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Old Nov 19, 2006, 7:19 AM   #1
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I just tried my new K28mm f3.5. because I bought it for ladscape I tried focusing using scale on the lens but it didn't come quite as I would expect. so after some checs I foud out that tis scale on the lens doesn't work with APS size sensors. I found a Hyperfocal Distance Calculator which allows to create scales for different lenses and different sensor sizes. here rea 100% crops from 3 frames I took. tripod and 2sec selftimer f22. RAW converted in rawshooter with sharpness and detail extraction set to 5.

first is using scale on the lens, second using scale for APS size sensor and third I manually focused on the roof. first is definatelly less sharp than last two but I cant decide between them.



here are links to full size photos, can you help me decide which is sharpest aroud full frame?

same order as crop
1
http://i63.photobucket.com/albums/h1...MGP1935-02.jpg

2
http://i63.photobucket.com/albums/h1...MGP1936-02.jpg

3
http://i63.photobucket.com/albums/h1...MGP1937-02.jpg

greg
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Old Nov 19, 2006, 7:26 AM   #2
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Manual focus gets it with my eyesight.
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Old Nov 19, 2006, 8:25 AM   #3
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In My eyes its Very Close, but APS Scale Here

BK/Phil
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Old Nov 19, 2006, 9:41 AM   #4
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manual, maybe
since it's a manual lens, i think i'd stay with that. a lot faster to do..

roy
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Old Nov 19, 2006, 9:53 AM   #5
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I'd say the manual focus looks a little sharper (tilted window area and streetlight to the right).
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Old Nov 19, 2006, 1:15 PM   #6
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Hi,

To my eyes I think the APS and Manual are very close.



Rudy
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Old Nov 19, 2006, 1:38 PM   #7
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thanks for your comments.
I couldn't see much diffrence myself between the last two. this crop here is from centre of the frame so it's not a surprise it's very close. I didn't know photobucket resizes photos to 800 pixels, so you can't really see difference. after loking closely at full size at the edges I couldn't see any difference either.

roy: I hoped to use this scale for landsacpe photos, and since thre's no rush in that (mostly) and I want to get best possible results I don't really care how long it takes. besides it's not that much more different. you just need to know hyperfocal distance for given aperture and set it on the lens.

I just have to go out and take more pictures, but because I don't have a car yet I'm too lazy to do it due to weather. it's just too cold for me to travel for an hour on train. maybe I'll force myself to do it next weekend?

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Old Nov 19, 2006, 3:03 PM   #8
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i looked and looked and find a bit hard to tell the difference btwn the aps scale and the manual focus. the aps scale seemed more contrasty but the MF has finer lines on the brickwork (it seems, to my untrained eye)

when you used MF, did your camera give you focus confirmation?

OTOH, when you get to the point where its a struggle to tell the difference using 100% crops, i tend to believe that any differences in sharpness is nelegible or for academic reasons. I was going thru the same questions when I got my Zenitar, checking and re-checking whether infinity focus was sharp. but in the end reached the conclusion that if i cant notice the difference then it is probably as good as it can get people arnt gonna be scrutinizing 100% crops to enjoy a good photo.

out of curiosity, can you post the link for the aps scale for hyperfocal distance? I also want to give the hyperfocal technique a try...




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Old Nov 19, 2006, 6:20 PM   #9
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I used this small program http://www.dofmaster.com/custom.html

you have to change circle of confusion in properties to make it work good. for APC sensor it's 0.02. it should be all explained on above webpage.

greg
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