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iPhone 13 Pro Max Globular Clusters,
D850 DSLR ISO Tests

Posted: 5 November 2021

Open: Thursday, 4 November 2021, 1809 MST
Temperature: 79°F
Session: 1687
Conditions: Clear

12" f/8 LX600 w/StarLock
2" 24mm UWA eyepiece
1.25" 15mm eyepiece
Focal reducer

iPhone 13 Pro Max

1815 MST: LX600 ON, StarLock OFF, High Precision OFF.

Viewed Venus, 102X and 163X. Viewed Saturn, then Jupiter, 163X.

1828 MST: Dome OFF.

Viewed M15 (globular cluster), 163X.

1830-1900 MST: Prepared D850 DSLR for imaging. Then relaxed on the observatory patio bench while waiting for the end of Astronomical Twilight.

Back in the observatory, observed M15, 163X. Mounted the iPhone 13 Pro Max on the 15mm eyepiece using the Levenhuk adapter. I also used the LiDAR cover. Took the following StarLock autoguided images of these globular clusters using NightCap Camera. Some were low in the sky when imaged.





M73 (open cluster)


Viewed M33 (Triangulum Galaxy), 102X.

Mounted the D850 DSLR at prime focus + focal reducer to do some ISO setting exposure tests. I have been wanting to do this for a long time; the Sky & Telescope article "Understanding ISO" (December 2021 issue, pages 54-56) prompted me to finally do it. This M33 (Triangulum Galaxy) image, StarLock autoguided, 5 minutes, ISO 100, White Balance 4550K, edited, is just a sample. I will post a full article on my D850 DSLR ISO tests once I complete the tests.


I then viewed Jupiter, 102X.

2056 MST: LX600 OFF.

2100 MST: Dome ON.

Next, I mounted the D850 DSLR on a camera tripod (non-tracking) for more ISO tests. This is a sample image, f/2.8, 10 seconds, ISO 100, FL 24mm) showing the Pleiades (M45) and the Hyades near the center.


2125 MST: Took a Sky Quality reading and reported the result to Globe at Night.

Close: Thursday, 4 November 2021, 2134 MST
Temperature: 62°F
Session Length: 3h 25m
Conditions: Clear, SQM 21.07

After I closed the observatory I went to El Rancho Robles Historic Guest Ranch and then the "remote area" at Oracle State Park to take some Sky Quality readings. Some attendees at the "2nd David H. Levy Arizona Dark Skies Star Party and Astrophotography Workshops", to be held at Oracle State Park, 22-25 September 2022, may want to stay at the ranch. Details on accommodations and the event are still being worked out.

The Summer/Fall 2021 issue of the Indiana University Alumni Magazine has an article on IU keepsakes. This is what they showed on page 39:

(Courtesy IU Alumni Magazine)

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