0   

Noem @Noem 16. Nov 2007, 11:51

The question of ISO and noise has been discussed to death and past.

However, there is a lesser known but not less important fact to know about the 40D's characteristics:
the clipping point depends on the ISO.

Following is the list of clipping points, depending on the ISO, but first a few notes:

1. the clipping points may vary. I saw images from another copy with slight variations,

2. the clipping points may depend on the color, though not too much. Even more, the two greens may have different clipping points,

3. the clipping points do not reflect the black current level, which is between 1025 and 1035 (again with variations).

However, the above variations mean only a small difference between the different values. I menationed these only to barr further fruitless discussions about irrelevant details.
So, the clipping points are

ISO 0100: 13824
ISO 0125: 16383
ISO 0160: 12743

ISO 0200: 16224
ISO 0250: 16383
ISO 0320: 12743

ISO 0400: 16224
ISO 0500: 16383
ISO 0640: 12743

ISO 0800: 16224
ISO 1000: 16383
ISO 1250: 12743

ISO 1600: 16224
ISO 3200: 16383

What does this mean for the photographer?

It means, that the highlights may be clipped simply due to the bad choice of ISO. The difference between the worse, 12743 and the best, 16383 is 31%, after discounting the black current level.

This is * 1/3 of a stop * one can lose, simply by selecting ISO 100 or some other ISOs.

I shot a scenery for demonstration, the dynamic range of which exceeds the 40D's capturing capability at good light:

What are the consequences?

1. DO NOT use a "bad ISO", namely ISO 100, ISO 160, ISO 320, ISO 640, ISO 1250,

2. DO NOT use ISO 200 with HTP On, as this ends up with using ISO 100.

Original Tema pa se nahaja tukaj
http://forums.dpreview.com/forums/readflat.asp?forum=1019&thread=25607049
 0   

Andrej @fotokaj 16. Nov 2007, 12:28

Čista logika; Canonov ISO 100 je v bistvu ISO 125, to se že dolgo ve. Kar se doslej ni vedelo je pa to, da je zaradi tega pri ISO 100 DR najnižji. Torej je pri 40D "base ISO", torej osnovni, izhodiščni ISO ravno 125 in tega se kanonaši držte.
Toliko o "podarjeni tretjini zaslonke", ki naj bi jo Canon nudil svojim uporabnikom. Seveda, za ceno kvalitete slike.
Nauk za Canon? Lahko nateguješ kupce, ne moreš pa pipetkarjev laugh
 0   

Peter Bernik @Noob 16. Nov 2007, 12:52

Že ko sem začel brati post, sem razmišljal če bi popravil naslov teme in vrinil besedo pipetkarska pred besedo tema upset . Pa ne zato, da ne bi smele biti pipetkarske teme (pišem, ker zagotovo kdo ne bi štekal, če ne bi), ampak zato, ker enostavno ne moreš sam določati kaj je zanimiva tema. To določi št. obiskovalcev in odgovorov.
[url=http://www.peterbernik.com/][img:58355b6b4e]http://blog.peterbernik.com/wp-content/images/podpis.jpg[/img:58355b6b4e][/url]
 0   

iztok @izo 16. Nov 2007, 12:55

kaj, noob, ti je idejo ukradel? biggrin
 0   

Peter Bernik @Noob 16. Nov 2007, 12:58

Kdaj sem pa jaz pipetkal bigeek ?
[url=http://www.peterbernik.com/][img:58355b6b4e]http://blog.peterbernik.com/wp-content/images/podpis.jpg[/img:58355b6b4e][/url]
 0   

iztok @izo 16. Nov 2007, 13:00

ma ne, nism tega mislil, hehe. joke grin
 0   

Noem @Noem 16. Nov 2007, 13:01

Brez panike, lahko spremeniš naslov, se ne bom užalil laugh
 0   

Peter Bernik @Noob 16. Nov 2007, 13:04

izo: ok zdj vem kaj si mislil. Se mi zdi...

Noem: zdaj itak bo zanimiva laugh .
[url=http://www.peterbernik.com/][img:58355b6b4e]http://blog.peterbernik.com/wp-content/images/podpis.jpg[/img:58355b6b4e][/url]
 0   

Robert @Kroma 16. Nov 2007, 15:46

Na 5ki se mi zdi, da je ISO 800 bolj problematičen glede šuma, kot ISO 1000. No ja nekaj takega.
Da mal zakuham: Nikona kupit, pa ne bo težav (vsaj takih ne). Bye
 0   

nejc @jetforce 17. Nov 2007, 09:29

A nima d3 iso od 200 naprej?


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