DK! Post Some IS0 1600-6400 a900 Samples Soon!

[David Kilpatrick]

OK, night time, 100W bulb lighting the entire same room (and not directly either, shade under the bulb uplighting the ceiling):



1/13th at f2 with the Sigma 24mm f1.8 lens, ISO 3200, ACR, no sharpening, no luma NR, 50 chroma NR; 2400K for the very warm tungsten light; image reduced to exactly match A700 12 megapixel height; 100% clip.



The whole shot - http://www.pbase.com/davidkilpatrick/image/103720732 to view at 24 megapixel size (it's cropped at the end for a better composition but is otherwise the full image height). This cat is unflappable, putting the Sigma right up to his face then firing the Alpha 900 no movement, no blink (twice as loud as a 700, if you have not heard one yet - extremely chunky mirror sound, like closing a car door every time you take a shot). I took some at 1/20, 1/30, even one at 1/10 and he was sharp enough for all of them but focus varied quite a lot with the Sigma, probably small movements on my part. SS worked perfectly.

David

[David Kilpatrick]

Oh, and ref the KM D5D result from Don:



This is a 6 megapixel size 100 per cent crop on the same basis - but I have applied web USM, as the really fine noise structure would take it OK:



You can tell how low and non-directional my lighting is - look at the slit pupil in Don's cat's eye, and the wide open pupil in mine (Birman cats often look wider-pupilled though and cats vary a lot in their iris/pupil reactions to light).

David

[David Kilpatrick]

Yes, I removed them. They were seriously underexposed shots in conditions where I should not have posted them, and your comments on low light exposure were correct - it is better to avoid that sort of lighting. My only concern was that some people were picking them up and referring to them as if they were trying to show how good the A900 could be, not how bad it could get. I don't really want to be feeding trolls bait for dPreview etc so I removed them (I also removed some other files, at the request of Sony, directly - I broke their embargo on using examples from the 16-35 and 70-400mm by showing them).

David

[bfitzgerald]

Oh well, never mind, we all saw them anyway

I guess that means no more sony stuff for David...lol

Are they upset?

[David Kilpatrick]

It's a bit frustrating when several sites have plenty of 16-35mm prototype shots up on line. I think, as ever, I was revealing a slightly negative aspect of the lens (distortion type) rather than just trying to take 'wow' pix to show off. Have you seen Uschold's A900 pre-test in the BJP? He praises the 24-70mm but says it has strong barrel distortion at 24mm and needs stopping down to f4 to improve sharpness - and that it has sudden vignetting fall off in the corners at 24mm on full frame, much like the 16-80mm CZ on APS-C. I am feeling happier by the day with my 17-35mm and 28-75mm KM D lenses!

David

[Javelin]

Oh oh... Your going to be written about in 100 notebooks at the next Sony board meeting

"I am feeling happier by the day with my 17-35mm and 28-75mm KM D lenses!

David

[lock]

"I'm going to try this one for sure."
That 's what I said and I did it before sending in the body.
I tried plain iso 3200 (1), iso 6400 +1 stop (2), and iso 6400 +2 stops (3). The last two were pulled back in Sony software with 1 or 2 stops to correct the exposure.
I used the 18-70 to take the pictures as my Tamron also went back to the factory for adjustments. A-mode, F6.3 at 1/50 sec, center weight metering.
I did use a lot of light/dark objects, clothes spread across the room/chair, to get as much noise into the scene given the exposures. I think these pictures do challenge the sensor much more than many of the cat shots presented here.

First the pictures without any NR, straight from raw but cropped in the order mentioned:
1)
http://farm4.static.flickr.com/3058/291 ... 96dc_o.jpg
2)
http://farm4.static.flickr.com/3273/291 ... 89ed_o.jpg
3)
http://farm4.static.flickr.com/3014/291 ... 44cc_o.jpg

Now with a default NR mode in Neat Image, the 'blotchy noise' option in the advanced menu:
1)
http://farm4.static.flickr.com/3288/291 ... f943_o.jpg
2)
http://farm4.static.flickr.com/3023/291 ... 8e96_o.jpg
3)
http://farm4.static.flickr.com/3010/291 ... 8d74_o.jpg


I'm not going to judge the pictures in terms of retained details, as in these conditions the lens is surely a limiting factor compared to e.g. my Tamron. If I look at noise however, the iso 6400+2 stops is the best, followed by the iso 3200. After NR the order is much the same but the differences between the two do become very small.
So it seems to work, but I never get the low noise levels Sonolta is showing us with his A700.

There are two questions I would like to ask you guys. I want to know why more light at a higher sensitivity seems to be more effective than using a lower sensor sensitivity. In fact, it does not seem to work that well with only 1 stop extra, but it does with 2.
Is it because pulling back the exposure hides some noise in the darker scenes but uses the extra light to gain detail against noise ? Or is there a non linear relation between noise and iso going from 1600 to 6400 in the A700 ?

lock

[lock]

Oké I did some make some mistakes in typing it. I changed it now. I sent the camera in because of FF with any lens faster than F/4.

If I should have used iso 3200, presumably because it's better, then why isn't the iso 3200 picture better than the +2 stops iso 6400 picture ?

[lock]

Thank Sonolta. The NI noise reduction was set to a default mode to simply make things comparable. Surely it isn't max. effect.

I was posting iso6400 +2 EV is a said I did. The factt hat you never posted something like this is very well possible. Most of your fantastic iso 6400 pictures are evenly lit or the crops of evenly lit parts. The same accounts for DK's catshots. The one cat lying on the bed and the 100crop at page 4 does not contain that many conrasting dark and bright areas as mine do. So I understand that mine are worse.
But they still serve the purpose of checking what the effect of the overexposure trick may be as there is 'enough noise' in the relativwely underexposed parts.

You said with iso 6400 it would lose fine detail compared to iso 3200. That was one of the surprises actually. I've got more detail in the iso 6400 picture with +2 EV than I got in the iso 3200.

If the camera comes back I will try more of this, as my two cats are quite a challenge: tricolore and a chocolate brown one. That's going to test some noise...

[InTheSky]

I will say that is the best picture i have been able to get from ISO6400 so far ... and this is probably what is missing in the A900, High ISO capability.



Full Sized image there :
http://www.pbase.com/nadeauf/image/1042 ... iginal.jpg

For ISO3200, tonight i have try some shots , and this is my best so far, i think this can become a good 6MPix noise free to eye ... but no more .


Full size again : http://www.pbase.com/nadeauf/image/1042 ... iginal.jpg

For ISO1600, it's depend of the situation, but we can get very good result.

Regards,

Frank

[bakubo]

I've got more detail in the iso 6400 picture with +2 EV than I got in the iso 3200.

This seems a bit strange to me. Why shoot at ISO 6400 with +2 EV instead of just shooting at ISO 1600?

[lock]

Correct. But Sonolta also mentioned he overexposed up to 2 stops and I simply did the same. It did it to find out how iso 6400 + 2 ev pulled back in the convertor with two EV (to get a normal expusere again) would compare any standard iso 6400. But in stead of comparing it with the standard iso 6400 (0 EV), I compared it with a standard iso 3200 picture and an iso 6400 +1 EV. The iso 6400 +2 ev was at least equal or better than the iso 3200 picture. I found this pretty weird.

But now that you said it: if you can do iso 6400 +2 EV you effectively mimic an iso 1600 shutter speed picture give that specific aperture, but with a two stop extra sensitivity. This causes the overexposure but you can pull that back with the convertor. This is why the iso 6400+2 ev was better than the standard iso 3200 picture: it's effectively an iso 1600 picture.