Tag Archives: nex

On averaging(,) wool and the shadow test

Noise is your friend, noise is your enemy. Depends on who you are. For a photographer noise is mostly unwanted.

So there are millions of options and tool, how to get rid of noise. The easiest one being reducing your ISO to 200 or lower. This might be OK if you have time and lots of light.

But there are other methods and I was trying out an interesting one: Image averaging.

Noise comes because the camera is afraid ?!

Noise comes because the camera is afraid ?!

Averaging is a method which depends on one fact: The noise in the pictures is always different. Basically you take some pictures, treat them and put them together in an image editing program by a special recipe. Each layer gets the following opacity in percent:

100 *1/(number of layers below + 1)

Hence the number sequence starting at the bottom is 100, 50, 33.3, 25, 12.5 and so on. If you want to get a little bit more theoretical background, have a look here at Cambridge in colour (a wonderful site for noobs and pros).

I tried it once with a moving shadow (top picture), which consists of 3 shots at ISO 1600 and one macro with the Yasuhara Nanoha at f/32 and ISO 100 (but longer exposure: 1,6 seconds), just enough to get enough light and not have the wool move because of the warmth of the light. I have the impression it also improved the sharpness.

I will definitely try again with macros.

Red wool

Red wool

At the end a small tipp for users of pixelmator: You can add pictures as layers by using the menu only. And the funny part is: You have to add every single picture as one. Red wool consists of 7 pictures…  …boring work until the fast guys from pixelmator bring us a new feature 😉

Quick test: Noise on Nex-7 video

I tried to find out what the impact of the ISO on video on the Nex-7, so I cycled through with the lens cap on. The noise was not that visible so I tried to do what you usually try to avoid. I added brightness and sharpening.

Let me know, what you think. For me it prooves my experiences, that videos start get noisy with ISO bigger than 800.

Review of Sigma 30mm f/2.8 EX DN Sharpness

So I made some further observations after the first review yesterday. I also got a message telling me that other and more detailed shots are needed to see. So here we go. Below you will find the corner and center crops from shots I took today in the morning. The shots were made handheld and the ISO was limited to 100. First the center shots of a street scene using apertures 2.8, 4 and 8 As you can see, the center gets sharper at f/4 to soften up at f/8. Next you will see the details in the upper right corner. As you can notice there is a slight purple fringing which gets softer when the lens is stepped down. Strangely enough the shot at f/4 is not sharp. I think the branch has moved in the wind, but the wall looks sharper.You can find the full SOOC shots here. As a conclusion I have to say, that for me the lens is very fine wide open. I haven’t considered if I prefer f/8 or f/16 for my night cityscapes. What still is strange to me is that the lens falls in to a resting position when turned off with a hearable soft *tock*. What I have not tested by now is the fact, that the lens seems to take long to “boot” – the Iris is closed and opens wide only to get stepped into positions. I will save this for the next blog entry. If you have questions you can also leave a comment. @Edit20120420: A reader mentioned that he thinks the blurriness at f/4 in the corner could be due to the exhaust of the truck you see. This sounds reasonable as everything is a little bit blurry in that corner.