JPEG Compression

Instead of talking about JPEG-Compression and its artefacts I'd rather show them to you.

JPEG is a format for image files which where the file size can be significantly influenced. The smaller the file size is the worse will the picture look like, especially in its details. This is because the JPEG compression in general is destructive.

Strictly spoken there is a number of compression algorithms standardized and possible within JPEG files. It is currently being discussed to introduce some additional non-destructive algorithm to the JPEG specification. However, I don't want to go into details of what theoretically may be possible but want to focus on the most popular algorithm which is very widely used. When you just click on "save as jpeg" then this is most likely the algorithm that is being used.

How UV-Filters may Damage Your Photographs

Often UV-Filters and similar (Sky, 1A, KR1, etc) are used for pure protection purposes only. Whether a filter is capable of protecting a lens at all is questionable and heavily discussed in the web. This article, however, focusses on the cost of this questionable protection - the damage that filters can do to your actual photography.

This kind of arrebation is always there when you use an UV filter for whatever purpose, although it is significant and clearly visible on night shots and other situations with very high contrasts. While collecting these example photographs I got a studio photography with two women in front of an illuminated white background. The girl's silhouette was visible in each other's faces caused by the same phenomenon that I am presenting here. Unfortunately one of these ladies did not agree to publishing the photograph in this context. That I have to respect.

For a start I show you the effects that Axel observed when he photographed some firework with a filter as protection.

Feuerwerk mit Spiegelungen der Feuerwerkskörper am Himmel

While sharping a photograph, it really does not become any sharper because no algorithm in the world can create image data that has not been there before.

The algorithm detects edges, that is where areas of different color or brightness actually touch. In the areas surrounding these edges the contrast is enhanced.
Doing so, it well creates an impression of sharpness.

 

(Unsharp mask with various values for radius. The original is top left.)

 

How to get proper images of a firework

Cheat-Sheet:

  • Use a good tripod
  • Use a remote control (a simple cable trigger is best)
  • 100 ISO and apetrure 11 or 200 ISO and f/16 respectively (starting point)
  • M + bulb or B
  • Focus manually to infinite
  • Release the shutter before the firework display (individual figure) begins, close it when it is finished.

Don't do new year/hogmanay

About 99.9% of all well done firework snaps are from professional altitude fireworks. Private fireworks play in a different league. You hardly know where exactly is is fired, how high it gets and the air is full of smoke. (And you are probably not sober yourself and will make mistakes :-) )

How the Sun may damage your Camera

Luckily this never happened to myself.

During the past years I saw worried questions about this risk in various forums and discussion groups. Amongst them I found view reports about actual damage. Some of these amateur photographers I asked for sample pictures and the permission to share it in this article. So don't thank me for this article but thank them for sharing their experience. However, I do not name any publicly because I don't want to expose them to any kind of embarrassment.

When the sunlight falls through the lens into the body then it will meet the inside of the body more or less focus. Basically that is what the lens is about, to focus the motive on the pane of the sensor or film. Let us look at this more closely in two scenarios.