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Help Needed - new Lens
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Sep 14, 2012 11:40:19   #
JohnK
 
http://www.kenrockwell.com/nikon/50-comparison/f-stops.htm

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Sep 14, 2012 12:09:42   #
Jer Loc: Mesa, Arizona
 
I ran into this problem also. The cause is an interest physics limits that cameras have. It has to do with "circle of confusion" or how the light hits the sensor so it's is in focus. As it turns out that, depending on the size of your sensor you have a limit as to what f/stops you can use before the focal point goes from sharp to fuzzy. The charts say my full frame starts seeing this effect around f/16. So if I use f/22 the "circle of confusion" starts getting fuzzy again. I'll see if I can find the articles about this and post them. I think they are on my other computer.
As someone else posted, it is best to shoot with a middle f/stop like f/8. If you do that and still have the problem then the answer is something else.

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Sep 14, 2012 12:44:37   #
jackinkc Loc: Kansas City
 
sygilligan wrote:
Hi,

I am having issues with my 18-135mm IS lens that came standard on my Canon 60D. It takes great photos up close with apertures in the f/5.6 to 8.0 range. But when I use it for landscape with apertures in the f/22 to F/29, the photos are not crisp. At first I was thinking it was the autofocus so I went out and did some tests using manual and auto to compare. It seems decent. I am thinking of trying a better lens (not a pro here so nothing in the outrageous price category, willing to spend $1000 but would prefer the $800 and under range). Am absolutely certain the lack of image quality is not due to camera shake, I use a tripod for landscape pictures, for the most part. I use the self timer for the slower shutters speeds. My previous Olympus DSLR took better landscape pictures than my Canon 60D...am absolutely thinking its the lens. I considered replacing the camera as well but I am thinking better lens might do the trick.
Hi, br br I am having issues with my 18-135mm IS ... (show quote)


Do no use f/stop under f/16 - NEVER use f/22-f/32. This is not necessarily true for film cameras but it is nearly always true for digital.

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Sep 14, 2012 12:55:10   #
CResQ Loc: Cobble Hill, BC
 
robert-photos wrote:
sygilligan wrote:
I am actually thinking that it has to do with the "sweet spot". Best photos are taken with f/5.6 and the focal length in the 50-60 mm range. If I want to take the really sharp depth of field landscape photos, there has to be a compatible lens that will work better.


The reply re:diffraction is correct especially with kit lenses.

Another cause may be setting your focus on infinity.
Because of the nature of DOF you should be focusing at less than infinity which will produde a sharper foreground while keeping the background in focus. If you are at f/5.6 at 50mm focused at 100 ft. pretty much all is in focus from about 40 feet to infinity.

Check the depth of field tables at:
http://www.dofmaster.com/doftable.html

Note that at infinity you have less foreground in focus than at say 100 feet for any aperture.

Your focus should be set at the hyperfocal distance to get the maximum amount of image in focus.

The hyperfocal distance is the closest distance at which a lens can be focused while keeping objects at infinity acceptably sharp. When the lens is focused at this distance, all objects at distances from half of the hyperfocal distance out to infinity will be acceptably sharp.
quote=sygilligan I am actually thinking that it h... (show quote)



Thanks for this link, I also downloaded the iPhone app, very useful. Cheers

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Sep 14, 2012 14:44:30   #
sygilligan Loc: Lititz, Pa
 
Thanks again. I did buy a wide angle lens for my landscape photos but will play with suggestions for my other all-purpose lens just to see what I can do with it.

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Sep 14, 2012 16:33:31   #
JohnK
 
This is really about optics, don't see what film vs digital has to do with it, though the crop sensor vs larger film sizes may come into play. Comments about using the hyperfocus point may not be correct either, as when googling the topic diffraction there are some very interesting topics that come up, some very technical indeed. There are some that say you should not user the hyperfocus point.... If a lens has a dof scale they say you should not use the infinity set at the aperature used but rather several stops shy of it. I do think aperatures smaller that 8 - 11 are not a good idea....

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Sep 14, 2012 16:39:57   #
robert-photos Loc: Chicago
 
CResQ wrote:
Thanks for this link, I also downloaded the iPhone app, very useful. Cheers


No problem, Vancouver and Vancouver Island is on my bucket list :thumbup:

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Sep 14, 2012 17:28:01   #
Jer Loc: Mesa, Arizona
 
JohnK is right. Also, see my earlier post.

Here are the links that explain the problem using the smaller f/stops on a 35mm or a 24mm (also, know as a crop frame) sensor.

It comes down to the larger the film or sensor the smaller f/stop you can use that will produce a sharp image.


http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm/

http://www.bobatkins.com/photography/technical/diffraction.html

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Sep 14, 2012 19:43:28   #
lighthouse Loc: No Fixed Abode
 
The difference between 10 and 17 mm is massive at the wide end.
For your camera 10mm is the way to go.
I do not know why people are recommending a 17-40mm for a 60D.
I love my 17-40 on my fullframe but a 10-20 is a much better option on a reduced format camera like the 60D.
Even if you plan to upgrade to fullframe somewhere down the track I would still get a 10mm for now.
That is how big the difference is.

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Sep 15, 2012 00:12:47   #
peggyjom Loc: Pacific Northwest
 
lighthouse wrote:
What you are seeing may be diffraction blur.
All lenses have a sweet spot where they are at maximum sharpness. For many lenses this is at about F/8 to F/11.
For some of the newer digital lenses I have seen numbers down around F/5.6.
At the small hole end of your lenses scale ie F/22 & F/29 you will have greater depth of field but you may see noticeable diffraction that seems to soften the focus the further away from your focus point.
If you are using hyperfocal focusing try to stay around F/11 if possible.

Zoom lenses usually have a sweet spot lengthwise as well. Do the results change with the focal length. I would expect this lens to be weakest at 135mm.

Make sure the IS is turned off when the camera is on a tripod. If the camera tries to correct blur that is not there, softness and broken IS systems can result.

Not sure what else to check.
What you are seeing may be diffraction blur. br Al... (show quote)

I use this lens often myself. I too stick around f11 at the smallest f16

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Sep 15, 2012 00:23:21   #
SENSORLOUPE
 
sygilligan wrote:
HA! I am reading about the Sigma 10-20 mm right now. Thanks for your help.


also check Tamron 10-24 I use it on my Canon 50D and 30D
just got it this year and like it

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Sep 15, 2012 12:55:00   #
al davis Loc: chesterfield virginia
 
canon 17 to 40 great lens and affordable.i have a 60d also and i agree it may be the lens.

http://www.flickr.com/photos/aldavisphotography/

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Sep 15, 2012 15:06:58   #
CResQ Loc: Cobble Hill, BC
 
robert-photos wrote:
CResQ wrote:
Thanks for this link, I also downloaded the iPhone app, very useful. Cheers


No problem, Vancouver and Vancouver Island is on my bucket list :thumbup:


When you make it let me know, I'll show you some great places for photograpy

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Sep 15, 2012 21:58:00   #
sygilligan Loc: Lititz, Pa
 
Thank you. Good reading, a little complicated so will reread several times.

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Sep 16, 2012 12:47:45   #
sygilligan Loc: Lititz, Pa
 
Here is a practice photo with my new Canon 10mm-22mm lens. Probably should have taken a few at an f/16 but was with a non-photographer so was just shooting test shots.



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