A900 vs D3X highlights/mid/shadow tones

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David Kilpatrick
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A900 vs D3X highlights/mid/shadow tones

Unread postby David Kilpatrick » Wed Dec 24, 2008 1:25 pm

I set up a test to see how the two uses of a similar sensor type compared at the highlight end, around native ISO. The Alpha 900 was able to focus accurately by AF on the side of the silver urn bowl which shows a slight bright edge against the paper. The D3X was completely unable to focus on the same spot by any AF method, and had to be manually focused; unfortunately the accuracy of manual focusing with standard screens in cameras like this is zero, and the Nikon screen provides very few visible engraving or marks to help adjust the dioptre correctly for viewing. So the Nikon focus point is different. This doesn't affect the aspect I wanted to check.

Raw file exposures were taken by tungsten light (this is not ideal, and automatically cuts highlight headroom by over one stop - approximately 1.5 stops of dynamic range is required for the camera to use tungsten WB in place of its presumed native daylight WB). The D3X's Tungsten preset is not as accurate as the A900, and produces a much warmer result. This makes the comparison difficult by eye and I have therefore used one extra control when processing the raw - I have set the WB based on the white paper, so that it matches the A900.

RAW Developer uses two very different curves to convert D3X and A900 files:

Image

While the A900 benefits (as you will see below) from using Nikon curve instead of its own, the curve Iridient have written for the A900 is too dark and makes the files need exposure correction - it makes the Nikon appear to be almost twice the true ISO value compared to the A900. For this test, I have processed a set of raw files taken at 1/3rd stop intervals all the way from 2 seconds to 1/8th, using the Nikon curve. The Nikon was set to ISO 100 (claimed to be 'native') and the Sony was set to ISO 160 (while 200 is said to be 'native'). The reason for this is that several technical reports indicate the sensor may have a real native sensitivity best expressed around ISO 125-160. Doing this gives the Nikon the benefit of 1/3rd stop versus the A900, and compensates for the slight tungsten value adjustment in raw processing.

Here are the two results, Sony to the left, Nikon to the right (or below depending on how you are viewing this):

ImageImage

The value in the bright rim of the silver next to the paper is around 242-244 RGB in both cases, and the highlights clip in the brighter reflections to 0-0-0 in both cases. The actual exposure needed by the Nikon was 0.5s at f/11, and the Sony 0.4s at f/11. This is within 1/3rd of a stop of the ISO settings, but it is based on values around 235-245. If 255 clipping is used for comparison, both 0.4s frames are a better match.

What you should be able to see is that the Sony image is much brighter as you get down into the shadow tones. I leave you to work out the benefits of this, and why the Nikon image is more contrasty and darker for the same highlight detail recording (hint: try moving the left hand slider of any photo to the right in Photoshop levels, and you will see a similar darkening).

Please note that the Iridient curves shown are not the same as post-conversion curves in ACR (or indeed in RAW Developer - there is a complete additional Curves window for applying these). These are camera input calibration curves, designed to correct for the way each different camera raw format records brightness values.

Sorry for the rather obscure nature of this stuff. I do not plan to write a blog post about this yet, because I don't know enough about it yet. Still learning. RAW Developer has been a useful tool (so has Raw Photo Processor) but two or three other raw processors need to go live with D3X conversion. I want to look at as many real-life shots in different converters as possible before making an conclusions. Just let's say I am very happy with some aspects of the A900 image handling at low ISOs, and as things stand right now, the strategy seems to have been to tune performance for low ISOs with maximum recovery of both highlight and shadow detail along with colour. Nikon has been much more concerned about how high ISO performance is perceived, and they seem to have sacrificed ultimate low-ISO flexibility to get better high ISO results.

It would be understandable for a sensor maker (Sony) to 'go by the book' and set everything up perfectly around the native base ISO - and typical of a camera maker, like Nikon, to deviate from specifications to squeeze something more for real photographic purposes, by experimenting with different reading and processing strategies.

David

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby bakubo » Wed Dec 24, 2008 6:55 pm

David Kilpatrick wrote:Just let's say I am very happy with some aspects of the A900 image handling at low ISOs, and as things stand right now, the strategy seems to have been to tune performance for low ISOs with maximum recovery of both highlight and shadow detail along with colour. Nikon has been much more concerned about how high ISO performance is perceived, and they seem to have sacrificed ultimate low-ISO flexibility to get better high ISO results.


Is there some technical reason why Sony couldn't use their current, maybe superior, method for low ISO and use something more like Nikon's for high ISO to get the best of both?

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby douglasf13 » Wed Dec 24, 2008 7:21 pm

Sonolta, it's interesting that you post links to dxo Mark, but you don't post links to the "print" comparison, only the "screen."

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby douglasf13 » Wed Dec 24, 2008 8:00 pm

Sonolta wrote:Hey fanboy..please do get a clue. If you can's see the excess noise or read DK's own words then you need to give up photography! I have shot almost 300k digital shots, licensed or sold thousands of them, and I have printed thousands as well.


I appreciate the name calling and forum flooding that has been your trade mark for so long on every forum you touch....photoclub alpha, dpreview, adobe, whatever. What a nightmare. Anyways, I agree that the A900 has excessive noise past ISO 800. The question here is about tradeoffs. You seem to be saying that the D3x images are better in every way, whereas I'm simply involved in discussing whether there COULD be trade-offs. Can we at least discuss such a thing without 200 posts from you? BTW, I've seen enough of your minor league football and aquarium shots to last a lifetime, and I'll make my own interpretations as to your expertise.

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby douglasf13 » Wed Dec 24, 2008 8:49 pm

I've already seen most of those as well. Whenever you disagree with a point, a barrage of photos and links comes from you ad nauseam, which doesn't help the conversation. I'm not saying you're a bad photographer, but, rather, a bad conversationalist. However, this "foe" thing makes it easier to navigate through the threads now. :lol:

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby fastson » Wed Dec 24, 2008 9:30 pm

Hey Sonolta. Where can I view those small samples in larger view? I mean the green foliage and waterdroplets etc. Beautiful shots right there.
Flickr - Sony A100, Sony A700 - SAL50F14, SAL16105, SAL1870, Minolta 35-70 F4, Minolta 70-210 F4, Tamron 90 F2.8 Macro

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby fastson » Wed Dec 24, 2008 11:17 pm

Thanks for posting those, truly lovely shots. I'm very much into a "green period" myself, too bad we're in the wrong part of the year.
Too bad about the crash. :( I usually keep all my photos on external harddrives and a server running RAID5, probably the best thing would be to burn everything but often I am too lazy for that, especially now when I have the A700.. its so easy to burn up a few GBs on the CF-card. :wink:

When the price is right I will start burning to BD-R discs instead. :D
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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby tbcass » Sat Dec 27, 2008 2:38 pm

Sonolta. I find it amazing you devote so much time and effort to prove that the D3X is better at high iso's than the A900. At 2.5-3 times the price it had better be better at something. Do you have stock in Nikon or is it some kind of emotional attachment? :?

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby yeahsure » Sat Dec 27, 2008 7:17 pm

Sonolta wrote:Hey fanboy..please do get a clue. If you can's see the excess noise or read DK's own words then you need to give up photography! I have shot almost 300k digital shots, licensed or sold thousands of them, and I have printed thousands as well.


When you have viewed maybe 400K files you start to get an eye for what prints well and what does not...believe me on this. I have a collection of 2000 hand made custom noise profiles here and I doubt many have worked with noise more than I have over the past 6 years.

Hi Sonolta, thank you for your good work.
I think after all that effort is about time to find a woman. Or a man if that is what you like best.
It seems you desperately need something on those lines.

Keep up with your good work.....

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby yeahsure » Sat Dec 27, 2008 10:16 pm

Sonolta wrote:Was that a lame attempt at an insult, or what?


No it was not lame.
Just 2 spoons of your own medicine.

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby bfitzgerald » Sun Dec 28, 2008 1:17 am

Keep em comin'

That works for me ;-)

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Re: A900 vs D3X highlights/mid/shadow tones

Unread postby [SiC] » Mon Dec 29, 2008 3:26 pm

Sonolta wrote:Read ya' loud and clear... :mrgreen:

Image

-Sonolta


Great capture there Don :)
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