November 26, 2014, 11:49:59 AM

Author Topic: Full Frame Vs Crop Sensor  (Read 31805 times)

Sporgon

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Re: Full Frame Vs Crop Sensor
« Reply #270 on: March 04, 2014, 10:42:37 AM »

A lot of people seem to have difficulty grasping this concept. Including some who think they know better in this thread.  ;D   Its shown quite well in this article.

http://www.luminous-landscape.com/tutorials/dof2.shtml

Note that no where in the luminous landscape article did the guy refer to subject isolation.
DOF and subject isolation (or background blur - or do you mean something else?) are not necessarily the same.
Taking pictures with a short focal length and short subject distance vs with a long focal length and longer subject distance (for the same framing, using the same camera and aperture) results in the same dof, but the latter will give you a much blurrier background.

How about - "For the same magnification of the area in focus (different lenses, different distances), longer focal length at the same aperture will give you same DoF and more background magnification".
Yes. Or, in simple statements, which I can remember easier :) :
The longer the lens at the same f, the more blur, but same dof.
The smaller the f at the same mm, the more blur, and less dof.
(assuming the same framing)

My point is that the article deals with pure theory of one aspect, sets up an experiment to prove that theory, ( correctly ) but then does nothing to put this into practical context, creating the real possibility of leaving someone who is new to photography, but trying to learn, more confused about what they find in practice.

That's all. There are people who post on CR who are better at putting pure physics into practical context.

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Re: Full Frame Vs Crop Sensor
« Reply #270 on: March 04, 2014, 10:42:37 AM »

ahab1372

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Re: Full Frame Vs Crop Sensor
« Reply #271 on: March 04, 2014, 11:09:36 AM »

My point is that the article deals with pure theory of one aspect, sets up an experiment to prove that theory, ( correctly ) but then does nothing to put this into practical context, creating the real possibility of leaving someone who is new to photography, but trying to learn, more confused about what they find in practice.

That's all. There are people who post on CR who are better at putting pure physics into practical context.
True, someone new to photography might wonder "what's the point?". I haven't read a lot on LL, but my feel is that that is true for most of their articles.

privatebydesign

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Re: Full Frame Vs Crop Sensor
« Reply #272 on: March 04, 2014, 11:51:31 AM »
It is just magnification and aperture, once you accept that, however convoluted the route to getting there, then it is easier on the mind.

Start to think magnification and aperture and all the inconsistencies and complications fall away.
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ecka

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Re: Full Frame Vs Crop Sensor
« Reply #273 on: March 04, 2014, 02:28:05 PM »
It is just magnification and aperture, once you accept that, however convoluted the route to getting there, then it is easier on the mind.

Start to think magnification and aperture and all the inconsistencies and complications fall away.

Well, there are other things involved in "magnification" which are not taken into account by most people who are trying to learn how things actually work, so it may be an oversimplification. This rule may not work that well when shooting something farther away, because UWA lenses would go hyperfocal, while the tele lens would still produce some blur in the background (due to stronger magnification) and that's the rare situation when the CoC thing becomes important before you actually take a picture. You have to take the convoluted route first, and then, if you survive :), you can calculate using the magnification and aperture, because you'll know the exceptions.
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privatebydesign

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Re: Full Frame Vs Crop Sensor
« Reply #274 on: March 04, 2014, 02:56:44 PM »
So the only important bit is to educate people on the apparently simple concept of magnification.

At the very essence of all this is:

1. How big is the object as you now see it in relation to how big it is in real life.
2. How big was the aperture opening.

The first allows for everything involved in the reproduction; focal length, distance to object, coc, sensor size, crop, print or screen size, and viewing distance. Each of those affects the magnification. Plugging these values into a dof calculator just allows it to calculate the magnification taking the print or screen size and viewing distance as standards for a set CoC, some calculators actually allow you to change the CoC and magically your DOF changes,  even though the image is already taken.

The second dictates the amount of blur in relation to the magnification.

Hyperfocal is a side issue with no merit, stuff falling within the hyperfocal is still not as sharp as the plane of focus. magnify it the same and it is just as blurred (try it with the images on the LL link, I did for a thread a long time ago). Indeed lenses marked hyperfocal scales are historically at least one stop wider than accepted norm CoC figures because they used a different value to calculate them. But the important bit is that hyperfocal is just another manifestation of magnification, it isn't sharp, it is just small enough to give the illusion of sharp.
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sdsr

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Re: Full Frame Vs Crop Sensor
« Reply #275 on: March 04, 2014, 03:44:40 PM »

I'm just going to say screw it and shoot everything at minimum focusing distance and wide open.  I don't care if all of my subjects are in focus... seriously... what do they expect... not to be blurry?


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jdramirez

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Re: Full Frame Vs Crop Sensor
« Reply #276 on: March 04, 2014, 04:43:17 PM »

I'm just going to say screw it and shoot everything at minimum focusing distance and wide open.  I don't care if all of my subjects are in focus... seriously... what do they expect... not to be blurry?


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Re: Full Frame Vs Crop Sensor
« Reply #276 on: March 04, 2014, 04:43:17 PM »

ecka

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Re: Full Frame Vs Crop Sensor
« Reply #277 on: March 04, 2014, 06:54:56 PM »
So the only important bit is to educate people on the apparently simple concept of magnification.

At the very essence of all this is:

1. How big is the object as you now see it in relation to how big it is in real life.
2. How big was the aperture opening.

The first allows for everything involved in the reproduction; focal length, distance to object, coc, sensor size, crop, print or screen size, and viewing distance. Each of those affects the magnification. Plugging these values into a dof calculator just allows it to calculate the magnification taking the print or screen size and viewing distance as standards for a set CoC, some calculators actually allow you to change the CoC and magically your DOF changes,  even though the image is already taken.

The second dictates the amount of blur in relation to the magnification.

Hyperfocal is a side issue with no merit, stuff falling within the hyperfocal is still not as sharp as the plane of focus. magnify it the same and it is just as blurred (try it with the images on the LL link, I did for a thread a long time ago). Indeed lenses marked hyperfocal scales are historically at least one stop wider than accepted norm CoC figures because they used a different value to calculate them. But the important bit is that hyperfocal is just another manifestation of magnification, it isn't sharp, it is just small enough to give the illusion of sharp.

It is all about the illusion of sharp. The actual plane of focus is always at it's thinest, which is the diffraction limit of a lens. However, when the CoC becomes as small as a single pixel of your camera sensor, it is perfectly sharp from that point and smaller. That's how you gain the depth (of field ;) ). You will cross the line when it is impossible to magnify it enough, because the resolution is too low.
« Last Edit: March 05, 2014, 04:53:32 AM by ecka »
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Northstar

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Re: Full Frame Vs Crop Sensor
« Reply #278 on: March 05, 2014, 08:57:30 AM »
It is just magnification and aperture, once you accept that, however convoluted the route to getting there, then it is easier on the mind.

Start to think magnification and aperture and all the inconsistencies and complications fall away.

PBD....you're right, i had always thought of the three.... focal length, distance to subject, aperture....but when i read what you wrote, "start to think magnification and aperture" only....you're right, it's easier to think of it that way.

thanks,
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Re: Full Frame Vs Crop Sensor
« Reply #279 on: March 05, 2014, 07:35:35 PM »
It is just magnification and aperture, once you accept that, however convoluted the route to getting there, then it is easier on the mind.

Start to think magnification and aperture and all the inconsistencies and complications fall away.

PBD....you're right, i had always thought of the three.... focal length, distance to subject, aperture....but when i read what you wrote, "start to think magnification and aperture" only....you're right, it's easier to think of it that way.

thanks,
north

Glad it helped, t least one person.  ;)
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Re: Full Frame Vs Crop Sensor
« Reply #279 on: March 05, 2014, 07:35:35 PM »