ASTROPHOTOGRAPHY WITH THE NIKON D70 DIGITAL SLR CAMERA Last updated: 17 May 2005

Prime Focus Astrophotography
Using the Scopetronix T-Adapter and T-Ring for the D70 I did some prime focus astrophotography through each of my telescopes. You can use these to determine what your results might be depending upon what telescope you have. Here is the set up on the night of 14 May 2005. From left to right: LXD55-8"SC w/UHTC, ETX-125AT, ETX-105PE w/UHTC, ETX-90RA, ETX-70AT.

All of the following test photographs were taken using an ISO 200 setting and the wireless remote to trip the shutter for the exposure. Exposure length and whether a 2X Barlow Lens was used is noted for each photograph. Image size was set at 1504 × 1000 with the quality set at JPEG Fine. Noise Reduction (NR) was enabled. Images have been edited (levels and sharpening, as needed), their image size reduced and JPEG compression applied. The "hat trick" method was not used for any exposures so vibrations due to DSLR mirror flipping may be evident.

Moon

Nikon's 18-70mm lens set for 70mm full telephoto, 1/160 second

ETX-70AT, 2X Barlow Lens (could not focus without it), 1/30 second

ETX-90RA, 1/30 second

ETX-90RA, 2X Barlow Lens, 1/15 second (longer exposures experience mirror flip vibration)

ETX-105PE w/UHTC, 1/30 second (mirror flip vibration at this and longer exposures)

ETX-105PE w/UHTC, 2X Barlow Lens, 1/15 second (mirror flip vibration at this and longer exposures; camera automatically detected portrait mode; DEC lock did not hold due to the weight)

ETX-125AT, 1/30 second (mirror flip vibration at this and longer exposures)

ETX-125AT, 2X Barlow Lens, 1/15 second (mirror flip vibration at this and longer exposures; camera automatically detected portrait mode)

LXD55-8"SC w/UHTC, 1/30 second

LXD55-8"SC w/UHTC, 2X Barlow Lens, 1/2 second (camera automatically detected portrait mode)

Saturn

ETX-70AT, 2X Barlow Lens, 1 second

ETX-90RA, 2X Barlow Lens, 4 seconds

ETX-105PE w/UHTC, 2X Barlow Lens, 2 seconds

ETX-125AT, 2X Barlow Lens, 2 seconds

LXD55-8"SC w/UHTC, 2X Barlow Lens, 1 second

Jupiter

ETX-70AT, 2X Barlow Lens, 1 second

ETX-90RA, 2X Barlow Lens, 1 second

ETX-105PE w/UHTC, 2X Barlow Lens, 1 second

ETX-125AT, 2X Barlow Lens, 1/2 second

LXD55-8"SC w/UHTC, 2X Barlow Lens, 1/2 second

Five things are evident from the above:

1. Need to turn off the automatic orientation detection in the D70.

2. Need to use a higher ISO setting and/or the "hat trick" method of covering the telescope aperture, opening the camera shutter, flipping the cover out of the light path for the duration of the exposure and the back, and then close the shutter. Otherwise vibration due to the mirror flipping is a problem, especially on the ETX models.

3. Focusing is difficult, especially with small aperture telescopes or high magnification. Using a "Hartmann Mask" would help.

4. Use of a higher resolution (the D70 can go up to 3008 × 2000) will allow cropping to increase the effective image scale.

5. For planetary photography the use of short exposures and stacking would help tremendously. I'll be working on that soon.

Watch for future updates. I will be doing more astrophotography with the D70.

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