Wednesday, January 23, 2019

Sea Lemon Nudibranch time-lapse

MLK Day on January 21st, 2019 offered a good opportunity for an extreme low tide at Pigeon Point in California during the full Moon following the total lunar eclipse over the Americas the day before. With such a gravitational pull on the Oceans, the tides at Pigeon Point went down to -1.65 feet at 4:39 PM. I decided to go down to the hidden sea cave that is not really well known because it is hidden from public view and it is only accessible during negative tides. It is a beautiful and fragile environment, but it is also somewhat protected from the Pacific Ocean waves during the lower tides. It also seems to be a nudibranch breeding ground that I love to photograph because the cave provides enough light to photograph but also eliminates water surface reflections of the sky above that can obscure the subjects in the water. I didn't really know what I would be photographing other than I wanted to try an HDR of the sea cave to try an capture the beauty of the sea cave in an extreme light zone.

After I did that with my wider lens, I went looking around the pools and soon came upon a classic member of the regions tide pools, the Sea Lemon Nudibranch (Anisodoris nobilis). I have a fantastic macro zoom lens that is ideal for real life tide pool invertebrate photography. It is a Nikon ED AF MICRO NIKKOR 70-180MM F/4.5-5.6. I'm glad I brought my foam kneeling pad because it was a relief to rest my knobby knees on it as I set up my travel tripod. As soon as I set up my camera and took a few photographs at different settings, I figured it might be interesting to just let the interval timer shoot a series of shots just to see what a time-laps would look like at one second intervals. I had no idea if this was a good interval for sea slugs and as I was shooting, I was thinking that two second intervals might have been more interesting for a 24 frames per second playback, but as it turns out, I think I was right to choose one second intervals for the playback effect of the sea slugs movements. During questionable time-lapses, it is often easy to over think the shot and to cut it short, only to ruin a perfectly good sequence. So I stretched my legs and looked around at other pools while the intervalometer did it's thing.

I sort of got lucky in that the Sea Lemon did a U-Turn in the field of view that enabled me to continue the captures beyond say 300 for a typical 10 second playback. The final sequence that you see is three different set ups as the Sea Lemon moved around, the first one was zoomed in closer and the sun had not quite set, but the light was diminishing rapidly. I realized through some test shots that the longer exposures was blurring the Sea Lemon so I needed to make sure the shutter speed was faster. I was able to shoot at 0.4 seconds with an f/8 aperture and a 640 ISO. You can see that the wave like edge of the Sea Lemon's foot is a little blurred compared to the rest of the body as is the gills and antennae. The second sequence, I kept the same settings but I moved the lens zoom from 180mm to 130mm that allowed me to capture a longer sequence with a larger framed area. I changed the settings to accommodate for the diminishing light in the third and final sequence by opening the aperture to f/5.6 and slowed down the shutter to 1/15th of a second, but it was still too dark, so I had to boost up the ISO to 6400 just to see how it would work. It turns out that it worked just fine for a time-lapse and it is still quite impressive for up close still shots. I use the Nikon D810 and the low light ISO settings are impressive in reducing noise at higher ISO settings. The last sequence was great because the Sea Lemon does an exit stage left and down to wrap up the shot! I could tell in scrolling through the shots that it was going to be a good time-laps but I didn't see a surprise visitor in the second sequence that was a creature that I have never seen before. It appears in the upper right hand corner of the image behind the U-Turning Sea Lemon and appears to be a Six-lined Nemertean (Tubulanus sexlineatus) that crawled just behind or under the Sea Lemon and reappears in the lower left hand corner of the frame in a clearer shot of the worm like sea invertebrate. It was a perfect Nemertean photo bomb! :D

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