Login or Join Now

Upload your photos, chat, win prizes and much more

Username:
Password:
Remember Me

Can't Access your Account?

New to ePHOTOzine? Join ePHOTOzine for free!

Like 0

iq and sensor size

Join Now

Join ePHOTOzine, the friendliest photography community.

Upload photos, chat with photographers, win prizes and much more for free!

New PortraitPro 12 SALE + 10% OFF code EPZROS814

Attention!

This topic is locked.
Reason: subject of complaints
Paul Morgan
Paul Morgan e2 Member 1315199 forum postsPaul Morgan vcard England6 Constructive Critique Points
21 May 2013 - 8:08 AM


Quote: Don't get me wrong - I'm a great advocate for the benefits a larger sensor area yields, but there are pros and cons with this and the convenience factor of smaller format sensors are not merely limited to weight advantage

Exactly Smile

Smaller camera`s are better in under water housings and are less cumbersome, I`ve just been looking at a new GH3 housing, very nice.

High end compacts use leaf shutters, very quite and more discrete, flash will sync at all speeds and without restricting flash power.

The newer smaller sensors can be good up to A3.

More and more of these fixed lens compacts are now using APS-C sensors, and there still small enough to carry in a coat pocket.

Sponsored Links
Sponsored Links 
21 May 2013 - 8:08 AM

Join ePHOTOzine for free and remove these adverts.

mikehit
mikehit  56326 forum posts United Kingdom9 Constructive Critique Points
21 May 2013 - 10:30 AM


Quote: More and more of these fixed lens compacts are now using APS-C sensors, and there still small enough to carry in a coat pocket.

No-one has been able to explain to me how we used to get 35mm film cameras as small as they were, but it seems impossible to get 35mm sensor cameras the same size (lenses and all). Is it that we have become spoilt and would not accept the quality of lenses they used to put on those things? Or is it really that electronics need more 'breathing space'?

mikehit
mikehit  56326 forum posts United Kingdom9 Constructive Critique Points
21 May 2013 - 10:31 AM


Quote: BTW, where's strawman nowadays? Multiple choice time

1 He is in the south of France on a beach sipping cool drinks while a series of nubile young ladies tend to him
2 He discovered latent athletic abilities and has a different life
3 He is working on a Pirelli Calendar
4 He lies at rest waiting for the time when EPZ needs his return
5 He is working on a next generation imaging device for a major player in the market

4.

MichaelMelb_AU
21 May 2013 - 10:52 AM


Quote: More and more of these fixed lens compacts are now using APS-C sensors, and there still small enough to carry in a coat pocket.

No-one has been able to explain to me how we used to get 35mm film cameras as small as they were, but it seems impossible to get 35mm sensor cameras the same size (lenses and all). Is it that we have become spoilt and would not accept the quality of lenses they used to put on those things? Or is it really that electronics need more 'breathing space'?

All together. Plus fashion trends of yesteryear's. Big - means good and "professional"Sad But as for me, the main contributor to the size of modern compacts would be the LCD/LED screen. Being large and flat it needs the camera to be reasonably thick to keep required rigidity( for both optical and structural reasons). Example - Canon PowerShot N camera. Small, but thick... Could be more compact in full-metal body and with non-zoom lens - re:iPhone.

MichaelMelb_AU
21 May 2013 - 11:18 AM

Add-on: The screen also steals "estate" necessary for multiple controls - many of those are not present in film cameras. This blows the camera size up. The latest attempts to slim the camera bodies down go two directions:
1.Touchscreens;
2. Multifunction lens and body controls.

Steppenwolf
21 May 2013 - 2:12 PM

I've been looking at the calculations on the on-line DoF calculator and I have a question.

It seems to me pretty obvious (as I've said) that the DoF of a picture taken with a particular lens (at same aperture, etc) on cameras with two different sensor sizes (say a Canon 5D and 7D) will be the same. I don't see how it can be otherwise. However, the DoF calculators show that the larger sensor camera has a greater DoF, which is counter-intuitive.

The only reason I can see for this is that they're possibly scaling down the CoC size for the smaller sensor camera - which seems to roughly account for the difference in DoF. If that's what they're doing isn't it wrong? This might be correct in the case of a film camera where they're using the same film, but what about the case where the FF camera and the APS-C camera are digital and have exactly the same pixel count (i.e. the APS-C camera has double the pixel density of the FF camera). The APS-C image, in this case, does NOT have to be scaled up to match that of the FF camera so the CoC should be the same for both.

I've tried this with different sensor cameras and the same focal length lens and the DoF is the same.

mikehit
mikehit  56326 forum posts United Kingdom9 Constructive Critique Points
21 May 2013 - 2:42 PM

Yet another of those damned variables.

If I recall correctly their explanations page says they assume a final print of fixed size for all calculations. Because the APS-C image is being magnified more to reach that same physical end size, an element on the edge of the CoC on the APS-C will be within the CoC of a 35mm sensor. When you backtrack those elements to their position on the original sensor the CoC of the APS-C is smaller.

Paul Morgan
Paul Morgan e2 Member 1315199 forum postsPaul Morgan vcard England6 Constructive Critique Points
21 May 2013 - 3:04 PM


Quote: No-one has been able to explain to me how we used to get 35mm film cameras as small as they were, but it seems impossible to get 35mm sensor cameras the same size (lenses and all). Is it that we have become spoilt and would not accept the quality of lenses they used to put on those things? Or is it really that electronics need more 'breathing space'?

Yes its the same with DSLR`s, some are much larger than there 35mm film counterparts.

CSC`s are doing a good job here.

ChrisV
ChrisV  7770 forum posts United Kingdom26 Constructive Critique Points
21 May 2013 - 3:13 PM

I'm getting a bit confused with this. Although I can accept it's used as a ground measurement, I can't understand what size of enlargement has to do with it except perceptually - unless you are cropping a portion of the image [in which case you are of course effectively altering the format]. The way I look at it, pixel density could be seen as analogous to film speed, since slower/finer grained films would yield more detail. I don't know for sure, but I don't think this had any bearing on the DoF calculation for any given format...

mikehit
mikehit  56326 forum posts United Kingdom9 Constructive Critique Points
21 May 2013 - 3:39 PM


Quote: I can't understand what size of enlargement has to do with it except perceptually

Perception is what it [DOF] all about. An image can look pin sharp on the LCD of your camera but look rubbish on the screen. A billboard from across the plaza looks sharp, but close up looks fuzzy.

The CoC is often quoted as being the separation at which two dots look like 2 dots and not one blob and visual acuity is key to this: if you put two dots on a poster you can see them as separate elements from a distance of 15" but they look like one object from 6 feet. Many DOF calculations assume that you are looking at an image from a distance approximately equal to the diagonal of the picture (for the 'standard 4:3 or 3:2 image) but the problem is that these assumptions are rarely stated.


Quote: pixel density could be seen as analogous to film speed, since slower/finer grained films would yield more detail.

Up to a point. But with digital you have the added complication of noise - the reason that the 5D1 was the peak of development with 12MP was because any higher density than that and the noise overwhelmed the image. Nowadays 12MP is beneath even the most basic consumer cameras.

Last Modified By mikehit at 21 May 2013 - 3:44 PM
ChrisV
ChrisV  7770 forum posts United Kingdom26 Constructive Critique Points
21 May 2013 - 4:30 PM

Yeah but there again you can see noise as analogous to film grain - higher ISO films being coarse grained and therefore once again yielding less resolution.

Whilst there's some overlap there with blur, as both are reducing the amount of edge detail, it surely only works up to a point and you still perceive gritty blur as blur. It tends to be lower end small format cameras that use aggressive noise resulting in edge smearing. Add to that you have chroma noise and luminance which are handled differently [even in RAW] by different camera manufacturers and you have a set of variables which would make any objectively consistent calculation near impossible. Except that whilst all these things undoubtedly contribute [or rather degenerate] image quality, I'm not sure they have more than marginal significance to the way defocussing is perceived, particularly in comparison to the effect of initial imaging circle?

mikehit
mikehit  56326 forum posts United Kingdom9 Constructive Critique Points
21 May 2013 - 4:42 PM

If I understand your comments correctly, I am not sure you should talk about circle of confusion and noise in the same sentence - again most CoC/DOF explanations I have seen talk about calculating DOF at highest image quality because this then gives a single variable (the lens) or at most 2 variables (lens + sensor size) and people equate high image quality with pinsharp quality.

The classic definition of DOF goes along the lines of 'The areas in which the image is acceptably sharp' but one article I read recently said you need to look at it from the other side "which parts are unacceptably less sharp than the sharpest part of the image" and the interesting point they made was that even a pinhole camera has a 'depth of field' - the sharpest parts of a pinhole image are total crap compared to a 5D2, but it still has a depth of field that degrades to mush. And if you look at it from that point, DOF is actually unchanged by high noise - it is just that the sharpest parts in a ISO 12,800 image on my 7D are poor compared to ISO 100 and the total DOF is unchanged.

Last Modified By mikehit at 21 May 2013 - 4:42 PM
Paul Morgan
Paul Morgan e2 Member 1315199 forum postsPaul Morgan vcard England6 Constructive Critique Points
21 May 2013 - 4:43 PM


Quote: Yeah but there again you can see noise as analogous to film grain - higher ISO films being coarse grained and therefore once again yielding less resolution

I`ve always loved grainy film, but digital noise is a totally different beast and is not so appealing Smile

strawman
strawman  1022006 forum posts United Kingdom16 Constructive Critique Points
21 May 2013 - 5:03 PM


Quote: It seems to me pretty obvious (as I've said) that the DoF of a picture taken with a particular lens (at same aperture, etc) on cameras with two different sensor sizes (say a Canon 5D and 7D) will be the same. I don't see how it can be otherwise. However, the DoF calculators show that the larger sensor camera has a greater DoF, which is counter-intuitive.

The DoF charts rely on a simplification of the maths involved, one of those being the subject is a significantly greater distance away from the lens than its focal length, and another depends upon a variable you select as the size of your circle of confusion. Note the circle of confusion size is a variable not a fixed parameter.

As a starting point you need to accept that the lens is only truly focused on one point, and for the rest we call acceptable focus based on the observer not being able to tell it is not in perfect focus. If you go back to the days of film people then looked at the final print, not the negative, to determine the final result. So when those people devised circles of confusion they tended to be looking at a fixed print size and determined what was an acceptable level of sharpness, and from memory most of those definitions were worked out on 10x8 prints. The thinking was if the print were larger you would move further back from the print as so the overall assessment of sharpness would stay fairly constant despite varying print sizes. If you do not move further back from the print then you would create an even tougher assessment criterion with a smaller Circle of confusion.

This means the size of the circles of confusion depend on the output print size (and in a way with digital the desired resolution) for some of their definition. For a sensor you will have a magnification factor to apply, with the smaller the sensor the larger magnification. Work this around to circles of confusion, then for a given level of circle of resolution in the final fixed sized print, the circle of confusion in the smaller sensor is smaller than for the larger sensor for the same output print and resolution size.

Working back to a DoF table for a lens, you could imagine a lens that could be made to work via mechanical adaptors on a m4/3, and APS and Full frame sensor system. You would then produce from each different sensor type the same sized output print to check its sharpness. Because of the different sensor to output magnifications you would need to set different circles of confusion sizes for each sensor, so the DoF for the lens would not be constant, rather it will vary depending on the sensor size.

And if you follow that logic through to how a digital camera is operated you could say the DoF achieved depends upon the sensor size and resolution you are trying to extract from the sensor. Perhaps the way to think of it is the lens is projecting an image of a fixed size. If you make the sensor smaller but wish to keep the same output image size you are looking at the image in far greater detail and are able to spot areas that are not critically in focus more readily.

If you take one of your existing images an crop it significantly you will have in effect reduced the DoF. This is why people heavily cropping images from a sensor reduce the DoF.

If you work from the basis of lenses behaving in a way that can be calculated it becomes fairly obvious.

mikehit
mikehit  56326 forum posts United Kingdom9 Constructive Critique Points
21 May 2013 - 5:07 PM

This gave me food for thought

http://theonlinephotographer.typepad.com/the_online_photographer/2012/06/in-defe...


Quote: ... most enthusiasts coming into photography since the start of the digital era did so via small-sensor cameras. To them, larger sensors with their greater focal lengths produce the exotic shallow-focus look they associate with "serious" photography. The problem begins when razor-thin focus becomes a gimmick or a crutch, a cliché, a contrivance, a visual tic, a distracting and annoying...sorry, I've been looking at way too much student work this week.

Don't get me wrong. Selective focus has always been among photography's most valuable techniques. Even apart from its usefulness in isolating subjects, there is a beauty to the plane of focus that belongs to photography alone, and many of us have gone through a fascination with it.

But if the current hobbyist obsession seems to regard minimal depth of field as a hallmark of a memorable image, some of us relics from the film age might argue pretty much the opposite. The richest photos—the ones we return to again and again, seeing more each time—most often work in layers. They show more rather than less, taking in the full spatial depth of our world rather than just one razor-thin slice of it.
....
Now there is one problem, or let's call it a challenge, when you no longer have masses of blur to hide behind. The deeper the focus, the greater the compositional demands.

Attention!

This topic is locked.
Reason: subject of complaints