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16 bit vs 14 bit vs Sony's 11 + 7 compressed file?

thomas

New member
(I see blocks all over the frame and not where Thomas circles in red for whatever reason.)
can you point us mere mortals to said blocks "all over the frame". I am not able to tell them (except those I've marked). Thanks!
 
V

Vivek

Guest
I see them on my screen. If you can not see them, perhaps you have to scale them up further and increase the contrast further?

Are we debating a portion of a screen shot of a processed image upscaled to 200% and further upscaled and "enhanced"?
 

ErikKaffehr

Well-known member
Hi,

The reason that many users don't observe the Sony raw compression is that it is actually quite good. What it does is to apply a curve to the data, so they sample densely in the darks and sparsely in the highlights. But whatever sampling density, it will in all probability be masked by shot noise.

There is another compression, and that is delta coding. For a block of sixteen pixels the minimum and maximum of those pixels is recorded and the pixels between are described bit 7 bit precision. This works except there happen to be very steep gradients in the image. But this is a rare case. Well, I never the less would call the delta compression brain dead, as it can cause artefacts, but it is very likely not cause of any artifacts attributed to it.

The only clearcut case it has been seen is that famous star trail case.

The raw digger site has a lengthy article on it: RawDigger: detecting posterization in SONY cRAW/ARW2 files | RawDigger

An artefact like the one below may be associated with data compression, but this one was observed on a 16-bit image from a P45+, and it is caused by colour profiles, as it disappears using Adobe Standard Profile. Capture One's profiles also have this artefact.


Regarding DR and bit depth, there were some very good discussions on the issue. In general MFD-s cannot deliver more than 13 bits or so of useful data, the recent CMOS based MFD sensor are actually said to be 14-bits. The useful number of bits is essentially full well capicity in electron charges divided by readout noise. Full well capacity may be around 60000 and readout noise may typically be something like 12-16 e- (electron charges) for CCD and perhaps 2-6 for Sony CMOS.

These two images postings I have written may shed some light on some of the issues:
http://www.getdpi.com/forum/629879-post14.html

http://www.getdpi.com/forum/630479-post27.html

I know that "voidshatter" has posted many interesting images and analysis on related aspects, but I don't really have the time to find all relevant articles.

Best regards
Erik
 

Hausen

Active member
This is a very interesting thread for me because I am right in the middle of a gear change cycle. Have hopefully sold my Leica Monochrom and SWC and and am caught in between getting a Pentax 645Z (35, 55, 150) or Sony A7r + 24tS-E or 17 TS-E +16-35. (And update to 50mp Sony when released)

I primarily shoot long exposure water landscapes. Rivers or the sea and want to get serious about selling some prints. I live in NZ and we are surrounded by both. I can see benefits in both systems but would welcome opinions here.

My head tells me the Sony A7r but my heart says go for the big guy. Have owned the A7r before but let it go because because I already had the RX-1, so I understand Sony.
 

ErikKaffehr

Well-known member
Hi,

The Pentax 645Z is a fine camera for sure. One thing of note is that you are limited to Pentax lenses with P645Z while on the Sony you can use most any lens ever made for SLRs with an adaptor.

In particular I don't think there is a T&S lens for the Pentax. On the Sony it is possible to use most MF lenses for T&S with a Mirex adapter.

Personally, I am pretty decided to go with the Sony, but not until they have the next generation of high res camera.

The main reason is that the A7r has no electronic first shutter curtain, which reduces camera vibration significantly. Also I expect the next version will be a bit more robust.

Best regards
Erik

This is a very interesting thread for me because I am right in the middle of a gear change cycle. Have hopefully sold my Leica Monochrom and SWC and and am caught in between getting a Pentax 645Z (35, 55, 150) or Sony A7r + 24tS-E or 17 TS-E +16-35. (And update to 50mp Sony when released)

I primarily shoot long exposure water landscapes. Rivers or the sea and want to get serious about selling some prints. I live in NZ and we are surrounded by both. I can see benefits in both systems but would welcome opinions here.

My head tells me the Sony A7r but my heart says go for the big guy. Have owned the A7r before but let it go because because I already had the RX-1, so I understand Sony.
 

Stefan Steib

Active member
As Erik already said: the differences in the Raw Editors and the used algorythms are probably much more showing in the results than the base file by Sony.
And I have worked with MF Backs a lot as well as now with my A7R. I can´t see any differences there. And yes: there is no true 16 Bit file on MF. This is an urban Myth spread by the makers. The chips don´t read out with 16 bit !

Greetings from Germany
Stefan
 

jerome_m

Member
And yes: there is no true 16 Bit file on MF. This is an urban Myth spread by the makers. The chips don´t read out with 16 bit !
Actually, with the exception of the new Sony sensor, the MF "chips" are CCDs and CCDs are analog, so they don't read out with bits at all... ;)
 

timparkin

Member
The differences are more to do with lenses and also the colour filters for the bayer array and also the spectral response of the CCD vs CMOS
 

algrove

Well-known member
This is a very interesting thread for me because I am right in the middle of a gear change cycle. Have hopefully sold my Leica Monochrom and SWC and and am caught in between getting a Pentax 645Z (35, 55, 150) or Sony A7r + 24tS-E or 17 TS-E +16-35. (And update to 50mp Sony when released)

I primarily shoot long exposure water landscapes. Rivers or the sea and want to get serious about selling some prints. I live in NZ and we are surrounded by both. I can see benefits in both systems but would welcome opinions here.

My head tells me the Sony A7r but my heart says go for the big guy. Have owned the A7r before but let it go because because I already had the RX-1, so I understand Sony.
David

I just went through a similar excercise and decided on the 645Z and could not be happier. I sent the a7r back as I could not find those images to my liking and also hated the vibration issues even with WA lenses. I bought it because I liked my RX1 so very much (and still do), but IMHO have decided it is the leaf shutter that makes that camera sing over the a7r. As for vibration with the 645Z, it is very well dampened and I use it with the waterproof remote (US$21). I use mirror lock up set to on and leave sounds on. The first click of the remote locks up the mirror and then after 5 beeps which represents 5 seconds, I hit the remote a second time which exposes the image with a swish sound.

So far in this thread the use of Hasselblad V lenses with the 645Z has not been mentioned. They make for very nice and inexpensive lens choices with the Fotodoix adapter (US$80).

Since I mostly shoot landscape with the 645Z, MF does not bother me and even with the AF/MF Pentax lenses I often shoot MF. Some of the newest Pentax lenses are sharp as heck to me. I was used to looking at P45+ files with a Hasselblad V, Leica Monochrom files and still use an M240 for street and occassionally landscape.

The weather sealing of the body (72 seals) and the currently 4 weather sealed lenses make for the perfect outdoor kit for me where the camera can stand bad weather much longer than I seem to be able to withstand it. The battery life is exceptional and they only cost US$44. I have shot all day long many times now and only once had to change batteries even while using LV a lot.

You should take a look at the Pentaxforum for much more information and comments from 645Z users. It also has a very nice lens section where one can read what other members say about specific lenses.

Why not consider renting a 645Z before taking the plunge in any direction.

This image was taken with the Hasselblad CF 250 on the 645Z and is cropped considerably. Double click to enlarge.
View attachment 87681
 
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mandonbossi

New member
Thanks so much for all the responses, really great to hear everybody's thoughts..

Am not sure I understood everything completely but was interesting all the same :)

To Jerome M, yes, something along the lines of what you referenced looks great to me..

With regards to what Ian Allen is shooting, I guess it is mainly the architecture that is most appealing.. For example Brasilia, Oslo Opera House and Cooper Union.

You mention that some of his pictures seem to be shot on film but I am wondering if this is more labelling than anything else as the second last image in his "Brasilia" series seems to suffer heavily from moire and I am under the impression that shooting large format film does not create such artifacts, as it can with digital and especially when sensorsdo not have an anti aliasing filter?
 

jerome_m

Member
To Jerome M, yes, something along the lines of what you referenced looks great to me.
If you mean
http://postcardsfromamerica.tumblr.com/image/74276500981 and want these colors, get an Hasselblad MF (any model) and use Phocus.



With regards to what Ian Allen is shooting, I guess it is mainly the architecture that is most appealing.. For example Brasilia, Oslo Opera House and Cooper Union.
Mostly film, I would say. Ian Allen references his pictures as "large format", so film and the colors are also typical of film (but that may be emulated).


You mention that some of his pictures seem to be shot on film but I am wondering if this is more labelling than anything else as the second last image in his "Brasilia" series seems to suffer heavily from moire and I am under the impression that shooting large format film does not create such artifacts, as it can with digital and especially when sensors do not have an anti aliasing filter?

If you mean the moiré on that image:
http://payload119.cargocollective.com/1/1/45850/4690306/Brasilia15_o.jpg,
it is typical of what one gets when scaling down this kind of pictures. The moiré one gets from digital without anti-aliasing filter looks different.
 
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