Another Sun Test

Friday, August 18, 2017

Although weather forecasts for the upcoming total solar eclipse on Monday are not at all favorable for the whole of the Midwest, I conducted another solar filter test on Friday afternoon, August 18, 2017. For this test I used my old Celestron 94168 F60 (EQ) mylar solar filter, intended for use on a 60mm refractor telescope. The settings for my Nikon D7200 DSLR camera were: 1/1600 shutter speed at f/9, ISO 640 and 300mm focal length. I simply placed the solar filter over the lens by hand and searched for the sun's disk. The left image shows the suns with clouds, while the right image is unobstructed. Note the three sunspots at left center of each disk. Sun images actually look blueish with this filter, but I warmed their "temperature" in Lightroom to create the image above. This was a handheld exposure test.


The Fast And Slow Of It

Thursday, August 17, 2017

Distant and high altitude cirrus clouds (background) appeared non-moving in this northwest sky perspective, looking NW from Bowman Woods Park in Cedar Rapids, Iowa on Wednesday evening, August 16, 2017. In direct contrast to that, low altitude cumulus clouds--tinted reddish by the setting sun--virtually raced across the horizon from left-to-right. This image, shot at 7:35 pm CDT, was captured using Aperture Priority at f/11. Nikon D7200 DSLR camera.


Boiling and Roiling On August 10

Sunday, August 13, 2017

There was plenty of convection action on isolated cells in Eastern Iowa on the afternoon of Thursday, August 10, 2017. Vertical cloud growths did not require time lapses as they were very noticeable to the naked eye. The cell seen above was captured at 3:45 pm CDT, with the camera looking east from Douglas Drive at Alburnett Road in north Marion, Iowa.

This 3:55 pm panorama looks southeast from the grounds at Oak Ridge Middle School in Marion. The western edge of the line of storms (foreground) was about 7 miles to the southeast, while the eastern edge (background, left) stretched about 53 miles to near Delmar, Iowa.

Radar image of the photograph above it, with my position indicated by the target icon.

4:20 pm. Eastbound on Boyson Road, just west of C Avenue NE in Cedar Rapids. Boiling storm cell is located about 18 miles distant, near the town of Morley. Nikon D7200 DSLR camera.


Perseids Peak Day One

Saturday, August 12, 2017

This multi-colored meteor streak was the first of three bright meteors I captured from Bowman Woods Park in Cedar Rapids, Iowa during the pre-dawn hours on Saturday, August 12, 2017--part of the Perseids Meteor Shower. This particular meteor--captured at 4:10 am CDT--featured a trailing vapor trail, but the trail was rendered invisible to the camera by the glare of the waning gibbous moon, whose light wash can be seen in the image at right. I selected this open area of the park with a clear view of the northeast sky and a wooded area to my back to block some of the obnoxious moonlight. Temperatures at this time were a surprisingly chilly 52 degrees F, requiring me to wear a light jacket. But not a single bug bothered me! The meteor is seen streaking through the constellation Auriga in this image. Above Auriga is the constellation Perseus--the radiant of the meteor shower. Below right of Perseus is the Pleiades, and below that the constellation Taurus. At bottom center of the image, just above the tree line is the -3.98 magnitude planet Venus, and at bottom right is the partially obscured constellation Orion.

4:14 am. Meteor number two, just left of the planet Venus at bottom left.

4:30 am. Meteor number three, just above and left of Venus.

Composite image of all three meteor images.

Stacked image of all shots taken during this session. A total of 156 20-second exposures were used, starting at 3:43 am and ending at 4:36 am. The settings for each exposure was f/2.8, 200 ISO, 11mm focal length. Nikon D7200 DSLR camera.

Closeup of very top image. Multi-colored Perseid meteor streak in the constellation Auriga. 4:10 am.


Revised Solar Eclipse Procedures, Revised Objectives

Friday, August 4, 2017

Continued research has caused me again to change my planned photography procedures for the total solar eclipse on August 21. For the partial eclipse phase, not a lot has changed from the last posting, except for these: It IS in fact possible to autofocus on the sun while the solar filter is attached. After autofocus is achieved by this method, I will switch to manual focus and further secure the lens with a small strip of electrician's tape. Bracketing will be the name of the game. The above Nikon D7200 DSLR image, captured handheld at 3:37 pm CDT, Friday, August 4, 2017, was part of a 7-stop bracket, set beforehand at 1/1000 second, f/5.6, 300mm focal length and 320 ISO. The best image of the seven (above) turned out to be a 1/1600 second shot, later enhanced in Adobe Lightroom 6. Note the sunspot at left.

As far as revised eclipse objectives are concerned, my new one may have been influenced a bit by some professionals out there who advocate a first time total solar eclipser to "forget the cameras and just experience it by eye." Duly noted, but to the sky photographer in me, that would be blasphemy! Well then, what about a compromise? Again, bracketing to the rescue. Just before totality occurs, the camera will be mounted on the tripod with only a settings change in shutter speed--now at 1/80 second. With the seven-stop bracketing available, a good capture of the sun's corona should be possible just after the show begins and the solar filter is removed. I will only have to concentrate on the sun being centered in the viewfinder for the opening moments. This hopefully will leave me with about 2 minutes worth of free and naked-eye enjoyment of this once-in-a-lifetime event!


Solar Eclipse Photography Practice

Thursday, August 3, 2017

Practice for the upcoming August 21 total solar eclipse. This session on Thursday, August 3, 2017 involved handheld captures and bracketing. My lens of choice for the event will be my Nikon AF Nikkor 70-300mm 1:4-5.6 G lens. Although not creating a particularly large image of the sun's disk, it will hopefully allow for a good view of its corona during totality. For capturing the partial eclipse phases, I will use my 62mm Seymour Solar Helios solar filter. This is a front threaded filter.

For the partial phases I will capture the sun with my Nikon D7200 DSLR camera handheld. This is because in my opinion it is not as critical to capture minute clarity during this time, and finding the sun in the sky is quicker. I have discovered that locating the sun at 300mm focal length is more difficult than one might think! My focusing procedure is as follows: I autofocus on a distant sky object, such as a cloud or aircraft (infinity setting is rarely accurate). I then switch to manual focus and further secure the lens with a 3-4 inch strip of electrician's tape. After this is done, I will thread on the solar filter and attach the lens hood (Nikon HB-26).

The composite image seen above is from today's five-stop bracketing sequence of the sun. In manual mode, I set the shutter speed at 1/800 second, f stop at 5.6 and ISO 320. From left-to-right, the shutter speeds created from bracketing are 1/3200 sec, 1/1600 sec, 1/800 sec, 1/400 sec, and 1/200 sec. The larger sun is an HDR-created image of the five. Note the sunspot at left of the sun's disk.

For the totality phase the camera will be mounted on the tripod, sans filter. I plan to use the same f stop and ISO, but will change the shutter speed to accommodate the low light. A remote cord will be used.


July 19 Clayton County Iowa Severe Weather

Saturday, July 29, 2017

An Enhanced Risk for severe weather for northeast Iowa was posted by the Storm Prediction Center on Wednesday, July 19, 2017. Sustained severe weather moved east from South Dakota in the morning into southern Minnesota and northern Iowa, reaching Clayton County by 5:50 pm. Before its arrival, I selected an open spotting location on Highway 13 at the top of a hill about one mile north of the town of Strawberry Point. Above, I await the approaching storm at 6:04 pm in this panoramic image facing northwest. Note its wind-driven "cake layered" appearance.

6:08 pm. The leading edge of the storm, now about 7 miles distant, has taken on a shelf cloud look.

6:11 pm. A dramatic capture of the leading edge of the shelf cloud in the NNE sky.

Also 6:11 pm. Turbulent leading edge of the shelf cloud in the SW sky. Storm movement was right-to-left in image.

Vertical capture of the same view a few seconds later. The leading edge of the shelf cloud has generated small and very brief funnels.

6:12 pm. The shelf cloud has created an sun-illuminated arch as it moves toward the back right of this panoramic image (southeast). Nikon D7200 DSLR camera.

Radar capture of the area for 6:05 pm. Note the red tornado-warned box in NE Clayton County.


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