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UWA and wide open
Hi!.

Is there any interest in going wide open while using the widest end of an ultra-wide angle when light is correct? It seems so from certain posts. I thought the idea with a wide angle was more to get as much sharpness as possible and therefore to use a small aperture..

Thanks!..

Comments (6)

S_NYC wrote:.

Hi!.

Is there any interest in going wide open while using the widest endof an ultra-wide angle when light is correct? It seems so fromcertain posts. I thought the idea with a wide angle was more to getas much sharpness as possible and therefore to use a small aperture..

Thanks!.

Too small of an aperture causes loss of IQ due to diffraction. Typically lenses perform best when stopped down about 2 stops, but every lense is different, and only testing will find the "sweet spot." For example, almost every lense in existence will perform better at f/8 than at f/16..

WRT wide open, one situation I can think of is shutter speed. When I shoot snowboarders going off jumps I adjust to suit shutter speed. There are countless times when I am using 28mm (35mm equivalent) wide open, and even use ISO400 to boost the shutter speed..

Tim'Be the change you wish to see in the world.' -Mahatma GandhiE3/E1/7-14/12-60/50-200/EC-14/C8080http://www.flickr.com/photos/timskis6/..

Comment #1

Ultra Wide Angle lenses in particlar are more likely to show increased vignetting and CA wide open. And, as stated, most lenses perform best when stopped down two to three f stops..

But your need for a high shutter speed to freeze action may override the need to hit that sweet spot 2 or 3 f stops in..

The greatest of mankind's criminals are those who delude themselves into thinking they have done 'the right thing.'- Rayna Butler..

Comment #2

S_NYC wrote:.

Is there any interest in going wide open while using the widest endof an ultra-wide angle when light is correct? It seems so fromcertain posts. I thought the idea with a wide angle was more to getas much sharpness as possible and therefore to use a small aperture..

As others have already explained, with an UWA, other factors are more likely to determine aperture - such as needing shutter speed in low light etc. - no lens is at it's best wide open and the DOF on short focal lengths is such that it's less likely to be a lens you use for creative shallow DOF (or available light) than others, as it's harder to get..

I just wanted to take up specifically on your latter sentence with regard to 'small aperture' and just clarify what you might mean by 'small'. For most of the scenes where you're likely to use an UWA lens, you're going to have pretty much infinite DOF from f5.6 upwards. Many people think that to get sufficient DOF for an outdoor landscape scene, you need very tight apertures like f16 or f22. With an UWA this is simply not necessary - it's not even necessary on general short focal lengths either (<30mm-ish)- as long as you choose your focus position carefully. I like doing landscapes and very rarely go beyond f11 for anything other than macro type work where I'm squeaking every mm of DOF I can out of the geometry..

I use a Tokina 12-24 on a Canon 20D and for almost all the work I do with it, I could put it at f8, pre-focus 15 feet away (a hyperfocal-type distance) put it in MF and everything I shoot from there will have infinite DOF. So you are best served by working at the sweetest aperture for the particular lens and unless you have some other creative reason for doing so (i.e. shutter speed to freeze action or choosing a lesser DOF, insufficient light etc.) leave it at that aperture - stopping down from f8 to f16 will lose more than it will gain - DOF will be maxed out around f5.6 at the wide end and maybe f10 or f11 at the long end of an UWA anyway..

So you're best served shooting at the sweetest aperture for the lens than stopping down too far and throwing away that advantage..

So many photos, so little time.http://www.peekaboo.me.uk - general portfolio & tutorialshttp://www.boo-photos.co.uk - live music portfoliohttp://imageevent.com/boophotos/ - most recent images.

Please do not amend and re-post my images unless specifically requested or given permission to do so...

Comment #3

Thanks, your second paragraph is very very helpful! I was indeed under the impression that using a wide angle lens correctly meant using it at the minimum aperture..

Would your advice be the same while using an allround lens like the Canon 24-105 on an Eos 40D between, say, 24 and 35mm (i.e. between 38 and 64mm on a 24x36 format camera).

Thanks again for your help..

Comment #4

S_NYC wrote:.

Thanks, your second paragraph is very very helpful! I was indeedunder the impression that using a wide angle lens correctly meantusing it at the minimum aperture..

On the contrary really. The shorter the focal length, the more DOF you have per aperture and the less need to stop down for DOF. Other than for maybe light considerations - I stopped down my UWA recently where I was trying to get a slow shutter speed on a waterfall in good light - you shouldn't need to move beyond the sweet spot of the lens even for infinite DOF for most scenarios. Most lenses are at their best in the middle range of apertures around f8 to f11 and an UWA will do just fine in that range for most applications..

Would your advice be the same while using an allround lens like theCanon 24-105 on an Eos 40D between, say, 24 and 35mm (i.e. between 38and 64mm on a 24x36 format camera).

It depends on what you're trying to achieve of course - if your intention is maximum DOF for outdoor scenes like landscapes, there are several factors to consider, not just aperture alone - and perhaps the single greatest is where you focus relative to the elements within your scene that you want sharp - relative to your chosen aperture and the optimal performance of the particular lens..

I think it is perhaps a popular general misconception that for landscape shots you need a tight aperture (f16 to f22) and to focus at infinity. I like doing landscape work and rarely do either. My general technique is to either focus on a particular foreground element I see as my main subject and tweak aperture to get the desired DOF from there, if that's the type of scene, or more often, for general landscapes, I use a hyperfocal type technique where I focus more towards the foreground at an aperture that when combined with my focal length should give me the desired DOF..

This works well through wide focal lengths, up to the 'standard' sort of focal lengths, which once you get beyond about 30 or 40mm, gets less reliable and needs a more specific focus aim..

The DOF you have is relative to 3 factors; focal length, aperture and distance from the subject - so where within the scene you choose to focus is an important decision too and perhaps one that gets overlooked more than the camera settings. As I said earlier, other than for macro, I rarely go tighter than f11 for any general photography - most of my landscapes will be around f11 - down to f8 depending on light and if say it's windy and I need shutter speed..

I've written a tutorial essay on my personal approach to DOF and how I focus landscape shots (and an explanation of hyperfocal, previously mentioned and how I check my DOF for the scene once focussed) and also see this DOF calculator - put in some apertures and focal lengths and try varying the focus distance and see what this does to the overall DOF numbers - I think you'll perhaps be surprised at how close you can focus and still get infinite DOF at short focal lengths and mid-range apertures. For example, if you focus at 15 feet away, at 30mm and f11, you have infinite DOF from 7 foot..

My tutorial: http://www.zenadsl5251.zen.co.uk/photos/doftut.html.

DOF Master: http://www.dofmaster.com/dofjs.html.

This is a series of landscape type scenes I did recently with my Tokina 12-24 on my 20D (I think it's the same size sensor as the 40D) - http://imageevent.com/boophotos/malham all were taken between f8 and f11..

So many photos, so little time.http://www.peekaboo.me.uk - general portfolio & tutorialshttp://www.boo-photos.co.uk - live music portfoliohttp://imageevent.com/boophotos/ - most recent images.

Please do not amend and re-post my images unless specifically requested or given permission to do so...

Comment #5

All I can say is THANKS for taking the time to answer my basic question and for sharing your depth knowledge of the subject. I'd be lost without posters like you! Thanks again!..

Comment #6

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