were (delightfully) basic. Had a good menu though. These flagship cameras have so much more, it may take time to find out howe to use it.
Now that I know my kit will be shipped this week - I'm really looking forward to it.

**Rondec** · 05-16-2021, 02:40 AM

I do wonder if this tech will be scalable to full frame and even 645 cameras. Nicer viewfinders are something that we all benefit from, even if we get used to them over time. Certainly we aren't going back to the MX days -- having auto focus does have its downsides (I still prefer to have it present on my cameras).

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05-12-2021, 05:03 PM	#91
Smolk Pentaxian Join Date: Feb 2010 Location: Eerbeek Photos: Gallery \| Albums Posts: 1,857	Originally posted by Andrea K A Canon user will never tell you that another brand has done something good Let's ignore any others, any negativity, better to focus on the strengths, which are plentiful now, and always were, recognised as such or not.

05-12-2021, 05:37 PM	#92
One3rdEV Senior Member Join Date: Mar 2013 Location: So-central, MI Posts: 285	Originally posted by Andrea K Mind that the improvement is "only" for APS-C shooters as FF shooters already have this kind of OVF experience. True, but many Pentaxians are ANXIOUSLY awaiting the OVF experience that FF shooters will be enjoying in the future. It will again be an opportunity for unique differentiation between Pentax and the FF competition.

05-12-2021, 05:43 PM	#93
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by Andrea K A Canon user will never tell you that another brand has done something good Nah, I know one or two Canonites and while both swear by L glass they know full well other brands do an excellent job as well...

05-12-2021, 06:23 PM	#94
grahame Loyal Site Supporter Join Date: Aug 2011 Photos: Albums Posts: 2,041	Originally posted by Not a Number The prism in the K-3iii is significantly larger than the one in the K-3ii. But the mirror is not significantly larger. Pentax only put a magnifying glass between the focus screen and the pentaprism. So the amount of light reflected into the prism is similar, but the image is larger, so must be darker. Maybe Pentax made a new focusing screen to make prism brighter.

05-12-2021, 07:35 PM	#95
mtkeller Veteran Member Join Date: Feb 2019 Location: Sioux City, IA Photos: Gallery Posts: 938	Originally posted by grahame But the mirror is not significantly larger. Pentax only put a magnifying glass between the focus screen and the pentaprism. So the amount of light reflected into the prism is similar, but the image is larger, so must be darker. Maybe Pentax made a new focusing screen to make prism brighter. I think every single one of us who has used the K-3 iii will tell you that, even if by some scientific measurement of bright/dark the OVF is now darker, the increase in size certainly makes it seem brighter. I feel like I read something about an adjustment to the focusing screen to improve clarity. I know sometimes under just the wrong light, my K-70 OVF would appear kind of textured. I haven’t run into that yet with the K-3 iii.

05-12-2021, 08:04 PM - 1 Like	#96
cfraz Veteran Member Join Date: Jan 2009 Location: Oregon, USA Posts: 521	Originally posted by grahame But the mirror is not significantly larger. Pentax only put a magnifying glass between the focus screen and the pentaprism. So the amount of light reflected into the prism is similar, but the image is larger, so must be darker. Maybe Pentax made a new focusing screen to make prism brighter. According to Ricoh, the brighter viewfinder image is owing to, in part, a high refractive index glass with lower reflection losses than in conventional prism glass. See the link in post 1 of this thread and also the features page of PENTAX K-3 Mark III - Ricoh, where they state: Quote: This viewfinder also provides an almost 10-percent increase in brightness, thanks to the improved reflectance of the pentaprism, while also assuring a nearly 100-percent field of view.

05-12-2021, 09:23 PM	#97
grahame Loyal Site Supporter Join Date: Aug 2011 Photos: Albums Posts: 2,041	Originally posted by cfraz hanks to the improved reflectance of the pentaprism, That must be a BIG improvement of reflection because there are only 2 interfaces in the pentaprism are mirror and others are total internal reflection and are 100%. The improvement makes OVF 10% brighter even after compensating the darken image caused by the magnifying lens . I still believe some modification on focusing screen might be easier. Just a guess. Don't take me wrong, I love MF lenses and love bigger viewfinder. I bought Fuji x-t1 over x-pro because the bigger EVF, and olympus em-1 over 5 or 10 mostly because the bigger finder.

05-13-2021, 01:06 AM	#98
Serkevan Site Supporter Join Date: May 2019 Photos: Albums Posts: 5,976	Originally posted by grahame That must be a BIG improvement of reflection because there are only 2 interfaces in the pentaprism are mirror and others are total internal reflection and are 100%. The improvement makes OVF 10% brighter even after compensating the darken image caused by the magnifying lens . I still believe some modification on focusing screen might be easier. Just a guess. Don't take me wrong, I love MF lenses and love bigger viewfinder. I bought Fuji x-t1 over x-pro because the bigger EVF, and olympus em-1 over 5 or 10 mostly because the bigger finder. Two mirrored surfaces are enough to mess brightness up, look at the pentamirrors... (Aight, technically there are 3 surfaces for light rays outside from the center because of the prism being a roof-type, but potayto potahto). They also removed the transparent LCD layer that shows the focus points. That increases brightness as well.

05-13-2021, 02:16 PM	#99
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,200	Originally posted by grahame That must be a BIG improvement of reflection because there are only 2 interfaces in the pentaprism are mirror and others are total internal reflection and are 100%. The improvement makes OVF 10% brighter even after compensating the darken image caused by the magnifying lens . I still believe some modification on focusing screen might be easier. Just a guess. Don't take me wrong, I love MF lenses and love bigger viewfinder. I bought Fuji x-t1 over x-pro because the bigger EVF, and olympus em-1 over 5 or 10 mostly because the bigger finder. Have a look at the image I included at post #90 above. The final mirrored surface before the eyepiece is no longer semi-silvered to provide for the viewfinder information, which is now introduced by the LCD panel on top of the focussing screen. While there will be some loss incurred by the LCD panel, I imagine that will be less than that from the semi-silvered mirror surface previously used. You could be right about the focussing screen, too, nonetheless, even though they haven’t talked about it in Ricoh’s discussion about the new system. Reducing the light scatter from the screen is the key to improving the brightness there.

05-13-2021, 05:03 PM	#100
Smolk Pentaxian Join Date: Feb 2010 Location: Eerbeek Photos: Gallery \| Albums Posts: 1,857	Originally posted by MMVIII That's fantastic. It's always good if someone can define his personal needs so well. Keep it up. Indeed. All these reviews go for the everything a can can hold approach, whereas individuals have their own needs - and might wish their cameras to be geared towards them. I like a good AF butI don't shoot formula 1.

05-13-2021, 05:14 PM	#101
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,200	Originally posted by Smolk Indeed. All these reviews go for the everything a can can hold approach, whereas individuals have their own needs - and might wish their cameras to be geared towards them. I like a good AF butI don't shoot formula 1. My car has a reported top speed of 215 km/hr, although I mostly use it around town. Some people relentlessly press the limitations of their requirements, and I have to wonder why saying it so many times seems to be needed. A camera maker has to satisfy a sufficiently broad range of needs to ensure a profit, but over time, and with competition from other makers, that range continues to expand, no matter how small our individual needs might appear after a while.

05-14-2021, 10:29 PM	#102
Smolk Pentaxian Join Date: Feb 2010 Location: Eerbeek Photos: Gallery \| Albums Posts: 1,857	Originally posted by RobA_Oz My car has a reported top speed of 215 km/hr, although I mostly use it around town. Some people relentlessly press the limitations of their requirements, and I have to wonder why saying it so many times seems to be needed. A camera maker has to satisfy a sufficiently broad range of needs to ensure a profit, but over time, and with competition from other makers, that range continues to expand, no matter how small our individual needs might appear after a while. But sometimes more is less, and a tool’s clarity of purpose lost. I always keep in mind what is indispensable to me and what might be a bonus and what a distraction.

05-15-2021, 04:55 AM	#103
RobA_Oz Site Supporter Join Date: Nov 2008 Location: Tasmania, Australia Photos: Gallery Posts: 8,200	Originally posted by Smolk But sometimes more is less, and a tool’s clarity of purpose lost. I always keep in mind what is indispensable to me and what might be a bonus and what a distraction. I think I understand what you mean, but it’s only less if the greater portion interferes with what the photographer is trying to achieve. If you can ignore the distractions, then they don’t matter. That, of course, might be a big “if” for some. Thus far, I haven’t had anything in my cameras that has detracted from my use of them, but I don’t have the latest in any of the three Pentax formats. Mind you, I keep finding useful things I didn’t know about with the ones I have, often thanks to these pages. Perhaps I’ll find out if/when I get a K-3iii.

05-15-2021, 10:58 PM	#104
Smolk Pentaxian Join Date: Feb 2010 Location: Eerbeek Photos: Gallery \| Albums Posts: 1,857	Originally posted by RobA_Oz Mind you, I keep finding useful things I didn’t know about with the ones I have, often thanks to these pages. That's true, I am expecting this myself. The only digital cameras I seriously used were the Sigma DP2 & 3 Merrills, great little things, but they were (delightfully) basic. Had a good menu though. These flagship cameras have so much more, it may take time to find out howe to use it. Now that I know my kit will be shipped this week - I'm really looking forward to it.

05-16-2021, 02:40 AM	#105
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,662	I do wonder if this tech will be scalable to full frame and even 645 cameras. Nicer viewfinders are something that we all benefit from, even if we get used to them over time. Certainly we aren't going back to the MX days -- having auto focus does have its downsides (I still prefer to have it present on my cameras).