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06-16-2011, 05:26 AM   #46
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akanarya's Avatar

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Location: Çankırı, Turkey
Posts: 210
QuoteOriginally posted by klh Quote

I don't know firsthand because I don't have my 15mm yet, but I understand that it is not ideal for portraits because of the distortion at the edges of the frame. Try shooting your family shots with your 18-55 set at 18mm and see how it looks.
in fact i need a wide for not a portraiture. I have a 28-75 for this purpose.
I need it for general scenes, for crowd and let a room the for model.

i use 18-55, but i need a bit more wider, much sharper, and smaller than kit so that i can carry with my 28-75 in my toploader bag.

if it will be faster, then it is going to be piece of cake. (I dont use flash, dont want to bump the iso much). But 15mm is f4, that is slower, but hey i dont know may be it takes equivalent or more light from 18/3.5.

I know, i want everything,
but i search and open to any suggestions.

06-17-2011, 08:02 AM   #47
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Location: Wellington, New Zealand
Posts: 9,781
QuoteOriginally posted by klh Quote
Comparing to this table (which, if my math is right, is the angle of view on a K20D sensor), I decided that 15mm (76 degrees) would suffice in most situations.
Your math was right, but you based the AOV on the sensor width. Commonly it is based on the sensor diagonal.

Assuming a sensor size of 23.4mm x 15.6mm and expressing the angle of view in terms of the sensor diagonal (as is commonly done) one gets the following values (rounded).

Focal Angle of
Length View
(mm) (degrees)
10 109
12 99
14 90
15 86
18 76
20 70
24 61
28 53
35 44
50 31
85 19
135 12
200 8
300 5
400 4

Last edited by Class A; 06-17-2011 at 08:09 AM.
06-28-2011, 08:47 PM   #48
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Join Date: Mar 2011
Location: Australia
Posts: 124
Well just ordered a new 10-20 f/3.5 . Big thanks to cmohr for your comparison shots, would've loved the 8-16, but the difference isn't too big for me based off your examples to warrant losing filters.

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