star trail

[denniskee]

last friday, some of us were shooting star trial next @ punggol mrt (no foreground because too bright, was thinking of including the lone bunglow at 1st).

I get a 40mm star trail with 320mm lens (100mm+2xtc+1.6xcrop on D60) for 5min when print 4R size

As rule of thumb, everytime we 1/2 the focal length, the area of coverage increase 4x.

So to get 40mm star trail with 150mm lens, 5min x 4 = 20min

40mm star trail with 75mm lens, 20min x 4 = 80min.

40mm star trail with 35mm lens, 80min x 4 = 320min.

Pls advice is a/m assumption is correct. Thanks.

[icarus]

Wah...dennis very cheem...
anyway, let me share my tips -
for star streaks:

1) use a large aperture (f2.8 - f3.5)
2) use cable release with lock
3) venue is important, skies must be cloudless, moonless. Zero light pollution
4) In Singapore, aim your camera towards the north
5) Exposure time (if zero light pollution) - 3-4 hours
6) take note of lens fogging during exposure...

these are my findings after several failed attempts...

[quekky]

how do u prevent lens from fogging?

[denniskee]

thanks james.

any suggestions to prevent lens fogging? we also had this problem towards dawn.

I dont want to stand there for full 2-3hr, using lens blower to blow the lens to prevent condensation.

remember reading something about wrapping the lens with tower or something.

btw, what focal length you use?

[yanyewkay]

I've never gone into the maths of the trail length but your results show about roughly what I've got -> longer lens = longer trails

Wider = shorter trails.. I was shooting at 17mm (before 1.5x crop) for an hour and got amazingly short trails

[denniskee]

I am still searching for a good site with good foreground to shoot star trail, ie some buildings or structure or sculpture. Any recommendation?

[sumball]

When to shoot again?

[SnapSnap]

Originally Posted by icarus Wah...dennis very cheem... anyway, let me share my tips - for star streaks: 1) use a large aperture (f2.8 - f3.5) 2) use cable release with lock 3) venue is important, skies must be cloudless, moonless. Zero light pollution 4) In Singapore, aim your camera towards the north 5) Exposure time (if zero light pollution) - 3-4 hours 6) take note of lens fogging during exposure... these are my findings after several failed attempts...

Thanks for sharing!!
Just wondering what ISO setting you would recommend for this type of shoot.

[denniskee]

Originally Posted by SnapSnap Thanks for sharing!! Just wondering what ISO setting you would recommend for this type of shoot.

go for slow film, ie iso 50-100. smaller grian size.

[SnapSnap]

Originally Posted by denniskee go for slow film, ie iso 50-100. smaller grian size.

Thank you! Thank you!!

[Fluorite]

I had done quite a few successful star trail shots on my D70. Choose film instead... It is must better. I had to manually focus my d70 on the foreground to infinity. I also realized that it is quite bright in most areas of singapore. So what most of us will do is to stop down. But that's the wrong way. Use ND filters instead. And when using digital BEWARE of ccd noise.

[denniskee]

Hi Fluorite,

May I know what exposure time was used? My D60 max out @ 3min (before noise comes in).

[denniskee]

Will appreciate if someone can advice me if my assumption in starter thread is correct or close to correct. If not, pls direct me to a simple to understand web site for shooting star trail.

Thanks.

[r32]

Shot with a 10D at 17mm, ISO 100, F/8, approx 1 hour exposure. Ambient temps are around 15 degrees celsius. Shot in RAW, original exposure was overexposed, and corrected in post process.

Flare is from stray light from nearby lights. This is the resized full frame - at 100% magnification many hot pixels were apparent.

[denniskee]

wah 1 hr exposure, like that cmos die faster lay.

guess its not taken in singapore right? read some cser said singapore only gets near straight star trails.

dont understand your statement :

This is the resized full frame - at 100% magnification many hot pixels were apparent.

so is this a 100% crop or not?? sorry ah, my english not very good.

thanks.

[r32]

I tend to assume that the CMOS being a piece of solid state electronic equipment, will not suffer wear and tear. The shutter would probably fail first. But the way DSLRs depreciate, it may not be worth repairing. But I digress.

That is the the entire frame at 17mm downsized for web. You can't see the noise at this size. But when you look at it at 100% you can see that many hot pixels are visible.

And its not taken in Singapore; taken just now in Brisbane - the Southern Cross is just on the bottom middle edge of the frame.

[Adrian]

Have you guys thought of shooting star trails at Pulau Ubin, Sentosa or Mount Faber? Any comments?

[g.e.r.a.l.d.i.n.e]

Originally Posted by quekky how do u prevent lens from fogging?

Use heat packs. You can buy them from Winter Clothing shops..pretty cheap..you can get them individually or in packs of 10.. Use a velcro or something like a rubber band, secure the heat pack ( one is enough) onto your lens ! :)

Don't have to use the blower and stand there for sooo long. ha! Really tiring if you're gonna do so..

[denniskee]

I think all 3 got seriouse light pollution problem.

[icarus]

Originally Posted by Adrian Have you guys thought of shooting star trails at Pulau Ubin, Sentosa or Mount Faber? Any comments?

Sentosa and Mt Faber are out... too much light pollution
Ubin *maybe*... but we will have to choose the northern part of the island.