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I am wanting to shoot some star trails and from a test shot I did I would ideally like about 45 mins of exposure time. However when I did my 8 min test shot it took almost 4 mins to write to card in Jpeg format. I have 3 spare batteries but no battery grip. I shoot with a Nikon D700 and only have CS3 software and photomatix. How can I manage this without getting any gaps in the star trails.
:How long would exposures need to be if bracketing them?
o bracketed shots continue to write to card as your taking them or start writing after the last shot is taken.
:Would it be possible to change a battery if it ran out?
: If he camera did alter position slightly changing a battery, would photomatix stacking alignment tool cope with star trails?
If there is no alternative to buying a grip then I will have to abandon the idea.
First thing forget about photomatix for star trails. Photomatix is used for HDR. Instead shoot RAW not JPEG (good practice anyway even for HDR). It will create problems with movement - stars and will either ghost or remove the trails. With one RAW set to 14 bit you can get just as much detail as 3 JPEGs at 8 bit in HDR.
From what you describe it sounds like you have long exposure noise reduction on - turn it off.
There are a couple of options either one long exposure, or 80 x 30 second exposures stacked in Photoshop to do this set to 30 second continuous shooting. Watch for fogging of the lens. Also when finished take 1 x 30 second exposure with the lens cap on so if the resultant image is noisy you can do a dark image bias (basically subtracts hot spots).
Noise with HDR would also be incredible with such a situation - even worse with JPEGS as you will be accentuating the sharpened artefacts.
Last year I took some star trails with my D300 (which is essentially a DX version of the D700) using exposures of up to 30 minutes.
I did have the battery grip on (so 2 batteries available) but, from memory, taking several such exposures in sequence did not even begin to use the second battery. So battery life should not be a problem and battery changing should not be necessary. By the way, you cannot change batteries mid-exposure.
If you are using a VR lens, make sure the VR is turned off. Also ensure you are not using AF. When you are using your camera in what is, essentially, a totally manual mode, battery drain should not be significant.
With exposures like that, you do need to ensure that there is no foreground or background illumination. Otherwise you will have those elements grossly overexposed. If you do want a foreground set against your star-trail sky, then fake it in Photoshop.
The advice from Nick above is very good, as he said your exposure write time will be the noise reduction, its best to turn this off.
One bit of advice I would add is to take a powerful torch to help with focusing. If you can find the North start try using this in your images.
Your D700 will have no problems doing an hour exposure and this is normally plenty.
There are advantages and disadvantages of both one shot and the stacking method. One disadvantage of the stacking method is you have gaps in the star trails from the delay between each shot, with most cameras this is normally around 2 seconds, you don’t notice it so much at smaller sizes but if you plan on blowing the pic up to a large size you will be able to see the gaps close up. The major advantage of the stacking method is your sensor gets a chance to cool down slightly during the gap between each shots so you get a lot less noise overall.
I was commissioned to shoot a book on just night images last year so I had to do hundreds of different star trail shoots and I still don’t have a preference over the stacking V one long exposure method, I think both methods work well and the look of the images is also very different. As I said there are lots of advantages and disadvantages for each method so I would recommend trying both on the same shoot and seeing which one you prefer.
The D700 has far more drain on the battery than the D300 - they use the same battery, and I moved from the D300 to the D700 (one of the few areas IMHO where the D300 is better).
Although I have had images to several minutes on the D700 with no problems (no light trails but using the big stopper) - One thing use the viewfinder shield or you will gety a horrible horizontal line (from experience).
Check out the work of John Patrick
http://www.ephotozine.com/user/newfocus-44720/gallery/photo/an-uninhabited-corne...
He has some excellent examples - not many of his exposures are longer than 20 minutes and thats at ISO100. Remember the base ISO of the D700 is 200 and thats where its at its best in terms of noise. (I find 400 better than 100 on the D700). So I would say 30 minutes may be too long unless you stop down to F11. F5.6 - 8 should be sufficient, or you will lose detail in some of the fainter star trails.
At base ISO you will be able to pull back a lot of detail out of the shadow area with the D700.
Quote: So I would say 30 minutes may be too long unless you stop down to F11. F5.6 - 8 should be sufficient, or you will lose detail in some of the fainter star trails..
Nick,
In terms of basic exposure you are probably correct. But when taking star trails, a smaller aperture and longer exposure are often desirable in order to create the desired length of the trails. The ones I did were at f/22 for that reason. In fact, I thought about using an ND filter just to allow even longer exposures and, thereby, even longer trails. (but it was a cold night so I chickened out!)
Thanks guys, all good quality advice, which is what I always get from these forums.
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