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  1. #1
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    Question sharpness and focus question(s)

    i was bored today so i made this cake and wanted to take some pictures of it. I have two things I am struggling with:

    1. sharpness (i cant seem to get the amount of detail i would like)
    2. focus (in the cutout shot, the autofocus kept hitting the outer sides of the cake but the middle is blurry)


    Any advice on how to fix these things in the future would be greatly appreciated. Both images were shot with the 50mm f1.8 lens
    Attached Thumbnails Attached Thumbnails sharpness and focus question(s)-cake_cut.jpg   sharpness and focus question(s)-cake_side.jpg  
    Canon XSi, Canon 18-55mm IS, Canon 50mm f1.8, Canon EF 70-300mm f/4-5.6 IS USM

  2. #2
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    Re: sharpness and focus question(s)

    I don't have the answer but that is the best looking cake I have ever seen. Send me the recipe lol....I can almost taste It through the screen!

  3. #3
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    Re: sharpness and focus question(s)

    Quote Originally Posted by danny wdr
    I don't have the answer but that is the best looking cake I have ever seen. Send me the recipe lol....I can almost taste It through the screen!
    teach me how to make good pictures and I will gladly make you one
    Canon XSi, Canon 18-55mm IS, Canon 50mm f1.8, Canon EF 70-300mm f/4-5.6 IS USM

  4. #4
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    Re: sharpness and focus question(s)

    lol,still trying to figure it out too

  5. #5
    project forum co-moderator Frog's Avatar
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    Re: sharpness and focus question(s)

    Not a Canon user so don't know but if you have a spot focus, use that and get the focus on the spot you want. At f/1.8 you're not going to have focus everywhere when you are that close.
    Another way,(don't know if it would work here), is to press the shutter release half way to focus on what you want focused and then holding it halfway, move the camera to get the composition you want and then take the pic. In this situation I think you needed a spot focus though.

    That is a nice looking cake. I love raspberries and blackberries.
    When will the cake be delivered?
    Keep Shooting!

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  6. #6
    Be serious Franglais's Avatar
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    Re: sharpness and focus question(s)

    According to the EXIF info the pictures were done at 1/60 f4 (200 and 400 ISO). Lets say you were about 20 inches from the subject.

    According to the depth of field calculator here : http://www.dofmaster.com/dofjs.html

    - the depth of field at this distance on this lens at f4 is about half an inch.
    - You need to increase your ISO or put the camera on the tripod so that you can use a small aperture and get a bigger depth of field. F16 would give you a depth of field of 2.23 inches which would look better

    The camera seems to have focussed on the closest part of the subject. In the first image this is cake edges right and left and in the second image it's the cake top edge (you're looking down on it). You would be better by selecting the center focus zone - the eye expects the center of the cake to be in focus in this image.

    I have the impression that the camera is back-focussing a little with this lens (the focus point is behind where you expect it to be). This can be adjusted in the repair shop but I believe that on the XSi you can't adjust for individual lenses. If it's focussing OK with your other lenses then adjusting for the 50mm would put the other lenses out.

    Gosh I'm hungry all of a sudden. Time for breakfast.
    Charles

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  7. #7
    project forum co-moderator Frog's Avatar
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    Re: sharpness and focus question(s)

    I now no longer trust my exif data program.
    When I checked exif data earlier it said iso 100, f/1.8, and shutter speed 1/50. It is the only one I checked exif on tonight so I'm pretty sure I remember that right.

    Is exif reliable? or what gives?

    Spot focus would help at any rate if you want the center of the cake in focus but then the outer edges would be out.
    Keep Shooting!

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  8. #8
    Be serious Franglais's Avatar
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    Re: sharpness and focus question(s)

    Quote Originally Posted by Frog
    I now no longer trust my exif data program.
    When I checked exif data earlier it said iso 100, f/1.8, and shutter speed 1/50. It is the only one I checked exif on tonight so I'm pretty sure I remember that right.

    Is exif reliable? or what gives?

    ...
    How strange.

    I downloaded the file onto my local hard drive then used ACDSee V10 to view it and read the EXIF data.

    I just double-checked it on Vista by right-clicking on the file and doing Properties - Details. They result was the same (ACDSee gives more details but the exposure and ISO are the same in both)

    What software are you using to read the EXIF data?
    Charles

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  9. #9
    project forum co-moderator Frog's Avatar
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    Re: sharpness and focus question(s)

    Sorry! I know how I goofed. Actually got this one mixed up with another I'd checked exif on.

    Ronin, pay attention to Charles and deliver the cake to him instead of me.
    Keep Shooting!

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  10. #10
    Be serious Franglais's Avatar
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    Re: sharpness and focus question(s)

    Quote Originally Posted by Frog
    ...

    Ronin, pay attention to Charles and deliver the cake to him instead of me.
    I just had my Sunday teatime cake (Pavé aux 3 chocolats = a local speciality).

    Send it to Frog to give him extra force. He must stay up all night answering these questions.
    Charles

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    Not buying any more gear this year. I hope

  11. #11
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    Re: sharpness and focus question(s)

    you both are providing valuable information, so i have no choice but to make two cakes
    i checked the EXIF data and Charles has the correct numbers
    Canon XSi, Canon 18-55mm IS, Canon 50mm f1.8, Canon EF 70-300mm f/4-5.6 IS USM

  12. #12
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    Re: sharpness and focus question(s)

    just a quick follow up on the issues.
    finally had a day of sunshine so we took the little one to the park. AMAZING sharpness and focus. so it comes down to what i have already known in the back of my head: light conditions make a world of difference.
    On some of the pics i think i can count my hairs on my head (luckily it is shaved so it wouldn't take long).
    anyway, lessons learned. thx gentlemen
    Canon XSi, Canon 18-55mm IS, Canon 50mm f1.8, Canon EF 70-300mm f/4-5.6 IS USM

  13. #13
    project forum co-moderator Frog's Avatar
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    Re: sharpness and focus question(s)

    Actually the light was very adequate for cake, especially since you used the flash.
    My guess now is that you did not use a tripod.

    Why did you use portrait mode on the second shot?
    Keep Shooting!

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  14. #14
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    Re: sharpness and focus question(s)

    no tripod. dont own one yet.
    as far as your second question: short answer is because i dont know what i am doing. so basically i was trying different things out and that seemed like the best shot i had
    Canon XSi, Canon 18-55mm IS, Canon 50mm f1.8, Canon EF 70-300mm f/4-5.6 IS USM

  15. #15
    Junior Member Rocker's Avatar
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    Re: sharpness and focus question(s)

    Quote Originally Posted by danny wdr
    I don't have the answer but that is the best looking cake I have ever seen. Send me the recipe lol....I can almost taste It through the screen!

    that makes two of us hahaha

  16. #16
    Be serious Franglais's Avatar
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    Re: sharpness and focus question(s)

    Quote Originally Posted by ronin2307
    ...
    finally had a day of sunshine so we took the little one to the park. AMAZING sharpness and focus. so it comes down to what i have already known in the back of my head: light conditions make a world of difference.
    ...
    When you take a picture you need three things, aside from the camera:

    1. The subject
    2. The light to suit the subject
    3. The right moment to do the picture

    When you feel you want to do a picture, take a moment to ask yourself if you have all three. If you don't then work on getting them.
    Charles

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  17. #17
    Senior Member freygr's Avatar
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    Re: sharpness and focus question(s)

    NOTE!!!!

    Since the first day of digital micro-photography I found that the AF program would never focus were I wanted it to. The only option to get consistent results was to use the MANUAL focus option, along with aperture priority. Even with the new DSLR cameras the AF sucks for closeup/micro-photography
    GRF

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  18. #18
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    Re: sharpness and focus question(s)

    thx to all for the advice
    Canon XSi, Canon 18-55mm IS, Canon 50mm f1.8, Canon EF 70-300mm f/4-5.6 IS USM

  19. #19
    Senior Member OldClicker's Avatar
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    Re: sharpness and focus question(s)

    Quote Originally Posted by freygr
    NOTE!!!!

    Since the first day of digital micro-photography I found that the AF program would never focus were I wanted it to. The only option to get consistent results was to use the MANUAL focus option, along with aperture priority. Even with the new DSLR cameras the AF sucks for closeup/micro-photography
    I'll agree if you are talking about something the size of a grasshopper's eye, but for that piece of cake, AF should be...well, a piece of cake. - TF
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  20. #20
    Mtn Bike Rider Singletracklovr's Avatar
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    Re: sharpness and focus question(s)

    I think the camera's AF did pretty good on the cake photo.
    It recognized the front edge of the subject and the focus is sharp.
    The problem was the 0.5 to 1 inch DOF at f4

    To improve this shot a smaller f-stop is required.
    I would recommend:
    Using the DOF calculator Charles posted to get the correct f-stop
    Increasing the ISO. Noise is easier to fix in PP than out of focus.
    Reduce the shutter speed.
    With no tripod. Set the camera on the table, maybe use books to get the height and use the cameras timer.

    I you still can't get the shot increasing the light in the room.

    hth
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  21. #21
    Senior Member freygr's Avatar
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    Re: sharpness and focus question(s)

    Quote Originally Posted by OldClicker
    I'll agree if you are talking about something the size of a grasshopper's eye, but for that piece of cake, AF should be...well, a piece of cake. - TF
    Yes you are correct but in the field I've had AF focus on a blade of grass not the flower. (with the now old Nikon D70 and older Olympus C-3030)
    GRF

    Panorama Madness:

    Nikon D800, 50mm F1.4D AF, 16-35mm, 28-200mm & 70-300mm

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