Random Thoughts... [Photographic Edition]

No, the range of Limited lenses.

Unless you've got a massive need for a 400/2.8, I don't see the problem.
 
Fair enough, although my original question was never really answered: is it still worth investing in AF-D glass?
 
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Get a D90, it's not like it's absurdly expensive.
 
Attention those of us who have switched to DST: Remember to change your camera's clock.

This public service announcement brought to you by the FinalGear messaging service. Have a nice day.
 
Ramseus said:
Attention those of us who have switched to DST: Remember to change your camera's clock.

This public service announcement brought to you by the FinalGear messaging service. Have a nice day.
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That's actually some advice I needed. Never even thought about it until I read that.

Edit: Nevermind, camera did it by itself. Thanks anyways.
 
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jayhawk said:
A question about gradient filters.

I would like to take more landscape photos, but do not want the sky to be blown out, or the landscape too dark; obviously I would want a ND gradient filter. Any recommendations? my size is 67mm.
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More importantly, what's the focal range you're working with?
 
Because talk is cheap I wanted to actually see the difference between circles of confusion between a full frame and aps-c lens for myself. EF-s 18-55/3.5-5.6 IS @ 55mm on the left, EF 50/1.8 on the right. I kind of rushed this because my mom was like "uhh, wtf r u doin? Can I sit down here or..." "yeah yeah yeah, just a sec" and the 18-55 @ f8 was a bit camera shaky despite being tripod mounted and mirror lockup being turned on (oops)

Anyways, my little thing here confirms what most people only know for a fact through theory, the reduced frame 18-55, at f5.6, has the DOF of a larger image circle'd full frame 50mm (pretend it's 55mm) at f8. Kind of hard to see downsized like this, but it's there. Obviously this is nothing new, I just thought some of you fine folks might like to see a practical demonstration of photography technobabble. Focus is, obviously, on the pillow. I know the exposures are different, like I said I rushed it.

And it's only 314 KB so don't whinge about it being too big, plox.

https://pic.armedcats.net/r/ra/ramseus/2010/03/16/dofdiff.jpg
 
^ On what was the 50/1.8 mounted?

If the answer is that it was mounted on your crop-frame body, I'm going to have to hurt you.
 
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How does an EOS 30v compare to an EOS 1? (not the n or v models). I think if i were to look at the pro bodies seriously, the eos3 is better then an eos 1/1n.
 
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epp_b said:
^ On what was the 50/1.8 mounted?

If the answer is that it was mounted on your crop-frame body, I'm going to have to hurt you.
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Does it look like it was on a different camera? :p
 
To me, it looks like all shots were made with the same camera (which means that there is no difference in DOF between these lenses), and that the ones with the 50mm prime were focused slightly more to the front (compare the sides of the chair's back rest).
 
Aaaaaaaaaand you are wrong. Congraturations. DOF has fuck all to do with the camera, it's all in the lens. If it were simply a factor of the format size then you would somehow magically gain DOF at the same focal length and distance to subject if you use a 645 MF camera and put a smaller film in it. Different image circle and flange to focal plane combinations mean different sized lenses are needed to cover the whole sensor/film. EF-s/DX lenses have smaller elements than EF/FX lenses, therefore smaller circles of confusion, therefore "more" DOF.
 
Okay then, explain to me this. You set the zoom lens to 50mm and the aperture opening on both lenses to 5.6, just as in your example. The focal length is identical. The diameter of the aperture opening is identical. How do you get different circles of confusion?
 
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Have you had a read though http://en.wikipedia.org/wiki/Circle_of_confusion ? Honestly I don't understand half of it because it's all confusing and a bunch of equations that I'm not going to bother ever looking at.

To put it simply, however, when you make a lens (or to put it another way, elements within a lens) with a smaller diameter the circle of confusion is smaller. Small lens, small circle of confusion. Crop lenses are cheaper than full frame lenses because they're only made to accommodate APS sized sensors, which allows the designers to use smaller (therefore easier to make and cheaper) elements. And out of focus happens with the circle of confusion produced is too large to be acceptably sharp. Since crop lenses produce smaller circles of confusion that means that the depth of field they give is greater than a full frame lens of the same focal length used on the same camera at the same distance.
 
What you're forgetting however is that the aperture opening determines how much of the elements the lens uses. The aperture opening limits the beam of light which enters the lens to a certain diameter. That means that it doesn't matter how large the elements of the lens are. If you look through a 50mm EF lens set to f/5.6 and a 17-55 EF-s set to 50mm and f/5.6, the image you'll see will be identical, which is why the same (crop) camera can not produce different images with these (general IQ aside).
 
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Yes, the aperture controls the amount of light passing through the lens and DOF and all that. What it doesn't affect is the base size of the lens, which is determined by a team of engineers based on the size of the image circle that they want the lens to produce. Look at the Panasonic LX3, the lens is f2.0 at the wide end and yet it's like the size of a (small) marble. That's because the sensor is tiny.

Back to the point: as we all know, the aperture size is what determines the depth of field. A 1.5x crop only requires an image circle 2/3 that of a full frame lens, therefore the physical aperture diameter for the same focal length and f-stop can be 2/3 the size of a full frame lens's diameter (were it to be larger than 2/3 that of the full frame lens' aperture diameter but still with the 2/3 reduced image circle then more light would be being passed and the f-stop would be larger; if the aperture diameter and image circle were both between 1x and 2/3x the size of a full frame lens then there would be extra - you might say wasted - light that isn't actually being captured by the camera). So, since the APS lens is designed to be cheap it used smaller cheaper elements that are 2/3 the size of an equivalent full frame's elements resulting in the depth of field on the crop lens being equal to the depth of field of a full frame lens of the same focal length stopped down around 2/3 of a stop.


HERE'S A PICTURE I DREW! TBH it's rubbish and I don't really know how to draw all the light getting bent around by a lens, just pretend that I do and that the supposedly focused light represents a circle of confusion.

https://pic.armedcats.net/a/an/anonymous/2010/03/16/mr_plow_thats_the_name.jpg

Are we clear yet? Or do you still want to refute the pictures that I took that clearly show the difference in DOF?
 
?

A 100mm f2 EF-S lens has a physical aperture of 50mm.

A 100mm f2 EF lens has a physical aperture of 50mm.

When I look at your test images I see the cushion on the right (foreground) is sharper in the pictures on the right, but the remote control (background) is sharper in the images on the left. I don't have an EF-S lens so I can't do the test myself, but maybe the focus point was different?
 
For all lenses, no matter whether they are made for crop or full frame cameras, all the figures like focal length and maximum aperture are in reference to the classical full frame. Therefore, the aperture openings of both lenses in your drawing at f/8.0 should be the same size, which leads to identical circles of confusion.

And I still say that the things you claim to have proven with your earlier pictures rest on faulty assumptions and a dodgy test setup (no offense, I too learned the hard way that bulletproof testing is extremely difficult).
 
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