Question about the EF 50mm F1.8 II


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alvyalvy

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Nov 20, 2006
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#1
Hello all,

I just purchased the above lens from John 3:16 at funan today and noted some "issues" with it and need to clarify with experts here if this is normal.

1. I had a problem getting the focusing to be sharp. I tried doing a simple portrait of my wife and concentrating on her eyes and even when using a tripod with my 350D mirror lock, i couldn't get the photo to be really sharp (every photo with f1.8). Tried to focus on some text printed on the canon box and nope, doesn't seem to be sharper than the lens kit that came with the camera. I tried mf instead and photo was noticeably sharper. tried auto focusing on some other text on a piece of paper lying on the table and noted that the text where i focus did not appear sharper than the text that were nearer towards me. tried many many times with f1.8 on various subject with tripod and proper lighting.. sometimes can focus sharply but mostly not as good as when i use mf. is there anything wrong or is this wat i should expect from a sub 100 bucks lens?

2. There is a very noticeable 1mm dust or scratch mark IN the lens..not on the front or back glass surface but on some glass element within the lens. The mark is noticeable for even a newbie like me to point out after careful looking at the lens. is this normal for this lens?

what would u do if u r in my situation?

thank you very much
alvy
 

Jul 17, 2005
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Clementi
#3
did u use the focus-recompose method with the centre af point? u can't do that :) it will throw your focus point OOF. manually select the AF point where your wife's eyes are at and shoot. and the 50/1.8 is not as sharp as the 18-55 wide open. but then again, it is 2 stops brighter, faster, and has better colour
 

alvyalvy

New Member
Nov 20, 2006
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#4
thanks for your reply.
in other words, am i right to say that i cannot use the other focusing point except the smack-right-in-the-middle focusing point for focusing? I'll try that as well as pushing down to f2.2 to see if it sharpens. Also do i have to care about the speck of dust or scratch which is 1mm etched in the middle of the glass element within the lens? is this a norm with beginner-consumer grade ef lens such as this one?

thanks again
 

alvyalvy

New Member
Nov 20, 2006
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#5
sorry it came to my mind that when i manual focus, it became sharper than AF...regardless of whether i'm using the centre focusing box or not..:dunno: is it my 350d or is it the lens behaviour? thanks
 

kietgnoel

New Member
Dec 24, 2004
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Planet Earth
#7
Hello all,

I just purchased the above lens from John 3:16 at funan today and noted some "issues" with it and need to clarify with experts here if this is normal.

1. I had a problem getting the focusing to be sharp. I tried doing a simple portrait of my wife and concentrating on her eyes and even when using a tripod with my 350D mirror lock, i couldn't get the photo to be really sharp (every photo with f1.8). Tried to focus on some text printed on the canon box and nope, doesn't seem to be sharper than the lens kit that came with the camera. I tried mf instead and photo was noticeably sharper. tried auto focusing on some other text on a piece of paper lying on the table and noted that the text where i focus did not appear sharper than the text that were nearer towards me. tried many many times with f1.8 on various subject with tripod and proper lighting.. sometimes can focus sharply but mostly not as good as when i use mf. is there anything wrong or is this wat i should expect from a sub 100 bucks lens?

2. There is a very noticeable 1mm dust or scratch mark IN the lens..not on the front or back glass surface but on some glass element within the lens. The mark is noticeable for even a newbie like me to point out after careful looking at the lens. is this normal for this lens?

what would u do if u r in my situation?

thank you very much
alvy
Sounds like a front-focussing problem.

You can test it by using this focus test chart. Download the pdf file. This was written for the Nikon D70 but the test applies to any DSLR/SLR. Read from page 11. Print out the chart that is on the last page. "Back-focussing" is mentioned in the document. It similar to your problem except that the point in focus is behind the intended point rather than in front as in your case.

To get your problem solved, bring both your camera & the lens to Canon for checking.
 

alvyalvy

New Member
Nov 20, 2006
39
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#8
Thanx for the link, I have never used multi AF point for focusing, strictly on 1 AF point and tt's the center one. BUt i do believe i may have screwed up when i lock focus and shift slightly to recompose and given the very shallow DOF, the eyes may have fallen out of the sharp zone...nevertheless i did many many test without recomposition , just point, focus and shoot, i still get less than sharp images unlike when i mf. I've went for a replacement and the nice chap at J3:16 promptly replaced one without questioning. of coz i showed him the dust speck and he agreed that it is no good. I'll try the test chart now to check this nw lens focusing.
 

sclau19

New Member
Sep 29, 2006
103
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#9
why dun u post some of your pictures to judge the sharpness. maybe its otherwise.
 

foreverlovex

Senior Member
Feb 1, 2006
861
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16
#10
if F2.2 still not sharp....go down further to F4 should be very sharp for F1.8
 

wanzw

New Member
Aug 15, 2006
919
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#14
at 1.8, the DOF is too shallow. do try shooting at 5.6 again. see if it is sharp.
 

alvyalvy

New Member
Nov 20, 2006
39
0
0
#17
Thank you all for your invaluable information. The replaced lens seemed to be fine though after doing the focusing test from the test chart, the lens is slightly front focusing a centimeter or more but much better than the previous lens. I also want to post my first portrait of my wife here..but hmm...she won't like it. I'll try to take my dog instead on post on another thread.

I'll close this for now.
Thank you so much.
 

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