Well ta-da! You are one of the first to experience my highly intellectual, brain-stimulating editions of Tech Tips!! I’m not much of a teacher. But I absolutely LOVE talking about photography, so that’s kinda all I’ll be doing here. I’m definitely no pro on any subject, but may have some useful tips for those who are interested in taking the leap to shooting in manual. I’m going to attempt (don’t hold me to it) to have a Tech Tips blog post once a week, so if you have any questions about shooting, using light, settings on your camera or anything regarding photography at all, head on over to my facebook page and ask! It may turn into a blog post!
Today’s question comes from Marilyn: How do you do a pic where you have 2 subjects and the one in the front is blurred so the main focus is the subject in the back? What’s the best setting to have your camera on for that, the best distance to be, the correct ISO…
Also blurring the back subject…
Is it focussing on the subject you want blurred, hold down button half and the refocusing on sharp subject?
This question refers to controlling your “depth of field”. How deep do you want your field of focus. I often shoot with a very narrow depth of field, and I love how it isolates my subject. Here’s an example of a photo shot with a narrow depth of field:
f/2.0, ISO 640, ss 1/800 (shot with 85mm lens)
Depth of field is determined not only by your aperture, but also by how close you are to your subject and the length of your lens. The closer you are to your subject, the shallower your depth of field. So if you are planning to do a headshot of someone, you don’t necessarily need to open up to an aperture of 2.0 or lower to get that nice creamy background. Here is a photo also shot at f/2.0. But because I’m standing further away from my loooovely subjects, and I’m using a lens with a shorter focal length (the 50mm), the background has more definition than it did in the previous pic.
f/2.0, ISO 200, ss 1/1250 (shot with 50mm lens)
So Marilyn, in answer to your question, here are two images that show exactly what you’re asking. If i’m understanding what you’re asking 😉
f/2.8, ISO 250, ss 1/250 (shot with 85mm lens)
My settings for these two images are exactly the same, but in the image on the left, I focused on Allen & Michelle. Because of the narrow depth of field, and my proximity to my subject, the leaves in the foreground appear out of focus. In the image on the right, I focused on the leaves, and the background appears out of focus.
With regards to focal length, the longer your lens, the narrower your depth of field will be. For example, standing 15′ from your subject, shooting with a Nikon D600 and 50mm lens at f/2.0, will give you a depth of field (area of focus) of 3.29 feet (according to an online depth of field calculator that I have linked below), whereas shooting with the same camera, from the same distance, with the same aperture with a 200mm lens, will give you a depth of field of 0.2 FEET!! That is RAZOR THIN! When I was just starting out, and had a couple of lenses to play with, I used that depth of field calculator a lot. It’s one thing to shoot a single subject with a very narrow depth of field, but what if you’re shooting a family? You want to make sure that EVERYONE is in focus. Even if there are a couple rows of people.
I use a wider depth of field when I feel that the location helps to tell the story. Like the image below – we were in a gorgeous setting, and I had no need for any background blur at all.
f/10, ISO 1000, ss 1/160 (shot with 14-24mm lens at 19mm)
But the biggest tip I can give you is to just get out there and practice. I have a kajillion pictures of two rocks on my kids’ picnic table, one slightly in front of the other, that I shot from all different distances and with all different apertures to try and become comfortable with controlling my depth of field. It is much more difficult to achieve sharp focus on your subject when shooting at very low apertures, so start a bit higher – maybe in the f/4.0 – f/5.6 range – until you’re comfortable with that, and then slowly work your way lower. It’s exciting to achieve gorgeous bokeh (that delicious background blur that I love), but the picture is worth nothing if the subject is not in focus. Just my 2 cents 😉
Hopefully that helps you understand depth of field a little bit more!
You also asked about which ISO to use, and that’s another blog post all by itself 😉 Thanks for the question!!