Not sure Im happy with my 70-200mm is mkii

[Richard Lane]

Hi Paul,


Beautiful Wedding Photos on your Website!


What time of day were these shot?


You mentioned that you were happy with your other lenses. I'm assuming that you meant you were happy with these lenses on the same 50D Body?


Is 70-200mm the longest lens in your kit?


As you are aware, the 200mm on the 1.6x crop (320mm) is going to give you a narrower angle of view, whichtranslates into agreater amount of image compression, as well asa shallower DOF, especiallyat the wider aperture.


It sounds like you like your first two photos better, because you have one subject and one background, so you are achieving your desired background blur, however in the rhino photos; you stated that you didn't like the OOF grass, so, you will have to treat the foreground grass as an additional subject in the photo, so as Neuro stated above you will need to stop down a bit.


You mentioned that you don't like to process your RAW personal photos out of the camera. I think that is a mistake, because RAW photos require some processsing, a simple jpeg conversion doesn't provide the neccessary adjustments. So, I would recommend that you make some minor adjustments in DPP or shoot in jpeg and RAW, or last choice shoot in jpeg only.


I'm assuming you are using a UV filter on your lens, but if you're shooting in overhead sunlight, then you should really try a Circular Polarizing filter in order to avoid that washed out flat look and desaturation of the colors.


Rich

[Fast Glass]

Here is a picture that has foreground blur, that is not a lens defect but something longer focal lengths have. But also shorter focal lengths too if the DOF is thin such as a 50mm prime shot low to the ground.


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John.

[neuroanatomist]

The rhino picture was shot f3.5, 1/640s at iso 100 hand held.


I dont like the area at the bottom of the picture which is going out of focus, I have tried 3 of these lenses and they all do the same. Although not on every shot.

The foreground blur results from basic photographic optics - depth of field. Based on 200mm on a 50D and the size of a rhino, I'm guessing you're around 13 meters from them. At 200mm f/3.5 and 13 meters from subject, your DoF is about 0.5 meters. You've probably got 2 meters of grass in the foreground, which is going to be progressively more out of focus further from the subject. Stopping down to f/8 or f/11 will increase your DoF, but even at f/11 your DoF for the distances above would be under 2 meters, meaning you'd still have some foreground blur.


For many, the ability to blur the foreground and background with a wide aperture, which serves to isolate the subject and add impact to the picture, is one of the big reasons to use a dSLR. Going from a 1.6x crop like your 50D to a FF camera like the 5DII enhances that effect, since the crop factor also applies to aperture as it affects DoF. A point-and-shoot camera, with a much smaller sensor, cannot achieve the thin DoF you get with a dSLR. This is why dSLR landscape shooters use wide angle lenses and very narrow apertures (and tripods for the long exposure times which result from the very narrow apertures). But those long exposures are not so good for wildlife. If you really want to have the whole image in focus, crisp from close foreground to distant background, and still keep a reasonably fast shutter speed, one way to achieve that for this type of shot would be with a P&S camera.


I suspect most of us were having trouble seeing the 'flaw' in the rhino picture because that sort of subject isolation is a often considered a desirable effect. Imagine your zebra picture if the fence in the background was clearly in focus - personally, I would not want that.

[peterborough_photography]

I fully understand DOF, what I cant understand is I only get the front of the image doing this on 70-200, I have several lenses that are as open as the 70-200 and never get the same effect.


The background on the Zebra photo was the effect I was after and opened the lens fully.


Im in the process of uprgrading bodies, Im currently looking at the 7d and the 5d mkii as I mainly shoot weddings im heading towards the the 5d.


Many thanks for your input.


Paul

[neuroanatomist]

Hi Paul,

I fully understand DOF, what I cant understand is I only get the front of the image doing this on 70-200, I have several lenses that are as open as the 70-200 and never get the same effect.

Several lenses with as wide an aperture...but do they have as long a focal length as 200mm (or longer)?


As I'm sure you understand, there are three main factors that affect DoF:

1. aperture - wider aperture with same focal length and subject distance means shallower DoF
2. subject distance - closer subject with same aperture and focal length means shallower DoF
3. focal length - longer focal length with same aperture and subject distance means shallower DoF

Factor #1 is pretty well understood by everyone - wide aperture means shallow DoF.


Factor #2 is partly why the fence behind your zebra is much more OOF than the fence behind your rhinos - you're a lot closer to the zebra than to the rhinos (subject-to-background distance is obviously a factor as well). Macro shooters have a clear understanding of this factor, which is why they struggle with DoF so much - shooting at working distances of a few inches means very shallow DoF, in the millimeter range even at narrow apertures.


Factor #3 means that longer lenses have shallower DoF - for example, that's why bird photographers shooting at 400mm often need to stop down (f/6.3 or f/8) to get even a relatively small bird completely in focus. Here's an example with my 7D at 400mm, f/6.3:





The oriole is in focus, but the branch in the lower right that also extends up through the frame is very blurred. That blurred branch was only a few inches in front of the branch on which the bird is perched.


If you've not had a lot of experience shooting at longer focal lengths, you might not have experienced the effect you're seeing in terms of foreground blur.


The other possibility, of course, is that you've got a defective lens, but I doubt that for two reasons. One, you stated you've tried three copies with the same result, and it really stretches the bounds of probability that you got three defective copies. Two, the platform that the lions are resting on, which is low in the frame like the grass in the rhino foreground, is in focus (but unlike the grass, the vertical part of the platform would be within/near the DoF for the shot).