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DPChallenge Forums >> Tips, Tricks, and Q&A >> Are you using the correct lens for portraits
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Showing posts 26 - 40 of 40, (reverse)
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 02/23/2006 07:49:03 PM · #26
Prof_Fate, I LOVE that shot, and yes, I like to shoot portriats with long focal lengths too!
 02/23/2006 08:29:35 PM · #27
Originally posted by laurielblack:

If I have to do that kind of math just to take a picture, I think I'll go ahead and eBay my kit right now. ;)


I hear ya girl. I feel the same way.
 02/23/2006 09:12:20 PM · #28
Originally posted by paddles:

It seems like some peoples' obsession with using the rule of thirds, calculating it down to the millimetre.


people here at dpc also are very serious about this. I have observed they tend to give high scores to such photos.
 03/07/2006 09:37:04 AM · #29
Hi
I believe that its all down to perspective.
To small a focal length results in big nose and small ears.
 03/07/2006 11:23:02 AM · #30
I have since run across a website or two on portrait instruciton, and they have the same theory about twice the diagonal,. BUT it matters what kind of portrait - head shot, 3/4, full length, one person or a group.

Another interesting point brought up I ahd not heard of before - camera position, vertically speaking. It should be placed mid point of the image - so you can stand for a head shot, but for a full length portrait you should have the camera at waist level, and of course keep the film plane parallel to the subject. Same issues as when photographing a tall building , a perspective problem.

Yes it's minor, but it is these subtle things that can make a big difference, but are hard as hell to figure out for yourself.
 03/07/2006 11:43:31 AM · #31
I've found it is mostly an issue of the compression effects of the lens. It all boils down to wanting to get a mild telephoto on whatever sensor size you are using. I used to really like using a 50 1.8 on a 1.6x crop camera for tight headshots. Since moving to a 1DII I find the 50 tends to not give enough compression when in tight (this makes sense as it has effectively gone from a 80 to a 65mm effective focal length. Still a good lens for 3/4 portraits though.)

I just wish there was a good 65mm prime option. I'm thinking about getting an 85 1.8 or 1.2 soon. The macro 100 f2.8 isn't bad for portraits either, but gets a bit too tight for most situations and I find something like the 70-200 zooms to be a bit too big and intimidating for the subjects when you are up close and not sniping.

100mm 2.8


Not flat enough with a 50mm on a 1.3x crop.


Still liking the 50mm for longer shots on the 1.3x crop


Course none of these are really 'rules' as such, so if you want lots of distortion, a 17 is the way to go for portraits :)
03/07/2006 01:10:49 PM · #32
Originally posted by paddles:
It seems like some peoples' obsession with using the rule of thirds, calculating it down to the millimetre. Illustrative story: At my friend's camera club, one of the judges is known for being obsessed with the rule of thirds and ignoring any sense of artistry. Once when he was scheduled to be judging, my friend submitted a photo of her cat; the photo was uninspired but she'd cropped it and measured it so that the cat's eyes were exactly at the rule of thirds intersection. The judge's comment was "This photo carries no emotion for me, but the rule of thirds was applied perfectly - I give it 13 out of 15." This confirmed my friend's complete lack of respect for the judge.


Funny! Even more amusing since the rule of thirds is a rough guideline to important intersections when considering the the golden proportion (1:1.618) measurements in fibonacci sequences (examples of which are here: //powerretouche.com/Divine_proportion_tutorial.htm ).
 03/07/2006 01:55:35 PM · #33
The math originally posted will also give you an idea of what type of lens will give an approximate 45 degree field of view, which is what we normally see not taken into consideration peripheral vision. In the example a 28mm lens would be normal for my camera anything smaller would be considered a wide-angle lens for my camera and anything larger would start to get into telephoto. Now there would be some give on each end, but the thing to consider is things start to get distorted the further I would get from the 28mm.
 03/07/2006 03:06:47 PM · #34
Originally posted by PhotoRyno:
The math originally posted will also give you an idea of what type of lens will give an approximate 45 degree field of view, which is what we normally see not taken into consideration peripheral vision. In the example a 28mm lens would be normal for my camera anything smaller would be considered a wide-angle lens for my camera and anything larger would start to get into telephoto. Now there would be some give on each end, but the thing to consider is things start to get distorted the further I would get from the 28mm.


Yup - it works out what a 'normal' lens would be then doubles it to get a short telephoto - which is ideal for most portrait work.
 03/07/2006 03:16:29 PM · #35
Portrait shooting is basically to flatter the subject outside of the artistic takes. While the 80/85 is most popular some subject require 100/135. It is simple: there is more spacial compression in the higher figures to assuage a long or over portruding nose or highly skull projections such as everly sunken eyes with the forehead bone obtruding.

The more compression, the less imbalance.
 03/07/2006 03:29:16 PM · #36
It totally depends what you want - bokeh, do you want to pull in the background, do you want a wide angle effect etc? But many other have commented this before me.

This for example is an environmental portrait that does not require any math. The noise is intentional...

03/07/2006 03:56:19 PM · #37
I was told that the farther you are away, the less distortion is present. Based on that theory, a 200mm lens would be better for portraits than a 50mm anyday. Only difficulty is the communication between you and your model. I was told that by a fairly well experienced photographer. Personally, I use the 50mm f/1.8 as well though
 03/07/2006 04:41:20 PM · #38
The whole issue of sensor size is a red herring IMHO. The reason the 80-100mm is the gold standard of portrait lenses has to do with the optical distortion range between 10mm and 1000mm. The 80mm creates the most flattering and natural look as the lenses go from fisheyed to super flat. If the sensor was ten times a 35mm frame, the 10 mm would record alot of fisheye. If the sensor was small enough the inverse. How much of the frame is filled is a cropping issue, not an optical issue.
 03/09/2006 09:53:19 PM · #39
Extremely long post alert!

Red Herring is right! In the end the question will still remain, what are you trying to do, specifics?

In any format choosing the right lens for portrait photography depends upon a great many things, most importantly is what you are trying to achieve.

IMHO, the second most important is what the different classifications (super wide, wide, normal, telephoto, super telephoto) do to the image.

Wides and wider, make closer 'things' appear larger than further 'things' (larger than they should). So taking a head portrait with a wide angle will make the nose appear disproportionate to the ears (you may not even be able to see the ears) and eyes.

Shooting with a 'normal' lens will produce a 'normal' look. (NOTE: Normal is not a based on AOV, if it were, a normal lens would have an AOV of ~150 degrees. Stick you finger way out to the side of your vision and you will still see it looking forward when it's out about 150 degrees.) Normal is a designation on how many objects appear in relation to one another from fore to aft. Or it may be normal because the focal length equals the cross dimension of the format. (equal enough for manufacturing that is)

But shooting a head portrait isn't flattering at all. People like portraits that are a bit 'flatter' than normal. Hence the reason for the 80-105 mm 'standard' in 35mm format. Telephoto to super telephoto lens tend to bring in the backgound objects, making them appear much closer than they really are.

An experiment you can try to accomplish this is you will need to find a distant object, such as a tall building - reasonably unobstructed - at least on one side. Get a person willing to participate.

Now using your wide angle lens, fill the frame top to bottom with your subject, also keep part of your distant building - reference object in the frame also. Take a photograph.

Now, change focal lengths to a normal setting for your camera (50mm in 35mm format, ~31mm for 1.6x cameras); fill the frame with your patient subject - again keeping the reference object/building in the frame somehow. Take a photograph.

Again, change the focal length to a telephoto, say 100mm in 35mm or ~63mm in 1.6x format. fill the frame with your patient subject - again keeping the reference object/building in the frame somehow. Take a photograph.

If you can, change to a much longer telephoto of 300mm/35 or ~185mm/1.6x and repeat the process one last time.

When you compare the different photographs back at home, notice the distortions. Your subject (person) fills the frame in each one but the building appears to move. Also, the wider the focal length, the size relationship between your subject and the build favors the subject (subject looks bigger than the building possibly (in two dimensions), but definitely the size ratio favors the person) While in the telephoto shots the size ratio favors the building most definitely. In normal, things are sized normally.

While I mentioned 35mm, 1.6x format, none of that matters. The only thing that matters really, is what 'type' of lens. Are you shooting L glass? No no thats not it. All that matters is wide, normal, telephoto etc for the format you are shooting.

Determining what is wide or telephoto is easy, these are designated depending on the which way they deviate from normal/standard for the format. What 'technically' determines a normal lens for a particular format? I do not know. That was determined long ago, in formats prior to 35mm. But it still applies to 35mm, 1.6x APS, MF, LF, tiny sensors, etc. Each format has a different standard - but they are all related by ONLY a factor.

format, calculated standard, available standard, 35mm Factor

1. 35mm, 50mm, 50mm, 1
2. APS, 31.25mm, unk, 1.6
3. 1.6x, 31.25mm, 35mm, 1.6
4. 6x6, ~90mm, 90mm, .546
4. 6x7, ~100mm, 100mm, .504
5. 4x5, ~187mm, 150mm, .267
5. 8x10, ~375mm, 300mm, .267

Why do the normals differ when you get to the larger format cameras? Exactly I don't know really, but I think it had to do with making the lenses back in the day. I think they tried to make things understandable by 1, using inches, and 2, using the cross measurement for the standard lens. an 8x10 has a corner to corner measurement of 12.8 inches, making it an easy 12 inch that is 304.8mm and darn close to the 300mm normal lens. Same way with a 4x5 the cross on that is 6.4 inches, making it 6 for ease and you come up with a 6 inch normal lens (152.4mm).

At the larger formats, the deviation in the rounding is less of an issue because it really didn't amount to much. These choice were made probably mostly for manufacturing concerns rather than 1 pixel here or there. (People were happy to take pictures, not worried in the slightest that the normal lens is truely 187.5mm, not 150mm)

But, when you decrease the format size, the deviations have a greater impact because of the deviation to cross measurement ratio. (Yeah I just made those terms up)

Should we worry about whether or not the standard is 31.25mm or 31.00 or 30mm or 35mm on a 1.6x camera? Absolutely not. Do you need to worry about the difference between 50mm and 35mm on a 1.6x? You tell me, it's your picture you are taking.

Tonight, I shot just about 250 shots of my daughter with a 50mm/1.8 lens. Filling the frame for headshots, I felt uncomfortable with how close I was and so did she. This was rather slight, but I noticed it. And it went away after a bit. So on that note, I think a little longer might be good.

Also, the perspective / size relationship of objects in the frame, they appear 'normal'. What do I mean, I think they nose was a flattering size compared to the ears. I would like to try a little longer, but not an 80mm - well maybe just for fun ;)

Normal on your 1.6x sensor is a 31.25mm lens. Good luck finding one. Portrait 'range' on your 1.6x camera is 50mm-65.625mm.

Want to calculate your normal? Find a format you are relating to and use Pythagorean theorem (a^2+b^2=c^2 or c=SQRT(a^2+b^2)) to both formats, both dimensions and divide both the results and be sure to convert to like terms (mm)

Eg. 35mm to APS/1.6x formats

35mm
----
36x24
c1=SQRT(36^2+24^2) = 43.3mm (this is the distance between frame corners)

APS/1.6x
--------
c2=SQRT(22.5^2+15^2) = 27.0mm (this is the distance between frame corners)

c1/c2 = 1.6 (this is the conversion factor, converting c1 format to c2 format) (actually it's 1.6037037037037 for those of you who think a 640x639 image isn't a square crop)

While I'm on a formula kick. Here is a formula that you can use to determine what focal length you need to fill the frame at a given working distance (working distance is the distance from the end of the lens to the subject)

Fl = Il * Wd / Sl

Where:
Fl = Focal Length
Il = Image Length (one of the sensor / format dimensions)
Wd = Working Distance
Sl = Subject Length (or portion of subject you are interested in, ie face)

Eg. I want to photograph a 5 foot (1524mm) tall school football player at a working distance of 60 feet (18000mm) and I want to fill the frame of my 22.5mm (portrait) sensor.

Fl = 22.5 * 18000 / 1524
Fl = 265.748mm

That 265.748mm is actual focal length, since we have taken into account the image sensor you don't need to factor it again. (ie. dont apply the 1.6x factor and think you only need a 166mm lens)

In closing, it doesn't matter what the factor is as long as you follow the guidelines or deviate from them as you see fit. Fill your frame, does the nose appear too large? Do you want it too? Do you need a super telephoto anyway because the witch you are photographing is self conscious about her nose, and thus you know how to make it appear smaller. (Hey even a 1200mm might not help some honkers out there - hence the reason I have no portrait of myself)

Best regards,

CN
03/09/2006 10:58:38 PM · #40
Extremely short, non-mathematical post alert!

Move toward/away from the subject until the perspective is what you want then pick the lens (or zoom) so that the portion of the subject you want fills the frame.

This works for any sensor size and aspect ratio. No calculations required.
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