Landscape F18

[Malok]

Am I correct in assuming that on the Drebel that the sharpest aperture is F18? My focus is landscape photography and I most of the time I would like to achieve the sharpest photos possible from the foreground to the horizon. I almost always use a tripod and so am not limited by shutterspeed. In most situations, will F18, give me the clarity I am looking for?

Malok

[Belmondo]

Am I correct in assuming that on the Drebel that the sharpest aperture is F18?

Malok
From what I understand, and based on my own experience, that isn't necessarily always the case. As a rough rule of thumb, the largest aperture setting on a lens will probably give you a somewhat softer image then at smaller settings. But once the lens is stopped down, even a little, it generally sharpens up. You'll see some people refer to the 'sweet spot', which as I understand it is the point at which the image doesn't get any sharper. It varies among lenses, but I've observed that to be the case on many of my lenses at around f/5.6 to f/8.0.

Of course, the smaller the aperture, the greater the depth of field, which in landscape work is usually desireable

[Malok]

Thanks for the input. I guess that what I am looking for is the "sweet spot" for my 18-55 kit lens. In some posts I have read that the sharpest setting is two stops down from the maximum. If this is the case, then it would be F18. If the "sweet spot" is to be found elsewhere the I would love to know.

Malok

[CyberDyneSystems]

f/11 (or 12?)

Two stops from 5.6 is not f/18 :)

At the wide end the lens is f/3.5 max.. so two stops would be f/7

[Malok]

It looks like I am counting from the wrong end! I was thinking that it was two stops down from the smallest aperture (f22), not the largest aperture(f4 or 5.6).

Thanks for the correction!

Malok

[Lesmac]

The minimum aperture depends on the lens, some lenses will stop down to f40 (sigma 17-35 mm F2.8 for instance), the more expensive L lenses, whilst stopping down to f22, are sharp throughout the aperture range.
It's correct the mid to low end lenses have an optimum quality range of apertures usually around f8 to f11, but most of the time f11 will suffice especially if using hyperfocal distance.
Hope this helps

Les


http://lesmclean.photoblink.com/

[CyberDyneSystems]

It looks like I am counting from the wrong end! I was thinking that it was two stops down from the smallest aperture (f22), not the largest aperture(f4 or 5.6).

Thanks for the correction!

Malok

lol,. it's because "stopping down" means a larger number.. which is bass-ackwards! :D :wink:

It makes it all muddled up (or down?)

But stopping down means to make the f/stop number higher :)

So you allways start at the largest aperture.. (or lowest f/stop # )

[iwatkins]

Even I am confused now :wink:

If it is of any help, I tend to shoot most of my landscape shots at f22 for maximum depth of field. Some of my lenses will go further, but it is then a balance between depth of field attained and the amount of time the shutter has to be open for (leading to wind shake, grasses moving, clouds moving etc.). I.e. I set f22, focus 1/3 of the distance I want to be in focus and let the shutter speed look after itself.

Cheers

Ian

[aeroshots2003]

Maybe this link can shed some light on the "sweet spot" :

http://www.photodo.com/nav/artindex.html

Check under : Equipment-Lenses, Improved Sharpness.

DIFFRACTION
It is a known fact that you can enhance DOF (or front-to-back sharpness) by stopping down, i.e. setting a higher aperture number.
At some point however the aperture is so small that diffraction (light, that becomes fuzzy at the aperture edge) represents a too big percentage of the image, thus becomes visible.

PERSONALLY
I try to stick at f/5.6 or f/8 and never go beyond f/11 for these reasons - I must admit I never experimented with those very small apertures, so I cannot speak from experiences.

DOF
depends on three parameters (or is it more?) : distance to subject + focal length + f stop, so not solely on the aperture setting.
In case of landscape photography I suppose you use something like 28mm and your subject is not at 10 feet but considerably further away. I think that in that case an f/22 setting would not result in much more DOF than f/11. Maybe someone can try this and post some pics for comparison?

Greetz,


Johan

[iwatkins]

Johan

I don't have anything handy for comparison at the moment.

But I almost always try to include foreground interest in my landscape shots. It (for me anyway) is what makes a good landscape shot.

I.e. my foreground may be at 4 feet (say some flowers/rock formation etc.) and I'll want that all the way out to infinity (OK, the horizon will do) within the DOF. Hence f22 or even more at times.

Cheers

Ian

[aeroshots2003]

Johan

I don't have anything handy for comparison at the moment.

But I almost always try to include foreground interest in my landscape shots. It (for me anyway) is what makes a good landscape shot.

I.e. my foreground may be at 4 feet (say some flowers/rock formation etc.) and I'll want that all the way out to infinity (OK, the horizon will do) within the DOF. Hence f22 or even more at times.

Cheers

Ian


I totally agree with your statement Ian. Landscape shots should not only consist of far-away elements, but the composition should best include a subject in the foreground. If this is at only 4 ft away, then DOF could only be created by f/22+. Yet I suppose that with a car, tree,... at 30 ft distance the backdrop should become sharp at f/11 (with wide-angels that is of course).

I'm still on wet film, so I couldn't post example images at short notice. But I've heard that the UK will have the best of weather tomorrow... :D :D

Any experience with diffraction as stated in the article?



Johan

[iwatkins]

But I've heard that the UK will have the best of weather tomorrow... :D :D


Yeah, I heard that as well. So I have even gone so far as to set the alarm clock to get up and get out there in the morning. Unheard of for me on a Sunday morning especially as I'll loose an hour of sleep tonight as we are switching to summer time tonight. :lol:


Any experience with diffraction as stated in the article?


I know exactly what that article means and I have indeed seen the effect. However, I don't think I have had any real life cases where it *badly* affected the overall shot as it is only noticable if you are actually looking for it. And even then, most of the effect is more likely to be down to caemra shake/poor focus etc.

If I get some play time tomorrow (I'm after a kingfisher tomorrow morning) I'll give it a go and see if I can't get some good examples.

Cheers

Ian

[aeroshots2003]

Ian,

if your wife gives you trouble because you're out so often for your hobby and neglecting her as your partner, here's the trick :

wake her up at 05.00 am and just ask : Fishing or sex? :shock:
she'll definitely respond : Go fish !!! :evil: :evil:
Of course she could always go for the other one... :wink:

Have a nice time out,



Johan

[WestFalcon]

I shoot kitchens at F11 and usually around 1/2 to 1/4 of a second with available light and usually add some incandescent fill light....tungsten. Pictures are beautiful and my depth of field on my 17-40 L lens is about 8 foot to infinity. No diffraction problems. My client gets gorgeous 16x20's from my 10D. I personally try to stay away from f 16/f22 etc....I think diffraction would hurt my images.

[photoguynorth]

There are two answers floating around here - the sharpest aperature (as noted - usually arounf F8 depending on lens) and maximum DOF. For landscapes such as you describe, you probably need more DOF than F8 will give you. When you don't need the DOF, then you can use F8 or so to get the maximum sharpness (of whatever is in focus).
Good luck!

[paul162brown]

In addition to everything that has been said, you should also learn about hyperfocal distances and hyperfocal focusing, to acheive true front to back sharpness from your shots.

F-stops are important, and some lenses have sweet-spots, and using F22 etc will give you the best chance of sharpness, but the point at which you focus within the frame makes more of a difference than you think!

Too much detail to explain here, but do any search on the web and there is lots out there.

Many wide lenses have hyper-focal markings on them, although this is getting rarer. As a very very very general rule of thumb, depth of field extends twice as far in front of the focal point than behind it, as so using F22 etc and by focusing on a point approx 1/3 into your shot, will achieve the best sharpness. Hope this helps.

Paul :)

[Rob Larsen]

Malok,

I second Paul's suggestion on learning about hyperfocal distances. There are hyperfocal charts available that will tell you that "if you focus here, everything from x to infinity will be in focus" for any particular lens and aperture setting. I find these charts very useful for landscape photography. I have a simple chart printed on an index card that lives in my camera bag.

You can find in depth information on hyperfocal distances here (http://dfleming.ameranet.com/hyperfocal.html).

A practical, less technical explaination is found here (http://www.photofocus.com/zine7/hyperfocal.html).

Happy shooting!

[jray]

The physics of diffraction is an important factor here. Although ~f/8 is considered to be close to the optimum aperture for sharpness in regards to 'most' 35mm lens designs, it's well understood that apertures above f/11-16 will become diffraction limited due to physics. Only the sharpness gained via additional DOF will offer image sharpness at the fringes of DOF, but it will come at the cost of a loss in sharpness at distances that are closer to the center of the DOF range. Take a look here for a few links:

http://www.fredmiranda.com/forum/topic/79827/3#655135