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04-28-2009, 10:36 AM   #136
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QuoteOriginally posted by Yohan Pamudji Quote
Noise performance is, actually, a function of the sensor, all else being equal. All else being equal, lower pixel density will translate to lower per-pixel noise levels.





Urban legend and blatantly false:
Re: A misconception .. by DPReview???: Nikon D90 - D40 / D5000 Forum: Digital Photography Review
Of course you can add your argument to the 100's over at dpreview.
The point is that these two cameras of rather different pixel density have comparable S/N when it is measured at the same spatial frequency scale.
I usually favor Emil Martinec's reasoning and tests...
Google him..

04-28-2009, 10:39 AM   #137
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QuoteOriginally posted by Pål Jensen Quote
That's really not the point. FF lens edge problems on FF are no worse than DA lenses edge problems on an APS DSLR. Have you seen the edge performance of the DA* 16-50/2.8?
I had opportunity to compare 17-70f4 and 24-105f4L on FF... "L" can produce really nice softnesses at the even close corners.... Propably itll be the same with 16-50 and 24-70L... (unless you'v got v bad copy of DA*)
04-28-2009, 11:09 AM   #138
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QuoteOriginally posted by jeffkrol Quote
Urban legend and blatantly false:
Re: A misconception .. by DPReview???: Nikon D90 - D40 / D5000 Forum: Digital Photography Review
Of course you can add your argument to the 100's over at dpreview.
The point is that these two cameras of rather different pixel density have comparable S/N when it is measured at the same spatial frequency scale.
I usually favor Emil Martinec's reasoning and tests...
Google him..
"When it is measured at the same spatial frequency scale" is the key phrase here. I was talking about on a per-pixel basis, not at a normalized spatial frequency. That might not be a "fair" comparison, but it's a practical one. Am I wrong to say that an X MP image from a FF camera will be cleaner than an X MP image from an APS-C sensor with similar technology? That's not a rhetorical question by the way; I really want to know.

Besides, 50D has gapless microlenses whereas 40D doesn't. Not exactly "all else being equal".
04-28-2009, 11:21 AM   #139
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QuoteOriginally posted by Yohan Pamudji Quote
"When it is measured at the same spatial frequency scale" is the key phrase here. I was talking about on a per-pixel basis, not at a normalized spatial frequency. That might not be a "fair" comparison, but it's a practical one. Am I wrong to say that an X MP image from a FF camera will be cleaner than an X MP image from an APS-C sensor with similar technology? That's not a rhetorical question by the way; I really want to know.

Besides, 50D has gapless microlenses whereas 40D doesn't. Not exactly "all else being equal".
The answer seems to be yes and no.
Noise, Dynamic Range and Bit Depth in Digital SLRs -- page 3
Bottom line: Among the important measures of image quality are signal-to-noise ratio of the capture process, and resolution. It was shown that for fixed sensor format, the light collection efficiency per unit area is essentially independent of pixel size, over a huge range of pixel sizes from 2 microns to over 8 microns, and is therefore independent of the number of megapixels. Noise performance per unit area was seen to be only weakly dependent on pixel size. The S/N ratio per unit area is much the same over a wide range of pixel sizes. There is an advantage to big pixels in low light (high ISO) applications, where read noise is an important detractor from image quality, and big pixels currently have lower read noise than aggregations of small pixels of equal area. For low ISO applications, the situation is reversed in current implementations -- if anything, smaller pixels perform somewhat better in terms of S/N ratio (while offering more resolution). A further exploration of these issues can be found on the supplemental page. Rather than having strong dependence on the pixel size, the noise performance instead depends quite strongly on sensor size -- bigger sensors yield higher quality images, by capturing more signal (photons).

The other main measure of image quality is the resolution in line pairs/picture height; it is by definition independent of the sensor size, and depends only on the megapixel count. The more megapixels, the more resolution, up to the limits imposed by the system's optics.


another thing to think about (though only slightly related)
Bottom line: High exposure zones and/or high ISO, where photon noise and pre-amplification read noise dominate the noise, are rather insensitive to what ISO is chosen once a choice of exposure is selected and care is taken not to clip highlights. Underexposing by a stop, and doubling the raw values in post-processing (that is, applying exposure compensation), yields the same image quality as 'proper' exposure under these conditions. On the other hand, in lower exposure zones at low ISO, where post-amplification read noise becomes important, the read noise goes down by a bit less than a factor of two (in electrons) when the ISO doubles. In this situation, underexposing by a stop and doubling the raw values in post-processing, yields more noise than proper exposure, particularly in shadows.

By the way, underexposing at lower ISO is precisely what Canon cameras do in the raw data when Highlight Tone Priority (HTP) is enabled; and what Nikon cameras do when Active D-Lighting (ADL) is enabled. Instead of using the ISO gain set by the user, the camera uses a lower ISO (but exposes with the indicated aperture and shutter speed), effectively underexposing the image; this provides more highlight headroom. In post-processing, the image data can be brought back up while preserving the highlights with a modified tone curve in higher exposure zones. The place where image quality suffers is in shadows at lower ISO, precisely as the above quantitative model predicts.




04-28-2009, 12:21 PM   #140
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QuoteOriginally posted by Pål Jensen Quote
That's really not the point. FF lens edge problems on FF are no worse than DA lenses edge problems on an APS DSLR. Have you seen the edge performance of the DA* 16-50/2.8?
The main issue is the performance of Pentax FA lenses on FF.

On APSC, several prime FA* and LTD lenses have worse edge performance wide open than the 16-50. How is that performance likely to improve on FF?
04-28-2009, 12:27 PM   #141
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QuoteOriginally posted by *isteve Quote
The main issue is the performance of Pentax FA lenses on FF.

On APSC, several prime FA* and LTD lenses have worse edge performance wide open than the 16-50. How is that performance likely to improve on FF?
you can be f4 on FF to have eq of f2.8 of 16-50 on APS-C...
04-28-2009, 12:37 PM   #142
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QuoteOriginally posted by RMabo Quote
What Ned simply tried to say, is that to take fully advantage of a 24x36 sensor, the lenses needs to be designed for it.
and by the same logic to take fully advantage fo a digital sensor the lenses need to be designed for it... true, but a lot of people still quite happy with a film era lenses nevertheless...
04-28-2009, 12:43 PM   #143
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Let me get my head round this....

Ned said…

"When asked about full frame (meaning 35mm camera body), we commented this would be very difficult in the near future. To those that continue to postulate or argue that the new camera better be full frame, ask yourself what lenses are you planning to use on this hypothetical new full frame body?

As I received a few comments on this, let me clarify my tongue-in-cheek comment. Anyone that is currently using a full frame sensor 35mm camera knows that they exact a high price in terms of the lenses that perform acceptably. Many lenses originally designed for film fall short in terms of distortion control and edge-to-edge sharpness when used with a full frame sensor."

You said…

Originally Posted by kenyee
BTW, I'm surprised no one has mentioned the FF part of Ned's post. The way I read it, their engineers have played w/ FF but think all current glass will be outresolved by the sensor, so they have no plans to produce FF until they run out of room w/ APS-C. What I don't get is why Canikon's FF systems seem ok (no one claiming the lens is outresolved by the sensor)?

Personally, I think Ned is full of bollocks on this one. A full frame camera with the same pixel density as a 15MP APS C sensor would end up being about the same pixel count as the Nikon D3X.

His argument also completely ignores the advantage of a lower pixel count full frame sensor WRT noise control, such as what Nikon has done with the D3.

Now you are saying…

QuoteOriginally posted by Wheatfield Quote

Also for the record, I have said that Pentax would have to come up with a new lens line to go full frame because the present lens line isn't up to the task.

As well, in another thread, I mentioned my opinion that Pentax will probably skip full frame and jump straight to medium format.

Just keeping things straight guys, I seem to have developed a cult of followers who either deliberately misread my posts or quote out of context to try to score their internet points off of me.
Excuse all of us for being confused, but you just accused a person who agreed with you of talking bollocks.....

As I said, quite unrewarding agreeing with you.

04-28-2009, 12:52 PM   #144
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Well, I have a 5D and a K20D, and I can assure you that almost all of my old FF lenses (and I own quite a few lenses, like SMC Takumars (24 up to 200mm), Carl Zeiss Jenas) are doing quite well on FF. I have not noticed weak corners on any of my pictures. But maybe that's because of my shooting style, as I almost never take photos at infinity, and never choose architecture as a subject, so maybe that's why I didn't notice it.

Would I say someting stupid if I say that I'm under the impression that the FF lenses I own work better on the 5D than on the K20D (yes, I know the 5D has less resolution than the K20D).
04-28-2009, 01:08 PM   #145
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QuoteOriginally posted by thibs Quote
Seems the guy who can't read is you.

Ned didn't write off FF concept, it writes off FF now because they do not have lenses to put on it, which is quite logical.
Having FF lenses and no FF camera isn't a big deal (except price/weight of lenses) the opposite is plain stupid, you'd be the first to cry because there's no lens to put on the body.
This still doesn't answer why FF users of other Brands are using some old Pentax glass. They even scarf up the A* 200mm f4 macro.
04-28-2009, 01:10 PM   #146
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QuoteOriginally posted by Asahiflex Quote
Would I say someting stupid if I say that I'm under the impression that the FF lenses I own work better on the 5D than on the K20D (yes, I know the 5D has less resolution than the K20D).
And that may well be the reason why it looks better, esp at 100%. The 5D has a similar pixel density to a *istD.
04-28-2009, 01:16 PM   #147
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QuoteOriginally posted by Blue Quote
This still doesn't answer why FF users of other Brands are using some old Pentax glass. They even scarf up the A* 200mm f4 macro.
I think the key word is "some". This does not mean it performs well enough to stack up against Canon L glass in the same arena.

I am sure some F and FA lenses will work just fine, but I am also sure than many will not. This is more or less what Ned said. Also, whether they perform as well on a 21MP FF camera as they did on a 12MP one is another issue.

Even if some of the old lenses work, to ship an FF camera without an up to date and effective set of new FF lenses would make business nonsense.
04-28-2009, 01:19 PM   #148
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I onced tested a K28/3.5 and SMC takumar 28/3.5 on my K10D, shooting a brick wall. Even on the cropped sensor, the SMC takumar has much worse corner sharpness at all the apertures tested, f3.5, f5.6, f8. It's very hard for me to believe that the takumar lens would perform well on a FF sensor.
04-28-2009, 01:32 PM   #149
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QuoteOriginally posted by *isteve Quote
I think the key word is "some". This does not mean it performs well enough to stack up against Canon L glass in the same arena.

I am sure some F and FA lenses will work just fine, but I am also sure than many will not. This is more or less what Ned said. Also, whether they perform as well on a 21MP FF camera as they did on a 12MP one is another issue.

Even if some of the old lenses work, to ship an FF camera without an up to date and effective set of new FF lenses would make business nonsense.
If you look, you will see I specifically mentioned the A* 200mm macro. I say this because I looked into a EF 180mm f/3.5L Macro and found it to be lacking. Apparently there are some macro shooters that think the A* is better than the 180mm L macro lens.
04-28-2009, 01:36 PM   #150
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QuoteOriginally posted by *isteve Quote
The main issue is the performance of Pentax FA lenses on FF.

On APSC, several prime FA* and LTD lenses have worse edge performance wide open than the 16-50. How is that performance likely to improve on FF?

The main issue here is that people treat corner issues as a particular problem for FF. This is not true; it is just as much issue on DA lenses on APS cameras.

I have most FA* lenses, all FA Limiteds and the DA* 16-50/2.8. The latter have more edge sharpness problems (and purple fringing, for that matter) than any of the above. And so you should expect; after all you are not using the edge of the FA lenses on an APS camera.

Some APS lenses have corner sharpness problems and some FF lenses have corner issues. Whats the difference?
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