Perpetual Photography Thread Eighteen

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Woz
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Post by Woz »

So following my flower pictures the other day I got curious about the difference between the OMD EM1 and the Canon 5DIII, so this morning I've done a pair of shots to compare.

These were shot in the same light, a minute or so apart and were processed in lightroom by copying the settings from one onto the other. The black level differs very slightly between the two and I had to reframe the crop slightly.
Both were shot on a 50mm equiv prime at 1.8 (the Oly 25mm 1.8 and the Canon 50mm 1.4...both lovely lenses in their own right).

ImageFlower Test by Woz!, on Flickr

ImageFlower Test by Woz!, on Flickr
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dataloss
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Post by dataloss »

I still prefer the Canon it just looks more real to my eyes ie a reach out and touch thing.
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Post by amcanally »

lol conversely I prefer the OMD - more magenta biased and a touch more vibrant.
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Post by Woz »

I also took a couple of JPG files on full auto...but didn't copy them off the cameras yet. Might be interesting to compare them too.
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Post by DeadYankee »

Canon is infinitely better. The top shot is positively garish by comparison.
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Post by Cirrus888 »

The olympus looks like it has more in focus and so looks livelier I think. The canon looks a little dark although it has deep colours which I like.
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Woz
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Post by Woz »

Yes, the smaller sensor on the Oly means that it has a greater depth of field at the same aperture.
I spot metered from the same point with both cameras but they have chosen slightly different exposure times...I'm guessing it's a tricky one to meter and I'd be happy with either. The Oly's picture certainly looks more 'zingy'...not sure it works with this subject but I had some amazing pictures out of it too.
I'm still torn between Canon and Olympus. I've used both brands at weddings and have had a lot of keepers from both. The 5 axis stabilization on all lenses for the Olympus is amazing and makes a hell of a difference in high pressure shooting situations!
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Post by Deron »

Cirrus888 wrote:Yes I tend to agree with you. Especially when you blow it up there is halo-ing.



Thank You !


aliman5000 - yes keep playing with your camera! I'm already 150,000+ shots in.


Image3 Strikes B&W by KHH D800, on Flickr


Nice...

I do prefer the colour one in the other ratio by far...

Seems to have a bigger sense of scale in relation to the houses...
"If you can't support us when we lose or draw, don't support us when we win." Bill Shankly
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Post by AndyWilson »

Actually a smaller sensor has less depth of field. That's normally more than cancelled out by using shorter lenses which do have more DoF.

Basically the DoF is defined by using a maximum acceptable circle of confusion when the image is enlarged to a standard size - 10x8 I think. The smaller the sensor the more fuzziness enlarging is going to cause. Of course this implies cropping the photo decreases the DoF too.

I had a big debate about this stuff on dpreview - I don't think this definition is really applicable to digital sensors - but I haven't worked out my reasoning why not yet :)
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Woz
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Post by Woz »

AndyWilson wrote:Actually a smaller sensor has less depth of field. That's normally more than cancelled out by using shorter lenses which do have more DoF.

Basically the DoF is defined by using a maximum acceptable circle of confusion when the image is enlarged to a standard size - 10x8 I think. The smaller the sensor the more fuzziness enlarging is going to cause. Of course this implies cropping the photo decreases the DoF too.

I had a big debate about this stuff on dpreview - I don't think this definition is really applicable to digital sensors - but I haven't worked out my reasoning why not yet :)


From the OED:

Depth of Field
NOUN
(In photography) the distance between the nearest and the furthest objects giving a focused image.


It's nothing to do with enlarging the image. It's about what is acceptably in the plane of focus in an image. As the light is more parallel on a smaller sensor compared to a larger one, more of the image is in focus for a given aperture.
You can clearly see it on the two images above - the plane of focus on the full frame Canon is shallower than the plane of focus on the 4/3 Olympus. Shallower plane of focus = less depth of field.

For extreme examples, look back at old plate camera images - they needed lots of light as the chemicals were not very responsive, so they needed wide apertures...but because they had massive plates for the image the depth of field was insanely small. Hence why they ended up having people propped against head stands to that they could stay still long enough with a smaller aperture!
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Post by AndyWilson »

Sorry but I too always thought smaller sensors gave deeper DoF until recently - I was wrong.

http://en.wikipedia.org/wiki/Circle_of_confusion
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Woz
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Post by Woz »

From your link, as a reference, they point to:

http://www.dofmaster.com/dofjs.html

Which uses circles of confusion in the calculation.

So, if I put in a 50mm lens at F/1.8 on a Canon 5DIII I get:

Depth of field
Near limit 9.4 ft
Far limit 10.7 ft
Total 1.29 ft

If I put at 25mm lens (it says to use the true focal length, not the 35mm equiv) at F/1.8 on a Micro Fourth Thirds sensor I get:

Depth of field
Near limit 8.86 ft
Far limit 11.5 ft
Total 2.63 ft

The smaller sensor has greater depth of field at the same aperture and the same equivalent focal length (I think this is what makes the difference and cropping would also have the same effect).


The calculator seems to take sensor resolution into account and does some weird stuff when you choose film on the drop down.
However, in meaningful discussion (and being a MF film user you must know this!) the larger the image capture area, the shallower the depth of field:
My Rolleicord has a max aperture of 3.5 and there's no way I could get a shallow DoF like this on 35mm film at that aperture and subject distance:
Image'scmitt front by Woz!, on Flickr
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Post by amcanally »

I totally understand why it's called a Circle of Confusion :thinking:

:lol::lol::lol:
andrew
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Post by paulsaz »

I remember having this argument a couple of years ago. I just resorted to what happened when I changed from 30d to 5dii and again when shooting film on medium format. The bigger the "sensor" the shallower the depth of field for an equivalent focal length and aperture. Couple of people swore blind I was wrong but I knew what my eyes were telling me.

I hired the Fuji 10-24 and went to London. Nice bit of glass.

ImageDino by paulsaz, on Flickr
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Post by AndyWilson »

The reason a larger sensor, or indeed film format, has less depth of field is because you have to use longer lenses to get the same photo, or move further closer.

An 85mm lens has less Dof than a 50mm lens which has less than a 35mm which has less than a 24mm

All "standard lenses" for their formats - all of which will give you similar coverage on 6x6, "Full Frame 35mm", APS-C and m43 respectively

It's all totally counter-intuitive, I argued against it for ages - but it's the rules of physics - given the same focal length, aperture and subject distance a smaller sensor will have less DoF
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Post by scoobyood »

It's not sensor size which dictates the DOF. It's the physical size of the aperture.. but the smaller sensors naturally have smaller lens' which therefore have smaller apertures. So they are linked.

Apertures and F-numbers

It turns out, the relationship between sensor size and aperture is very similar to that between focal length and sensor size. It's the physical size of the aperture that defines depth-of-field, not its F-number. Two lenses offering the same angle-of-view with 25mm diameter apertures will give the same depth-of-field of shot at the same shooting distance and when viewed at the same output size.

So, let's consider the effect of that 25mm aperture in the lenses we've been discussing. Both lenses give the same angle-of-view, so you're likely to shoot them with the same shooting distance - since that way you'll get the same framing in both photos.

Now think about what that means in terms of F-number (focal length/aperture diameter). The 25mm aperture in the 100mm lens would be considered to be f/4 (100mm/25mm), whereas the same-sized aperture in the Micro Four Thirds lens would be an f/2 (50mm/25mm). The table below shows the calculated depth-of-field for the two lenses, shot at the same working distance:


Canon EOS-1D X 100mm 25mm f/4 Near 16.1m
Far 26.3m
Total 10.1m

Olympus OM-D E-M5 50mm 25mm f/2 Near 16.1m
Far 26.3m
Total 10.2m

As you can see, although the lenses are quite different, the 50mm f/2 lens is giving the same framing and the same depth-of-field as a 100mm f/4 lens is on Full Frame. As such, you can say that a 50mm f/2 for Micro Four Thirds is equivalent to a 100mm f/4 Full Frame lens in terms of both field-of-view and depth-of-field.

We don't expect you to take our word for this. Conveniently, it's become fashionable for manufacturers to produce 85mm equivalent, F1.2 lenses, which makes it relatively easy to show the ways in which they are, and aren't equivalent. We'll demonstrate this on the third page of this article.


So, on the big lens, you are going to need to stop it down a bit to get a 25mm aperture, but on the little Olympus you'll need to have it wide open to get a 25mm light hole.

http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care?utm_campaign=internal-link&utm_source=features&utm_medium=sidebar-block-ReviewPage&ref=features
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Post by Ricardodaforce »

Some images from a couple of recent corridas de toros:

<iframe src="https://www.flickr.com/photos/ricardodaforce/14439036487/in/set-72157645390687262/player/" width="800" height="530" frameborder="0" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>

<iframe src="https://www.flickr.com/photos/ricardodaforce/14678787821/in/set-72157645390687262/player/" width="800" height="530" frameborder="0" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>

<iframe src="https://www.flickr.com/photos/ricardodaforce/14714706445/in/set-72157645390687262/player/" width="800" height="480" frameborder="0" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>

<iframe src="https://www.flickr.com/photos/ricardodaforce/14552806458/in/set-72157645390687262/player/" width="800" height="480" frameborder="0" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>
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Post by daboy3000 »

I can't believe they are still allowed to torture animals in Spain. Not a nice subject matter!
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Post by Ricardodaforce »

daboy3000 wrote:I can't believe they are still allowed to torture animals in Spain. Not a nice subject matter!


In Spain's defence those photos could have been taken in France, Mexico, Peru, Colombia, Venezuela, or Ecuador.
Aware of sensibilities I haven't posted photos of any blood-letting.
This is a photo forum and the photos we take reflect the world around us. My world happens to contain a lot of stuff which is culturally very different to what I grew up with.
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Woz
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Post by Woz »

AndyWilson wrote:The reason a larger sensor, or indeed film format, has less depth of field is because you have to use longer lenses to get the same photo, or move further closer.


Yes, I acknowledged that in my post. You need a 25mm on the Oly to get the same coverage as the 50mm on the Canon FF.
Moving closer has a massive effect on the DoF, but it will also affect the proportions of the image so it's not really applicable - you don't want to be using a 24mm lens for a close up portrait unless you want a slap from the subject!

AndyWilson wrote:An 85mm lens has less Dof than a 50mm lens which has less than a 35mm which has less than a 24mm

All "standard lenses" for their formats - all of which will give you similar coverage on 6x6, "Full Frame 35mm", APS-C and m43 respectively

It's all totally counter-intuitive, I argued against it for ages - but it's the rules of physics - given the same focal length, aperture and subject distance a smaller sensor will have less DoF


But the point you're making only matters to physicists, not image makers. What people care about is how much DoF you get when you produce the same image on different formats.

For that discussion, what I've said is true - if you try and recreate the same image in the same conditions with progressively larger sensors, you will have to use different lenses and the depth of field will reduce as the sensor gets larger.
Try and get natural bokeh with an iphone!
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