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iq and sensor size

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lemmy
lemmy  71774 forum posts United Kingdom
17 May 2013 - 11:04 AM


Quote: All of this is a long way from the original query of whether an entry level DSLR with kit lens has better image quality than a high end compact when making a relatively small size print.

Better and relatively in any question guarantee an argument, simply because they are both comparative terms. If the terms of the question are undefined then there can be no definite answer. If it is simply a matter of opinion, then we all have those for our own personal reasons and arguments are, again, superfluous.

It reminds me of the Rev Samuel Smiles' remark as he was walking though the narrow streets of one of the rookeries near St Paul's. Two women were arguing loudly from windows across the street from one another. Smiles remarked that they could argue as loing as they wished but they would never agree. "Why is that, Samuel", asked his companion. "Because they are arguing form different premises", observed Smiles Grin

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17 May 2013 - 11:04 AM

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Paul Morgan
Paul Morgan e2 Member 1314978 forum postsPaul Morgan vcard England6 Constructive Critique Points
17 May 2013 - 12:11 PM


Quote: All of this is a long way from the original query of whether an entry level DSLR with kit lens has better image quality than a high end compact when making a relatively small size print

Yes in typical EPZ style, some do like to argue Smile

mikehit
mikehit  46191 forum posts United Kingdom9 Constructive Critique Points
17 May 2013 - 12:20 PM

Ooooooh, no they don't






Paul Morgan
Paul Morgan e2 Member 1314978 forum postsPaul Morgan vcard England6 Constructive Critique Points
17 May 2013 - 1:05 PM

Smile Smile

Steppenwolf
17 May 2013 - 2:08 PM


Quote:
The problem is that when stating 'larger sensor has shallower DOF' you never qualify with 'generally' or explain ho you personally use a lens or explain the circumstances as you have here. One example I have quoted to you before is wildlife which very often requires cropping of some description whatever the sensor size and because of this 'FF has shallower DOF' mantra I have seen several people incorrectly assume that for shallower DOF they need FF instead of APS-C. Whereas if they are cropping it is the chareacteristics of the lens that makes the difference. So as I see it, if you insist on stating 'FF hgas geater DOF' you will always have someone who rebuffs it - not out of bull headeness but becuse you don't explain your self properly.

I try to avoid stating the "bleeding obvious". I think someone would have to be remarkably stupid to think that taking a picture with an FF camera and cropping it to the AOV of an APS-C camera would result in a different DoF to taking a picture (with the same lens/settings) with an APS-C camera. When you crop the FF picture it's no longer FF - it's an APS-C sensor.

I know that quantum theory leads to some interesting conclusions about particles that are infinitely distant from one another affecting each others' behaviour, but I don't think this holds true in the macro world. I don't think that the cropped out part of the FF sensor has in some way affected the picture taken by the rest of the sensor.

PS.

That Python sketch of the argument was years ahead of its time. At the time the fact that someone would pay to have an argument seemed ridiculous, but the internet now has many sites that cater for people whose sole purpose is to conduct pointless arguments. The political forums are really amusing.

ChrisV
ChrisV  7727 forum posts United Kingdom26 Constructive Critique Points
17 May 2013 - 3:00 PM

The problem is, that as in the longer version of the sketch, some people imagine they're in the insult rather than the argument room.

Paul Morgan
Paul Morgan e2 Member 1314978 forum postsPaul Morgan vcard England6 Constructive Critique Points
17 May 2013 - 3:42 PM

No I`m wise to you Chris, it happens in every thread, you come along and bait.

Serves you right Smile

ChrisV
ChrisV  7727 forum posts United Kingdom26 Constructive Critique Points
17 May 2013 - 3:58 PM

;sigh;

simmybear
simmybear  832 forum posts
17 May 2013 - 7:16 PM

When I started photography as a lad my dad used to buy me Kodachrome 25 ASA slide film and I was always pleased with the results and where necessary used a flash (Sunpak DC3)- I recognised its limitations and enjoyed my photography.

Now age 52 I hear people complaining at IQ when using 400, 800, 1600 ISO things I could have only dreamed of in those days.

Not surprisingly at 80 or 100 ISO almost all cameras can produce excellent prints when viewed at even large sizes. For those who wish to "pixel peep" at 1600 ISO please spend a fortune on a medium format back, or a full frame DSLR, BUT at the end of the day great pictures are made by great photographers and even using a cheap and cheerful P&S they could shoot the socks off most of us.

May I humbly suggest that instead of all this Angst over IQ etc. that we should instead focus on improving technique - and live happier and more fulfilled photographic lives.

MichaelMelb_AU
17 May 2013 - 11:41 PM


Quote: .....
When you crop the FF picture it's no longer FF - it's an APS-C sensor.
....

Hey, you DSLR owners! You can crop your EOS5D to OM-D!SmileSmileSmileSmileSmile Mate, you just made my day! Thanks for the bleeding obvious morning laugh!

Last Modified By MichaelMelb_AU at 17 May 2013 - 11:43 PM
Steppenwolf
18 May 2013 - 8:18 AM


Quote: .....
When you crop the FF picture it's no longer FF - it's an APS-C sensor.
....
Hey, you DSLR owners! You can crop your EOS5D to OM-D!SmileSmileSmileSmileSmile Mate, you just made my day! Thanks for the bleeding obvious morning laugh!

Well that seems to be the point that you've been banging on about - insofar as I can make head or tail of what you're saying. You've either been saying that DoF is dependent on the lens, not the sensor, which is obvious (bleeding or otherwise), or you've been trying to say that larger sensor cameras don't have a smaller DoF - which is plain wrong/misleading. Take your pick.

LenShepherd
LenShepherd e2 Member 62437 forum postsLenShepherd vcard United Kingdom
18 May 2013 - 9:07 AM


Quote:
It would work if cameras were created with circle of confusion in mind, but they are not. This circle has pretty wide tolerances depending on one's eyesight, image processing preferences, etc. Nor anybody ever takes any consideration of it when taking the images.

With respect to you the laws of physics do not agree with your opinion.
Going further the circle of confusion varying with format is the scientific way of calculating the differences in depth of field when changing format and lens focal length to retain the same angle of view.
Going further still I am one of the many who often take format depth of field into consideration when taking an image. You imply you do not - but that does not mean nobody else does, or that if you tried it for yourself you would find depoth of field does vary depending on the format used.


Quote: Let's do some maths. If we take two top cameras - Nikon D800 and Olympus OM-D we will find that OM-D has crop factor 2. That means OM-D forms image similar in proportions to D800 with lens that have 2 times shorter focal distance. A lens with the same focal distance may be used on D800 too - and produce similar DOF.

Sorry - the physics and reality show that your suggestion they have the same depth of field is untrue.


Quote: The trick is, Gaussian blur is flat, and DOF induced blur changes gradually - as circle of confusion grows. It's like introducing film grain in digital image - not quite the same.

Gaussian blur can be very similar if you apply increasing amounts of Gaussian blur as distance increases Grin

MichaelMelb_AU
18 May 2013 - 9:24 AM


Quote: .....
You've either been saying that DoF is dependent on the lens, not the sensor, which is obvious (bleeding or otherwise), or you've been trying to say that larger sensor cameras don't have a smaller DoF - which is plain wrong/misleading. Take your pick.

There's no contradiction here. DOF depends on the lens, not sensor. The legend of larger DOF in cameras with smaller sensors stems from advertising rubbish and some practical experiences with cameras that have their lens fixed permanently. Cameras with changeable optics may have whatever DOF is required as long as a lens with suitable focus distance and aperture range may be found. And the larger the sensor is - the wider is diapason in which DOF can be controlled by the photographer. The point that smaller sensor cameras have larger DOF comes from practice the same way as "knowledge" of the Sun rotating around the Earth comes from everyday observations of it. Bleeding obvious, but wrong.

Last Modified By MichaelMelb_AU at 18 May 2013 - 9:31 AM
MichaelMelb_AU
18 May 2013 - 10:17 AM


Quote: .... I am one of the many who often take format depth of field into consideration when taking an image. You imply you do not - but that does not mean nobody else does, or that if you tried it for yourself you would find depoth of field does vary depending on the format used....

While you take DOF re:format into consideration - I create the DOF I need. DSLR affords for that, 4/3 too, but in tighter limits, and with a compact I need to resort to your way to do the things - for nothing better to do. But you are correct on one thing - many people judge the SLRs by compact use experience. Naturally, DSLRs are not good enough for them Grin

LenShepherd
LenShepherd e2 Member 62437 forum postsLenShepherd vcard United Kingdom
18 May 2013 - 10:25 AM


Quote: .....
DOF depends on the lens, not sensor. The legend of larger DOF in cameras with smaller sensors stems from advertising rubbish

What you say indicates you perhaps do not fully understand the subject.
DOF (from the whole of the captured area) depends primarily on the lens aperture (smaller apertures mean more DOF), the focus distance (closer means less DOF), the focal length of the lens (shorter focal lengths have proportionately closer hyperfocal distance with more DOF) and when using different format cameras the amount of image enlargement required to achieve a sharp looking 10x8 inch print. The important detail you are overlooking is the amount of enlargement needed (mathematically expressed as the circle of confusion) while still retaining a sharp looking image varies with format size. Smaller sensor images require more enlargment than larger sensor images to reach 10x8 inch print size equivalent.
The appropriate circle of confusion for the format being used is an essential component of DOF calculations. Because of this sensor size is one of the factors which affects the amount of DOF.

Last Modified By LenShepherd at 18 May 2013 - 10:31 AM

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