[kadajawi]

I think if you want a better viewfinder you might have to sacrifice AF.


I guess they could use the more sensitive AF sensors they have now and use a less translucent mirror (sacrificing low light AF capabilities). Or maybe they could make the mirror so that It is only translucent where the sensors are located. That could make for an odd experience in the viewfinder though... (then again we would be able to see where and how big exactly the sensors are...)

[rawr]

sacrificing low light AF capabilities

Nooooo!
That's mainly what I want a FF for.

Or maybe they could make the mirror so that It is only translucent where the sensors are located.

On a conventional DSLR (eg the K-3 or the Canon 5D3 illustrated here) that's pretty much how it works already, and has for a long time. Pic related:

[jonby]

I think if you want a better viewfinder you might have to sacrifice AF.

While losing AF may be necessary to get a fully optimal viewfinder, I'm not sure that it's necessary to get a better viewfinder. I think there is scope to increase viewfinder magnification, for example, without losing so much brightness that ditching AF is necessary.

All else being equal, the apparent brightness of the viewfinder is a function of the degree to which it is magnified. To my knowledge, the largest magnification currently used by any FF camera is 0.76x (Canon 1D X). The K-3's viewfinder magnifies at 0.95x and is considered to be one of the best available on an APS-C camera. If a FF camera's viewfinder was 0.95x magnification then its brightness would therefore be at the same level as the K-3 but 1.25x larger than that of the 1D X. Since I haven't heard any complaints about the brightness of the K-3 viewfinder, I'm guessing that most people would be happy with this in a FF too - especially given the benefits of a larger view.

I guess they could use the more sensitive AF sensors they have now and use a less translucent mirror (sacrificing low light AF capabilities).

This is an interesting point. I would like to know exactly how much light is lost through the mirror translucency required for AF. The option to reduce the translucency and therefore the AF sensitivity in return for a brighter finder may offer a good compromise for some, although this may be a difficult sell for many (rawr being one!).

Since having AF will always compromise the viewfinder to a greater or lesser degree, it becomes a matter of priorities as to where to set this compromise. I personally would like to see the priority moved towards the viewfinder, but I'm also interested in the possibility of having two FF cameras - one with AF and a good but more or less standard viewfinder, and one purely manual focus model with an exceptional viewfinder. That way it's more clearly defined in the marketplace.

---------- Post added 07-05-14 at 06:01 PM ----------

On a conventional DSLR (eg the K-3 or the Canon 5D3 illustrated here) that's pretty much how it works now. Pic related:

My technical knowledge is limited here, but as I understand it, the rest of the mirror must be of reduced reflectance in order to avoid having a dark patch where the AF window is. Either that or there is something in the prism which achieves the same thing. Either way, since a portion of the light coming through the lens is clearly being directed to AF in the central portion of the image, the rest of the image must be reduced in brightness to compensate. Can anyone shed any light (!) on this?

[Kunzite]

While losing AF may be necessary to get a fully optimal viewfinder, I'm not sure that it's necessary to get a better viewfinder. I think there is scope to increase viewfinder magnification, for example, without losing so much brightness that ditching AF is necessary.

All else being equal, the apparent brightness of the viewfinder is a function of the degree to which it is magnified. To my knowledge, the largest magnification currently used by any FF camera is 0.76x (Canon 1D X). The K-3's viewfinder magnifies at 0.95x and is considered to be one of the best available on an APS-C camera. If a FF camera's viewfinder was 0.95x magnification then its brightness would therefore be at the same level as the K-3 but 1.25x larger than that of the 1D X. Since I haven't heard any complaints about the brightness of the K-3 viewfinder, I'm guessing that most people would be happy with this in a FF too - especially given the benefits of a larger view.

Spot on.
And perhaps a bit of brightness can be recovered by using better components (e.g. better optics, all HD coated) in the viewfinder. Do that, increase the magnification a bit (even 0.9x would be noticeable - the viewfinder will be slightly larger than the ME Super's, due to 100% coverage) and offer an interchangeable matte screen suited for manual focusing with fast lenses (that would cut some brightness, perhaps it shouldn't be by default). And - don't forget about eyeglass wearers, please.

Regarding the primary mirror, my guess is that it's uniformly reflecting/letting light pass (the area not used for AF is just blocked out by the mirror's support). It's simpler to make this way, and it avoids the brighter margins effect.

[jonby]

Spot on.
And perhaps a bit of brightness can be recovered by using better components (e.g. better optics, all HD coated) in the viewfinder. Do that, increase the magnification a bit (even 0.9x would be noticeable - the viewfinder will be slightly larger than the ME Super's, due to 100% coverage) and offer an interchangeable matte screen suited for manual focusing with fast lenses (that would cut some brightness, perhaps it shouldn't be by default). And - don't forget about eyeglass wearers, please.

All good points. Yes with the larger magnification, the angle of view increases, so you would need a larger eyepiece in order to allow viewing of all corners easily - especially for eyeglass wearers. This is where it starts to get expensive, I guess. Your point about the manual focus screen is an important one - it needs to allow for the maximum degree of accuracy in focusing, which means reducing the brightness as I understand it too, but daylight shooters who do a lot of MF will be happy to make this compromise. Offering it as an option rather than the default would seem like a good idea. A better viewfinder is one of the key selling points of FF, and having the largest magnification on the market could be the USP that Pentax is looking for.

Regarding the primary mirror, my guess is that it's uniformly reflecting/letting light pass (the area not used for AF is just blocked out by the mirror's support). It's simpler to make this way, and it avoids the brighter margins effect.

Yes that's exactly what I was thinking.

[kadajawi]

Since I haven't noticed any darkening around the areas where the AF sensors are I'd say the whole mirror has the same translucency. Actually I might want to see the AF sensors, it'd be good to see the exact position and size of the AF sensors.


As for how much brightness the mirror loses... the Sony SLT cameras use the mirror to redirect light for the AF sensor, with most of the light going to the image sensor all the time. Someone has tested one of those mirrors and says 1/3 EV is lost, a permeability of 72-76%... around 75% of the light goes through. That seems like quite a bit.


I have no clue if it is technically possible to do a mirror that lets through different amounts of light at different places, or how much that would cost to mass manufacture. But if they could do it I'd be interested.


Also imagine how sensitive the AF sensors are, despite the mirror taking away most of the light. How good would it be if there was no mirror? I could imagine if they had a mode where the main mirror folds away but the AF sensors are still in the light path that would be pretty nice.

[rawr]

How good would [AF] be if there was no mirror?

It depends, I guess.

The result isn't always great in terms of low light AF (eg Sony A7r), but it can work really well (eg Panasonic GH4 or Sony A7s). Pic related:



Mirrorless AF light sensitivity can turn out OK, but focus acquisition performance may be another matter. Phase-detect AF, as provided by most conventional DSLR's, still seems to have the edge in terms of focus targetting and tracking. Hence some mirrorless (eg Sony A7) add both AF technologies (phase-detect and contrast-detect) into the camera sensor.

[kobi.]

A dslr for left handers? Would corner 10% of the market in one day.

Square sensor?

i'm left hand and i don't see me shoot with left hand customize camera

[Fogel70]

I have no clue if it is technically possible to do a mirror that lets through different amounts of light at different places, or how much that would cost to mass manufacture. But if they could do it I'd be interested.

Another option is to use a mirror that can vary replection/transparancy. In transparant mode close to all light will be recieved by the AF sensor. And in full reflection mode all light is sent to OVF.
They just need to make the switching between mirrored and transparent mode quicker.

You Tube

You Tube

[kadajawi]

That's cool, though how about power consumption? How reflective is it really?


It seems like PDAF sensors on the camera sensor are not as good as the ones a DSLR uses... not as sensitive. Probably those are bigger etc.

[Fogel70]

That's cool, though how about power consumption? How reflective is it really?

Her is another similar product with data sheet.

Kent Optronics - Switchable Mirror / Switchable Glass

It seems like PDAF sensors on the camera sensor are not as good as the ones a DSLR uses... not as sensitive. Probably those are bigger etc.

I think it would be perfectly fine to use it with separate AF sensor, just like on every DSLR.

[kadajawi]

Her is another similar product with data sheet.

Kent Optronics - Switchable Mirror / Switchable Glass

I think it would be perfectly fine to use it with separate AF sensor, just like on every DSLR.

Nice. There are still some losses though, and maybe the thing isn't "pure" enough for photography. But you could also take photos near silent cause the mirror doesn't have to be flipped up.


I'd like to see camera makers to think outside of the box. I don't see any major innovation. Only small improvements. The last time they really thought outside the box was with mirrorless cameras and with Lytro.

[Poit]

OK, so to summarise the suggestions to date (and filtering out the endless wishlists that really don't equate to 'different'), the realistic ideas for a different Pentax FF we have are:

- Features vs price-point (the simple answer);
- An LX-style camera incorporating interchangeable elements, particularly viewfinders, but other elements (such as sensors) have been suggested too;
- If not interchangeable viewfinders, then a new hybrid viewfinder system, for which a patent apparently exists;
- A different sensor format altogether. Some suggest a 'scaled-down' medium format, or square sensor. Interesting concept, certainly different; and
- Any combination of the above.

It certainly answers my original question of how a Pentax FF might be different. Whether any of the above materialises is another question, but thanks for all the suggestions anyway. New and novel suggestions welcome.

[kadajawi]

I'd be surprised if you couldn't change the viewfinder screen on any of the FF cameras out there. Heck, it was possible on my *istDS!

Different sensor format... what for? So that completely new lenses are needed? I fail to see the point.

A friend is shopping for a new camera. Can't find anything he'd be happy with. He wants the sensor from the Sony A7S. The stabilization from the Olympus OM-D E-M1. The AF (especially for video) from the Canon 70D. The video functionality from the Panasonic GH4/Sony A7S. I agree (except for video AF, which I don't care about).

[ElJamoquio]

I'd be surprised if you couldn't change the viewfinder screen on any of the FF cameras out there. Heck, it was possible on my *istDS!

People buy the Canon EE-S screen all the time to chop down to pentax dimensions.