Bokeh with Multiple Subjects

HAbraham · 02-07-2012, 07:07 AM

I bought the K5 about a month ago. It is my first DSLR, so please bear with my novice questions.

I picked up the Pentax 77mm f/1.8 limited lens for portraits. Up until yesterday, all my portraits were of a single subject. The K5 made it easy. Just throw it into aperture priority, set it wide open, point and click. The results were consistently beautiful with a creamy bokeh that made my shots look amazing.

Yesterday I went on an outdoor shoot with two subjects. I followed the same pattern but when I got home at least half of my shots were unusable because the variance in depth of field was enough that one of the subjects was often out of focus.

Is there something on my camera that was telling me my DOF was too shallow for the lighting conditions? If they were out of focus in my view finder I failed to notice it. (I got enough decent shots to save the shoot but I missed some really great shots due to DOF issues.)

Pa. Patriot · 02-07-2012, 09:27 AM

The 77mm, at typical portrait distances (~10ft) will only have a few inches depth of field shot wide open (1.8)
There is nothing in the camera that indicates DOF other than the viewfinder, and the stock viewfinder focusing screen is unable to represent the shallow DOF of faster lenses. It helps a lot to switch to a focusing screen such as the canon ee-s, but it's still going to be somewhat hard to discern your actual DOF in the small dark K5 viewfinder.

Keep shooting, experience will be the most accurate tool. Remember as distance to subject decreases, so does DOF. Since most portraits are relatively close to the camera you are limited in how to increase DOF and retain bokeh. The only way to increase dof for a given focal length and aperture is to increase distance to subject. Without more distance you need smaller aperture. But, experiment with the smaller aperture since at 77mm, even F:2.8 produces nice bokeh if the subjects are separated adequately from their background and 2.8 nearly doubles your usable DOF.

freewheelin25 · 02-07-2012, 09:27 AM

I was in the same boat after Christmas trying to figure out the 77mm 1.8 and K5 combo. I have two suggestions: First I would put the aperture at f8 or f11 when shooting multiple subjects. Also, I would purchase and watch this course: Lynda Foundations of Photography Exposure. This was the best course for explaining how to properly use the camera. The K5 along with the 77mm 1.8 combo produce photos that have amazed my friends and wife. My wife was mad at me for spending so much money on a camera, but now she is taking a class and loving the camera because our photos get so many compliments from friends and family. I've been reading books, watching videos and of course practicing like crazy and at first the prime lens was awkward indoors, but as time goes on I find the 77mm 1.8 to be the perfect focal length and I wouldn't trade this lens for the world. I

JinDesu · 02-07-2012, 09:35 AM

The k-5 has a DOF preview doesn't it? Not very useful to me when I tested it in the store because everything got dark!

However, if my understanding is correct, the camera uses the widest aperture of your lens for you to look through, so if you are shooting wide open or even stopped down once, the out of focus parts in your viewfinder should match your picture. If you want to be certain of what your DOF is, try using a DOF calculator (can get one on a smartphone) or memorize some typical values.

**maxfield_photo** · 02-07-2012, 10:28 AM

The FA 77 has a DoF scale printed on the barrel, take a look. At f/1.8 at typical portrait distance there's not much wiggle room, maybe an inch or two. The old photojournalists had a saying: "f/8, and be there!"

reeftool · 02-08-2012, 09:27 AM

I find it difficult to get a real accurate DOF before shooting the shot. The DOF preview just stops the lens down and since you are shooting wide open, will be essentially the same view you were already seeing in the viewfinder. Live view does a better job in some quick tests but I haven't tried it in a real working situation and even then, the small LCD isn't the same as a computer monitor or looking at a print. Some of the more technical members can probably explain things but the actual DOF you get from your shot usually won't be the same as you see in the viewfinder, even using the DOF preview. For a 2 person portrait, you would want to stop the lens down just enough to get the appox 18-24 inch area in focus and still have the bokeh you desire which certainly won't be the same as 1.8 but may still blur enough. You may have to move your subjects or even use a different lens to get what you want. As you explore questions like this, you soon begin to understand why there are so many lenses out there. It appears to be redundant but they really aren't. An experienced portrait guy will have his favorite lens for different shots.

02-07-2012, 07:07 AM	#1
HAbraham New Member Join Date: Feb 2012 Location: Minnesota Posts: 2	Bokeh with Multiple Subjects I bought the K5 about a month ago. It is my first DSLR, so please bear with my novice questions. I picked up the Pentax 77mm f/1.8 limited lens for portraits. Up until yesterday, all my portraits were of a single subject. The K5 made it easy. Just throw it into aperture priority, set it wide open, point and click. The results were consistently beautiful with a creamy bokeh that made my shots look amazing. Yesterday I went on an outdoor shoot with two subjects. I followed the same pattern but when I got home at least half of my shots were unusable because the variance in depth of field was enough that one of the subjects was often out of focus. Is there something on my camera that was telling me my DOF was too shallow for the lighting conditions? If they were out of focus in my view finder I failed to notice it. (I got enough decent shots to save the shoot but I missed some really great shots due to DOF issues.)

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02-07-2012, 09:27 AM	#2
Pa. Patriot New Member Join Date: Oct 2011 Photos: Albums Posts: 23	The 77mm, at typical portrait distances (~10ft) will only have a few inches depth of field shot wide open (1.8) There is nothing in the camera that indicates DOF other than the viewfinder, and the stock viewfinder focusing screen is unable to represent the shallow DOF of faster lenses. It helps a lot to switch to a focusing screen such as the canon ee-s, but it's still going to be somewhat hard to discern your actual DOF in the small dark K5 viewfinder. Keep shooting, experience will be the most accurate tool. Remember as distance to subject decreases, so does DOF. Since most portraits are relatively close to the camera you are limited in how to increase DOF and retain bokeh. The only way to increase dof for a given focal length and aperture is to increase distance to subject. Without more distance you need smaller aperture. But, experiment with the smaller aperture since at 77mm, even F:2.8 produces nice bokeh if the subjects are separated adequately from their background and 2.8 nearly doubles your usable DOF.

02-07-2012, 09:27 AM	#3
freewheelin25 New Member Join Date: Oct 2011 Posts: 18	I was in the same boat after Christmas trying to figure out the 77mm 1.8 and K5 combo. I have two suggestions: First I would put the aperture at f8 or f11 when shooting multiple subjects. Also, I would purchase and watch this course: Lynda Foundations of Photography Exposure. This was the best course for explaining how to properly use the camera. The K5 along with the 77mm 1.8 combo produce photos that have amazed my friends and wife. My wife was mad at me for spending so much money on a camera, but now she is taking a class and loving the camera because our photos get so many compliments from friends and family. I've been reading books, watching videos and of course practicing like crazy and at first the prime lens was awkward indoors, but as time goes on I find the 77mm 1.8 to be the perfect focal length and I wouldn't trade this lens for the world. I

02-07-2012, 09:35 AM	#4
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	The k-5 has a DOF preview doesn't it? Not very useful to me when I tested it in the store because everything got dark! However, if my understanding is correct, the camera uses the widest aperture of your lens for you to look through, so if you are shooting wide open or even stopped down once, the out of focus parts in your viewfinder should match your picture. If you want to be certain of what your DOF is, try using a DOF calculator (can get one on a smartphone) or memorize some typical values.

02-07-2012, 10:28 AM	#5
maxfield_photo Site Supporter Join Date: Mar 2011 Location: Cincinnati, OH Posts: 1,216	The FA 77 has a DoF scale printed on the barrel, take a look. At f/1.8 at typical portrait distance there's not much wiggle room, maybe an inch or two. The old photojournalists had a saying: "f/8, and be there!"

02-08-2012, 09:27 AM	#6
reeftool Pentaxian Join Date: Dec 2007 Location: Upstate New York Photos: Gallery \| Albums Posts: 9,553	I find it difficult to get a real accurate DOF before shooting the shot. The DOF preview just stops the lens down and since you are shooting wide open, will be essentially the same view you were already seeing in the viewfinder. Live view does a better job in some quick tests but I haven't tried it in a real working situation and even then, the small LCD isn't the same as a computer monitor or looking at a print. Some of the more technical members can probably explain things but the actual DOF you get from your shot usually won't be the same as you see in the viewfinder, even using the DOF preview. For a 2 person portrait, you would want to stop the lens down just enough to get the appox 18-24 inch area in focus and still have the bokeh you desire which certainly won't be the same as 1.8 but may still blur enough. You may have to move your subjects or even use a different lens to get what you want. As you explore questions like this, you soon begin to understand why there are so many lenses out there. It appears to be redundant but they really aren't. An experienced portrait guy will have his favorite lens for different shots.