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05-07-2009, 10:11 AM   #1966
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QuoteOriginally posted by GoldenWreckedAngle Quote
Thanks for the tip. I'm checking into it now. Looks promising.
Check out panoguy's post about it here too:
https://www.pentaxforums.com/forums/post-processing-printing-software/54579-e...e-removal.html

05-07-2009, 11:22 AM   #1967
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QuoteOriginally posted by jeffkrol Quote
Actually if you convert at 16 bit it is the same. ADC is at most 10-12bit anyways....
It is not the same. ISO amplification is performed at the analog stage, before ADC, where there are no discrete bit values. The signal has something like infinite bit depth (there is, of course, a signal-to-noise ratio that lowers the quality of the signal even in the analog domain) until it is converted to digital. In all analog-to-digital conversion there is data lost during the quantization process, and if you are really serious about quality it is in your best interest to perform only one quantization of the analog signal and then not amplify it further digitally.

For every full stop amplification you make post the ADC process, you lose 1 bit. If you capture an image at ISO 100 with 8 bits per channel (256 discrete values), and amplify it in post to ISO 800, you only have 5 bits (32 discrete values) left of actual data. Now, if you had taken the picture at ISO 800 to begin with, you would have had a noisier image due to the SNR ratio of the sensor, but each pixel would have a full 8 bits per channel of actual captured data. See the difference now?

Last edited by Erik; 05-07-2009 at 11:37 AM.
05-07-2009, 12:08 PM   #1968
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QuoteOriginally posted by Erik Quote
ISO amplification is performed at the analog stage, before ADC, where there are no discrete bit values. The signal has something like infinite bit depth (there is, of course, a signal-to-noise ratio that lowers the quality of the signal even in the analog domain) until it is converted to digital.
Erik, as this topic is coming back -- and because we have a few posts to go until 2009 -- let me comment on this.

Just on your remark now -- not if shooting at higher ISO makes sense as this involves a couple more factors ...


First, I see exactly at what you are at. And theoretically, you are right.

But there are two factors which are destroying your argument, totally actually:

- The quantization noise on the analog side coming from the finite number of photons. Aka "Shot noise".

- The amount of noise in the signal after quantization. Of say 12 Bit after quantization, about 4 Bit are noise (per pixel scale, K20D, ISO 200). These 4 Bits are valuable information still, because they give an area of ~16x16 pixels a fine tonal rendition - Sort of Floyd-Steinberg dithering.


But, and this is why you are wrong, there is nothing to gain to amplify before quantization to only end up having more bits to encode the noise. There are already enough of them.


Addendum:
I concede that a dark pixel would have less Bits in the noise. But still enough to encode the noise well enough.
--

Maybe, this is enough "science" to settle this side track discussion. But I am not sure.


BTW.
High ISO still makes sense to avoid extreme quantization noise (e.g., to shoot 100 rather than 1600 would be bad if image is underexposed at even 1600 ...) and to reduce some low spatial frequency banding artifacts.

Last edited by falconeye; 05-07-2009 at 12:22 PM. Reason: Addendum
05-07-2009, 12:36 PM   #1969
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QuoteOriginally posted by farfisa Quote
Oh man, I hadn't even discovered the noise reduction benefits yet. Wierd, when I first looked at that thread the posts were all dated 2007, but now they are dated 2009. I'm a little confused but I'll bookmark it anyway - Thanks.


Last edited by GoldenWreckedAngle; 05-07-2009 at 12:44 PM.
05-07-2009, 01:24 PM   #1970
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about the not-yet-patented pentaxforums idea (variable iso), this (marketing blurb) sounds similar: (panasonic gh1)

Intelligent Exposure optimizes the exposure for each part of an image, preventing blocked shadows and blown highlights and helping ensure that gradation and details are reproduced beautifully.

it is unclear how it works (automatic post processing of the raw image, or true variable iso across the frame? i seem to remember i read somewhere about variable iso, but not usre if it was about the panasonic)
05-07-2009, 02:29 PM   #1971
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What happen with the Chinese secret agent?

Does anybody know what happen with the Chinese guy (is he Chinese or working for Pentax in China?) who posted these secret blurry photos of K7?
05-07-2009, 02:44 PM   #1972
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QuoteOriginally posted by HermanLee Quote
Does anybody know what happen with the Chinese guy (is he Chinese or working for Pentax in China?) who posted these secret blurry photos of K7?
AFAIK, is Ned back in the USA
05-07-2009, 02:45 PM   #1973
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QuoteOriginally posted by nanok Quote
about the not-yet-patented pentaxforums idea (variable iso), this (marketing blurb) sounds similar: (panasonic gh1)

Intelligent Exposure optimizes the exposure for each part of an image, preventing blocked shadows and blown highlights and helping ensure that gradation and details are reproduced beautifully.

it is unclear how it works (automatic post processing of the raw image, or true variable iso across the frame? i seem to remember i read somewhere about variable iso, but not usre if it was about the panasonic)
DANG LURKERS... HOW DARE THEY!

05-07-2009, 03:06 PM   #1974
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QuoteOriginally posted by Art Vandelay II Quote
I think the A900 is actually larger than the 5D Mark I, but smaller than the D700. Either way, anyone that has an anti-FF opinion is doing themselves a disservice not to go test the A900 out at a camera shop. It might change your opinion real quick; it did mine.
I have not found the A900 in a store yet. But I would like to have a go at it. It is an ugly camera, but that actually has my sympathy, my Z-1P was no beauty either, but it really served me well. I found the A700 to have some of the cheap feel that the A100 had. But the A900 should be different material, so likely have a different feel as well.


QuoteOriginally posted by Art Vandelay II Quote
I agree with you on that one. I'm not sure why, but the D300 (and D200) VF seems really warm when looking through it. The Canon 50D looks really cold and dim if you do a side-by-side comparison. I think Oly should be commended for what they did with the E-3 VF. It is in a different league from the rest of the 4/3's cameras. I actually consider most 4/3's VF's to be damn near unusable. If not unusable then un-enjoyable for sure. The E-520's VF is so bad that it actually takes the fun out of using an OVF. So they did a heck of a job on the E-3's prism in comparison. I'm hoping the K7's will be of a similar design. If it is a 1.15x or something in that ballpark it might be just large enough to make me forget all about FF.
They did good on the VF in E3. I think the reason that it disappointed me, was with all the hype, I thought it would be to the level of D200, A700, K20, etc. But it was for sure the best 4/3 Viewfinder.
All this have just made them go in the front, when it comes to Live-view.

(The VF in the D300 is better than in the D200. The D200 is on the level of K10, the D300 is better than K10/K20).


QuoteOriginally posted by Art Vandelay II Quote
You must like wearing cargo pants

As I said in another post, I don't consider any SLR whether it be FF or APS-C to be portable. I plan on getting Olympus's m4/3's system for that.

Have no cargo pants. But I use mountain ascent jackets, for when hiking etc.

These type of outer shells are made, so you can carry a 1 liter Nalgene bottle inside the pocket. Arcteryx, Marmot, North Face, Outdoor Research, Patagonia; all have jackets in this league.


I used this set-up when Heli-skiing, and backpacks were not allowed inside the chopper :
http://www.dpreview.com/forums/readflat.asp?forum=1036&message=31368258
(Pictures are not the best; as it was cloudy, and so the sky and snow are kinda hard to tell apart)

And another time, I came by some boarders and skiers doing jumps at a competition :
http://www.dpreview.com/forums/readflat.asp?forum=1036&message=31342090


Z-1P with A-series 35/2.8, and magnifier eye cup, being swallowed :
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Last edited by Jonson PL; 05-07-2009 at 03:32 PM.
05-07-2009, 03:17 PM   #1975
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QuoteOriginally posted by jeffkrol Quote
Actually if you convert at 16 bit it is the same. ADC is at most 10-12bit anyways....
Underexposing and "push processing" is just as effective as in camera boost for a good part of the image.
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.
Noise, Dynamic Range and Bit Depth in Digital SLRs -- page 3

Hi Jeff, thanks for the link.
Iíve read more about the info given by Emil, since you first introduced; and I must say that it is very good. Though often over my head. But he is also good at bringing in down to basics in discussions





QuoteOriginally posted by Sebbe_J Quote
Have it been posted before? Found it on pbase
Should Pentax one day come out with FF camera, it would be awesome if they reintroduced some of the FA* lenses. Adding sealing, and maybe improving the 28-70/2.8 range, to 24-70 instead.
Or else one could just weld the 31 lmt. on the body and be done with it


I would like a FF Pentax digital one day. I would just use it differently, then I do the crop ones. I welcome the K7 (with a pancake), as the Pentax DSLR are just very easy to bring along, when photo ops can occur.

(Pentax has spoiled us with now this latest 15 mm pancake as well. Should I wish for more, it would maybe be a 120 mm, or 135mm f/4.5., coming in at 240 grams, and 5-6 cm length.)


Here is MZ-M with K 50/1.2, going inside fleece vest :
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05-07-2009, 03:27 PM   #1976
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if that's how you want to play it, i might start posting pictures of my k20d, lenses and tripod going... ahem.. going inside my car. yeah, that's it, you'd be amazed how much i can fit behind my seat. wait, that doesn't sound right.

am i carrying too much gear?

/me walks away, pondering..
05-07-2009, 05:11 PM   #1977
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K20D+nifty fifty is an ok fit for a cargo pocket, but let's face it, a cargo pocket right above the knee with a heavy object in it is going to see a lot of swinging around and banging against your leg during any real movement. With these smaller dimensions for the K-7, I suspect you could stuff it in a front pocket of most of my pants with the DA40 on it. I carry thick paperbacks around in them all the time. Different shape, yes, I but I suspect it could work.
05-07-2009, 09:06 PM   #1978
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Just to keep the thread going, the latest pic:
Translation result for http://www.camera-pentax.jp/

This is the best pic yet isn't it? It shows the left side of the camera more clearly now.
05-07-2009, 09:15 PM   #1979
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QuoteOriginally posted by PentaxPoke Quote
Just to keep the thread going, the latest pic:
Translation result for http://www.camera-pentax.jp/

This is the best pic yet isn't it? It shows the left side of the camera more clearly now.
You know the thread has gone far off course when the most off topic post in 3 pages is the only post thats actually on topic.
05-07-2009, 09:41 PM   #1980
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QuoteOriginally posted by nixcamic Quote
You know the thread has gone far off course when the most off topic post in 3 pages is the only post thats actually on topic.
Happy to get things going again
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