[ElJamoquio]

There is one stop less depth of field with full frame than with APS-C. Basically, if you are shooting with a 55mm at f2.8 you will get an equivalent photo with an 85mm on full frame shot at f4. This assumes that you want to keep your framing the same between the formats. If, however, you shoot a 55 mm at f2.8 on APS-C and on full frame and keep your shooting distance the same, your photo will look very different and while the APS-C image may have narrower depth of field, it probably won't be useful.

Absolutely correct.

[ElJamoquio]

Normhead's method is the best I think Just try it out yourself and see the DOF difference.

Sure, but with either system you can just stop down.

[jsherman999]

Like I said above if you dont shoot wide open that much, FF wont matter. APSC can do the job in a lighter, smaller package.

However using FF doesnt mean you have to rely on narrow dof. You can always stop down one more stop to achieve what you can get with APSC. Nothing wrong with background being in focus indeed, but what if you want it to be blurred?

The advantage of FF is that you have (at least) two options that you didnt have with APSC 50mm prime: to further thin DOF using an longer lens (85mm/1.4), or to use a zoom lens (28-75 or 70-200).

In my case, the ability to use 28-75/2.8 lens alone is worth going FF, as it replaces three lenses that I use alot: 16-45/4, 35mm/2, 50mm/1.4 (that I always use at f/2). Less lens change means less stress and more keepers

As for it being a low hanging fruit. In weddings and events you might not have a choice of background, so more DOF choices often helps.

Again as with everything in photography, use what works for you. I do still use APSC myself when FF is unecessary.

Well put.

[jsherman999]

I just am not someone who pursues narrow depth of field. .

This is a misconception I see a lot. I don't know of any FF shooters who bought into the format simply to 'pursue narrow depth of field'.

Here's literally what I'm usually doing when shooting my kids: taking whatever DOF I get that corresponds to the shutter speed and framing I want/need. Maybe 7/10 times I like that look better than the DOF I would have gotten from an aps-c shot from the same FOV, distance and aperture, maybe 2/10 times I like it the same, and maybe 1/10 times I like it less. For that 1/10th time, I stop down and shoot again, and I got it. (if the shot hasn't moved from me in that time.)

On the Sidelines 180mm f/2.8 FF == 120mm f/1.8 aps-c

Girl On Swing 180mm f/2.8 FF == 120mm f/1.8 aps-c


I'm saying that I just like what I get better, and I'm generally not pursuing anything differently. The subject is a little bit more isolated, the background less of a worry. If I want to bring in the environment more, I just have the option of stopping down.

50mm f/2.2 =~ 33mm f/1.4 (wide-open (f/1.8) seemed just a little too narrow for this series)


There are occasions when I have more static subjects and actively pursue the most narrow DOF possible at distance, to try to mimic that LF/Civil War look I love, but usually I'm taking what I get and liking it more.


.

[Winder]

The DoF control issue is way over blown. If you have an interesting subject nobody will really care if it was shot on APS-C or FF. For me it is more about the glass.

On my Contax 645 the 80mm F/2 is may people lens. When I still had my Canon 5D the 85L was my people lens. On the MF and the FF sensor these are great lenses with a really good working distance. On APS-C the 85mm is still a great lens, but it becomes pretty long. Almost too long for a lot of indoor venues. I always find myself in places where the 85mm is too long, and its my best lens.

Sure, I can buy the DA* 55mm and get back to the equivalent FoV, but a 55mm lens will never render like an 85mm lens.

To me its more about the glass and the cleaner ISO than it is the DoF.

[SyncGuy]

This is a misconception I see a lot. I don't know of any FF shooters who bought into the format simply to 'pursue narrow depth of field'.

Here's literally what I'm usually doing when shooting my kids: taking whatever DOF I get that corresponds to the shutter speed and framing I want/need. Maybe 7/10 times I like that look better than the DOF I would have gotten from an aps-c shot from the same FOV, distance and aperture, maybe 2/10 times I like it the same, and maybe 1/10 times I like it less. For that 1/10th time, I stop down and shoot again, and I got it. (if the shot hasn't moved from me in that time.)

On the Sidelines 180mm f/2.8 FF == 120mm f/1.8 aps-c

Girl On Swing 180mm f/2.8 FF == 120mm f/1.8 aps-c


I'm saying that I just like what I get better, and I'm generally not pursuing anything differently. The subject is a little bit more isolated, the background less of a worry. If I want to bring in the environment more, I just have the option of stopping down.

50mm f/2.2 =~ 33mm f/1.4 (wide-open (f/1.8) seemed just a little too narrow for this series)


There are occasions when I have more static subjects and actively pursue the most narrow DOF possible at distance, to try to mimic that LF/Civil War look I love, but usually I'm taking what I get and liking it more.


.

This is what we term as environmental portraits, and in such theme, a larger format is much preferred.. For years, most people have been taken in by the big corporates that APSC is good enough...

Furthermore, even for landscape shooters, i believe that most of the photos photographers take are in one way or another, environmental portraits. Sure, you don't need FF for macro, and the argument is that landscape shooters do not need FF unless you print big.

Hence, the advantage of a bigger sensor for environmental portraits, which actually is almost a daily happening, have long been eroded and long lost..

[SyncGuy]

The DoF control issue is way over blown. If you have an interesting subject nobody will really care if it was shot on APS-C or FF. For me it is more about the glass.

On my Contax 645 the 80mm F/2 is may people lens. When I still had my Canon 5D the 85L was my people lens. On the MF and the FF sensor these are great lenses with a really good working distance. On APS-C the 85mm is still a great lens, but it becomes pretty long. Almost too long for a lot of indoor venues. I always find myself in places where the 85mm is too long, and its my best lens.

Sure, I can buy the DA* 55mm and get back to the equivalent FoV, but a 55mm lens will never render like an 85mm lens.

To me its more about the glass and the cleaner ISO than it is the DoF.

Winder, just curious, do you currently have lenses with aperture markings?

Specifically a 50mm and an 85mm lens.

Edit: Or may be a lens with a FL to be used on FF and an APSC equiv. e.g. 28mm and a 50mm, or 50mm and 85mm..

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Last edited by SyncGuy; 10-25-2013 at 12:32 AM.

[Rondec]

This is a misconception I see a lot. I don't know of any FF shooters who bought into the format simply to 'pursue narrow depth of field'.

Here's literally what I'm usually doing when shooting my kids: taking whatever DOF I get that corresponds to the shutter speed and framing I want/need. Maybe 7/10 times I like that look better than the DOF I would have gotten from an aps-c shot from the same FOV, distance and aperture, maybe 2/10 times I like it the same, and maybe 1/10 times I like it less. For that 1/10th time, I stop down and shoot again, and I got it. (if the shot hasn't moved from me in that time.)

On the Sidelines 180mm f/2.8 FF == 120mm f/1.8 aps-c

Girl On Swing 180mm f/2.8 FF == 120mm f/1.8 aps-c


I'm saying that I just like what I get better, and I'm generally not pursuing anything differently. The subject is a little bit more isolated, the background less of a worry. If I want to bring in the environment more, I just have the option of stopping down.

50mm f/2.2 =~ 33mm f/1.4 (wide-open (f/1.8) seemed just a little too narrow for this series)


There are occasions when I have more static subjects and actively pursue the most narrow DOF possible at distance, to try to mimic that LF/Civil War look I love, but usually I'm taking what I get and liking it more.


.

I have noticed that a lot of magazines use more of a photo journalism look, where they shoot people with wider angles and try to include some of their natural environment/setting with them. It is clearly a different look from classical portraiture, but I think it can be more telling. In particular, when I do scrap books, I prefer photos where the backgrounds are identifable. Here we are at the zoo, here we are on a hike. I like narrow depth of field too, but I just don't like the constant beating of that drum that I hear sometimes.

[BrianR]

And you can accurately use the DoF equations to predict DoF? I'd like to see your numbers compared to practical results, measured in the field with modern lenses. That might make them meaningful. It must have been done somewhere. I assume since this theory seems to be used endlessly around here, somewhere there are empirical results backing it up.

Do you not believe the DoF equations? You can check out the derivations in the link I gave. He goes over the assumptions he's making, and mentions how applicable they are to the cases under consideration. I'm not optics expert, but they do seem pretty reasonable and they're there for you to read and dispute if you wish. From that point the rest is pretty straightforward math that you can check yourself. In any case, they aren't exactly new or controversial.

No, I don't sit down with a calculator to decide what settings I need to get a DoF of 50cm at 2 m if that's the sort of thing you're wondering. But understanding what variables have what effect on DoF- that's something I do use regularly, at least in a localized differential way. Planning to print bigger? This means a smaller CoC for acceptable focus, so I need to stop down more than if it's just going to be a small web graphic and I want the same stuff in focus. Moving in closer for higher magnification? Stop down more to keep the same DoF. Always, the equations have steered me in the right direction, so I'm pretty happy with them.

[Andi Lo]

I just want to correct a misconception that APSC is always good enough. In fact no, it's not always good enough. Not trying to constantly beat the drum or anything but want to help people see what you can do with FF. Saying that FF has nothing to offer is like saying a 50mm prime has nothing over a kitzoom, that one goes to 50mm too right? Or that natural light is always enough, there's never a need to add flash, as it's all still just light and we just need to work around it.

Try to use the best tool for the job, when it's APS, use APS, when it's FF, use FF.

[Winder]

Winder, just curious, do you currently have lenses with aperture markings?

Specifically a 50mm and an 85mm lens.

Edit: Or may be a lens with a FL to be used on FF and an APSC equiv. e.g. 28mm and a 50mm, or 50mm and 85mm..

Only on my Contax lenses and my 31mm LTD.

[Rondec]

I just want to correct a misconception that APSC is always good enough. In fact no, it's not always good enough. Not trying to constantly beat the drum or anything but want to help people see what you can do with FF. Saying that FF has nothing to offer is like saying a 50mm prime has nothing over a kitzoom, that one goes to 50mm too right? Or that natural light is always enough, there's never a need to add flash, as it's all still just light and we just need to work around it.

Try to use the best tool for the job, when it's APS, use APS, when it's FF, use FF.

Honestly, any photo you can take with APS-C, you can also take with full frame, but not the reverse. The only thing is that currently, there is no full frame camera that will give me auto focus and features I expect with my k mount lenses. If such a camera comes out, that will certainly change the equation.

I'm not really against full frame at all. I just think people pound APS-C when the differences aren't as profound as some make them out to be.

[Andi Lo]

Honestly, any photo you can take with APS-C, you can also take with full frame, but not the reverse. The only thing is that currently, there is no full frame camera that will give me auto focus and features I expect with my k mount lenses. If such a camera comes out, that will certainly change the equation.

I'm not really against full frame at all. I just think people pound APS-C when the differences aren't as profound as some make them out to be.

Profound or not is really subjective, imo. How much that difference can affect your photos depends on what you primarily shoot

But yes, like you I pine for the day when Pentax FF comes out. If K-02 is FF and has focus peaking, I'd be happy enough and will buy it for sure.

[normhead]

Honestly, any photo you can take with APS-C, you can also take with full frame, but not the reverse.

Nope, any picture you can take with FF, you can take with APS-c. There may be difference in the out of focus areas but you can take the picture.
Because of the practical limitations of FF sensors, ei, less pixel density... you can always achieve more magnification on the area covered by the crop sensor using APS-c.

My buddy has one of those Canon point and shoots with an 850 mm equivalent lens... he got images of a Merlin with his little portable do everything camera than I got with my K-5 and A-400. It sucks... but bigger isn't always better. Deal with it.

[traderdrew]

If you're leaving the focal length, aperture, and focusing distance the same then this is what you'd expect. This calculator is assuming that the final print size is the same, so the acceptable circle of confusion on the sensor changes (since the image on the crop sensor is magnified more to get the print than the full frame sensor, we use a smaller acceptable circle of confusion), which affects the DoF (see The DOF equations if you'd like the full gory details).

Where these things pretty much always go wrong is not clearly defining what parameters are staying the same, and what are changing. In the calculator you've linked to, you're changing the framing of the subject if all you change is the format. Usually, when people say "FF has shallower DoF than crop" they're implying that the framing of the subject stays the same in one of two ways:

1) Change the distance to subject to keep the framing of the subject the same. Focal length and aperture remain the same. (this method is for people with a closet of film cameras and lenses)

or

2) Change focal length to keep FoV the same. Distance to subject and aperture stay the same. (this method is for DA lens apologists)

In both situations, the magnification of the subjects image on the Full Frame sensor is higher than on the Crop sensor, and this more than counters the effect of the differing circles of confusion for the two formats (see the simplified equation 13 in the DoF equation link above). Try a few numbers in this calculator:

Similaar DoF and FoV calculator - www.similaar.com

Keep the focal length and aperture constant. Note the Field of View, Height/Width and the DoF. Change the format, but now change the focus distance until the Field of View, Height/Width is the same as before to represent the same framing of your subject (the perspective has changed of course).

Do a similar experiment with changing the focal length so the FoV is the same on the two formats and keep the distance the same so the Field of View, Height/Width is also the same.

It seems to me this is the best answer to my question.

So it seems the DOF calculator I linked in the first post here, "assumes" as you say that the final print size is the same. Therefore it is cropping the FF image to produce the same size image that a crop sensor produces in order to arrive at those calculations?