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With a laser mounted in the center of the secondary, we can bounce it off the center of the primary (with a special plug inserted for this purpose) to see both how well the secondary is pointed at the primary, as well as how co-linear they are. This is important to make sure the telescope is in focus.
Picked up a used 6" reflector telescope that needs alignment often. Came with a laser "eyepiece" and instructions.
December 6, 2025 - Sunrise alignment at Angel's Gate Lighthouse. Photo Shoot with Mario Duque, Ryan Torres, and Austin Dewart at 6:47 AM.
Part of the Alignements de Lampouy in Brittany, Northern France. Again, these alignments are a few thousand years old. It's not known what they signified, though my guess is something about the sun, the moon and the seasons. It reminded me so much of Kilmarten, Scotland. These were visible from the road. The still-standing menhirs nearby were not visible from the road, and we saw them only when we were looking at these. Read my travelogue for trip details. September 2007.
Former Pacific Hwy alignment through Murwillumbah bypassed with the opening of the Chinderah - Yelgun deviation in 2002.
The NSW Main Roads Department had to build this "cow bridge" when a short deviation was made through this cutting, as the new road bisected a dairy farmers access. It looks like it is still used to herd the cows to and fro.
Another BIG painting! I wanted to try the Liquitex Basic paint and I only have one tube so I went with that and some Craft Titanium White. Turned on the music and sang along with Carole King, great music and just perfect for me. I was a bit hesitant to start, but once the brush hit the canvas (cardboard) the rest was wonderful. Connie, you're an angel for sharing this with us.
When putting back together I notived the alignment was creating shadows. In this picture, I tried to highlight what a bad alignment looks like. A shadow midway in each sectional.
Workforce Alignment workshop "Building strong partnerships to support Wisconsin’s workforce need." A conversation hosted by UW Oshkosh, Department of Workforce Development, Fox Valley Tech and WAICU.
Aligning the head on the floppy disk drive using an old Amstrad laptop and a test unit called a 'Microtest' This uses the normal analogue alignment disk. Note the special alignment tool screwed into the stepper motor bracket at the rear of the disk drive (left side in the photo)
I'm trying to find out the following:
* does optical distortion of a lens at a given focal length change with aperture.
I did this by taken 2 pictures at 2 different apertures and identical focal length.
I overlayed them in gimp and set the layer type to subtractive. so what you see is pixel A - pixel B. i.e. the greater the difference, the more luminance and color. Less difference the more black.
However, I forgot that it would be a good idea to pick a focal length that actually shows some visible distortion so the effects can be more easily seen.
As it stands, this lens is pretty ok at 31 mm.
I do notice that it is not possible to align the images entirely. In the image, you can see that I aligned both layers so that around the 92cm mark, the millimetre marks are most black and with the least halo like edges.
The green edges which you can notice at the decimeter marks (the boxes) are on the right side in the left side of the image, and vice versa on the left side of the decimeter mark on the right side of the image. This to me seems to indicate some sort of a scaling issue, i.e. likely caused by zoom lens creep.
I've prepared another alignment this time properly done on the left side. the difference is about 6 pixels. Relatively speaking: +/- 0.05% as measured from the center.
What Does show though is that there is no barrel/pincushion distortion difference between the f/4 image and the f/22 image. Sadly, looking up the measured distortion for this lens, dxomark.com reports 0% distortion around the 30mm focal length:
www.dxomark.com/index.php/Lenses/Camera-Lens-Database/Can...
So even if there was an amplification effect of aperture on distortion, this experiment fails to show it due to hitting the perfect distortion free focal length for this length.
Another round at 24mm is needed I'm afraid, since the lens doesn't fare so well with regards to distortion.