|Two configurations have been tested:
- in parallel to the refractor on the GP-DX equatorial mount, no guiding, using two diffrent lens: 180mm f/2 Nikon and 28mm f/2.8 nikon
- at the focal plane of the Astropysic ED120 refractor, GP-DX mount, no guiding
All the images have been acquired in Raw format.
To avoid the "stars filtration" effect, the mode 3 is used:
- Set the camera in "noise reduction" mode
- At the end of the exposure, the camera will start automatically the dark image acquisition. Shut-down the camera. The green light indicating that the camera is writing the image on the memory card is flashing.
- When it stops flashing, power-on the camera to take the next exposure.
- The exposure being triggered by the IR remote controller, it requires that you select again this mode as the IR device is deselected when shutting-down the camera.
- You are now ready to start the next exposure.
The focus has been made "on the fly", using camera zoom or "hand-modified" olympus magnifier "vari-magni" to be attached on the camera viewer. This is clearly the weakness of the procedure, and it would have been better to transfer the image to the PC for a full-resolution display and iterative adjustment.
The image processing has been done using IRIS software. Three dark exposures have been acquired at the same exposure duration. The .NEF images are converted into .pic image with IRIS, dark subtraction, then converted back in rgb .pic images (convert to CFA). White balance is sometimes tricky to adjust. Additional processing using either ddp or modified equalization to enhance white aera and increase contrast.
|Raw ".NEF" image
||Dark Image Raw
||Same dark, with thresholds adjusted to enhanced contrast
||Final processed image