# Night photography and aperture setting - conflicting info?



## lespaul (Aug 20, 2011)

Ok, so Im delving into night photography (landscapes, etc w/tripod) and have a question on aperture setting. 

On many tutorials online people suggest using the widest (ie. smaller number aperture, 1.8 for example) on their lens. Although I completely understand why we would want to set it at this (ie to maximize light entering lens) this doesnt make sense since Im limiting my depth of field (and for a landscape I would expect to have to set it to the largest aperture value (ie. f22 or something equivalent to have everything in focus). 

So question is, do I set it to the smallest f stop (ie. 2.8, 1.8, etc) or the largest (ie. 18, 22, etc)??  (I know this will significantly increase shutter speed, but Im using tripod and cable release)

I also assume I would only use the upper and lower ends of f stops - why/when would I use the f stops in between (5.6,11, 15, etc)

Every tutorial I see seems to be contradicting each other.

Remember this is for landscape night photography. 

Thanks


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## Kerbouchard (Aug 21, 2011)

Generally, you would want to shoot at around f/11 to f/13 for landscapes...but that's just in general.  All the settings are useful.  It depends on your subject and how you want the photo to turn out.

As far as using the extremes, like f/22, it's generally not recommended.  You start loosing sharpness due to diffraction at the smallest apertures.


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## tirediron (Aug 21, 2011)

Look at a depth of field table. Factor in your camera to subject distance and focal length; is it even am consideration?


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## Compaq (Aug 21, 2011)

Here'y my take on this. The camera'slight meter is less accurate in low light situations. That's why you want to set a _starting exposure, _just to have an exposure that the camera says is correct. For this starting exposure, you want to make as good use of the camera's light meter as possible: you want it to be as accurate as possible, so you set the exposure so that the most light will hit it:

Largest aperture
High ISO
And whatever shutter speed that will be correct.

Now, here's when then FUN starts! Say you got a starting exposure of f/2, ISO-3200 and 1/4th of a second. However, that won't work for you. You want to take the shot at f/11 (for a bigger depth of field), ISO-100 (to reduce noise). Which shutter speed?? Well, let's count stops 

Going from f/2 to f/11 is a difference of 5 stops (2.8-4-5.6-8-11), which means we must increase our shutter speed by 5 stops to keep the exposure more or less constant:
1/4 - 0.5 - 1 - 2 - 4 seconds. Now we  have

f/11
ISO-3200
4 seconds

BUT, we want ISO-100. So we count stops: 3200-1600-800-400-200-100... That's a six stop difference. That means we must increase our shutter speed by six stops. That gives us: 256 seconds, which we'll call 300 seconds. The steps are 
4 -> 8 -> 16 -> 32 -> 64 -> 128 -> 256~300=5 minutes.

Now we have an exposure of f/11, ISO-100 for 5 seconds.

You're shooting in BULB, obviously. You're still deciding on your exposure settings, you just need to make the calculations yourself, as you are exceeding the camera's preset shutter speed limit. I hope this helped a little 

So:

- set a starting exposure where you maximize light entering the lens and the sensor's sensitivity to that light (to get an accurate reading of the scene)
- stop down the aperture until you're were you want
- Stop down to ISO-100
- Calculate stop differences and set your shutter speed thereafter
- shoot 

(I chose f/2 for my starting exposure because I have only memorized the stops upward from f/2. If I started with f/1.8, I'd be lost in the in-between apertures lol)


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## cameleon (Aug 21, 2011)

Compaq said:
			
		

> Here'y my take on this. The camera'slight meter is less accurate in low light situations. That's why you want to set a starting exposure, just to have an exposure that the camera says is correct. For this starting exposure, you want to make as good use of the camera's light meter as possible: you want it to be as accurate as possible, so you set the exposure so that the most light will hit it:
> 
> Largest aperture
> High ISO
> ...



Dude!!! Extremely helpful!!! Awesome


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## Compaq (Aug 21, 2011)

Hmm, I've made a mistake somewhere in there  ISO-3200 to ISO-100 is a five stop difference, not a six stop difference. Meaning that the final shutter speed would be 2.5 minutes.
But I hope the moral of the story came through...


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## KmH (Aug 21, 2011)

tirediron said:


> Look at a depth of field table. Factor in your camera to subject distance and focal length; is it even am consideration?


Plus the focal length of your lens is a factor too.

Using a 12 mm lens, on a crop sensor camera, at f/2.8, with a focal point 200 feet from the camera, the near limit of the DOF is 8.42 feet in front of the camera, and the far limit is at infinity. Online Depth of Field Calculator

For comparison, if you are using a 18-55 mm kit lens at 18 mm, and wide open at f/3.5, with that same 200 foot focal point distance the near limit of the DOF is then 14.6 feet in front of the camera, and the far limit is still at infinity.


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## lespaul (Aug 21, 2011)

Thanks everyone for the wonderful tips. 

@Kerbouchard - thanks for the tip on using f stops other than f22. I was wondering why my landscape pics were not always in focus, since i had set the f stop to f22 and focus on infinity. I didnt take into consideration that light begins to diffract at f22, etc (Im assuming this is only when using long exposures). 

@tirediron - thanks for the tip, but unfortunately Im not very good at guesstimating the distances of building/landscapes - which is why i just play is safe and set to f22 and focus on infinity. Hopefully over time I can better hone this skill and determine my distances better. 

@Compaq - thanks for the great time, love the analytical approach to this. Was of much help, thanks!

Thanks again everyone, me and my Nikon D90 are happy!


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## manaheim (Aug 21, 2011)

Some great insight there from Compaq on how all this crap works.

However...

First and foremost, if you're doing night photography you want to be using a tripod or some other method of steadying the camera. Tripod is best, but I've seen people do it with their backpack and such, so you can always improvise something in a pinch. The key is you need to NOT be holding the camera.

Once you have that covered, you need no longer worry about using high ISO... use the lowest ISO your camera can handle natively for maximum quality. I know Compaq wasn't suggesting you necessarily use high ISO, but in case it might have been implied I wanted to say... no don't do that. 

Now back to the original question... aperture.

First off, keep in mind that DOF is not only affected by aperture choice, but also by distance from your subject. The further away you are from your subject, the deeper your DOF. This means when you shoot something like a landscape, you can VERY easily use VERY wide apertures and have all your key elements in focus. Whatever is 5' in front of you may not be in focus, but everything from, say, 100' to your subject likely will be. (i pulled those numbers out of my butt, btw... the point is... don't feel like you need to use a smaller aperture to get what you want in focus)

Second, because we're using a tripod, we don't need to worry about using maximum aperture because we have the time we need to get the light in. On ISO 200, most any night photography scene should be able to be captured inside of 30 seconds on anything under F8/11.

Third, understand that aperture affects quality. On _all _lenses maximum and minimum aperture are going to be the worst place to be on the lens. Usually 2-3 stops down from maximum is peak performance, and you're usually in pretty good shape until F11 or so... but then quality starts to drop off due to light refraction around the blades of the lens. Think of a lens as you would think of a hose. Wide open hose gets a solid clear steady stream. Squeeze that hose closed and you get a spray. You don't want spray when water=light. You want the light to go exactly where it needs to go, and not spray all over the sensor. It's not a perfect analogy, but it's a good visual model. You want to know your lens, but the point is generally going full wide will work, but isn't always the best choice.

Finally, understand that in night photography your aperture also affects compositional elements... namely light source stars. As you stop down your lens the bright light sources refract around the blades of the lens. This is the _positive_ effect of light refraction in night photography because it creates stars on bright light sources which is very cool. Note that different lenses have different effects and will start to create stars at different levels, so you need to experiment... but generally most lenses will do this around F8.

A couple examples...

With a Sigma 10-20 f4/5.6...







With a Nikkor 50 mm 1.8... (the mac daddy for many things, including night photography)







So the overall summary of this is generally... you don't tend to want max aperture, and if you have light sources like in a skyline you're going to tend to want stars... so generally for maximum quality and effect you're going to pick somewhere between F4 and F8, depending on your subject.

Here's a sample of my work to give you a sense of an "end result"... (btw, I just posted in another thread on night photography (in denver, I think)... if you find that there are a lot of more generalized tips in there for night photography.. it's a bit of an obsession of mine.)


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## Kerbouchard (Aug 21, 2011)

lespaul said:


> Thanks everyone for the wonderful tips.
> 
> @Kerbouchard - thanks for the tip on using f stops other than f22. I was wondering why my landscape pics were not always in focus, since i had set the f stop to f22 and focus on infinity. I didnt take into consideration that light begins to diffract at f22, etc (Im assuming this is only when using long exposures).



No, diffraction occurs with every lens regardless of the shutter speed.  Generally, lenses are not their sharpest wide open(i.e. 2.8/1.8/1.4, etc) so most will stop down(use a smaller aperture) to increase sharpness.  It also increases the depth of field.  So, for landscape photography, it would make sense to stop down as far as you possibly can(i.e. f/22) especially if you are on a tripod, except for one thing.  As the aperture opens less and less, the percentage of light that is dispersed by the edge of the aperture blade has a greater overall effect.

If you google diffraction lens resolution, you will find more info than you ever cared for.

More to the point, google diffraction limit and your specific lens.  Chances are, somebody has already done the work for you and will let you know at what point, stopping down is starting to rob you of sharpness.


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## Compaq (Aug 21, 2011)

If you've had a basic physics course in school, consider this:

light can be viewed upon as waves. When waves travel through a small opening, then will bend:






The same can be said for the light passing through your small aperture. In theory, an ideal lens will suffer from no such thing wide open.


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## manaheim (Aug 21, 2011)

Kerbouchard said:


> lespaul said:
> 
> 
> > Thanks everyone for the wonderful tips.
> ...



I suspect you didn't read what I wrote above... it almost never makes sense to stop down to such a small aperture when shooting landscapes.  You don't need the small aperture to get all the key elements in focus and the quality issues from refraction are fairly significant.


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## lespaul (Aug 21, 2011)

Manaheim - thanks for the input. I'll experiment with using the aperture set to its maximum (ie. 1.8, 2.8, etc). I guess I just have a hard time using the aperture at its max setting for landscape shots - since its been engrained in my brain since to only us this when I want a small DOF, but I guess its not exactly so. But I will definetly experiment and report back, thanks again for tip. 

Also, I love the last pic you posted - do you recall the settings on this shot?


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## Kerbouchard (Aug 21, 2011)

Dude, I'm sick of your petty crap.  No, I didn't read the post that you made 7 minutes before the one I made.  I suspect you didn't read my entire post, either...especially the part following 'except for one thing', where I say it doesn't make sense to stop down to such a small aperture when shooting landscapes.  Also, a point that I happened to make in the second post of this thread.



manaheim said:


> Kerbouchard said:
> 
> 
> > lespaul said:
> ...


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## manaheim (Aug 21, 2011)

Kerbouchard said:


> Dude, I'm sick of your petty crap. No, I didn't read the post that you made 7 minutes before the one I made. I suspect you didn't read my entire post, either...especially the part following 'except for one thing', where I say it doesn't make sense to stop down to such a small aperture when shooting landscapes. Also, a point that I happened to make in the second post of this thread.



That's ok, I'm pretty sick of you throwing all your misinformation around the forum.

That said, I see that wasn't the case here... your phrasing was a little confusing and threw me off the path.

But hey, by all means, freak out because of my little disclaimer which was actually me trying to correct you without being an asshole.

Cheers!


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