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Just a quick update on the fine art photography front.  Last night I finally had a chance to break out my chemistry and step wedges to do some testing and calibrations for my carbon transfer print workflow.  I’ll talk more about carbon transfer printing in another post, but it’s basically the most archival of all photographic printing processes, with prints dating back to the 1800s looking brand new today.  The most defining characteristic of a carbon print is the very cool 3D relief of the gelatin standing off the paper a bit.  It’s an exquisite sight when done with highly textured or detailed images.  But it’s only practiced by a few hundred people in the world, because….

It’s an incredibly fickle and time consuming method of putting images on paper.  To date I’ve spend nearly two years off and on trying to get a print, to no avail.  It’s a maddening technique when you don’t have the right work environment and uninterrupted time to devote to the process.  But I think I’ve solved my prior issues and am nearing my first real carbon print.

Unlike my first attempt years ago, my gelatin image didn’t float off the surface of the paper before my eyes during development.  I also didn’t have any shadow areas of the image lifting off the paper, which we call “frilling”.  I’m still dealing with some gray highlights and underexposed shadows, but I’ll hash these out with some chemistry and exposure changes in the coming nights.

I love this stuff, as frustrating as it can be.

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The last few days I’ve been busy getting my darkroom area set up, and it’s nearly done and ready for developing and printing.  The safelight has been installed, darkroom sink plumbed, and yesterday I cut new glass to refurbish my NuArc UV exposure unit for printing handmade alt-process prints.  In the next few days I hope to get back to testing my carbon-transfer process using that fancy color chart and step wedge you see on the table there.  Lots of testing ahead I’m sure, given I tried off and on for over a year in Hawaii to get a decent print and failed.  It’s that hard of a process if your environmental conditions aren’t dialed in.  In Hawaii the humidity and some other factors prevented me from succeeding, but I’m starting from scratch with a better workspace here, so I’m anticipating better results.
But before I can print, I need a light tight cabinet to dry sensitized films and tissues in, as well as some beakers and protective gear for mixing up my chemistry.  That is next on my list this week.  Hoping to have print updates soon thereafter.
-R

Wet area on left, dry area on right.  Temp/humidity gauges, glass plates and reference texts...oh and a Brownie Camera to refurbish.

Wet area on left, dry area on right. Temp/humidity gauges, glass plates and reference texts…oh and a Brownie Camera to refurbish.

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ISO 640 Shadow Noise Comparison

News flash: If you’re shooting RAW images on your DSLR and using either the on-screen preview image or camera histogram to judge your exposures, your camera is lying to you and giving you too much noise and an inferior image range.

Okay, maybe “news flash” is a bit alarmist, as this has been covered before, but we decided to run our own test on our Canon 5D MKII body to test it’s noise floor at all ISOs, then test the difference between the “proper” exposure and what exposure is needed to maximize the image data in RAW format at any given ISO.

Noise Test
For the noise test we simply put the lens cap on, set the camera to 1/250 @ f/8 and made one exposure per ISO from “Low” to “High”. This gave us 21 black-looking images.

The images were imported into Lightroom 3 with zereod out exposure, blacks, bright/contrast, noise reduction, tone curve, sharpness, etc. Then we modified the tone curve Dark setting to +100, and the Shadows setting to +100 to make the noise more visible.

Switching back and forth between Lightroom slides can make it hard to judge which exposure is noisier than another. It helps to look at the contact sheet here to see which images are darker than their neighbors.

ISO noise test for Canon 5D MKII

ISO noise test for Canon 5D MKII (click through twice to see larger version)

The darker images have less noise than lighter images. ISO 50 (Low) looks pretty good, and then the next best is ISO 160, which surprisingly looks better than both 100 and 125. Noise starts to climb again from 200 to 250, then drops at 320. Similar results from 400 to 500, then again a drop at 640. Same with 800 to 1000, then a drop at 1250. But after 1250 the noise looks pretty linear all the way up to the “High” setting. This shows that the camera sensor doesn’t have a totally linear noise gain as ISOs climb. Certain higher ISOs are better for shooting less noisy images.

The reason we’re testing this isn’t just to find the best ISOs to shoot at with the lowest noise. It’s going to be the foundation for testing our proper RAW exposure settings, which incidentally will reduce noise among other things. So why test at inherently noise ISOs when we can start off with our proven least noisy ISOs?

RAW Exposure Test
So here’s the deal: Your camera preview image and histogram represent an in-camera processed JPEG, not the actual data in the RAW file. We were always told not to base our exposures on the image since we couldn’t calibrate the screen, but now we know the histogram isn’t even accurate either. What’s a photog to do? Well…test!

Our set up isn’t super scientific, but it was more important for consistency between shots than anything else. So we set up one Alien Bees B800 strobe over an Xrite ColorChecker Color Rendition Chart, a blank piece of white paper and a cup that was lined with black felt to provide a solid shadow on the felt background. The felt background gave us a texture to judge our final shadow detail range and noise levels off of, particularly in the shadow of the cup. The camera set up consists of a Canon 5D MKII, with no noise reduction settings, and a 70-200L IS lens. Exposures were determined with a Sekonic L-508 light meter. Bracket exposures were adjusted by varying the flash output, not the lens aperture, which would have introduced sharpness and contrast variations.

As an example for ISO 640, the camera and light meter were both set to ISO 640. The light meter determined our normal exposure to be f/16. After setting the camera to f/16, where it will stay for the duration of the test, we adjusted the strobe to underexpose the first shot by one stop, so we monkeyed with the strobe setting until our light meter gave us a reading of f/11. Then we made our first exposure with the camera. We followed the same strobe adjustment method from -1 stop to +2 stops in 1/3 stop increments, since our camera ISO, shutter speeds and apertures follow a 1/3 stop interval. If your camera does ½ or whole stops only, those would be your intervals to test at.

RAW Exposure Test Setup

RAW Exposure Test Setup (looks like our cell camera could use some noise reduction!)

After capturing our range of ISOs and under/overexposures for each, we imported everything into Lightroom 3. Our first step was to sync our color balance across all images, and we also tagged each ISO’s “normal” exposure with a single star so we could more easily reference them later. We also zereod out the exposure, fill, blacks, tone curve, sharpening and noise reduction settings across all images.

Then we focused on one ISO series of shots, starting with the +2 exposure. Our goal is to use the Exposure slider to bring the image back down to where the brightest whites are just below their clipping level. You can see them clipping by either clicking the upper right arrow in the LR histogram box, or by holding your Alt button down as you adjust the slider. In our case the +2 was too overexposed to retain any detail, even with the slider at -4. The camera sensor is effectively saturated with photons and can’t record any highlight info to the RAW file. So we try the same method on the +1.6 exposure for that ISO. For our ISO 160, +1.6 was still clipping, but for ISO 640, this +1.6 exposure was perfect. Just shows you that things aren’t linear and that you should test for all possibilities.

For ISO 640, our highlight clipping disappeared at -1.15. This is the amount of exposure correction needed then for ISO 640 images captured at +1.6 exposure. Knowing this combination we can now make a Lightroom preset to normalize our “overexposed” shots upon import, for any ISO you test!

We haven’t tested all ISOs, but here are our settings from what we’ve tested as of this writing:
ISO L (50): +.3 exposure, -.75 LR exposure slider
ISO 160: +1.3 exposure, -1.15 LR exposure slider
ISO 640: +1.6 exposure, -1.15 LR exposure slider

The “Low” ISO didn’t deviate too much from the factory setting, but the higher ISOs definitely benefit from some overexposure during capture. These overexposed shots looked clipped on the camera screen/histogram during capture, but retained plenty of highlight info in the RAW version. So there is definitely a disconnect between the in-camera processed JPEG preview and the actual RAW file info.

The magic of all this lies in comparing the new normalized image to the old normal exposure. Find your tagged one-star normal image and compare it with the new normalized image in side-by-side mode in the library module. What we see is a significant amount of noise reduction and more shadow detail, particularly at the higher ISOs. In this screenshot of the ISO 640 side-by-side we can see that the normalized image on the right has better shadow texture, better shadow transition gradation on the cup, and less noise. In the ISO 160 side-by-side, you can even see the cup separation from the felt background in the dark shadow area in the normalize image on the right.

ISO 640 Shadow Noise Comparison

ISO 640 Shadow Noise Comparison (click through twice for larger version)

ISO 160 Shadow Noise Comparison

ISO 160 Shadow Noise Comparison (click through twice for larger version)

ISO 640 Color Noise Comparison

ISO 640 Color Noise Comparison (click through twice for larger version). The colors are shifted a tad, but the noise we're concerned about is noticeably less in the normalize version on the right.

Because we’ve overexposed during capture, commonly called Expose To The Right (ETTR), we effectively shifted our data up toward the upper areas of the tonal range, where sensors record more information. As a result we don’t have a true black on our normalized histogram, so we can fiddle with the black setting or tone curve to bring some black tones back in. How much really depends on how high or low key your subject matter is, and you’ll probably have to do adjust this on a case by case basis.

For those of you who shoot primarily for highlight details and don’t give two flips about shadow detail or overall range, these tests may not matter much. Since the camera is inherently underexposing a bit, you’re in no danger of clipping your highlight detail. But for people who want to exploit their sensor’s maximum dynamic range, have less noise, smoother shadow gradients and more shadow detail, knowing your camera’s true RAW capture exposures will help.

What are you thoughts on this? Can you think of other tests we should run or ways these results could be useful?

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We recently had the pleasure of shooting four groupings of luxury products for a six page spread in Desert Companion Magazine, for their advertising client GGP.  It was an awesome gig with great stylists and art direction.  GGP, which runs three Las Vegas luxury retail venues including Fashion Show Mall and the Shoppes at Palazzo, filmed a behind the scenes video of the shoot.  It includes the luxury products, the photography equipment and some interviews with key players in the shoot, including Radiant Photography owner Ryan Weber.

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Radiant recently had the opportunity and challenge to shoot the Oldenberg “Flashlight” sculpture on the UNLV campus for Desert Companion magazine.  I say challenge because the shoot required an evening shot of a matte black sculpture, lit only by mixed ambient lighting, on a college campus that has students walking about.  So I packed up my tilt-shift lenses one Saturday night and headed on down to UNLV to see what I could do.

Being a weekend evening, I didn’t have too many bodies walking through my images.  I was also able to pull long exposures to yank some color out of the sky, courtesy of the reflected light pollution from the Las Vegas Strip.  Now the challenge was getting a three-story matte black object to maintain detail and color fidelity from top to bottom.  The area was lit with a mix of high-pressure sodium vapor, mercury vapor and halogen light sources…a perfect white balance nightmare.  However I brought along some flash heads and a battery pack so I could at least fill the shadowy sculpture with some color correct fill light, right?  Well, kinda.  I did a bit of light painting, but with the intensity of the light needed to light the black monolith, there was just too much flash spill onto the surrounding trees and cement.  So I went the multi-exposure, multi-white balance route.

A series of exposures were made for the highlights all the way to the shadow details that I’d later tone map in Photoshop (no, I don’t use tone mapping software, as I prefer to do it manually layered in PS).  Same thing for the various white balances, although much of the scene was lit under high-pressure sodium vapor lamps which are nearly impossible to white balance, due to their spectral output.  It’s light nerd stuff I won’t get into here.   Anyway, back at the office I processed all the exposures and pulled an under-, over-, and properly exposed frame from each composition.  I then layered those and used masks to tonemap the final image, which has greater highlight and shadow detail than any single exposure I captured.

All in all a great challenge and fun image to work on.  The image below is the magazine layout and unfortunately is quite compressed, so the detail is lacking.  I’ll post up a better shot soon.

Radiantphotography.com Oldenberg Flashlight

Oldenberg "Flashlight" image by Radiantphotography.com

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The awesome LVSK8 art show is upon us again and I’m working on a new skatedeck design for this year’s show. Last year I did a hand-carved tiki (see it here), but this year I’ve put much time and effort into researching how to get a photographic image onto wood. The answer seems to be water-slide decal transfer paper, which I have yet to try. I just ordered a batch online and will make some test prints to transfer to an old deck before I do the final piece.

I figured the show’s deadline was a good excuse to complete a half-finished project that has been collecting dust in the garage for about two years. Late last night I finished building the motion rig for shooting moving cars. Depending on what camera angles and distance away from the car I desire, I have some more support arms to fabricate, but this rough start is functional for some shots. I hope to post a blog post and video strictly on this rig sometime. It uses some steel tubing, insanely strong magnets, fence hardware, and a Super Clamp.

Anyway, here is a sneak peak at the theme of the deck, although probably not the final shot I’m going to use. (Keep clicking on the image to get into a higher res version two pages from here)
Ryan

68 Cadillac motion rig

68 Caddy with motion rig for LVSK8 IV art show deck (Copyright 2010 - Radiant Photography. Rights reserved.)

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