Wednesday 15 July 2020

Night photo update on Raspberry Pi HQ camera with 16mm lens

To continue from yesterday's post, yesterday evening I took some photos of near and far street lamps (heavy cloud so no stars...). The results show the same effects, but possibly more pronounced.

Overall the bloom is greatly improved by stopping down to 2.8. In some circumstances there may be a further slight improvement by going to F4, but the difference is pretty small.

All these photos are taken with 2 second exposure.

Tuesday 14 July 2020

Raspberry pi HQ Camera and 16mm lens quality

The 16mm lens sold alongside the Raspberry Pi HQ lens is a really nice lens. After some misgivings about the image quality I got with some early testing, some more careful tests show that the lens has a rather specific problem that can easily be avoided, although it does slightly limit what it can do.

I have compared the photos from the HQ camera and 16mm lens with the images from a DSLR (crop sensor) using a 55mm lens which gives very nearly the same field of view. I also did a couple of tests using the canon lens with the Raspberry Pi camera, and there is little improvement (if any) over the results with the standard 16mm lens. Give there is 15X price difference, this is pretty remarkable.

 What is the problem?

The only problem I have found is that wide open (F1.4) the lens has significant bloom, which can really show up on some types of photo (Distant street lights at night have a big bloom around them; stars do as well, although it is not usually as noticeable.)

The good news is that this problem disappears rapidly as the lens is stopped down and from F2.8, there is no real evidence of the problem. Sample images at the end of this page.