02-17-2013, 02:07 PM #1
- 80 Posts
Anyone that comes from a photography background should have sensed this, but I'm here to give an explanation to all the noobs, and open this to discussion, since this questions still appear to be popping up in this forum.
The issue with the Lumia 920's camera has to do with the aperture adjustment under different lighting conditions. Aperture (aka F-stop), is basically how wide the shutter opens when taking a photo.
Aperture is the key to getting that "blurred" out background effect, when taking a picture of a subject in the foreground. Here is an example:
The effect like this is achieved by using a "wide open aperture".
Aperture is also used for other purposes, e.g. Night photography. When you have little to no light (night time), you want to use a wide open aperture (either that or a slow shutter speed, to allow the light to come in over a longer period of time, which requires the use of a tripod - not feasible with a smartphone). Having the shutter wide open is great for night photography. However, when you're taking daylight photos, with plenty of light, and just want everything to be in focus (your typical smartphone shot), you want to have a small aperture. A small aperture will eliminate the "background blur" effect, and generally everything will be in focus and SHARPER.
This is where the 920 camera fails. There is no way to manually adjust aperture, and the "auto" setting is absolutely dismal, dismal at adjusting it. In fact, I'm curious to know if the "auto" setting adjusts aperture at all under different lighting conditions. Or if this lens is even capable of an aperture adjustment? So I conducted a simple test to figure it out.
I've taken two photos, one in the dark of night and the other a landscape during a bright, sunny beautiful day (all settings on auto - not that it matters with this locked down software). So how did the 920's camera perform in terms of aperture adjustment?
F/2 corresponds to a completely wide open shutter, and as you can see, it doesn't matter if it's at night or during the day. You're taking a picture with a completely wide open shutter. This is exactly why daylight/landscape shots are blurred out.
Any photographer who has experience with a DSLR will tell you that a typical daylight landscape shot you'd want your F stop to be anywhere from F/8 to F/22 for maximum sharpness.
So again, my question becomes: is the 920's lens even capable of a different aperture other than F/2? Or are we locked in. I cannot for the life of me understand why the software would be coded to leave the aperture at F/2 under all circumstances, so my guess is, it's a hardware limitation with the lens.
Anyone with half a brain is free to chime in, the 'OMG PORTICO MADE IT SO MUCH BETTER' people should refrain please. Thanks.
- 02-17-2013, 02:23 PM #5
Seriously, the users of this forum are the worst I've ever seen. Why is everyone here so damn negative!? The op spent time to write out an informative post which makes a lot of sense to me, and is followed up with junior high style bullying.
Thanks OP.. This is something worth investigating.. Ignore the brats..
02-17-2013, 02:24 PM #6
- 17 Posts
With all due respect, OP, the softness inherent in 920 images is far less due to the aperture of the camera module than it is due to the image processing algorithms.
1) For what it's worth, a person familiar with the process of imaging should be able to tell you that just because you have an aperture of f2, it doesn't mean that bokeh (aka background blur) is easy to come by. Bokeh is definitely affected by aperture, but it is also affected by the size of the sensor & the distance to object - in the same way that an f2 lens on an Micro Four-Thirds system would have less background blur than an SLR having an f2 lens, our f2 lens would have far less blur than an equivalent lens on a Micro-4/3 system.*
1.1) I'm using the term background blur, but the same thing applies to image fidelity/blur in general. Despite the f2 lens, we still can get sharp photos because the distance from the lens to the focal plane (aka sensor) is miniscule compared to that of the lens to the subject. Even in macro mode, the ratios would be far from 1:1.
2) The camera module/lens is in fact fixed at f2.0 - To have an actually variable aperture would require the presence of a physical diagram that closes off the passage of light. Nope, we don't have that.
3) Again, the image processing algorithm is the main issue. We have the advantage of having a very low light capable system, but one still has to deal with noise - and I suspect the folks at nokia overemphasized the importance of noise reduction in the algorithm. It's simple, if you examine the noise structure of a low light photo from a 920 - you'll realize that instead of the normal RGB chromatic noise, we have clumps of pixels. That's the noise algorithm at work - and it eats up some of the image fidelity in daylight.
4) Portico does make a difference. I won't say it's "much" better, but the folks at Nokia definitely worked on it, so you'd be best off appreciating their work.
*Edit: You should also be somewhat informed of the phenomenon of the hyperfocal distance, that is, given a sensor size and aperture, there exists a focusing distance beyond which all light rays approach the lens parallel to one another - the net effect of this is that all objects from this distance on are effectively in focus; aka sharp. The hyperfocal distance would have rendered much of the point of your daylight photo moot.
- 02-17-2013, 02:36 PM #8
- 02-17-2013, 02:45 PM #11
Cellswapper.com - Cellswapper.com - Get out of your Cell Phone-Mobile-Wireless Contract Get out of your cell phone contract or find a short term wireless plan to name a few. I always buy my phones outright, I don't want to be stuck in a long term contract. 30 days and out for me.
02-17-2013, 02:55 PM #12
- 55 Posts
I think the word "terrible" in the heading is what most people on here will have problem with, replace that with "soft" and it would read much better.
I for one, think the pictures the current Lumia range take are amazing for phone. I've shown some on my SLR and 920 pics to friends and with a quick look can't see much difference.
- 02-17-2013, 03:10 PM #13
LOL! You're correct! It reminded me of this thread talking about a "MASSIVE WEIGHT DIFFERENCE" What a Letdown- Massive Weight, Thickness only to find out he was talking about a few grams.
Pictures/Videos taken with your 920!
- 02-17-2013, 03:17 PM #14
I appreciate your information, and I'm sorry that you feel disappointed by the 920, however I don't think that you were sold a pig in a poke. My 900 was perhaps, but the 920 was sold as having a better camera, particularly in Regards to low light and video, than the other cell phone cameras available. It delivers as advertised. I have about $4k in semi pro camera body and L Series lenses, and I know they will always deliver better photos than my cell phone, but I am able to take photos with this phone that simply put were not possible before. If you read the specs before buying it you would have known that its aperture was fixed at 2. This was readily available information that would have told someone as astute as yourself that it is unlikely to be a rival to any camera with an adjustable aperture when taking landscape shots.
Try enjoying what it DOES do very well for you, candid portrait shots etc, and take your "real" camera for important shots.. That's what I do and the L920 really is a huge leap in cell phone cameras. I have no doubt that Nokia will be releasing a Win Phone with variable aperture and settings for Landscape, Portrait, Action etc before your contract is up!
Sent from my RM-820_nam_att_100 using Board Express
02-17-2013, 03:36 PM #16
- 100 Posts
Thanks for the effort in your post. Nice and educative, except, I think you err in directly linking blur in in-focus regions to aperture blur (which affects mostly out-of-focus regions, if you get the focusing right - see Focusing Basics | Aperture and Depth of Field for a nice explanation). In my opinion, the daylight pictures may be off (in terms of "sharpness") because
1. Nokia wants to take advantage of the OIS and tends to keep the shutter open for that much longer, causing blur in in-focus regions. They should ideally be keeping that low in good lighting conditions, but may be the auto mode logic does not do a good job in switching between good, mid and low lighting conditions. One way to test this is to capture a slowly moving objects in good lighting conditions. If your moving object comes out blurrier than most static objects in the same distance, you know this is the cause - OIS cannot account for object motion (or large camera motions either)
2. Software processing of the images - something that has been said before and I think this is the part that they tried to address in Portico (less denoising often implies sharper, albeit noisier, images, even with sophisticated algorithms)
3. Focus issues - the 920 has a F2.0 lens. As compared to F2.4 lenses found in most phones, these lenses will have a smaller region of focus, and anything beyond that will come out blurry (the actual distance of in-focus plane increases as the region of interest goes further from the camera). If the subject is not too far off, getting the focus plane wrong (this is also a software) will cause the actual in-focus regions to be blurrier
4. Lens focus - typical cell phone lenses tend to have limited adjusting mechanism to change the focal length. Now this is a conjecture without any technical proof, but if the 920 happens to have a near focused lens (to favor creating sharper near objects with nice bokehs with the F2.0 lens), then far off objects will appear less sharp.
Other than the last part, which I doubt is the case, everything else is a software issue and Nokia has enough good minds in their imaging teams who should be able to figure the problems out. Whether they put in those resources or not, is a different matter. Also, different companies have tendencies to favor a certain kind of end results - Company A may favor sharp images and not mind the haloing of high contrast edges and noise, but Company B may prefer the softer edges over the ringing artifacts in high contrast edges. Further added to mix is the contrast, which may make image appear to be "sharper" or softer (a higher resolution image with low contrast may appear "sharper" than a lower resolution image with higher contrast - given a specific scene)...
just my $0.02....
P.S. : Note that in a lot of places I have sharpness in quotes, since what we really want to be interested in is resolution and not sharpness. Sharper pictures do not necessarily reveal more details. They just appear to do so, and the human vision system can be tricked into thinking of something to be sharper than another. Sharpness is not the same as resolution, which in my opinion is more important for most cases. Agreed though, without the raw data, details lost cannot always be regained.
02-17-2013, 03:37 PM #17
- 1,070 Posts
Fully open @ F2.4 .. originals straight from the phone. Click for full resolution.
02-17-2013, 03:49 PM #18
- 1,340 Posts
I've read enough photography forums to know that many photographers tend to share the same type of arrogant attitude as the OP.
Coming out and calling people "noobs" off the bat isn't going to help your cause. And if the OP does have a photography background then he should have known not to expect miracles from a cell phone camera.
As one of the posters above mentioned, the lens has a fixed aperture of f2.0 so it's not fixed to that value on purpose through the software.
- 02-17-2013, 06:25 PM #19
My expectation was that camera phone processors will not replace the technology of a full point and shoot or DSLR, "right now" that is unrealistic at this point. I think you were setup for disappointment. When compared to other Phone cameras then it hold itself very well. If you are going to be that critical then I suggest you use a camera only device. But the 920 images are pretty damn good for that casual use. It's all about your philosophy of use, but a serious photographer would never use a phone and get paid for pictures from them.
02-18-2013, 12:27 AM #20
- 88 Posts
L920 daylight pictures miss sharpness everywhere in the frame. Its not like the camera focuses on something (like in OPs first picture), and that something gets sharp lines, and everything else is out of focus. No, nothing in the picture gets that sharpness of other high end phones. Any lens should be able to focus on something, but L920 has a hard time to do so in daylight. (Well not really focusing, but post processing). Close-ups are excluded, which we know how great they turn out.
And yes, Portico made daylight photos so much better and nobody changed lenses. The OP needs to get off his high horse.
02-18-2013, 02:00 AM #21
- 36 Posts
Totally wrong my friend! Especially when you pretend not to be a noob, you should get your facts straight. First, there's no lens on a smartphone with an adjustable aperture...all are fixed. Nokia decided to go with the widest one (f2 ), which of course has the most naturally occuring lens blur. But their decision was justified by other user scenarios : macro photography and low light. As you mentioned, somewhat on the surface of the topic only, shallow depth of field gives you incredible close-up shots, also in lowlight it simply let's more light in without excessive and noisy ISO settings or shutter speeds. So of course there's some tradeoff - there aren't sharp AND wide lenses even in the DSLR space let alone ones that can be mounted on a smartphone. And still that tradeoff in my opinion is not that radical. Landscape photos after update are up there with other smartphones. Andyes, why so snobby when clearly you know close to nothing after asking if the aperture can be adjusted...
- 02-18-2013, 08:40 AM #22
To the OP, I don't support or disagree with what you said. What you wrote was pretty informative and the examples/proof you posted was good. I just hope you made this same complaint to Nokia through their proper channels as you have done here at WPCentral.
02-18-2013, 09:41 AM #24
- 562 Posts
The 920's camera is fantastic for a cellie.
- 02-18-2013, 09:45 AM #25
A very well-informed explanation.
I'm not sure about others but I remember there is one user that said, when you half-pressed the shutter button to focus, the image look very sharp, but right after you full-press the shutter button, the image will appear slightly softer (a bit out of focus) And I do notice this as well.
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