advise for star trails with the K10D?

[xpiotiavos]

hi all,

 

well, i was driving back to school the other night, and, when i noticed that it was a clear, cool, moonless night (and that i was in the middle

of nowhere, Alabama) I decided to pull over and try some star trail shots. i quickly realized that 1) i have absolutely zero experience doing

really long exposures and 2) i wasn't as alone on the highway as i needed to be for this kind of photography.

 

moral of the story is: i'm going to be trying this again first chance i get. i took the below shot with the K10D, 18-55mm II @ f/3.5 mounted

on a tripod (obviously). The exposure time was around 13 minutes, i think.

 

anybody else tried their hand at star trails with the K10D? (if you do, lets see the pictures!) anyone got any handy advise for my next

attempt?<div></div>

[orly_andico]

13 minutes is a very long time... i'm sure that image is very noisy.

 

there was an article in Sky & Telescope regarding doing star trails with DSLR. What you do is take multiple shots, say 2 minutes each, take 30 shots one after the other. Then stack them in Photoshop or similar so you get the complete trails. But each shot only has a very small "star arc" but with the benefit of having less noise.

[mountainvisions]

Looks good to me Adam.

<P>

I like the traffic trails, ads to a boring shot. Star trails without a foreground are kinda boring.

<P>

Nothing with the K10D, I actually haven't tried star trails in a while.

<P>

The main issue has been weather. It's either been cloudy, windy, rainy or cold when I've had the energy to do it.

And then there are just the times I've been too tired after a day of hiking/paddling to mess with it!

<P>

My only digit<a title="Star Trails Over The Raquette River"

href="

<img src="http://static.flickr.com/1226/1025572771_06d3b27f47_d.jpg" border="0"/>

</a>al keepers...have a few on film I need to scan but this is it for now:

<P>

<a title="Big Dipper Over Carry Falls" href="

<img src="http://static.flickr.com/1134/1026429154_c35cd8bc80_d.jpg" border="0"/>

</a>

[garydem]

some info-

 

-on dslrs if you try to hold the shutter open for a long time heat builds up in the sensor and electronics, creating noise. the longer the shutter is open the more noise. so what was possible with fiom slrs csnnot be done with the digital version.

 

-this does mean you cannot take a several minute exposure, you can but at some point the heat will build up and get you noise faster than the signal is recording.

 

-so, for astrophotography in observatories then cool the cameras using liquid nitrogen. you and i cnnot affard this setup. so what you do is to take for startrails a series of shorter shoits and use software to link them togetther. one such program is Startrails.exe. try google.

 

-the other pics of the sky is for such thing as the planets or nebuela. for this you do the same thing but instead of making a trail you stack the images. a program to use is Registax. try google. they have found thsat the camera to use, is, would you believe a digicam, in movie mode. simply attach to ma telescpoe and fire off 200frames or so and use registax to stack them. stacking addes the signal together, after thst yoiu use a dark fram and subtract out the noise. you are left with the subject against a black sky. see the registax website for examples.

 

-you need a tripod and cable release. if your dslr has mirror lockup use it for registax shots.

 

-for the moon see the next reply.

[garydem]

to take a picture of the moon you need-

 

long lens 1000mm(35mm equivelent) about.

high iso(800?) to force afaster shutter speed.

 

exposure-the moon, odd as it sounds is hign noon sunlit. just like noon on earth. we are 240000 miles to moon, BUT earth or moon is 93000000 miles to sun. that determines exposure. use sunny 16 rule. that is for a full moon 1/iso at f16. some use a sunny 11 rule for moon. This is called the loony noon rule. then bracket like crazy. shoot a very hign shutter speed to start, take more than 1 shot at each shutter speed(3) then go down to about 1/30sec.

 

use stong tripod.

 

use cable shutter release or self timer. if self timer this will take a while, and you will have to keep adjusting moon in viewfinder.

 

Use mirror lockup if your camera has it.

Turn IS,VR,SR off, your camera is on a tripod.

 

DO NOT TRUST LIGHT METER IN CAMERA. it is being fooled by all the black sky. even spot meter, if available will not help, it won't go small enough to get moon only. moon is only 1/2degree wide, smaller than any spot meter.

 

get away from city. turbulance and lights are bad news.

if 1000mm or so not available, use biggest available. crop in post-processing.

not as good as big lens but will work.

shoot many pics, you can always delete later.

 

happy moon pics. good luck.

also-

sunny 16 rule-

i/iso is shutter speed. if iso is 100 then shutter speed is 1/100about.

fstop is 16.0.

 

the f stop is f16. this a starting point. any lens is not at max sharpness at f16, so adjust fstop to f8 or f11, and move shutter acccordingly.

 

check moonrise times in your area. you want about 3 hours after moonrise to start your pic taking. this gives the moon time to get far enough above the horizon to clear the horizontal atmosphere and turbelance.

 

you also need crystal clear skys. NO rpt NO haze, clouds, or humidity. humidity is noticable if you have corana around the moon, this could also be haze. in which case shoot on another night.

 

happy moon pics.

 

gary

second reply-

on the subject of lenses-

 

i use the bigma(sigma50-500+1.4converter). a smaller lenses will work, you just have to crop. but, if cropping heavily do not expect a lot of detail, you just won't get it. though remember any lens is multiplied by the crop factor. so your 135 becomes about 200-205mm.

 

i shoot at iso800 and at f8.0 end up at about200th-400th of a sec. when start taking the shot i start at 1/1000 and go down to about a 1/30. i also shoot three shots at each shutter speed, thus increasing the odds of getting a good one somewhere in the bunch. i expect to hit the good shots as stated at about 200th-400th.

 

do not shoot if high humidity or haze or any kind of atmosspheric turbelence. it just is a waste of memory and time. i shot originally in a park in Detroit michigan on what i thought was a clear night, forget it. i actually got some good pics 200 miles north on the shore of Lake Huron. much better.

 

0ne thought, if available you can try putting a 2X converter on the lens, that would get to over 400mm. there are also several moon pic takers that use more than i converter. 2 2Xs or a 2X and a 1.4. it sound odd but the results are worth it. they are better than the crop heavy method.

 

do not underestimate how bright a 3/4 or just under full is in terms of brightness. it equal to highnoon on a cloudless day in the summer.

 

focus-

 

put lens on manual focus. then put it on infinity(assuming lens does not focus past infinity,some do) or manual focus.

 

f16.0 comes from the rule of 16. it is the starting point. if you want f8.0, as i use, then you move the shutter speed accordingly to get back to the EV. it is 1/iso for shutter speed under rule of 16. for f8.0 and iso500, for example, you move 2stops or 1/125. at iso500 the shutter speed is 1/500.

 

by the way, the above set of instructions work, i just got back from oscoda michigan, i live in detroit, used the same instructions, it worked.

 

also, with my setup: pentax *istD, bigma50-500 at 500, 2x converter, this gives 35mm equiv of 1500mm. the moon's size is almost exactly 1/2 of the short side of the frame. in other words, you need all the telephoto power you can get.

 

 

[mcmanamey]

http://www.photo.net/pentax-camera-forum/00MIjR

 

http://www.photo.net/pentax-camera-forum/00NG0x

 

Actually, when it's cold outside, go out at 2am or so - and the heat isn't nearly the problem. yeah, there's some noise,

but it's fun to see what you can do w/o software. I'm pretty sure one of the above links shows a 45 min exposure - noise

wasn't bad at all. Those are just the 2 threads about stars that were easiest to find. The only image stacking Matt has

done is when we shot a nebula.

 

I agree with justin - I like the car lights. Foreground makes a star shot. If you really want to be alone - literally get to the

middle of nowhere. Unfortunately, even state highways are too busy. the green flare is basically lens flare - this is just

what happens at night.

[jaophotography]

Adam - I have found that with star trails, take your camera and experiment. I personally don't use the noise

reduction for long exposures, and have never seen the difference with or without. Of course I always shoot long

exposures on the lowest ISO setting (100). I also created my own piece of 'equipment' to hold the shutter button

down. I take a piece of electrical tape and stretch it across the shutter button, this holds the button half way

down, and then I activate the shutter, and the tape holds it just fine. (it takes some adjusting!)

 

I don't have any pictures close by that I shot with the k10d, but if you don't mind here is one I shot last night

with the k200d.

 

BTW, does anybody see that bright spot close to the left corner on the top edge?

 

-Jon<div></div>

[jaophotography]

Great picture Adam, I like the action(?) in this shot! Slow speed action(?) :-)

 

Keep it up!

 

Jon

[a few images]

At first glance I thought you capture some aurora borealis in your shot.. That 'nasty green flare'... maybe it is?

[mcmanamey]

OH - I know this is late, but I was discussing the photo w/ matt again last night as we drove back in from the observatory.

The green glowy stuff (and probably Jon Reid's light purply area, too) are light pollution. I call it night time lens flare, but

that's not as acurate as light pollution & atmosphere interacting.