donaldejose said:
Hence, if you are in low light and want to keep the full face reasonably sharp grab your D400 DX body because that allows you to do at f2.8 what you will need f4 to do if you are using your D4 body? Is this true?

No. The D4 must be light years ahead in IQ /ISO performance than any DX body - don't ever expect DX to catch up FX unless there are 5 years or so between models. So it would be more logical to up the ISO 1 stop on the D4 and still shoot at f2.8.

Slight error here. I am not trying to find what is "right." I was simply experimenting to find the minimum f-stop that would tend to keep that rear eye in focus when using classic portrait lenses in the 100mm range at a classic head and shoulders portrait distance. The rule of thumb seems to be f4 will do it on an FX body and f2.8 will do it on a DX body.

We could say DX gives you a one stop DOF advantage in low light when shooting portraits and trying to keep the full face in reasonable focus. This is not generally commented upon as an advantage to shooting DX. It may be a factor when the new D400 and D72000 come out if they have high ISO equivalent to the new FX bodies. Using f1.8 in DX(and equivalent lenses) will give you about the same DOF as f2.8 in FX and shooting at f2.8 in low light will give you about the same DOF as using f4 on an FX body. Hence, if you are in low light and want to keep the full face reasonably sharp grab your D400 DX body because that allows you to do at f2.8 what you will need f4 to do if you are using your D4 body? Is this true? Conversely, if you are working in f2.8 available light and want to blur the background more grab the FX body and shoot at f2.8 in FX rather than in DX because it will give you shallower DOF in the same light? Just have the model turn her head more directly to you to keep both eyes sharp (or do a profile where you won't see that rear eye or just let it blur).

Yes to all Donaldjose ...

Just a note - I am not much into portraits but when I do shoot some ( mostly my kids ) , I never stick to one aperture. f1.8 ( usually avoid ) , f2.2 , f2.8 , f3.5 etc. Trial and error doesn't cost a penny these days. So don't worry about getting it all perfect in all shots and remember there is no "right" - as you are trying to find - that works for all situations in photography.

Good reminder golf007 though I have rarely come up with any light requiring less exposure than 1/4000 f4 . Sunny 16 gives 1/4000 f2.8 ( f4 with base ISO 200 ). Surely of help if the intention is to go f1.8, f1.4 ...

Can we say, as a rule of thumb for use when setting up your camera for a shot, that an equivalent lens on a DX body when used for the same framing of the subject will give you a DOF equivalent to about one stop more in FX? Or stated the other way: FX provided about a one stop equivalent shallower DOF than does DX with the same f-stop and the same framing using an equivalent lens? Hence, in my example above of head and shoulders framing using equivalent lenses; the DX combo at f2.8 will produce DOF equivalent to the FX combo at f4 and the same would be true for DX f4 to FX f5.6 or DX f5.6 to FX 8? Is this DX/FX effect the source of the comment I have seen to the effect that "FX isolates the subject more?" I have always shot DX until a few months ago when I picked up my first FX body so I had no practical experience with that comment.

One thing that has not yet been brought up is the use of ND filters in order to achieve a shallower depth of field.

And I quote: "Although ND filters are primarily used to achieve longer exposures, a less common application is to enable a shallower depth of field in very bright light. For example, most SLR cameras have a maximum shutter speed of 1/4000 second, so a subject in direct sunlight might therefore require an f-stop greater than about f/4.0 (at ISO100). With a 2-stop ND filter, one could reduce this to f/2.0 — yielding a dramatic improvement in background blur and subject isolation....On the other hand, these situations are rare, and can usually benefit more from photographing the subject under dimmer (and likely less harsh) lighting. These situations are also unlikely to require anything stronger than a 2 or 3-stop ND filter."

donaldejose said:
Paperman: I understand needing to get close if you are using the same mm lens. But when you are using an equivelent mm lens you don't need to get closer. You are at the same distance from the subject with the same framing with a 60mm on a DX body as you are with a 85mm on a FX body. I tried it just this morning. So why wouldn't the DOF be the same? I don't understand.

Look at it this way then. You don't actually have a 75mm lens on the DX - it is a 50mm cropped into 75mm.

f-stop is the ratio of lens opening to focal length and we know it is the key factor in determining the DOF . Greater the opening, less the DOF.

The 50mm on DX ( acting like a 75mm ) STILL has the opening of a 50mm lens . It creates more DOF than the FX with 75mm on.

Hi all,

If you approach the calculator differently you'll get a different result. With the 60mm f2.8 at 5ft the DOF is _.23ft and the 85mm f1.8 at 7.5ft DOF is .24ft, but both yield the same frame equivalent and approximate DOF.

For me, the bokeh of the 60mm f2.8 or the 85 f1.8 are equally pleasing and I have both lenses and use them on the D7000. The DOF is more narrow with the 85mm, but the standoff is greater. The 50mm f1.8 is a much better 90mm/85mm 'workalike' in the DX world (with even a slightly shallower DOF), and I have that lens, too.

Things that are important are 'standoff' - how far you are from the subject, and how much room you have to work.

Also, and not trivial, for what use is the product to be used? Some folk are going to want a tad more sharpness in the faces of their loved ones. Printed content tends to muddy a bit, too, making a great blur a gamble, and lenses to tend to preform better at f4/f5.6 than at wide open. I keep that in mind when considering aperture options.

I'm not suggesting a return to the Group f64 (they were using view cameras - somethings were completely different), but it did precede the current trend it selective focus.

My best,

Mike

I would like to way my opinion here and let me know if I on or off base.

To my understanding is DOF has nothing to do with the sensor but is a combination of distance to target, f stop and focal length. I find it easier to think of everything from an FX perspective since that is what everything is base around. A 60mm lens is always going to give the same DOF regardless of the sensor behind it. All the sensor does is apply a crop to that image. So on a D800 with the 60mm all the DX sensor is doing is removing you from having to crop the image later. I find it best to think of it as using a teleconverter. If you put a 1.5 converter on that 60mm lens and take that shot from your D800 don't you get the same image, DOF and everything else? I think it might be a problem to think of lens on DX bodies as having a equivalent focal length to FX since you do not get those statistics. I prefer to think of them as merely a cropping tool.

Paperman: I understand needing to get close if you are using the same mm lens. But when you are using an equivelent mm lens you don't need to get closer. You are at the same distance from the subject with the same framing with a 60mm on a DX body as you are with a 85mm on a FX body. I tried it just this morning. So why wouldn't the DOF be the same? I don't understand.

It is all because with an FX body, you have to get closer to the subject to get it the same size it appears on a DX body frame.

This changes the ratio of distance "front of object" to distance "back of object", thus the difference in DOF.

Some discussion of DX v FX DOF with the same framing by the same lens is on another thread:

Here is an example: "Another way of looking at the FX vs DX DoF is if you want to get the same framing (i.e FoV) with the same 135mm lens on both FX and DX cameras then you'll have to move the FX camera closer to the subject and/or the DX one farther away. This will also create the effect of a greater DoF on DX and a more shallow DoF on FX." iris chrome

http://nikonrumors.com/forum/topic.php?id=6178&page=2

Notice iris chrome is taking about using the same lens on two different bodies. I am talking about something different: using equivalent lenses on different bodies.

Let's take my example of head and shoulders framing with an FX body using an 85mm lens and the same head and shoulders framing with a DX body using the 60mm Nikon Micro (a 90mm FX equivalent lens). In order to achieve the exact same head and shoulders framing the two cameras will be the same distance from the subject. Right or wrong? I tried it and I am standing the same distance from the subject at the same framing. Standing the same distance and using the same f-stops with equivalent lenses will produce the same DOF? Right or wrong? I don't really want to do another series of photos to test it so I used the DOF calculator [http://www.dofmaster.com/dofjs.html] to test equivalent lens/body combinations. It computes a DOF of 0.65 foot for a 60mm lens on a D7000 body standing 7 feet from the subject and a 0.42 foot DOF for a 90mm lens on a D800 body standing 7 feet from the subject. If we input a 60mm lens on a D7000 body at f2.8 the DOF calculator gives us a DOF of 0.46. So Paperman seems to be correct that the FX format produces a shallower DOF at the same f-stop, same distance from subject with equivalent lens then the DX format produces. There seems to be a one stop equivalent DOF difference. If you are shooting a 60mm lens on a DX body you would have the same DOF at f-2.8 that I had a f-4 using a 85mm lens on an FX body. Thus, when I say f-4 provides a reasonable balance between DOF and bokeh for classic portrait lenses with classic head and shoulders portrait framing would that same DOF balance exist at f-2.8 if you were shooting a 60mm lens on a DX body? Is that what the DOF calculator shows? Or am I doing something wrong here?

It seems to me if I am using the DOF calculator correctly f2.8 on a DX body with a 50 to 60mm lens should keep both eyes reasonably in focus while you need f4 on an FX body with an 85mm lens. Is that correct?

I don't understand why the optics would not yield the same DOF with equivalent lenses standing the same distance from the subject with the same framing. It seems the optics would be the same in that situation and you would have equivalent DOFs with equivalent lenses.

donaldejose said:

As to DX sensors, many of the photos in this thread were taken with a DX sensor body. I would think a 50mm lens on a DX body would equate to 75mm and an 85mm lens on a DX body should equate to 127.5mm or a 60mm macro lens on a DX body would equate to 90mm so when you use any of those lenses on a DX body and frame your subject head and shoulders I would expect the f-stops would be about the same as I found for 85mm on a FX body. Why don't you try it if you have 50mm or 60mm or 85mm and a DX body and post your results? Are the eyes on DX at f-4 different than mine? I would be interested to know.

50mm on DX is 75 mm on FX - that much is true. However, DOF at 50mm on DX at a certain f-stop is NOT equal to the DOF at 75mm at the same stop on FX. So you can not make that simple conversion. Full format provides shallower DOF.

Paperman: Sure, f2.8 (and maybe f2?) will work if the face is flat to the camera and more than f4 would be better if the face is turned more away (but if turned much more you won't even see that rear eye to worry about whether or not it is in focus!). I was just looking for the minimum f-stop which would work at head and shoulders distance with a lens from 85 through 105mm: the classic portrait lens and the classic head/shoulders portrait distance. This is all about head shots where you are not blasting the subject with light. In the studio one usually uses f8 and there have been a number of studio shots on PAD recently at f11 or so. If you want to do a half or a whole body portraits you may be using 50mm on FX and 35mm on DX and you will have a different DOF at f4. My originally stated constraints were: What f-stop are you going to need to bring that rear eye into reasonable focus so it is not so obviously out of focus when you frame your subject head and shoulders with a classic portrait lens? The distance from the subject is subsumed in that constraint. I tested it, tried to illustrate my results and found that unless the face is directly facing you the rear eye will be significantly blurred at f1.8, f2 and starts clearing up (acceptabley?) at f2.8 and generally is acceptable at f4. Unfortunately, my original photos were biased by a front focus issue with this body/lens combo and so I re-shot these examples one I corrected the front focusing. That's all. That's what I found and shared it here for anyone interested in the subject. Of course, those f-stops apply only to the original constraints of using a portrait mm length lens at head and shoulders distance for a classic portrait look. Other lenses and other distances were not tested by me and may well have different minimum f-stops for a reasonably sharp rear eye.

As to point of focus, I mentioned that the small AF sensor spots in the D600 are a help because they are small enough to let you attempt to focus just on the near eye tear duct (or as you might say, the near side of the nose). These are just starting places for the effect you want to produce if you are shooting head and shoulder portraits and you don't (or cannot) blast the subject with strobes. F-4 is a nice compromise because it allows for reasonable depth of field and reasonable bokeh (as long as there is some distance between the subject and the background). That is all I am saying, and trying to demonstrate, here. You can see the bokeh produced by f-4 in the portrait I just posted on PAD.

As to DX sensors, many of the photos in this thread were taken with a DX sensor body. I would think a 50mm lens on a DX body would equate to 75mm and an 85mm lens on a DX body should equate to 127.5mm or a 60mm macro lens on a DX body would equate to 90mm so when you use any of those lenses on a DX body and frame your subject head and shoulders I would expect the f-stops would be about the same as I found for 85mm on a FX body. Why don't you try it if you have 50mm or 60mm or 85mm and a DX body and post your results? Are the eyes on DX at f-4 different than mine? I would be interested to know.

Very nice images shared - no argument about that. Therefore it is a nice topic to follow; a lot to learn from portrait masters ... Some images are truly breathtaking ...

However, I still can't seem to understand the struggle ( from Donaldjose ) to generalize the f-stop to be used for getting both eyes in focus. I mentioned my concern for neglect of distance before, I will mention the angle the face makes with the camera now. f4 may be OK with this angle and this distance but what if she turns her head a bit away - increasing the distance between both eyes ?. f4 won't be enough then . What if she turns towards the camera to an angle which will make f2.8 possible ? What about focusing in between the 2 eyes; won't that change things ?

And what about those using APS-C sensors ? More than half in this forum are on a different format which makes these generalizations meaningless .

You have to know Donaldjose that every portrait is different; what you want to see in every portrait is different . With so many variables, you can not just pick an f-stop and say this works for all.

Once more, wonderful portraits from many participants ...

I fixed the front focus on my D600/85mm f1.8 combination and retook two of the photos to see the difference between f2.8 and f4 when the face is at an angle and you focus on the near eye. I come to the same basic conclusion: f2.8 lets the rear eye fall out of focus (but not too distracting on head and shoulders size and would be less noticeable the further you are away) while f4 does a better job of keeping that rear eye in focus and still yields acceptable bokeh. You can judge the bokeh and eyes from the head and shoulder sizes. The crops of just the eyes more accurately show the rear eye focus or lack thereof.

First, 85mm and f2.8 gives this:

Close up of eyes at f2.8:

Now let's use f4 to sharpen up that rear eye and still give us acceptable bokeh:

Close up of the eyes at f4:

You can see that when you focus on the near eye and use f4 the increased DOF brings that rear eye more into focus and I don't think f4 kills your bokeh. Higher cleaner ISO on the newer bodies will allow us to use f4 (such as with the new 70-200 f4 lens) more frequently.

One eye in, one eye out. 24 mm f/1.4

Good idea, thanks. I have never tried focus stacking. Will have to do so.

Macro and other lens bokeh:

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This technique might be the answer in solving DOF and good bokeh.

http://www.youtube.com/watch?v=fJiEw4VCcYU

NR thread that relates to Focus Stacking methodology: http://nikonrumors.com/forum/topic.php?id=1829

Mike: Nice contribution and great photos to demonstrate your comments. Thanks.

One great idea I got from your comments is to try my 60mm AF-D Micro on my D7000 body (would then equate to 90mm f2.8) as a portrait lens. It just may give sharp eyes and good bokeh. Anyone else here use Macro lenses wide open or one stop down for portraits?

Hi all,

Nice photos everyone and a nice discussion.

Bokeh isn't quite defined only as DOF, and as noted is quite subjective. It's more of the 'quality' of the background/foreground that is out of focus and varies by lenses, even in the same focal length, and can vary, by quality level, in f-stop selected by distance from lenses to subject as delineated from the background/foreground by their distance(s) to the subject and the quality of 'out of focus' objects.

I would suggest that a slower f1.8 might be a more economical and smarter lens in some focal lengths for most photographers that faster f1.4 or f1.2s.

I use a Micro 60mm lens at f2.8 or a bump down, too, and think it is a nice lens.

The 50mm f1.8 is a good cheap lens and works great at at wide or a bump down as well.

But stopping the 50mm down to f8 keeps a scene sharp when you want it.

and you can cheat and use the same lens at f2.8 and the same photo for another display of the same actor for another play ;-)

Inside, and with the room to work, you can stop down with a 85mm to f4 for a really sharp photo with adequate DOF for both eyes, and significant sharpness to tell a decent story.

or outside wide open at f1.8 at a distance, to tell another story.

I have had the more expensive lenses (and in some cases my organizations have had them) and they were nice to use because they were bright and easier to focus and see the subject, but I don't really think they produced significantly better results for the cost.

From habit I tend to check my DOF and usually will stop down a bit to err on the side of more 'in focus' than out.

Naturally, creative focus within the 50mm lens, at f2.8, we could highlight a cast member.

From all this, I suppose that I'm suggesting that there's a lot of options you should consider when choosing lenses and apertures. I have only two thumbs, and few rules to use with them. Like a goose, I wake in a new world every day. We're shooting a lobby display this week and I hope I come up with something, soon.

Real soon.

Bokeh is another matter and subjective. I can't address that, you'll have to come to grips with that on your own.

My best to all,

Mike

cpgregrio: Thanks for the examples at 70mm. I say you are getting great bokeh at f2.8 and 70mm. 70mm on DX is the same as 105mm on FX which is one of the "classic" portrait lenses along with 85mm on FX. I would say you have demonstrated that great bokeh can be obtained at f2.8 and you really don't need to shoot at f2 or f1.4 just to get nice bokeh around your subject. [Of course one may need f1.4 for other reasons such as shallow depth of field or ability to shoot in very low light.] We all are knowledgeable in some areas and "fumbling noobs" in other areas of photography. You are doing great with portraiture. A 70% keeper rate is higher than mine.

general comment on a different subject: Here is another idea about camera settings for portrait shooting: use Auto ISO as a moving variable rather than as a constant. Let's take the D800 and let's just say you are satisfied with the quality of the image from ISO 100 up to ISO 800. Let's assume you are shooting with an 85mm or 105mm lens and are confident you can hand hold it well at 125th of a second or that you are shooting with the 70-200 VR zoom and are confident you can hand hold it at 125th of a second with VR. Let's say you are happy with bokeh and DOF at f2.8. Now you can set your Auto-ISO to vary up to 800. You can set your camera mode to Manual, set your shutter speed to 125th of a second, set your f-stop to f2.8 and let your ISO vary according to the changes in the light. You could limit your ISO upper bound to some number less than 800 if you wish and use the same technique. You can set your shutter speed to 250th of a second if you have shaky hands and no VR on the lens you are using and use the same technique. As you look through the viewfinder the ISO your camera is selecting will be displayed in the data bar. You can watch it move up and down and see that it will adequately cover the range of light you are working in. I usually shoot in A mode with a set ISO and let my shutter speed vary but I think with such good ISO up to 800 in the modern DSLRs it just may be better to let that ISO move around a bit and not keep it a constant 100. Just an idea for a different technique to consider an try.

@donaldjose, thanks for liking the photos of my daughters. They're always happy to be my test subjects. It only costs me a trip to a fastfood for a meal after the shoot and they are very patient when it's taking me forever to figure out what camera settings should i be in for being still a noob. Frankly, i don't get much time shooting due to work and i only get to be with my family for an outdoor shoot every 6 months when im on vacation (i work in the middle east).

Allow me to hijack this thread for a while. I acquired the 70-200 f/2.8 VRII (here in saudi) before going on vacation last year. Geez, I spent countless hours reading online forums and poring over enormous sample photos. After several sleepness nights trying to decide whether its worth the money considering im just a hobbyist, i finally gave in to my wordly desire and decided to make a go for it.

My very first shoot with the lens are with kids. I have no idea at all how the lens/camera will behave or what optimal settings should I be in. It's a hit & miss kind of stuff at first. Suddenly, I forgot all what I have read online. Soft and OOF on most instances since I have no clue how to handle the beast shooting kids darting here and there. VR or no VR?? I fumbled a lot but I managed to hit keepers around 70%. I guess not bad for a stupid fumbling noob.

Back to the topic of DOF & bokeh, here's a couple of shots wide open @ short focal length.

D7000 70-200 f/2.8 VRII ISO100 f/2.8 1/350 @70mm (ambient light, see EXIF)

D7000 70-200 f/2.8 VRII ISO100 f/2.8 1/125 @70mm (ambient light, see EXIF)

D7000 70-200 f/2.8 VRII ISO100 f/2.8 1/135 @80mm (ambient light, see EXIF)

This one i missed the focus due to poor handling on my part. Again, it's the expression that matters. Going back to DOF & bokeh, notice at 70mm, it's nice and creamy. I have no regrets having this lens.

D7000 70-200 f/2.8 VRII ISO100 f/2.8 1/125 @70mm (ambient light, see EXIF)

Look at this one Mike (squamishphoto) just posted on PAD: rear eye is nice focus at f8.

cpgregrio: Your daughters are very cute: enjoyed seeing them. Very good examples of great bokeh at f4! Thanks. I also love the colors you have achieved. You are shooting at much higher mm than I was. What would happen if you were shooting at 85mm or 105mm? Do you have any such shots taken as the low end of your 70-200 on the D7000? 70mm on DX will equal about a 105mm prime on FX.

Squamish and golf: Got to hand it to you guys. You were right about this 85mm lens front focusing on my D600. Tested it this morning and found it would focus about 1 inch in front of the focus point (which required a +6 correction in AF-Fine Tune (in setup menu). This would have biased my initial posted photos by throwing that rear eye more out of focus. Much thanks! Got to get things set right to produce the best results, don't we?

Jumping in to the merry (& informative) discussion about DOF & bokeh and adding to donaldjose's post regarding starting point. These shots were taken at f/4 with the subject at a reasonable distance from the background which resulted in nice creamy bokeh. That said, I don't need to be always wide open at f/2.8 with the 70-200. As donaldjose also mentioned, it's more about the expression and the connection with the model (with my two daughters for these photos) than the technical sharpness. My apologies dear forum members for flooding you with these shots. :)

D7000 70-200 f/2.8 VRII ISO100 f/4 1/500 @165mm

D7000 70-200 f/2.8 VRII ISO100 f/4 1/500 @165mm

D7000 70-200 f/2.8 VRII ISO100 f/4 1/250 @190mm

D7000 70-200 f/2.8 VRII ISO200 f/4 1/350 @175mm