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Old Aug 28, 2010, 10:35 PM   #21
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The first thing you'll notice when looking at those two images is that, because of the larger image sensor, the T1i has a much more shallow the depth of field than the S1800. At those settings, on the S1800, everything from about 2 feet to infinity will be in focus. But with those settings on the T1i, anything closer than 4.98 feet, or further than 5.02 feet will be out of focus. Another issue with your comparison is that the T1i was shot at 210mm, which is an angle of view of about 8, but the shot you took with the S1800 was shot at 5mm which is an angle of view of about 75! While they're both photos of grass, that's where the similarity ends.

The differences are so extreme that, with those photos, you're really trying to compare apples and oranges.
Wow, you can figure all that out? How did you figure out the angle of view?

And yes, I'm aware of the differences in the photo. In our photo shoot, our first 30-40 shots were shot as closely as photo to each other just for sake of comparison. I'll try to find some of those pictures. Then it'll be a fair comparison. If I can't, I'll definitely get them on Monday when I go to his house.
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Old Aug 28, 2010, 10:49 PM   #22
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The EXIF data attached to the images includes the exposure settings and focal length. The angle of view of a lens of a particular focal length is easy to find from a variety of sources. And the depth of field can be determined from DOFMaster.com.

I don't think you'll be able to get images from each camera that are as comparable as you'd like. Shallow depth of field is a feature not a bug. It's one of the big reasons that people switch from P&S digicams to dSLRs. At this point, it seems to me that what you're trying to do is eliminate that as a consideration, and I don't think you'll be able to.
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Old Aug 28, 2010, 11:00 PM   #23
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At this point, it seems to me that what you're trying to do is eliminate that as a consideration, and I don't think you'll be able to.
Yup. We spent hours trying to figure it out how to large DOF before going on the photo shoot. There were lots of shots that had large DOF, but most of what I have is not comparable. We're having a "rematch" very soon. He is returning the t1i body and getting a t1i with 18-55mm kit. Here's a large DOF shot, which is actually a pretty good shot for that lens.

t1i city

I really wonder why my S1800's color is so dull?

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Old Aug 28, 2010, 11:17 PM   #24
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A shallow depth of field is an advantage, not a disadvantage. If you want to do a real comparison between the two cameras, tape a page from the Sunday Newspager to the wall (something from the Classified Section might be good), light it well, and, from the same distance, take photos of it (filling the frames) with both cameras, trying multiple aperture settings.

DOF won't be an issue, and you'll be able to compare the sharpness of the different systems. I still predict that, because of the lower quality lenses, the T1i still won't do very well.
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Old Aug 28, 2010, 11:40 PM   #25
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A shallow depth of field is an advantage, not a disadvantage. If you want to do a real comparison between the two cameras, tape a page from the Sunday Newspager to the wall (something from the Classified Section might be good), light it well, and, from the same distance, take photos of it (filling the frames) with both cameras, trying multiple aperture settings.

DOF won't be an issue, and you'll be able to compare the sharpness of the different systems. I still predict that, because of the lower quality lenses, the T1i still won't do very well.
That's an interesting comparison. We tried doing macro shots, but he wanted to stop because the lens he's using takes really crappy macro shots, far worse than my S1800.

My S1800, very surprisingly, can take AMAZINGLY detailed macro shots, but it can't take very good text shots, which I find strange.

BTW, I edited my previous post. There is a new image.

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Old Aug 29, 2010, 8:45 AM   #26
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The Canon 18-55 IS kit lens is a good choice. It is very good optically, and it's not very expensive. The shot you posted looks a lot better than the earlier shot you posted, presumeably that you shot with the 28-90.

He's right, the lenses he has would not do well at their closest focusing distances. The leses aren't very good and the close focusing distance simply magnifies the flaws.

Text is tough, especially serif typefaces. The strokes are thinner than the strokes used for sans-serif typefaces, which requires a camera to be especially sharp to acurately capture the image.
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Old Aug 29, 2010, 10:07 AM   #27
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The first thing you'll notice when looking at those two images is that, because of the larger image sensor, the T1i has a much more shallow the depth of field than the S1800. At those settings, on the S1800, everything from about 2 feet to infinity will be in focus. But with those settings on the T1i, anything closer than 4.98 feet, or further than 5.02 feet will be out of focus. Another issue with your comparison is that the T1i was shot at 210mm, which is an angle of view of about 8, but the shot you took with the S1800 was shot at 5mm which is an angle of view of about 75! While they're both photos of grass, that's where the similarity ends.

The differences are so extreme that, with those photos, you're really trying to compare apples and oranges.
I agree to some extent but lets put the myth that sensor size changes DOF to bed. What changes is FOV not DOF. I most often hear this with full frame vs crop bodies but it applies here as well. If you take a still image with two cameras with identical aperture and crop the larger sensor to match that of the smaller one the images will be IDENTICAL (with the exception of IQ from snesor to sensor). This can be proven more readily with an identical lens and say a 5DII vs a 7D. Bottom line is DOF is a calculation based on focal length and aperture and has nothing to do with sensor size. It appears more pronounced on FF sensors due to FOV but is actually the same.

The first thing about a DSLR is learning how to use it properly as its a totally different world from the P&S. This is certainly comparing an apple to a grapefruit. Shallow DOF is actually a pro for the DSLR not a con. Its all dependant on subject matter on where the aperture will be set and glass has everything to do with it! Typically for landscapes you want a broad DOF and will choke down the aperture and go for longer shutter time but the inverse is true when you want to introduce bokeh and make the background blur away into a heavenly bliss and make your subject "POP" instead of being just part of a busy image that takes away from your intended subject. Here are two samples where shallow DOF makes the shot. In the first sample had the aperture been choked down you would have seen all the other players, the goal in the background and the circular bright spots is the sun bouncing off the windsheilds of cars in the parking lot. Image 2 would have shown the mulch covered walkway, the bushes in the background and the wooden privacy fence. You cant get these results from a P&S camera. First at f2.8 on 400 L second at f2 on 200L















Now the inverse is true when you want to get a broader DOF with landscape images. Two examples shot on the same day first at f2.8, second at f16 both with 24-70L












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Old Aug 29, 2010, 10:48 AM   #28
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I agree to some extent but lets put the myth that sensor size changes DOF to bed. What changes is FOV not DOF. I most often hear this with full frame vs crop bodies but it applies here as well. If you take a still image with two cameras with identical aperture and crop the larger sensor to match that of the smaller one the images will be IDENTICAL (with the exception of IQ from snesor to sensor). This can be proven more readily with an identical lens and say a 5DII vs a 7D. Bottom line is DOF is a calculation based on focal length and aperture and has nothing to do with sensor size. It appears more pronounced on FF sensors due to FOV but is actually the same.
That is assuming you were to take the two cameras and crop to the same field of view.

However, what people refer to when saying that you get a shallower DOF with FF over APS-H or APS-C or 4/3 etc is that if you were to frame your subject the same with same distance between camera and subject, you would need a longer lens on the FF then each of the following. With this longer lens you will get a shallower DOF for the same aperture setting.

So someone shooting with FF and a 400mm will have the same field of view as someone on a APS-C (Canon I'm assuming so 1.6x crop) camera with a 250mm lens. If they both shoot a subject (let's say footballer) at f2.8 the FF shooter is going to have a much shallower DOF than the APS-C shooter.
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Old Aug 29, 2010, 10:59 AM   #29
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That is assuming you were to take the two cameras and crop to the same field of view.

However, what people refer to when saying that you get a shallower DOF with FF over APS-H or APS-C or 4/3 etc is that if you were to frame your subject the same with same distance between camera and subject, you would need a longer lens on the FF then each of the following. With this longer lens you will get a shallower DOF for the same aperture setting.

So someone shooting with FF and a 400mm will have the same field of view as someone on a APS-C (Canon I'm assuming so 1.6x crop) camera with a 250mm lens. If they both shoot a subject (let's say footballer) at f2.8 the FF shooter is going to have a much shallower DOF than the APS-C shooter.

Exactly and as I explained it but with a different take. Bottom line is sensor size plays no part in the calculation for DOF, only FOV but I do have to disagree with the point that most people who refer to a shallower DOF on a FF body do not know the difference and attribute it to the sensor when the calculation is based on FL and aperture (if you look back at the post I quoted....because of the larger image sensor, the T1i has a much more shallow the depth of field ) the reasoning is incorrect. You are correct that if you close the gap to get the same framing with a FF body as that with a 1.6 crop the DOF will get more narrow but this is not a result in sensor size, its a result in changing the Focal plane. The only difference that the sensor makes if shot with identical distance and identical FL is the FOV. But the inverse is also true that if you crop the ff to match its the same DOF.

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Old Aug 29, 2010, 11:05 AM   #30
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It depends, here most people in the know point the less knowledgeable to dof master so they can plug in the focal lengths against body. Usually we explain that DOF is affected by focal length, aperture and distance between camera and subject, for those looking for a blurred background we also point out that getting the subject further from the background helps.
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