The D700 Does Astro, and Rules!

Best friends: the D700 and the ED80

Well, can't believe it, but I just got using my D700 for astrophotography for the first time over the course of 2 of the past 3 nights. Yes, that's right, after nearly 6 months, clear, moonless nights finally fell on my nights off from work. So, after a pair of nights shooting with the D700 under the stars, I can feel pretty safe in offering some commentary on its under the stars capabilities.

Three words: the D700 rules!

1. To start with, for anyone who does AP and doesn't have a live view dSLR, consider dumping your current camera and getting one. On my old Canon 30D, I focused on bright stars through the viewfinder and then started taking short focus test pictures to dial in exact focus. To do this, I would take a picture, blow it up all the way on the LCD and, if it looked a little out of focus, would then turn the knob on the scope, shoot, and check again, comparing the current to the last picture to look for a change. I'd do this again and again until the stars were at their smallest. Sure it worked, but it was quite a pain in the neck. The D700? Just go into live view mode, zoom in all the way on a 2^nd to 3^rd magnitude star (brighter ones glare and are harder to focus on) and just turn the dial until the star is at its smallest and, presto, perfect focus all night.

Try doing this at 600mm with an APC-C cam!

2. More forgiving polar alignment. With the D700 and its monster FX sensor, one loses a lot of magnification power as your scope essentially shrinks by a third compared to when it's used on an APS-C camera (My Orion ED80 goes from “900mm” to a true 600mm focal length). However, on the plus side, with that loss of power, one doesn't need to be as precise in polar alignment, which is another time saver as less time spend fiddling and measuring your mount, taking test shots, and adjusting means more time for photographing deep sky wonders.

3. No cords. Coming from camp Canon, not a single Canon dSLR offers a built-in intervalometer function, not even the top of the line 1D models. Nikon? You can get this all-important for astro feature with the $1,300 D7000. Why does this matter? Simple, cords are a pain in the neck. In addition to providing more things to mess around with, a wired remote can, unless you have a way of attaching it to your mount, fall off from the spreader and pull itself out of the camera just enough to not make it work. The D700? Just dive into the menu, go to the 'timed shooting' function, set yourself up, press the 'ok' button and forget it, you're shooting all night without any stupid wires to worry about.

4. Battery life. The D700 is like the Energizer Bunny, it just keeps going and going and going . . .

A test shot of M22 for 8 seconds at ISO 6400
5. Noise (or lack thereof). After playing with a D7000 and owning the D700, I can honestly say that the 4 year old FX sensor is still at least a stop better than the best current APS-C chip. So, if skyglow is not a problem, feel free to crank it up to even ISO1600 in order to maximize the photons you capture in your RAW (or NEF in Nikon lingo) files.

Now, not all is rosy . . .

There's no way around it, that big FX sensor has drawbacks, namely vignetting with less than perfect glass. In the case of the ED80, there's no denying that the scope doesn't fully cover the sensor. However, with your scope, this may be different. So far, my 120mm f8.3 achro doesn't seem to have any of these problems. However, when shooting through the little apo, the flat frames will be a must!


Author's note:
Please excuse my hasty processing, once I do it the right way with a hundred light frames (plus all the rest), the results should be truly spectacular.

 

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