Why another picture very similar to the first one?
After I uploaded the first picture of the ceiling of St. Peters church, I was asked if it would be possible to buy the file for restoration purposes.
Naturally I’m not opposed to selling my pictures but the first picture was a labour of love to show the wonderful symmetry of this church therefor I haven’t thought of making a large reproduction.
The mixture of daylight and tungsten lighting as well as the equicircular projection, made it impossible to use this image for restoration purposes.
So I decided to make a new picture, this time using my 300mm lens.
The reproduction presented the following challenges:
1. Without synthetic light, the fresco is too dark.
2. As said before, the mixture of daylight and synthetic light is very bad for colour accuracy.
3. The Viennese authorities has installed 2 extra lights, one in the centre of the dome where you can see the bird -which symbolises the holy spirit- and one in the front window.
Unfortunately the colour temperature of those lamps is completely different from the dome lights and it’s not possible to switch them off. They are switched on until 12pm.
4. The centre of the dome has no additional lightning except those with the different colour temperature.
5. The first test images showed, that with 300mm focal length even at F 14, the depth of field is not enough. F 14 is the smallest aperture for getting 100% sharp images with a 5d)
So, the final image will have a lack of sharpness in many areas.
The problems with the lightning were solvable, although rather inconvenient: I started the shooting at 12pm as the extra lights are switched on until 12pm.
The colour temperature I worked out with a grey card. Nowadays, most photographers are using a sensor for metering the colour temperature but I don’t trust this method. With a sensor you can only meter the colour temperature before the light passes through the lens, but each lens has it’s unique colour shift, with a grey card you are able to meter the light after passing through the lens. That’s why I prefer the "old fashioned" method.
Because the centre had no lightning, it was underexposed at this moment. After taken all the images I had the idea to make the central images the next day and try to combine the two images later. I marked the tripod points and took the 4 central images the next day.
This time with the centrelight only to avoid white balance problems due to different lights.
Combining the two images was the last step and took some time but worked very well.
To solve the depth of field problem I took all images below the fresco with two different focusing points.
Before the stich I combined all pictures with different focusing points and I was really astonished to see, that for some images, particularly the windows, I should have better taken three focusing points.
But in the end I think I got a really good and large repro