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05-07-2008, 02:30 AM   #1
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30mm lens for portrait

I've been told before I'm a little crazy but this time it may be true as I'm seriously consider to buy the 30 mm f/1.4 EX DC HSM Sigma over the Pentax FA 50 f/1.4 for use in portrait shots.
If it's not too late please STOP ME.

05-07-2008, 02:38 AM   #2
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QuoteOriginally posted by quantum Quote
I've been told before I'm a little crazy but this time it may be true as I'm seriously consider to buy the 30 mm f/1.4 EX DC HSM Sigma over the Pentax FA 50 f/1.4 for use in portrait shots.
If it's not too late please STOP ME.
Why Stop you?
You could make some very ... unique portraits
(like no one has done before )
05-07-2008, 03:21 AM   #3
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Honestly I think it's a mistake, if you're getting it for portraits. Not only it's a bit short but it's not as good optically and it's more expensive.
05-07-2008, 06:32 AM   #4
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I'd stick with the 50, or the 40 Limited.

05-07-2008, 07:52 AM   #5
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30mm is a bit close for portrait because you exaggerate the facial features a bit too much (i.e. the nose), however if you're taking pictures of "upper bodies" then it's not so bad
05-07-2008, 10:43 AM   #6
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It would be good for "environmental portraits," but not for head and shoulders. I think the old guideline was 1 & 1/2 times the diagonal of the format for head and shoulder shots. Not knowing the diagonal of the digital format, I can't suggest a specific focal length, but 30mm is definitely too short. However, having said that, I find most head and shoulders portraits boring, and prefer the person in their environment; it seems that the 40 or even the 50 would be a better all-around choice.
05-07-2008, 11:31 AM   #7
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Perhaps you could branch into group portraits?
05-07-2008, 12:38 PM   #8
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The diagonal measurement of the asp-c sensor is about 29mm, making a 30mm a normal lens for this format. This is why a 28mm is so handy to me. The 50mm makes a great lens for head and shoulders shots, while a 28,30 or 35mm would work well for full figure shots. Try it before you buy it. Stick one on your camera and take a shot of the salesman.

Dave


Last edited by Big Dave; 05-07-2008 at 10:51 PM.
05-07-2008, 03:47 PM   #9
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31 ltd is a pleasant focal length with APC camera.

On a FF camera, my favorite focal length is 50mm. So 31 ltd shall be a multi-purpose lens for sure. It really has an edge to the image quality comparing to Fa 50 f1.4 photos. You get more consistent performance with 31 ltd.
05-07-2008, 05:30 PM   #10
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The issue with feature exaggeration is a real one. Noses tend to grow and chins to recede. This is not a matter of distortion. Rather, it is a matter of perspective and cannot be corrected with PP.

The 1.5x crop factor does not make a 30mm into a normal lens. While the FOV is similar to a 45mm, the perspective is much different. To see what I mean, set up a table-top test with three objects (all about ketchup bottle size); one at the edge, one about 6" behind that and to the side, and a the last another 6" back and to the side of that one and directly behind #1.

With your handy kit lens set at 20mm and the camera pointed at the "waist" of the ketchup bottle, position the camera so the front bottle fills the frame vertically and all three bottles are at least partially visible. Do the same at 30mm, 45mm, and 55mm...each time adjusting the camera position so the front subject fills the frame. If possible, fill out the series with a shot at somewhere between 80mm and 135mm. The difference in relative height, and apparent distances of the three objects between the test shots should be VERY apparent. Imagine the same factors if the first object were the subject's nose and the second their ear!

I am not saying that you can't take portraits with a 30mm, just that the time and place for doing so may be rather limited depending on subject and what you are attempting to portray.

Cheers!

Steve

Last edited by stevebrot; 05-07-2008 at 05:38 PM.
05-07-2008, 06:20 PM   #11
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QuoteOriginally posted by stevebrot Quote
The 1.5x crop factor does not make a 30mm into a normal lens. While the FOV is similar to a 45mm, the perspective is much different.
I disagree. It isn't because of the focal length that perspective changes, it is distance to the subject.

For example, if you are taking a picture of someone from 15 feet away with a FF camera using a 46mm lens. Then you picked up a K10D with a 31mm lens and framed it exactly the same as you did with the FF camera with the 46mm lens, you would still be 15 feet away. All things otherwise being equal, the portraits would be identical.

.
05-07-2008, 06:53 PM   #12
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QuoteOriginally posted by stevebrot Quote
The 1.5x crop factor does not make a 30mm into a normal lens. While the FOV is similar to a 45mm, the perspective is much different.
A person with a zoom lens framing the same picture once at 30mm and once at 45mm, he will get similar foreground in the pics but different perspective/background. Your statement is correct only for this case and it's nothing to do with crop factor, it's because the photographer moved.

OTOH, one person with 30mm on 1.5x crop and one person with 45mm on film camera shooting from same spot will get similar pics with similar perspective.

I need to turn this into my signature
05-07-2008, 07:17 PM   #13
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QuoteOriginally posted by TomInJax Quote
I disagree. It isn't because of the focal length that perspective changes, it is distance to the subject.

For example, if you are taking a picture of someone from 15 feet away with a FF camera using a 46mm lens. Then you picked up a K10D with a 31mm lens and framed it exactly the same as you did with the FF camera with the 46mm lens, you would still be 15 feet away. All things otherwise being equal, the portraits would be identical.

.
You may have something there...any physicists in the crowd? I know that what you are saying is true for flat subjects taken straight on and for all subjects as distance approaches infinity.

I recently did a series similar to what I described because I doubted the very assertion that I made in my original response. Strangely, the shorter focal length images still exhibited the typical "wide-angle look" (exaggerated perspective and greater DOF). The normal still looked "normal" (though cropped) and the longer focal lengths still looked like they were taken with a telephoto (flattened perspective and narrowed DOF).

Before I got my K10D, I figured I would mount up my 28mm and use it as a short normal. I tried this for awhile, but was not happy with the results. The 28 is rectilinear and has very low distortion, but regardless of FOV, the pictures never really "looked" right. Strangely, they looked like crops from a picture taken with a 28mm lens!

In any case, I would suggest that the poster try it out. If the results are good...go for it!

Steve

BTW...I would have posted my test pictures, but I deleted them...perhaps I will redo the test?
05-07-2008, 08:44 PM   #14
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Ok...tell me my penance and I will comply...I have erred...

Here are two images taken with the kit lens at identical distance, angle, and camera setting. One was taken at 55mm and the other at 35mm. Both were cropped to enclose the same subject matter.

Tell me (without looking at the exif), which is which:

View Picture EXIF
Name:  IMGP4949.jpg
Views: 3375
Size:  155.4 KB

View Picture EXIF
Name:  IMGP4948.jpg
Views: 3025
Size:  145.6 KB

Steve
05-07-2008, 08:59 PM   #15
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nice test steve ... good thing i got it right
maybe a lens isn't the best thing to use as a subject tho, too bad you didn't use ketchup bottles :P
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