Why my night shots are not sharp?

[aussiearef]

Hi guys,

I have taken a lot of night shots (long exposure) using a tripod and various apertures (from f3.5 to f22) etc but none of my photos are sharp. I have Canon 550D and this lens: http://www.the-digital-picture.com/Reviews/Canon-EF-S-17-85mm-f-4-5.6-IS-USM-Lens-Review.aspx

samples below:

IMG_0008 | Flickr - Photo Sharing!
IMG_0002 | Flickr - Photo Sharing!
Thanks for any advice

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[manaheim]

Um those look way better than average to me.

Granted, F22 is likely to be less sharp overall on any lens, because the light will refract pretty heavily around the aperture blades.

I generally recommend somewhere around F8. It gives you a good star effect on the light sources with minimal refraction overall.

If you search the forum for posts by me and look for Manaheim's Ultimate Night Photography Guide or something like that you'll find a pretty comprehensive guide on this stuff.

That said, seriously, these look very well done.

[cgipson1]

My suggestions would be:

#1 Dont shot at F22 for long exposures... especially at 1600 ISO. You will get both major noise and diffraction kicking in when doing that. Try using F8 or F11 max... with calculated hyperfocal distance focusing.

#2 If you have a filter on your lens, take it off!

The one shot at 1600 is noisy more than anything... that is why it doesn't look sharp.. that and diffraction.

The one shot at 400 is actually a pretty nice shot.... but still some diffraction kicking in.

[Sw1tchFX]

Keep the lens at f/5.6 or f/8. Drop the ISO to 100. Use a cable release. Your night shots should look perfect at those settings.

[AaronLLockhart]

As charlie just said, it looks to me like you have UV filter installed on the lens, resulting in flare from the lights. The majority of this will disappear if you remove the filter. As for the clarity at F/22, as the rest said... it's diffraction. I'm not going to tell you to "never shoot long exposures at f/22." However, just remember that you are always going to have diffraction at that aperture, and you will never be able to avoid it. I shoot at that aperture(f/22) all of the time. However, I'm not expecting clarity in those photos when I do.

[unpopular]

What does ISO have to do with diffraction? Also I've heard that you should turn off IS when using a tripod.

But i agree. these look sharp to me. Maybe OP is looking for pats on the back?

[aussiearef]

Thanks guys
Sw1tchFX, if I keep the iso on 100 and aperture on say f8, then how long I will have to keep the shutter open for?

[unpopular]

2x longer than at f/22, 1600

Depending on the camera's native ISO, it may be better to shoot at ISO 200. Check reviews at sites like dpreview for what ISO will give the best noise/dynamic range ratio.

[KmH]

I don't see any lens flare, but I do see diffraction spikes from the many over exposed light sources. The diffraction spikes are caused where your lens aperture blades overlap, and using a small aperture.

The cityscape shot (#1?) my seem blurry to you because the lights are so overexposed adjacent pixels in the image sensor were saturated.

As your focus point gets more distant, you can open up the lens aperture while keeping the same DoF.

ISO has to do with diffraction by using an inappropriate ISO for the shot, which causes other exposure settings to also be changed in ways that diminish overall image quality.

Geez, I hate Flickr. I can't see the photo's EXIF data.

Both of these were good candidates for blending 2 exposures, or using HDR, multiple exposure (3 or more) combining techniques.

[Sw1tchFX]

Thanks guysSw1tchFX, if I keep the iso on 100 and aperture on say f8, then how long I will have to keep the shutter open for?

I dunno how long...depends on what you're pointing it at.

[AaronLLockhart]

I don't see any lens flare

Keith, Look underneath the bridge and you will see a series of flares arching up towards the bridge starting from the second support beam at the base of the bridge. Then, if you continue your eyes right into the sky portion of the right side of the photograph (in photograph #1) you will continue to see that flare in the sky.

[manaheim]

Thanks guys
Sw1tchFX, if I keep the iso on 100 and aperture on say f8, then how long I will have to keep the shutter open for?

I'd bet my hat you're looking at about 60s on ISo 100... 30s at 200.

Keep in mind you should also be shooting raw, expose to the right, etc.

[unpopular]

it would be nice to ETTR at night when you need it the most, but in practice it's not really practical....

[rokvi]

Thanks guysSw1tchFX, if I keep the iso on 100 and aperture on say f8, then how long I will have to keep the shutter open for?

I dunno how long...depends on what you're pointing it at.

Set your ISO really high until the levels at a faster shutter seem right, then however many stops it takes to get to native 100 or 200 ISO is how many steps you add to your exposure time.

[BuS_RiDeR]

Try focusing manually and setting your focus to infinity or slightly shy of infinity. /shrug

Oh and turn "off" VR or IS...