Deep sky with Nikon D70
Acquiring Deep Sky images is the real test to estimate the performances of the Nikon D70. Opportunity at Pic du Midi observatory was given under good observing conditions, this 2004 summer.

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

Images have been reduced and compressed compared to original size.

Milky Way one shot of 5 min exposure - 400ISO - 22th July 2004 - white balance Nikon program: "Cloudy" +2

Milky Way - cygnii area one shot of 5 min exposure - 800 ISO

Milky way one shot of 5 min exposure - 800 ISO

Images have been reduced and compressed compared to original size.

Andromeda Galaxy M31 two shot of 5 min exposure - 800 ISO - cropped

North America nebula two shot of 5 min exposure - 800ISO - 25th July 2004

H & X perseus one shot of 5 min exposure - 800 ISO

Dumbell one shot of 5 min exposure - 400 ISO

Omega Nebula one shot of 5 min exposure - 400 ISO

Lagoon Nebula one shot of 5 min exposure - 400 ISO

• Images with wide-field lens like the 28mm are quite spectacular, 5 minutes exposure with no guiding is acceptable.

• Images with 180mm tele-lens provide good view of messier object, with the vision of the sky around. With no guiding, some exposures have been rejected. Also, additional exposures would have been useful to increase the signal to noise ratio

• Images at refractor focal plane was quite challenging. Focus was done using a bright star. With no guiding, 30 seconds was the absolute limit and about 50% was rejected due to guiding glitchs. The temporay installation of the GP-DX mount did not help to prefectly aligned the mount, and no PEC was used. Few minutes of exposure is clearly not enough, the image quality can really be improved that way.