Underexpose or High iso for Nikon D40X, which is best?

[carlos_rodriguez3]

<p>Here is the case I got today:<br>

There was a carnival with lots of dancers, customs and carnival cars, similar to the classic brazilian "Carnaval". In the past I shot everyting with flash, using a 50-200 4-5.6 G VR lens. But for this event I tried to shot without flash, using only artifical light "on" the cars. Most of them have lots of light.<br>

At first I tried using ISO 800 and 1/30, f/4, but they were underposed by 1 or 2 steps. I was unsure what was best, underexposing (and later deal with grain) or... uisng iso 1600 (and, also, later deat with grain). I decided for the second and results were very good. I left exposure to1/30 and f/4. Of course, some pictures were blurred by vibration and dance movement, but I got some fine shots.I got rid of must of the grain (photoshop) and here are the results:<br>

<a href="../photo/8679133">http://www.photo.net/photo/8679133</a><br>

Also...<br>

<a href="../photo/8678751">http://www.photo.net/photo/8678751</a><br>

<a href="../photo/8678892">http://www.photo.net/photo/8678892</a><br>

But... I am curious, if I had underxposed (iso 800 would I have better results?<br>

I can always use normal flash, but I find the lights of this Carnaval cars very appealing.<br>

What would you have done?<br>

Nikon D40x<br>

50-200 f/4-5.6, VR lens<br>

SB-600 flash<br>

Carlos Rodriguez</p>

<p> </p>

[hans_janssen]

<p>The only way is: expose correct, underexpose and correct it in pp gives noise. A faster lens would do miracles, some like a 70-200 2.8.</p>

[oskar_ojala]

<p>I tested this long ago with my D70 and raising the ISO produced much better results than shooting at a lower ISO and correcting exposure in raw conversion (I used ACR as the converter). So don't be afraid to raise the ISO, underexposure especially at high ISO produces a lot of noise and bad tonality.</p>

[mats nilson photography]

<p>In fact, since changing ISO doesn't alter the sensor's inherent characteristics in any way, you <em>effectively</em> underexpose by raising the ISO setting. <em><strong>But</strong></em> - the camera's image processing engine is built to deal with that kind of underexposure, trying to make the best out of it. After all, that's why it will let you dial in a higher ISO in the first place. However, if you deliberately underexpose at a given ISO setting, the camera will assume it's intentional and not do much about it.</p>

[pete_s.]

<p>Assuming you shoot raw it's better to raise the iso but when you reach unit gain at the sensor there is no point going any higher. Actually staying at that ISO is better than raising the ISO since you'll get more dynamic range. It may sound illogical at first but it's not.</p>

<p>According to http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/#unity_gain unity gain of the D200 is ISO800 so it's logical to assume that the D80 is the same.</p>

<p>So raise the ISO as needed up to ISO800. Then shoot "underexposed" and raise the exposure in the raw processor instead. Noise will be the same but you will get some additional dynamic range to record highlights that would have be clipped if you set the camera to ISO1600 or ISO3200.</p>

<p>If you shoot jpeg you can't do this since the jpegs will be underexposed and you will have lost some of the tones in the image due to jpegs being gamma corrected (and raw is not).</p>

<p>PS. In this particular case using a faster lens like the Sigma 50-150 f/2.8 or if you have the budget a Nikon 70-200 f/2.8 VR would have been better. And something like a 85 f/1.4, 105/2 or 135/2 even better.</p>

<p> </p>

[carlos_rodriguez3]

<p>Ok, use high iso instead of underexposing, I got that.<br>

What about using a fast lens like a 50mm f/1.8, instead of a 50-200mm f/4-5.6 vr? And later crop the picture to the subject size. This way I can use lower iso, faster shutter speed. The final result would be a small pixel size picture, maybe 500x750. Can I enlarge it to 6mp (2000-3000) and get better results? I mean better results than using a budget tele with high iso and low shutter speed.<br>

Is that an alternative, or am I getting it wrong?<br>

Fast lens, crop to the subject and enlarge or....budget tele, high iso, slow shutter<br>

Carlos</p>

<p> </p>

[lightsmith1]

<p>You have the right idea in getting a faster lens which is a better option for many reasons. The 50mm f1.8 will enable you to use a setting of ISO 400 instead of ISO 1600 with your camera but the tradeoff is that the depth of field will be half as much. Check a DOF chart for a subject at 8 feet with the 50mm lens at f1.8 and at f4 and you will notice a substantial difference. If you were close and photographing a couple in a normal pose one person would be in focus but not the other. There are times when the best solution is a tripod and a cable release.</p>

[kate_compton]

<p>One more thing to consider, the 50mm f1.8 doesn't auto focus with D40X.</p>