Another Post-Thanksgiving Outing

It was such a perfect Thanksgiving weekend - Temps in the low 70s and a perfect blue sky. On Saturday was the final football game of the year - archrival Arizona State was in town for the big game. If AZ wins, they qualify for a bowl game, lose and they are done till next Fall. Can't get much more dramatic!

I took the opportunity to do a little road trip to "A" Mountain, otherwise known as Sentinel Peak, located about a mile to the SW of Tucson's downtown area. It has a paved road to the peak, a few hundred feet above the desert floor and the view extends from south to north - an expansive view that is popular all day long!

I chose to set up my TEC 140 refractor and take some photos of my favorite landmarks, and with Arizona Stadium a mere 3 miles away, used it as a target to evaluate a 2X converter (doubled the focal length, thus the scale of images). At left is a photo taken with a 50mm "normal" lens with my fave targets labeled.

I've used this telescope to image AZ Stadium before. Seeing effects (atmospheric turbulence caused by mixing of different temperatures of air) usually limit the sharpness at 3 miles distance. But still, the scope is ALMOST sharp enough to recognize people from 3 miles! Shown here are the full frames of the Canon 6D of the stadium view. Clearly seen is that in the view with the 2X converter at right, the image is larger and field of view is narrower. The real question is whether use of the converter provides any advantage, or can you just enlarge the straight image in Photoshop...

Of course, the real limitation on this blog is that images are limited to 1600 pixels wide, while the camera has almost 5500 pixels across the image! So just showing you the full image above you are losing a huge amount of resolution because each pixel there shows an average of almost 16 pixels in the original image (4 across and 4 high).

So here is the answer. Shown here at left are full resolution crops from single images from each configuration. The fields of interest are the same - the 2X converter version below is on the left side without the converter so you can compare directly (taken a few minutes apart, 2X later). It looks fuzzier, but again, because the scale is doubled, is resolution any worse? I think the answer is no - the bowl games played are about equally legible, as are details in people and clothing being worn. I think both are limited by the atmospheric turbulence - the effect can be seen in the horizontal white line in each - wiggles seen in it is caused by turbulent air mixing at these large magnifications... Oh, and by the way, I went to some length to minimize vibration - used a 2-second delay after pushing the camera button, and also locked up the view mirror to minimizw "mirror slap". So it is a wash for distant objects to use the converter or not. Perhaps closer objects less limited by "seeing" might work better with the 2X converter...

I then moved to a few of my other favorite targets. At left is the old Pima County Courthouse, with its distinctive tile domed roof. It is interesting that it is seemingly surrounded by newer boring architecture...

Also photographed, but not detectable by eye mid-afternoon was the "window" of Window Rock. A good 16 miles away from my "A" Mountain observing location, it is visible by eye from Midtown when conditions are right - preferably evening or morning twilight. Here the scope makes shooting it simple!




I also did a 10-frame mosaic past AZ Stadium up through the NE side of town. Combined together in Photoshop it shows the stadium, Catalina High School just above and left of the stadium (in truth about 3 miles past it!), Tucson Medical Center upper left of stadium, then the Mount Lemmon Highway which leads up the mountain in the far distance on the NE side of town. Right about where the road disappears, "Bad Dog" overlook can be seen - another favorite lookout of mine! Of course, here the mosaic is only the 1600 pixel limit wide - was more fun in the original nearly 15,000 pixels wide with the full camera resolution...

And one more shot are some of the homes creeping up the foothills of the Catalinas. I think these are about 12 miles away and you can see how they get permission to build right next to the National Forest boundary considerably up the slope of the foothills. Good thing they don't get much snow and ice here - can you imagine climbing those hills in slick weather?!

After an hour taking in a shooting the view, I headed home. It was an exciting game - the home Wildcats hanging on to a thin lead, then at the end the "Scum Devils" overtook and won the game by a single point! Next year!