[Alan 2]

Hi Alan,

I talked about the diffraction limit above (post #127) and about DoF (post other thread, #47) earlier. Consult for details.

Basically,
Depth of Field depends on Field of View (to be considered a constant here) and aperture in mm, only!
So, to keep the Depth of Field constant, you keep the aperture in mm constant.
Constant aperture (in mm) means to keep d = f / F constant, where F=f/d is the F-stop number).

So, in your example above, if you increase f by 1.5x when going from APS-C to FF, like 200mm to 300mm), you increase the F-stop number by 1.5 as well to compensate (like F9.1 to F13.6).

This is what you write. Now without a calculator


On the other hand...

The diffraction limit
x = 1.22 lamda F
is increased as well, meaning you obtain the same number of pixels below the diffraction limit.

This is what you write.


Additionally, if you stop down, you gather the same amount of light (smaller F-stop but larger sensor), leading to the exact same noise.
This means the following:
You may stop down a larger sensor (by the corresponding crop factor compared to a smaller sensor) and obtain the following:

• Same Depth of Field.
• Same noise.
• Same diffraction-limited number of pixels.
• => the same image...

Thank you for having pointed this out.

However, the advantages of a larger sensor are as follows:

• You have the choice to not stop down, giving you more artistic choices and options for better noise or better resolution (at the expense of a more shallow DoF).
• It may be easier to build, say, a diffraction-limited F2.0 50mm FA lens than a diffraction-limited F1.3 33mm DA lens.

I hope that this clarifies what benefits a larger sensor may have and which it won't.

I’m glad you agree. I was just kind of getting information from different sources and trying to understand the issues involved as pixel density increases in DSLRs. I think what we all could use is some controlled test on just what the effect of diffraction really is. I’m hearing a lot of wild theories about pixel density, and how great it would be to have a 28 MP FF camera. But if a photo taken at F13 with a 28 MP FF camera looks no better (and possible worse) then a photo taken at F9 with a 12 MP 1.5x camera there may be some very disappointed landscape photographers. I have no idea on what the results would be on a diffraction test. At this point I would be unwilling to invest any money into FF until I was sure what I was getting into.

If diffraction does cancel out resolution at smaller apertures that may be the limiting factor in digital. Interestingly, as far as I know film doesn’t have a diffraction limit. The only limit is the diffraction limit of the lens. Perhaps small aperture shooters should pick up a few of the give away priced MF cameras just in case things don’t quite work out as planned in the digital world.

[ibk]

Well, after some extensive searching, I found the site of the Japanese magazine "Digital Photo".
And it's in the June issue, not July.
and it's not about FF...

It's about 645D!

ƒfƒWƒ^ƒ‹ƒtƒHƒg

Just translate it with google.

It says -
PENTAX developed the prototype medium-format digital camera with a live-action report.

But I'm wondering if it is from the translation and the actual words are - ...camera with a live-view?

Someone with Japanese?

[Pål Jensen]

Well, after some extensive searching, I found the site of the Japanese magazine "Digital Photo".
And it's in the June issue, not July.
and it's not about FF...

It's about 645D!

But this particular camera has been scrapped and will not use this sensor if it ever see the light of day. In other words, it has no bearing on the potential FF camera coming from Pentax this fall.

[thibs]

But this particular camera has been scrapped and will not use this sensor if it ever see the light of day. In other words, it has no bearing on the potential FF camera coming from Pentax this fall.

First point: The camera had not been scraped, the development has been frozen until .. they decide to ahead.

Second point: AFAIK the Kodak CCD has never been able to produce a LiveView output. If the original text indeed points to a LiveView, it doesn't NOT use the Kodak CCD.

[Matjazz]

But this particular camera has been scrapped and will not use this sensor if it ever see the light of day. In other words, it has no bearing on the potential FF camera coming from Pentax this fall.

Judging from interview of Pentax executives they don't plan 35, but if once it will happen it will be after 645.

* full-frame 35mm: The concept is clearly doable, and a development plan would be possible "I think~I guess" (as in, "we haven't done such a plan"). I can't say it would be impossible. But the priority is the 645, not 35mm. Pentax don't have the resources to do both at the same time, so any 35mm camera would be developed after the 645 is released.

When asked if there is any planning or awareness of a possible 35mm camera in the future regarding lens development, the answer is that lenses are focused on APS cameras (as that is the volume segment they're developing). As for old FA lenses, there are issues with using such lenses with a 35mm digital sensor. Implies a 35mm camera would entail a whole new setup of lenses and other accessories as well, effectively making it a separate system.

I certainly hope they make 645D and stand out of the crowd rather than follow it with 35 sensor camera.

[Pål Jensen]

Judging from interview of Pentax executives they don't plan 35, but if once it will happen it will be after 645.

I certainly hope they make 645D and stand out of the crowd rather than follow it with 35 sensor camera.

I'm aware of that interview and that is the official Pentax statement: "no FF". However, it doesn't necessarily have to be true. Whats more interesting is that the statement doesn't make sense; ie they say they don't have the resources do codevelop FF and 645D at the same time. This is probably true. But the fact remains that it is indeed the 645D thats put on hold! At least accoding to official info.
In addition, the first info from Pentax about the freezing of the 645D said it was due to a change of priorities to a high-end, K-mount DSLR; which is in accordance with the statement that they will not develop a 645D and a FF K-mount DSLR at the same time.
I believe that the 645D before FF is a smokescreen and only reflect Pentax original schedule, replaced 1,5 years ago, and that they don't want to spil the beans about the intention of an imminent FF camera.
The sources for an imminent Pentax FF cameras are so many that I find it hard to believe it is just hogwash.

[falconeye]

PENTAX developed the prototype medium-format digital camera with a live-action report.

Thanks for the link.

Using Google, I am able to single out the words:
実写レポート = Live-action report
レポ = Repo
ート = Notes
実写 = Live-action
実 = Actual
写 = Photographs

So, to me it means a report about the suspended 645D project with photos in the article.

[falconeye]

if a photo taken at F13 with a 28 MP FF camera looks no better (and possible worse) then a photo taken at F9 with a 12 MP 1.5x camera there may be some very disappointed landscape photographers.
[...]
Interestingly, as far as I know film doesn’t have a diffraction limit. The only limit is the diffraction limit of the lens.

Alan, you are jumping to conclusion here and miss the point.

The limits we have been talking about apply to perfect optics which is diffraction-limited at all apertures. However, such glass isn't currently a product.

Current good glass typically has its sweet spot at f/4 and isn't diffraction-limited there. And doesn't become so if you stop down to f/5.6 for DoF on FF.

And of course, it is always the optical lens which is diffraction-limited. Neither film nor sensors are.

Thought I'd post a link to
"The JOY of Pixel density". Keep your eyes posted...........
The Joy of Pixel Density: Open Talk Forum: Digital Photography Review

Jeff, the post is is nearly impossible to understand
The key is: you must compare the small image in the left hand corner to the large image on the right side (as those are the corresponding 100% crops).

The test could be useful because it compares the same amount of light falling onto the same size sensor surface (hosting a different numbers of pixels).

However, it isn't: The boost of exposure by a factor 135 means that the entire image was contained in 8-Bit RGB values 0 - 2. So, what we see, is a demonstration of different read-out noise (which is higher with the P&S but more than compensated by their higher number).

So, the lesson is that smaller pixels may help with the read-out noise. As will many other measures as well. Interesting for engineers. But not us.

[alexgn]

About lens again IMO the only lenses that could match in quality a 25 Mp sensor are FA 31 and 43 Ltd. FA 77 it's not up to task in resolution and to think one will buy a 3k camera to use a 100 USD old lens it's ... not practical. May be true for some Pentax fans but it's not a business model for growth.

The Pentax future (same as ALL THE OTHERS EXCEPT Olympus) is in APS-C for at least some years (and quite a few).

Radu

Carl Zeiss is making some interesting lenses with AF for Sony. CZ also makes MF for Nikon and Pentax. I think those new lenses are capable of matching high resolution sensors. For example, the new 18mm f/3.5 Manual Focus would be a very popular choice for landscape applications on FF cameras. CZ has made some fantastic wide angle prime lenses in the past.

There's no need to produce 25MP FF sensor. Canon EOS 5D is a 12MP camera, and has been in high demand for 3 years now. Canon does not have a fantastic line up at wide angle. Nikon just recently released two lenses to match their FF cameras: the 14-24mm and the 24-70mm. Their primes are outdated.

Sony will release 24MP FF camera at the end of this year. I think this is official now. There are few lenses for Sony’s cameras but those are outstanding. For example, Carl Zeiss Vario-Sonnar 24-70mm f/2.8 SSM is optically better than the counterparts from Canon & Nikon. And so is the 85mm f/1.4 with AF for portraits.

Anyway, Pentax make a body with FF sensor or at a least a prototype. Every manufacturer (with exception of Olympus & Panasonic) is heading in that direction.

Carl Zeiss is making some interesting lenses with AF for Sony. CZ also makes MF for Nikon and Pentax. I think those new lenses are capable of matching high resolution sensors. For example, the new 18mm f/3.5 Manual Focus would be a very popular choice for landscape applications on FF cameras. CZ has made some fantastic wide angle prime lenses in the past.

There's no need to produce 25MP FF sensor. Canon EOS 5D is a 12MP camera, and has been in high demand for 3 years now. Canon does not have a fantastic line up at wide angle. Nikon just recently released two lenses to match their FF cameras: the 14-24mm and the 24-70mm. Their primes are outdated.

Sony will release 24MP FF camera at the end of this year. I think this is official now. There are few lenses for Sony’s cameras but those are outstanding. For example, Carl Zeiss Vario-Sonnar 24-70mm f/2.8 SSM is optically better than the counterparts from Canon & Nikon. And so is the 85mm f/1.4 with AF for portraits.

Anyway, Pentax make a body with FF sensor or at a least a prototype. Every manufacturer (with exception of Olympus & Panasonic) is heading in that direction.

Alexgn,

I was talking only about "older" FF lens. I have no doubt that a modern, specially build for digital FF lens could manage quite easy a 24 Mp sensor and even more. As was pointed by more knowledgable members than myself of this forum in the last years lens coatings have improved a lot and I think the manufacturing methods and optical glass it's also better. And this is the same for all manufacturers for all but the chapest of lenses.

Radu

[Alan 2]

[QUOTE=falconeye;291447]Alan, you are jumping to conclusion here and miss the point.

The limits we have been talking about apply to perfect optics which is diffraction-limited at all apertures. However, such glass isn't currently a product.

Current good glass typically has its sweet spot at f/4 and isn't diffraction-limited there. And doesn't become so if you stop down to f/5.6 for DoF on FF.

And of course, it is always the optical lens which is diffraction-limited. Neither film nor sensors are.




I agree I am jumping to conclusions, and very likely without a complete understanding of the issues involved. That's what I'm trying to get a handle on.

[*isteve]

I think that Pentax needs a FF as soon as posible in order to be a serious contender in the marketplace even if they sell only a few and lose money on it. The availability of a FF means "we are 'Pro' also" and subsequently will boost the sales of other models if they can break loose some heavy advertising money. The two leading monikers are plastered all over the place and overwhelmingly influence the average consumer.

So according to you a company 1/30th the size of Nikon with a handful of engineers and one glass foundry should use all their resources attempting to develop one camera to compete with a Nikon D3 (at a loss) and a whole new range of lenses then compound the loss by trying to match Canon's marketing budget?

Of course they could use the same resources to compete in the two most profitable sectors (D40 and D300) and make money, watch how the market goes and come out with one next year if its worth it.

Whats your rush? Would you spend $3000 on a FF Pentax for a miniscule real world improvement over one I can happily buy for $800?

[Pål Jensen]

Alexgn,

I was talking only about "older" FF lens. I have no doubt that a modern, specially build for digital FF lens could manage quite easy a 24 Mp sensor and even more. Radu

A lot of the good Pentax manual focus lenses have been converted to the Canon mount and used very successfully on Canons 21mp FF body. Some of them are generally considered to be the best lens of its type ever made in spite of being over 20 years old.

[Pål Jensen]

So according to you a company 1/30th the size of Nikon with a handful of engineers and one glass foundry should use all their resources attempting to develop one camera to compete with a Nikon D3 (at a loss) and a whole new range of lenses then compound the loss by trying to match Canon's marketing budget?

Of course they could use the same resources to compete in the two most profitable sectors (D40 and D300) and make money, watch how the market goes and come out with one next year if its worth it.

Whats your rush? Would you spend $3000 on a FF Pentax for a miniscule real world improvement over one I can happily buy for $800?

I don't think Pentax will make a D3 competitor. THey will make a D700 and EOS5 competitor. And regardless of the past, this sector is going to be the next thing where profit are going to be found. In Pentax view, the K20D is the D300 competitor at a much lower price.
If the FF Pentax is indeed around 28mp, then it will be a tremedous image quality boost over everything else currently on the market and well worth $3000.....

...But there is more to it than that; theres also the issue of being seen as a contender. Of having a "complete" line-up.

[fishy]

theres also the issue of being seen as a contender. Of having a "complete" line-up.

Agreed. Recently again I heard a salesrep recommending C*n*n over Pentax because of just that.
However, another pro camerashop in the Netherlands is considering to drop Pentax completely because they can not get supplies... Not sure which is the bigger problem...