I finished editing the images from the Iceland trip last week and quickly got the photography itch again. I realized that fall color may have peaked out near Asheville, but the elk rut might still be happening. My wife and I made the decision to take a day trip to Cataloochee in the Great Smoky Mountains National Park on Saturday only two hours before leaving. I enticed Alison to come along by promising a stop at Farm Burger in downtown Asheville - one of our favorite restaurants in the region. I was happy with a few of my shots from my trip to Cataloochee a few weeks ago, but not thrilled about them. I knew I could do better and that this was my last chance until the rut starts up again next year.
When we arrived, the roads into Cataloochee were already congested. The bright colors of Autumn were lingering, and seemingly everyone from the region was there to see them. This didn't deter us. Near the park entrance lay about half a dozen cows at the edge of the woods in the shade. I didn't notice a bull at first and the cows were about 100 yards away. Then, the cows rose and started walking away from us and into the woods. A bull elk came out lazily trailing behind them, stopping frequently to eat grass. I made a few exposures during this migration to the woods, then we drove on, stopping at the historic school and farm house so that Alison could admire the hundred-year-old architecture. We waited in the pasture where I got most of my elk shots last time, but no elk appeared. We didn't hear any bugling either. We decided to drive back to the entrance where the cows were hanging out. Once there, we spotted a bull among the cows and abandoned vehicle. It was clear from the bull's body language that the rut was over. He was lazily grazing and paying little attention to the cows. He made no attempt to bugle, either. This was not one of the larger bulls; they were nowhere to be seen. Nonetheless, he was an impressive animal. He was also very close to the road and paying no attention to me or the other photographers at the roadside. I made dozens of photos while the bull, cows, and a couple adorable spotted calves grazed and did little more. Despite the inactivity of the post-rut, I was able to get safely and comfortably close - much closer than before. I used my 70-200 VR (on a DX sensor for an equivalent focal length of 105-300mm) for the entire encounter - no super telephoto needed.
"What ISO are you using?"
On that final technical note, I'd like to talk a bit about camera settings. While I was crouched down at the edge of the field firing off a burst of exposures of elk, another photographer approached and asked, "what ISO are you using?" I don't like interruptions when I'm in my photography "zone", but I do like to help out when people have questions about photography. I looked at the ISO of my last frame and simply answered, "1600, but it varies between 400 and 1600." The gentlemen responded, "Wow! That high? Really?" and walked off. A few minutes later a lady asked a different photographer a few feet from me what ISO he was using. I didn't hear his answer because the bull elk lifted his head for the first time all evening and I shifted my attention to getting that shot. Later on the drive home I had plenty of time to ponder this question and why it even needed to be asked. Had I more time to answer the gentleman, I would have responded with a much more complex answer. The answer to the question, "What ISO are you using" is "it depends."
When I'm photographing wildlife, I set the shutter speed I want to the highest fraction I can and set my aperture to a value that will keep my subject sharp enough and still blur the background. In order to do this, I shoot in manual mode. Ideally, my shutter speed would be set to anywhere between 1/640th and 1/1250th sec in order to freeze the subject in motion. The elk weren't moving fast and were keeping to the shade, so I let it go down to 1/320th if necessary. My aperture range was f5.6-f8. To avoid blowing the highlights (the evening sun was shining on the back of the elk giving great rim light) I dialed my compensation down to -2/3 of a stop. So what about that pesky ISO? It depends on the situation. It depends on the light.
A high ISO causes noise and degrade image quality, color, and sharpness. Generally, I want the lowest value possible. I also need to know the highest ISO I can use to get acceptable results with my particular camera. My D7000 (used entirely for this shoot) is excellent at high ISOs up to 1000 and acceptable up to 1600. In fact, Nikon's sensors make noise look more like film grain, which is more pleasing than digital noise. The guy that asked me about my ISO was shooting an older APS-C Canon model. I know for a fact from being a Canon shooter for 7 years that 10 year old cropped sensor Canon's do poorly at ISOs higher than 800 (modern Canon's, just like Nikon's, are far better now). So I guess this explains his shock at my answer of 1600. What I didn't have time to explain is that I use what some Nikon pros call "ISO priority mode." In other words, I set my ISO to auto while in manual mode for wildlife. First, I go into my camera's menu and select auto ISO and dial in the maximum I'm willing to go (in most cases, 1600). Then, I set my base ISO to 400 and let the camera handle it from there. It will actually select the lowest ISO (from the whole native range if need be up to 1600) for a scene that gives me the proper exposure with the aperture and shutter speed that I have selected manually. So, I don't have to think about ISO when shooting wildlife. I just fiddle with my shutter speed and aperture as needed. If the camera needs ISO 1600 to get a sharp and well exposed image then so be it! So, the short answer to "what ISO are you using" is "the one needed to get the shot!"