Backyard Summertime Sky Over New Jersey. Solar Disk and Sunspots.
One of the websites that I follow for sunspot and auroral (northern light) activity is SpaceWeather.com. I noticed yesterday and today that there are three new sets of active sunspots (1260, 1261, and 1263). My telescopes have solar filters to allow safe viewing of the solar disk. The following images were taken with a 3.5″ and 7″ Questar telescope and clearly show the sunspots. The third image has some clouds passing in front of the solar disk. The solar filter for the 3.5″ telescope is darker (lets through less light) than the filter for the 7″ telescope. This required increasing the ISO and decreasing the shutter speed for the smaller telescope. Another issue with the smaller telescope is that it is much more sensitive to mirror slap and shutter motion. In order to get a sharp image, I used the mirror-up feature and waited 30 seconds to let the entire system stabilize. With the larger telescope this is still a problem, but attenuated due to the overall extra weight of the telescope relative to the Nikon D3s camera. The higher magnification of the larger telescope however, increases the effect of vibration. Focusing was done viewing the image through the camera using LiveView — and using a HoodMan to be able to view the LCD screen. After shooting images (and videos) for about 30 minutes, I did get a sensor over heating warning (which then turned LiveView off).
A DSLR video and still image of the July “Thunder Full Moon. These were taken with a Nikon D3s camera and Questar 7” telescope. The moon disk just fits within the D3s sensor, and is clipped in the video. The official full moon is on the 15th, but these images and the video were taken within 4 hours of the full moon on the 14th. I used Adobe CS5 Premiere Pro to edit the video. The digital art version of the full moon was created using Nik Color Efex Pro — Weird Lines Filter.
Backyard Summer Night Sky in New Jersey. Waxing Gibbous Moon. DSLR Night Video + Telephoto Lens Testing.
After several days having problem with taking video images of the moon with the Nikon D3s, I finally figured out what the problem was. I was pointed to a reference on the net about an undocumented feature in Live View that impacts video capture (Thanks to Howard Ignatius). The secret sauce is “use the OK button”
“- There is some misinformation online stating that the camera does not allow true manual control over ISO, shutter speed, and aperture in video mode. That is absolutely not true. The feature is undocumented for some reason, but if you hit the OK button while in live view, a light meter will appear and it switches to whatever mode that you currently have set on the camera (manual, aperture priority, etc). That means if you’re on manual, then you can adjust all of your settings as you please. Push the INFO button to cycle through different display modes, including a live histogram, horizon level, grid, etc.” http://www.davidbergman.net/blog/how-to-get-manual-exposure-video-mode-on-the-nikon-d3s/
Bottom line, I now have manual control of the camera when taking videos!!!!!
The following video contains 15 second segments of the moon with different telephoto lenses comparing with and without the lens “vibration reduction” being enabled. When on tripod there is a difference. Let me know if you see the difference. The telephoto lenses and telescope used include the 600 mm f/4 VR, 600 mm f/4 VR + TC-E III 20 (1200 mm), 500 mm f/4 VR, 500 mm f/4 + TC-E III 20 (1000 mm), 400 mm f/2.8, 400 mm f/2.8 + TC-E III 20 (800 mm), 300 mm f/2.8, 300 mm f/2.8 + TC-E III 20 (600 mm), and Questar 3.5″ telescope (~1500 mm). The video was put together using Adobe CS5 Premiere Pro.
I’ve also included a still image of the waxing gibbous moon (97%) taken with the Nikon D3s and Questar 3.5″ telescope (ISO 1600, ~1500 mm, f/16, 1/1000 sec).
Jet Transiting the Waxing Gibbous Moon. I am still having issues with the video mode automatic gain “feature” with the Nikon D3s. In doors with normal light levels it doesn’t seem to be that much of a problem. However, when trying to take video images of the moon through a telephoto lens, the moon is over-exposed. During the testing, I managed to catch a jet transiting in front of the moon. I happened very quickly (less than one second). The video below shows the transit across the lower part of the moon 1) as is; 2) zoomed in from 100% to 250%; and 3) zoomed in at 250% and slowed down to 33% speed. There was also some cloud cover moving during the sequence.
[Insert Video Here]
I also took some still images of the moon with the same camera and lens, but with a TC-E III 20 teleconverter. The goal was to see how sharp an image of the moon I could get with a 1200 mm lens. Focusing was through “Live View”, and to minimize camera shake used the “mirror up” mode to allow the system to stabilize. The D3s allows the use of “Live View” and “mirror up” because “Live View” is now selected via a button on the back of the camera. You don’t have the ability to use “Live View” and “mirror up”. The first still image of the waxing gibbous moon at 92% illumination was taken at ISO 200, f/8, and 1/200 second. The second at ISO 200, f/16, and 1/50 second. If I did my calculations right for a 1200 mm lens on a FX sized sensor, the moon should only move ~0.2 pixels for a 1/50 second exposure.