Pinched optics – the cure

If you’ve been following my geeky astronomical posts lately, you’ll see that my new telescope suffers from triangular stars, caused by pinched optics. I’ve also been posting about the problem on Astronomy Forum. Just to recap, the telescope currently produces pictures like this. The effect is subtle, but if you click on the picture to […]

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Pinched optics

I’ve been having an ongoing problem since buying my telescope a couple of months ago. Stars appear triangular, as you can see in this picture of Pleiades. I’ve done some research and it seems the most common cause of triangular stars is a defect called “pinched optics”. The primary mirror in is held in place […]

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Long telephoto lenses

If you want to take photos at the so-called “super telephoto” range, then you have a few options. They have relative costs and relative merits. Let’s go through the main ones. Genuine super telephoto lens I’m a Canon shooter, so I will refer to the Canon lenses – but the same applies to Nikon, Sony […]

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Mirror lenses: worth it?

A few weeks ago I attempted to take some photos of the moon with my 300mm lens. The results were pretty good, but I wanted more, more, more! At 300mm, the moon is still quite small in the frame, and the photo I just linked was cropped a fair bit to “zoom in” some more. […]

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A new sculpture

This is a new sculpture that has been erected in Royal Fort gardens to commemorate the centenary of the University of Bristol. It’s a series of tall, narrow mirrors arranged to make a maze. Like a house of mirrors – with gaps. I recommend giving it a visit!

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