Night photos at F22?

[james_tigerwoods]

I did a star trails photo last night and it was an abject failure - rather a waste of 2 hours.

I have a pretty good idea what I've done wrong (no reference point, etc) Link - I've done better.

Anyway - I'm reading up on using F stops for night photography and I'm unclear as to what I should use as I've managed to confuse myself greatly.

I've had decent results with F4.5, 48mm, 30sec, D3100, Nikkor 18-70 - Better than the above anyway.

Is F22 worth using or is 4.5 better?

Thanks

(A very confused) JTW

[DIW35]

f/22 is way too small for star photography, not to mention diffraction problems at that setting. Given that some stars are extremely faint, using a larger aperture will increase the chance of capturing what little light is out there. I wouldn't go any smaller than the f/4.5 that you already have had some success with, and personally would probably be using f/2.8 on a good lens where keeping things sharp wasn't an issue.

[RobbieKB]

james_tigerwoods said:

I did a star trails photo last night and it was an abject failure - rather a waste of 2 hours.

I have a pretty good idea what I've done wrong (no reference point, etc) Link - I've done better.

Anyway - I'm reading up on using F stops for night photography and I'm unclear as to what I should use as I've managed to confuse myself greatly.

I've had decent results with F4.5, 48mm, 30sec, D3100, Nikkor 18-70 - Better than the above anyway.

Is F22 worth using or is 4.5 better?

Thanks

(A very confused) JTW

The short answer is no. Not only is F22 not going to produce the best star trails, it will also make the image softer, not to mention a lot noiser. You are fair better off combining many shots than trying to do it all in one shot.

As a general rule of thumb, the faster the lens the better. For astrophotography you usually want as wide as possible but star trails are a little different.

I don't know anything about Nikon but I'm guessing that's a crop sensor. Experiment with these settings:

Fastest aperture (let's say f/4.5)
ISO 1600-3200 (800-1600 if it's not a crop or if it's overexposing due to light pollution)
Exposure of 30 seconds
Image stabilisation OFF
In camera noise reduction off (this is because it will take a double exposure and thus double the time).

Then either use continuous shooting or an intervalometer and combine them in post processing for the trails.

[james_tigerwoods]

Thanks for this - I've tried a higher ISO but there is just enough light out there for some unwanted noise so 4-800 iso works best.

If it's clear tonight I'll try again.

What use is F22 then? I've never used much more than about 11....

[vaderface]

http://www.pistonheads.com/xforums/topic.asp?h=0&a...

Give this a read, all the info you need.

And pics to give you some ideas aswell. Hope that helps!

Mart

[RobbieKB]

james_tigerwoods said:

Thanks for this - I've tried a higher ISO but there is just enough light out there for some unwanted noise so 4-800 iso works best.

If it's clear tonight I'll try again.

What use is F22 then? I've never used much more than about 11....

400 ISO is too low for the correct exposure time unless you're in Galloway Forest Park or somewhere equally as dark!

[2slo]

james_tigerwoods said:

What use is F22 then? I've never used much more than about 11....

Not much is the short answer. It's as narrow an aperture as many lenses go to but f/16 is usually all you need to get everything in focus in a landscape shot. At f/22 you'll just see a softer image.The only time I'd consider using f/22 is if I desperately wanted a long exposure shot and didn't have the required filters to hand. As the aperture gets narrower, the exposure time gets longer, all other settings being equal.

[DibblyDobbler]

james_tigerwoods said:

Thanks for this - I've tried a higher ISO but there is just enough light out there for some unwanted noise so 4-800 iso works best.

If it's clear tonight I'll try again.

What use is F22 then? I've never used much more than about 11....

Funnily enough I was out with 4.5hero the other night shooting light trails (carousels etc) and he was boffing on about f22 - seems that's what he always uses for light trails (it's crap for star trails as above!)

[DibblyDobbler]

oh and Rob Dickinson has a rather good tutorial which may help - see here:

http://zarphag.com/2012/11/star-photography-a-guid...

[james_tigerwoods]

Thanks all - I'll give it a go tonight