Tag Archives: RAW

HDR with an IR Converted D200

When I had my D200 converted to (deep) IR I nearly immediately noticed that the tonal range was significantly less than usual.  I was shooting RAW to make sure I captured all the data, but when I got it back to the computer it was totally unnecessary since the histogram showed the image was neither stressing the top nor the bottom of the possible 8-bit range, much less the 12 bits or so that the D200 could normally capture.

That didn’t make me real happy, but when I tried to tone map a single image in Photomatix, the limited data really became evident:

Single image tonemapped

Single image tonemapped

D200(IR), RAW, ISO 100, F8, 1/40

The banding in the clouds at the top is the proof of the narrow tonal range.  The range of IR is there, but just not captured in a single narrow tonal range image, as is evident when multiple bracketed images are used with similar tone mapping settings on an true HDR image:

Three stop bracket tonemapped

Three stop bracket tonemapped

D200(IR), ISO 100, F8, 1/40±1 stop, 3 frame HDR

No banding or any evidence of too narrow tonal range.

So, I’ve learned that with the D200(IR) I need to bracket at least three exposures to get an adequate tonal range for tone mapping.  Not sure why one exposure won’t capture a full range of data…

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Shoot RAW, Reduce Noise?

Great Blue Heron

Great Blue Heron

Shoot RAW and you’ll have less noise.  OK, you and I both know that among RAW’s many benefits over JPEG, lower noise isn’t one of them.  Or is it?  Well, yes and no.

Technically, the level of noise you see in a JPEG can (should) be exactly the same as RAW, depending on the RAW conversion, not on JPEG’s inherent noise.  But look at the following pictures, noticing specifically the decreasing noise levels between them:  (These are screen shots pulled out of Aperture, thus the red highlighting in a few places.)

Two stop underexposed, adjusted in post

Two stop underexposed, adjusted in post

One stop underexposed, adjusted in post

One stop underexposed, adjusted in post

Correct exposure

Indicated exposure, adjusted in post

(Technical note:  All three shots are identical in camera except for exposure.  All three RAW files were adjusted identically except for exposure and recovery.  D300 @ ISO 400.  1/2500@f/5.6, 1/1250@f/5.6, 1/640@f/5.6)

Due to the Heron’s bright white feathers, the first shot is the greatest exposure I could get by with without blowing them out.  It’s actually a 2 stop underexposure compared to what the meter suggested.  Then in Aperture I gave it one stop boost and brought back the highlights with recovery.  In effect, this is the best I could have done with a JPEG.  (In fact the shadows are better due to the greater dynamic range maintained in the RAW file.  JPEG would not have had the same amount of data available.)  Note the very noticeable noise in the background.  Also, note in the pupils (and in many of the other background areas not visible in the crop) you can see a lot of dark areas that are pure black.

The second shot was given an additional stop in the camera.  This is the correct exposure for most of the scene, with the white feathers being the major exception.  So, in Aperture I left the exposure flat and just dialed in the same amount of recovery as the first one to regain detail in the white feathers.  That couldn’t have been done with a JPEG, as there would have been no data available to help out the feathers.  Note the much lower noise levels.  Also, all of the dark areas have detail in them.

Finally, the third shot was exposed as the camera meter suggested, giving a one stop overexposure to the scene.  In Aperture I pulled back the exposure by one full stop and matched the same recovery setting of the other two pictures.  As expected this gives a near exact exposure match for the other two.  The 14-bit RAW file from the D300 sensor has plenty of headroom to handle the highlights which are blown out by 1.75 stops, so I am able to bring them back to be basically the same as in the other two exposures.  The real benefit here, though, is the further reduction in noise.  It looks pretty good!

So does RAW have less noise than JPEG?  No.  But it does give you the headroom to overexpose by one, one and a half, maybe even 2 stops and then pull the exposure back in post, effectively reducing the noise levels and increasing the amount and quality of the detail in your shadow areas.

Had I thought of it at the time I would have also shot this at ISO 200 to determine if the overexposed shot (final shot above) had lower noise than I would have gotten simply by reducing the ISO.  The difference seems more dramatic than the nearly invisible difference between ISO 200 and 400, so I think this is better, but I’ll have to try it out to be sure.

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The Down Side of Using a Car as a Blind

Snowy Egret

Snowy Egret

I’ve read a number of authors suggest the idea of using your automobile as a simple and effective blind for wildlife photography and I’ve gotten some shots I would have otherwise missed by doing it. The other day I learned that the idea is not without its own problems.

I was in Florida with only a little extra time before a flight and I was trying to grab a few shots of the incredibly numerous and varied birds there. It was therefore not only a handy form of camouflage, but also a practical necessity for me to stay in my car for some of the shots.

 

Screen Shot 2015-06-29 at 6.09.02 PM

Here’s a 100% view of the full-frame Snowy Egret shot on top. It was my first shot after I pulled up to this spot so I was just grabbing something in case it spooked. The framing was poor and the highlights blown out, but it also wasn’t sharp. I was shooting RAW so I wasn’t too concerned about the highlights, and I was going to shoot some more to get the framing better, but I just couldn’t get the thing sharp. In fact it got worse and worse!!!

Screen Shot 2015-06-29 at 6.11.49 PM

 

Eight shots later, here’s what I got (no adjustments of any kind on any photo on this page). I was rubbing my eyes trying to figure out why stuff was coming in and out of focus without me even touching my camera!

A great feature of shooting from within a car is the ease of finding sturdy stuff to rest your arms on, so I didn’t think I was having a camera shake problem. Seeing that my shutter speed was 1/3000 of a second, I knew that wasn’t the case, even at 500mm. And this wasn’t the look of camera motion.

I finally pulled back from the camera and looked at the scene. The whole thing was shimmering! The heat from the car was rising up right by the window I was shooting out of and ruining the view. That was then magnified by the lens. Because of the direction of the mild breeze I could have been shooting out of the passenger side and never had a problem. But on my side of the car, boy was it a problem!

So from then on I have kept in mind another consideration when shooting from the car. If the wind is blowing from the front or opposite side of the car, I need to get out to shoot or else the sharpness will be suboptimal.

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