Talk to me about this bokeh...

[zulu42]

Still surprised about that first shot with the butterfly. I would have bet money on backdrop.

 

[Derrel]

Thanks Derrel.

Cleared up my mistaken assumption that one controls the amount of blur in the background primarily by controlling DOF.

I would say that one controls the amount of blurring in the background mostly by,first, choosing the right lens focal length. After the focal length has been selected, then the choices surround things like A)how close is the camera-to-subject distance, which has a LOT to do with the degree of depth of field B)how far behind the subject is the background and C)what f/stop will be used. Those are the four factors that are most commonly able to be controlled. A fifth factor would be capture format size (m43,APS-C,FX being the three most common sizes today).

But in general, I'e always picked the lens focal length first. If I want to "blow out" the background, and really,really make it blurry, I go for the 300mm or 200mm or 180mm primes, or the long end of a 70-200 or 70-300 zoom lens.

If you use 300mm on a 70-300mm f/4~5.6 "consumer" type zoom lens, you can get a pretty nice background blur. Of course, the really fast-aperture lenses, with BIG, wide apertures, really do offer amazing background blowout. This is where the 300/2.8 has been so good for so long, and where the 200mm f/2,and now the 105mm f/1.4, have come to be sort of "trending" lenses among the high-end shooters.

There is something to be said for high-dollar, exotic lenses, the ones that offer very wiiiiiide apertures!

Still, one can get pretty good results using more moderate lenses, like the 100mm f/2.8 from Canon, or the older 135mm f/2.8 lenses from many manufacturers. The old, once-popular 135mm f/2.8 Ai or Ai-S is still available in a manual focusing, Nikon F mount for around $75-$100, and can easily be adapted to Canon EF or to mirrorless bodies.

 

[zulu42]

I'm going to try out some shots at around 200-300mm on my big dumb Tamron just for fun.

Not sure if anybody has brought up defocus control. A different conversation as far as lens mechanics, but If I wanted to consistently feature artsy blown bokeh back and foregrounds, I might learn some more about that also.

 

[JBPhotog]

Digital focusing screens today aren't what they used to be like in my F3HP's but I still hung on to my beloved Nikkor 105mm f2.5 AI until the f1.4E version was available. I always loved that focal length but the 105mm f1.4E is simply superb with its exceptional rendering quality. It will become one the Nikon's legendary optics and produces gorgeously rich images in the same league as the Nikkor 200mm f2.0 and 300 mm f2.8.

 

[CThomas817]

2. The lens is longer and allows for a wider depth in the focal plane?

Longer focal length lenses will produce a more shallow DOF, not wider.

If you think of DOF in space, then the term "wide" is practically meaningless.

DOF is figured as being a range of acceptable focus beginning at some distance from the lens and extending back toward the background. The concept of width does not apply, but thickness does.

Please obtain a DOF calculator that you can have with you (on your phone) at all times, and start using it. Its regular use will help clear up any confusion you may have.

I fully understand what a shallow depth of field is and I understand that you can obtain a more shallow depth with a longer focal length lens. What I'm saying is... 15 feet from my subject at f/2 on an 85 mm - my entire subject will not be in focus. Perhaps the ears, crown of the hair will start to blur. 30 feet from my subject at f/2 on a 200 mm lens - will more or less of my subject be in focus? My question is how much wiggle room I have within the focal plane, not what overall DOF is achievable. I will get the DOF calculator and figure it out. Thanks.

 

[CThomas817]

When I first saw the thumbnails I thought it looked like someone's trying to beam the kid up to the mother ship. Seriously, I see a whitish/lighter brighter streak vertically above and below the subject thru the image - when I click on it to enlarge it I don't see it.

The other two are so edited/processed... how in the world could you get a butterfly to pose right in front of someone like that?? and keep a child there waiting til a butterfly happens a long? (Or hold a cat long enough? lol) The blue butterfly? fake, and the pink foreground? yeah, boofed up cotton candy sounds about right... And why is the girl glowing?? where is that light coming from??

I can see the edge around the blue sweater of the other girl. And again, the light around her makes no sense. I agree about the backgrounds and foregrounds not going together, at least it's hard to tell. I don't know what was edited together or how or why people like it.

At best, it's a photo illustration.

Oh I am totally aware that these are "optically enhanced" to some degree but I was specifically asking about the bokeh.

 

[CThomas817]

I'm going to try out some shots at around 200-300mm on my big dumb Tamron just for fun.

Not sure if anybody has brought up defocus control. A different conversation as far as lens mechanics, but If I wanted to consistently feature artsy blown bokeh back and foregrounds, I might learn some more about that also.

Right... your lens just has to have it!

 

[CThomas817]

We want to keep in mind there is a lot of information on the depth of field issue. There is much less information available on the Internet regarding background blur. There are just a few photo illustration examples that I know of. Imagine that we have a 50 mm lens, an 85 mm lens, a 200 mm lens, and a 300 mm lens. If we shoot at F4 with each of the lenses and move the camera farther and farther and farther away from the subject, to maintain a full body person in the picture, what you'll find is that the longer the focal length at F4, the more blurred the background. Now, if you do the mathematics and use 1/4 of the length value for each lens, it will tell you the approximate aperture width in millimeters at F/4. Yes, the exposures will be the same, because the relative value is f/4, but the larger the physical width of the aperture-- the blurrier the background. This is why for several decades, the 300 mm lens has been used to blow out backgrounds, because even at F4 it has a very blurry background rendering when used on people, at normal people photographing distances

Thank you for understanding my question!!

 

[JBPhotog]

At 15 feet an 85mm at f2 has enough DOF to capture all you need to get a face in focus and then some. The field of view will of course be different than a 200 at 30 feet.

Remember, DOF is calculated as the zone of acceptable sharpness based on the circle of confusion for your sensor.

FYI:

 

[Designer]

30 feet from my subject at f/2 on a 200 mm lens - will more or less of my subject be in focus? My question is how much wiggle room I have within the focal plane, not what overall DOF is achievable. I will get the DOF calculator and figure it out. Thanks.

Here is a screen shot when I plugged in the values you gave me. As you see, the total DOF is only .54 feet, so your subject's thickness should be only about 6 inches. (joke) Obviously nobody is that thin, so you'll get some blur at the back of her head.

 

[Designer]

(attached)

 

[Braineack]

However in the Nikkor G-series 85mm side-by-side tests I have seen, the f/1.8 model and the f/1.4 model are pretty close in terms of the type of bokeh and the amount of blur possible. In fact, I really do not think the 1.4 model has much advantage whatsoever.

It's been a while, but I thought I had read it had better sharp to soft transition, a bit mushier blur, and a little sharper where in focus. But yeah, marginally at best probably not the best example to pick. But comparing the 50mm 1.8g and a 58mm 1.4g...

 

[JBPhotog]

(attached)

View attachment 163964

These are for a DX sensor, the OP is using an FX sensor, different CoC calculation.

 

[Designer]

(attached)

View attachment 163964

These are for a DX sensor, the OP is using an FX sensor, different CoC calculation.

Oh, right you are! My mistake. Anyway, she can run the calculation herself.

 

[JBPhotog]

(attached)

View attachment 163964

These are for a DX sensor, the OP is using an FX sensor, different CoC calculation.

Oh, right you are! My mistake. Anyway, he can run the calculation himself.

I did that for him in post #39.