Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
It pretty much is a personal choice. However, it has been demonstrated that more MP can't be discerned by the average viewer. I'd read the various reviews on that camera and similar ones just to make sure you are getting the features and performance you want. It probably doesn't make as much difference these days...but one thing to check is the startup time. Meaning the time between you hit "on" and the time the camera is ready to take its first picture. Also of importance is the "shutter delay". The time between pressing the button and when the camera takes the picture. In both cases, the shorter the better.
IMHO, I'd go for the optical zoom over MPs and 3X optical 6X digital.
If course, you should have also asked what software is best used with your digital camera. Just to make it a little less OT. :-)
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
What are you going to use the camera for? Are you going to be doing a lot of post processing of the pictures? Are you planning on making large prints? Web page photos? Digital picture frames? Are you going to be taking pictures at max res, or at a lower res because of storage requirements? Are you going to be using the zoom to frame your shots? Is the zoom fast enough, and easy to use?
These are all factors that affect the proper camera choice for you. If you are not that good at framing shots, or the zoom is slow/hard for you to use, then a higher res picture that you can crop later to properly frame your shot is a good idea. If you are going to be taking a lot of pictures, with limited chances to change memory cards, and are good at framing your shots using the zoom, then a lower res camera with a good optical zoom may be the right choice.
To give you an example, I spent years taking pictures with a 35mm SLR camera. For things like weddings I mainly used a 35-70 zoom. I can not stand my sister's camera with digital zoom. But she loves it. If I take the plunge and get a digital SLR, she would hate using it. (She can not take pictures with my 35mm SLR.) An extreme example, but a valid one.
Mikkel
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
There's digital cameras, and there's Digital Cameras.
I'm very happy with my Canon 30D which I bought just before it was superceded by the 40D.
I'm not as steady as I once was, so I find the image stabiliser on the first lens very handy. I regret that my longer lens, 100-300 doesn't have it.
I was recently photographing in Victoria's Parliament House, using available light (the Youth Parliament was in session, so no flash). Exposures down to 1/5 sec seemed okay, doing nothing more than leaning on available furniture.
It can focus through glass, which I think compact cameras cannot.
Best, it plays very nicely with Linux:-)
Now, the only problem _I_ have with Panasonic (and Sony) is that it's an electronics company. The most important part of the camera is the glass, without good glass the rest really doesn't matter.
I think some are sourcing their lenses from Leica. As a journalist noted, I'd like a Leica, but they're too damned expensive.
Nikon, Canon, Olympus have been pretty much at the front in (consumer) SLR and compact cameras in recent years, with Pentax and Ricoh not far behind.
On Mon, 2007-11-05 at 18:56 +0900, John Summerfield wrote:
It can focus through glass, which I think compact cameras cannot.
Some can. My Canon PowerShot A520 can, it's got through the lens focussing using the image *AND* infra red assist. The latter being something you can turn off, and probably want to, to photograph through glass.
'tis only a compact, and generally fully automatic, but has manual overrides for most things. If it weren't for the costs of film processing, and the delays, I'd much prefer to keep on using my 35 mm SLR, but this one is quite nice for a digital compact. The biggest bugbear, for me, is the delays in turning on, and after you press the shutter. I cannot take candid shots with it, nor any other type of spur of the moment shot.
I can use it with Linux, it's actually less of a pain than plugging the camera in to Windows. But the USB connection is not using the camera as a plugged in USB drive, it uses one of the transfer protocols. I found it much quicker and convenient to pull the SD card out and plug the card into my computer.
Mikkel L. Ellertson escribió:
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
What are you going to use the camera for? Are you going to be doing a lot of post processing of the pictures? Are you planning on making large prints? Web page photos? Digital picture frames? Are you going to be taking pictures at max res, or at a lower res because of storage requirements? Are you going to be using the zoom to frame your shots? Is the zoom fast enough, and easy to use?
Home use.
I'm looking at this one, for price and especially the 6X optical zoom feature.
On Nov 4, 2007 9:50 PM, Martin Marques martin@bugs.unl.edu.ar wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
I just bought one of these a few months back. I am quite happy with it. Some of its highlights: - can take a picture quite quickly from power on to shooting the pic. - compact and robust body ... although I see that they are coming out with a cheaper model lately with a flimsier feeling plastic body. - good colour ... by my eyes anyways. - good battery life - motion stabilization
Some lowlights: - custom USB cable - custom battery - the JPEG encoding used for the pictures is quite grainy when digitally zoomed in.
/Mike
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
You have received some good information, but I thought I would put in my two cents worth. First a bit of truth in advertising. I shoot with a couple of DSLRs and an older compact, all are made by Nikon.
The reference to dpreview is perhaps the best site for you to get reviews, but beware of flame wars between, for example, Nikon and Canon shooters. I have never seen a digital zoom image worth a hoot in IQ (image quality) I think of digital zoom more as a novelty. I have never used the digital zoom on my compact.
I am happy that you seem to have not fallen for the megapixel advertising stuff. (More MP will get you more resolution in an image. My cameras are 4 MP, 6 MP and 10 MP.) But I have seen images printed with a high quality ink jet at 11 x 14taken with my 4 MP compact after processing with Photoshop Elements (Sorry about the Windoze reference). It wasn't the highest quality image, but acceptable, and at 4 x 6 up to 8 1/2 x 11 the results are pretty good. Not up to the resolution of a 6 MP or 10 MP at printed at 11 x 14 or 16 x 20, but I think you will find 5 MP OK.
The best thought on photography I have heard is that it is not the camera that determines the quality of an image, it is the person behind the camera.
dlg
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
I have two digital cameras.
One dSLR (Pentax) which was my first. I got the Pentax because I had Pentax SLR lenses that worked with the dSLR. Saved money at the start.
Purchased a point and shoot for those times that we just want a picture.
Both use SD cards and I can swap cards between the cameras.
I prefer optical zoom and was one of the things I was looking for.
Both camera's plug and work in Linux with no problems though I use the SD cards more than plugging the camera into the computer.
One feature that I must have on any camera is a view finder. I hate having the display on in dark locations and sun light can make and LCD display impossible to see to take pictures. This is a very big complaint around work with the point and shoot cameras.
One other feature that I would have liked on my point and shoot is to be water resistant but at the time, I didn't have the extra money. These resist dust and dirt a lot more than normal point and shoot cameras.
Tim wrote:
'tis only a compact, and generally fully automatic, but has manual overrides for most things. If it weren't for the costs of film processing, and the delays, I'd much prefer to keep on using my 35 mm SLR, but this one is quite nice for a digital compact. The biggest bugbear, for me, is the delays in turning on, and after you press the shutter. I cannot take candid shots with it, nor any other type of spur of the moment shot.
I was walking the streets of Melbourne, crossing one and someone hurtled past illegally on a motorcycle. Up with the Canon, one click and he was captured. If I'd had "sports" activated, there'd have been three or more frames of the cycle.
The problem with an SLR is its size: as someone said here (Perth, not the list) recently, if you have one of those slung around your neck, you might as well don the Hawaiian shirt and Bermuda hat too.
the Pentax I have (did I mention it?) is slow.
Michael Wiktowy wrote:
On Nov 4, 2007 9:50 PM, Martin Marques martin@bugs.unl.edu.ar wrote:
Some lowlights:
- custom USB cable
Something to watch for, my Pentax has a non-standard cable, and a voice recorder I bought recently has yet another design.
- custom battery
My Canon's is rechargable, and a recharger comes with the camera. Combined with no film costs, it makes for very cheap photography.
- the JPEG encoding used for the pictures is quite grainy when
digitally zoomed in.
Ignore digital zoom. It's a hoax. Anything the camera can do, your computer can do too, and digital zoom does not improve the size photo one can print.
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
There's a 10x zoom point-and-click camera that was recently released (Kodak, I think). It uses 2 lenses to accomplish the high zoom ratio.
As for optical zoom vs. number of megapixels: optical zoom is definitely better. Although it's not really a comparison because number of megapixels doesn't correspond... but if you think in terms of digital zoom vs optical zoom: digital zoom is just a crop of the image (followed by algorithmic stretching - which can really be done after downloading the image into your computer). Ignoring the cropped area, a 2x optical zoom is very approximately similar to a jump from 6MP to 25MP (or 11MP from 3MP, etc.) The real comparison comes from the printed copy - as others mentioned already, 4"x5" will look great at as little as 3MP.
Konstantin Svist wrote:
Martin Marques wrote:
Hi all, sorry for the OT, but as many people here have more knowledge then me on this topic I'll just ask.
I'm about to by a digital camara and I was looking at a Panasonic Lumix with 5MP and 6x optical zoom.
I tend to see the 6x zoom more interesting then having 7 or more MP, but I'd like to know if I should go for more MP or stay with the good zoom.
Once againg, sorry for the OT.
There's a 10x zoom point-and-click camera that was recently released (Kodak, I think). It uses 2 lenses to accomplish the high zoom ratio.
Canon's had a 10x for a while, my cousin Elaine has one. I found it hard to hold at the extremity, I tend to shake too much.
As for optical zoom vs. number of megapixels: optical zoom is definitely better.
There is no relationship between zoom of any kind and megapixels, except more megapixels and better optical zoom both add to cost.
The more pixels does translate to better printed images, and my local camera vendor assured me 3.2 Mp is good to about A4. Which probably translates to marginal to the trained eye.
More pixels also translates to more scope for cropping later; a digital (3.2 Mp) image that prints well at 6x4 from a full frame will probably not give you a good picture of that tiny flower in the corner.
Although it's not really a comparison because number of megapixels doesn't correspond... but if you think in terms of digital zoom vs optical zoom: digital zoom is just a crop of the image (followed by algorithmic stretching - which can really be done after downloading the image into your computer). Ignoring the cropped area, a 2x optical zoom is very approximately similar to a jump from 6MP to 25MP (or 11MP from 3MP, etc.)
The use of zoom affects what's in the focussed image inside the camera.It does not affect the size of that image. That's true of both film and digital, and the larger focussed image afforded by medium and large-format cameras goes to explain why the yield bigger, better pictures.
The real comparison comes from the printed copy - as others mentioned already, 4"x5" will look great at as little as 3MP.
Someone on the radio here recently said that 15 Mp is about where film sits (though I suspect that depends on the film; when I was shooting file regularly (and I mostly didn't use colour), I went for slower, preferably professional film).
On Tue, 2007-11-06 at 10:53 +0900, John Summerfield wrote:
The more pixels does translate to better printed images, and my local camera vendor assured me 3.2 Mp is good to about A4. Which probably translates to marginal to the trained eye.
I found my 4 meg camera to just about manage an A4 sized print, but only for distance viewing, and only when the source photo was taken under good conditions. Close up, you could see JPEG artifacts, and artifacts from the camera and printer (I use the local photo mini lab for my prints) that try to sharpen the picture more than it really is. Unfortunately they nearly all try to crispen pictures, rather than print pictures as they are, or use a camera which has better native resolution (that's optical and electronic, in combination), in the first place.
Nearly all electronic imaging relies on artificially peaking the resolution. Turn off the detail enhancement, and you think "yuck, it's very soft," like the old soft filters used on female movie stars, even on $20,000 cameras. Conversely, for film, back when you could still get your photos processed optically, and you had a decent camera, even a moderately priced consumer camera, we had better looking prints (from the decent labs).
Granted that enlargements tend to be viewed at a distance, and that does hide some defects, but some are not viewed that way. Such as family photos sitting in a frame on the desk. They'll probably not be A4 sized, but still can be big enough to expose some failings in the system. Never mind someone who wants to be arty, and do big blowups that will have people gazing intently at them.
On Mon, 5 Nov 2007, Konstantin Svist wrote:
Martin Marques wrote:
The real comparison comes from the printed copy - as others mentioned already, 4"x5" will look great at as little as 3MP.
What is needed for 11x14?
Bob Holtzman wrote:
On Mon, 5 Nov 2007, Konstantin Svist wrote:
Martin Marques wrote:
The real comparison comes from the printed copy - as others mentioned already, 4"x5" will look great at as little as 3MP.
What is needed for 11x14?
Probably depends on the viewer's eyes and the subject matter. Chat to .. Some people who sell digital cameras, at camera shops. Some are enthusiastic photographers. Don't expect good advice from your computer shop;-) .. Some folk at your local camera club. .. The next professional photographer you see.
At 9:52 PM -0700 11/5/07, Bob Holtzman wrote:
On Mon, 5 Nov 2007, Konstantin Svist wrote:
Martin Marques wrote:
The real comparison comes from the printed copy - as others mentioned already, 4"x5" will look great at as little as 3MP.
What is needed for 11x14?
For large(r) enlargements, a (large) low-noise sensor is more important than more pixels, according to posts on another list I'm on. See http://db.tidbits.com/article/7860 .
On Tue, 2007-11-06 at 13:17 +1030, Tim wrote:
On Tue, 2007-11-06 at 10:53 +0900, John Summerfield wrote:
The more pixels does translate to better printed images, and my local camera vendor assured me 3.2 Mp is good to about A4. Which probably translates to marginal to the trained eye.
I found my 4 meg camera to just about manage an A4 sized print, but only for distance viewing, and only when the source photo was taken under good conditions. Close up, you could see JPEG artifacts, and artifacts from the camera and printer (I use the local photo mini lab for my prints) that try to sharpen the picture more than it really is. Unfortunately they nearly all try to crispen pictures, rather than print pictures as they are, or use a camera which has better native resolution (that's optical and electronic, in combination), in the first place.
Nearly all electronic imaging relies on artificially peaking the resolution. Turn off the detail enhancement, and you think "yuck, it's very soft," like the old soft filters used on female movie stars, even on $20,000 cameras. Conversely, for film, back when you could still get your photos processed optically, and you had a decent camera, even a moderately priced consumer camera, we had better looking prints (from the decent labs).
Granted that enlargements tend to be viewed at a distance, and that does hide some defects, but some are not viewed that way. Such as family photos sitting in a frame on the desk. They'll probably not be A4 sized, but still can be big enough to expose some failings in the system. Never mind someone who wants to be arty, and do big blowups that will have people gazing intently at them.
-- (This computer runs FC7, my others run FC4, FC5 & FC6, in case that's important to the thread.)
Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists.
Jpeg is a horrible compression algorithm. I have no idea why it was chosen. It is lossy, has artifacts in the result, often smearing the image or showing a fingerprint like Moire pattern (most image processing software has an anti-moire filter specifically tailored for JPEG ) and other artifacts. There are better compression algorithms, but many if not all are proprietary. Somewhere in Europe about 2005, there was a new lossless algorithm similar to LZ in compression size or slightly better, and HP licensed it, but I don't know the name. LZ and GIF are also lossless, but GIF somehow lost the ability to do color from what I understand. The problems endemic with images deal with the representation, and the problem with something called tilt, which is an artifact of the digital image capture method from CCD's. CMOS devices don't exhibit this or at least don't have to because the underlying technology is different.
CMOS is becoming the imaging technology of choice, but CCD's will be around for a while. The CCD's also suffer more from blooming, (for those of you with film experience, think of acetate contamination) where intense light will affect the surrounding pixels. CMOS doesn't experience this from the base technology although a poor screen which is the surface that covers the detectors may cause a similar effect from light diffusion.
The number of megapixels to replicate 35mm film is dependent on several issues, from the size of the imager, to the depth of field of the lenses, and the formation of the screens, along with the design of the technology. However, for a normal 1/4 to 1/3 inch die, 15MP seems about right. For larger imagers, such as the focal plane imagers for 35mm cameras, somewhat more mp may be required. Cannon's current top model now offers the EOS-1Ds Mark III with 21Mp. For still more resolution, the high end manufacturers like Hasselblad offer large format digital SLR's with larger image sensors and >30Mp right now. Hasselblad's H3D II for example offers a sensor of 48x36 and 39Mp. which yields a 44 nanometer pixel size for capture, and the lenses are standard Hasselblad system lenses, so if you put on a telephoto with a 5 degree field of view (about 1000mm lens), you would get a pixel covering 641 nanodegrees, with a dynamic range of about 108db (film is typically only about 65db). The problem comes in storing and manipulating raw images of this size. However the recent introduction of 8-32Gbyte flash is going to make this technology more palatable. Add the ability to fully seal the camera, which will reduce dust and other problems with long term use, and the writing is on the wall about film. In addition, using encryption, and internet, a professional's images can be anywhere in the world in seconds. Even theaters are starting to join the digital revolution, with fully solid-state projectors. For some examples look up Texas Instruments DMD projectors and chips. There is also a single pixel camera using a dmd device to scan the focused image. For still or slow speed, this would permit really flat images with no pixel difference issues at all, very good for some kinds of scientific studies. Additionally there are highly optimized scientific sensors capable of looking from the very low infrared to the very high ultraviolet regions and beyond that are finding niches in microscopy, biology, satellite, astronomy and other fields of research. Some of these images cannot be captured with any existing film due to sensitivity issues, changes in required focus (look at your camera if you have an slr. See the red mark on the focus barrel? That is for infrared film.) and other issues (like getting the film back from space).
Some other sensors offer amplification of the detected image, which is similar to low light image intensifiers with perhaps less capability, but fewer problems and greater reliability.
Most of the complaints about digital images are actually a result of the post processing that most consumer cameras do on the image. However, if you have a camera that offers it, try capturing the raw image and bring it into a high quality bit of photo processing software, and check out that result. I think you will be surprised.
A full sized 8.5x11 image at 3Mp would give you a pixel size of 7.72microns (7.72e-6 inches) in area. This translates to about 360 linear dpi. At 3' the average human eye can only see 3/1000" errors. at 12" that would be 1/1000" errors, and so this image would be on the edge of what you could see. To get this quality, you must use photo quality jets, ink, paper and your printer must be in tip top condition. I don't know the latest on Laser stuff, but you can look it up.
Regards, Les H
Bob Holtzman wrote:
What is needed for 11x14?
If you know in advance that you're going that big (or bigger), don't use a digital camera. Use a lower-end digital camera to take a snapshot, find the settings you like by taking a few shots (the main appeal of digital cameras is instant feedback), then use an analog camera with same settings to finish the job. You can then get the film processed, printed and scanned onto a picture CD (here's your digital copy) and you keep the negatives which you can 1) blow up to a pretty large size, and 2) re-scan for higher resolution later on, if you wish to. All of this will cost less than having your digital photos printed out.
see http://www.kenrockwell.com/tech/free-digital-camera.htm
With digital, I'd say you need ~18MP to get the same quality as you would with 3MP for 4x5.
On Nov 6, 2007 2:30 PM, Konstantin Svist fry.kun@gmail.com wrote:
Bob Holtzman wrote:
What is needed for 11x14?
With digital, I'd say you need ~18MP to get the same quality as you would with 3MP for 4x5.
To be exact ... 23.1 MPix (3MP*(11*14)/(4*5)) if you want the same pixel density.
At those CCD resolutions, I would think your optics quality becomes more and more of a limiting issue.
/Mike
Michael Wiktowy wrote:
On Nov 6, 2007 2:30 PM, Konstantin Svist fry.kun@gmail.com wrote:
Bob Holtzman wrote:
What is needed for 11x14?
With digital, I'd say you need ~18MP to get the same quality as you would with 3MP for 4x5.
To be exact ... 23.1 MPix (3MP*(11*14)/(4*5)) if you want the same pixel density.
Yeah, I rounded off a bit too much :)
On Mon, 2007-11-05 at 21:52 -0700, Bob Holtzman wrote:
What is needed for 11x14?
I'd try the obvious, simple, test. Look up the cameras that you're interested in buying, go to their websites, download a sample image, take that to your local photo lab, and ask them to print an enlargement from it. Or do the same with your own printer, if that's how you're going to make prints.
You can also ask the photo lab their opinion about what's needed, but I've noticed that mine seems to find nothing wrong with some rather crap quality images. You need samples in your hands to scrutinise.
On Tue, 2007-11-06 at 11:40 -0500, Tony Nelson wrote:
For large(r) enlargements, a (large) low-noise sensor is more important than more pixels, according to posts on another list I'm on. See http://db.tidbits.com/article/7860.
That can hold true, even for non-enlargement. Diverging from my interest in photography to my work in video production, I've never liked the shrinking of the image sensor. When things went down from 2/3 inch, to 1/2 inch, to 1/3 inch, we noticed increases in noise (physics is involved, and that article does describe it quite well and quickly), needing more light on the subject, reduction in image quality thanks to the image sensors simply not being miniaturised very well (they couldn't, or wouldn't, build them as well as they managed to build the larger ones), and the optics of smaller lenses are generally not as good as larger lenses (small aberrations in a small lens are proportionally a larger amount of that whole lens, so give worse distortions than a physically similar small aberration in a larger lens).
Les wrote:
Jpeg is a horrible compression algorithm. I have no idea why it was chosen. It is lossy, has artifacts in the result, often smearing the image or showing a fingerprint like Moire pattern (most image processing software has an anti-moire filter specifically tailored for JPEG ) and other artifacts. There are better compression algorithms, but many if not all are proprietary. Somewhere in Europe about 2005, there was a new lossless algorithm similar to LZ in compression size or slightly better, and HP licensed it, but I don't know the name. LZ and GIF are also lossless, but GIF somehow lost the ability to do color from what I understand. The problems endemic with images deal with the representation, and the problem with something called tilt, which is an artifact of the digital image capture method from CCD's. CMOS devices don't exhibit this or at least don't have to because the underlying technology is different.
Any image format is a compromise between conflicting needs. You want an image format that expands without practical limit? You need an algorithmic format. It's what postscript (without bitmaps) does.
You want an exact image to some defined precision. Choose dots per inch in two dimensions plus some number of bits per pixel to represent colour: 8 bits (256 colours) is generally regarded as pretty horrible.
That's what a bitmap does, and it uses a lot of storage space. Images are compressible to varying degrees depending on the amount of detail they contain.
JPEG is a compromise, chosen because it's more compressible, at some loss of detail. The amount of compression is selectable, and the more compression the more loss of detail.
It's used because it can give good compression, and in many cases the lost detail doesn't matter too much. JPEG images out of my cameras look fine on my computer. My Canon claims to be able to store around 1000 photos at its highest resolution on my 4 Gb CF card. However, if I want to get the best quality images my camera can do, I use its native format, called "raw," and store many fewer images on the CF card.
According to my camera's handbook, raw images occupy about 8.7 Mbytes at its highest resolution. I have several choices with JPEGs, the best quality & largest takes 3.8 Mbytes
Some image compression algorithms are described as "lossless," meaning that they preserve the original detail.
Others, such as that used in JPEG, are lossy - they sacrifice detail to save on storage.
Poor image quality is more likely to result from use of digital zoom. Here is one pixel at the camera's native size. . Here is the same picture, zoomed to twice the linear size: .. ..
Properly scaled, it's a square box.
Tim wrote:
On Tue, 2007-11-06 at 11:40 -0500, Tony Nelson wrote:
For large(r) enlargements, a (large) low-noise sensor is more important than more pixels, according to posts on another list I'm on. See http://db.tidbits.com/article/7860.
That can hold true, even for non-enlargement. Diverging from my interest in photography to my work in video production, I've never liked the shrinking of the image sensor. When things went down from 2/3 inch, to 1/2 inch, to 1/3 inch, we noticed increases in noise (physics is involved, and that article does describe it quite well and quickly), needing more light on the subject, reduction in image quality thanks to the image sensors simply not being miniaturised very well (they couldn't, or wouldn't, build them as well as they managed to build the larger ones), and the optics of smaller lenses are generally not as good as larger lenses (small aberrations in a small lens are proportionally a larger amount of that whole lens, so give worse distortions than a physically similar small aberration in a larger lens).
Pretty much the same story in film. I have a Mamiya C330 TLR. It shoots 2.25" square negatives. The Canon SLR I have can't come close (but it's lighter and cheaper to run).
Tim wrote:
On Mon, 2007-11-05 at 21:52 -0700, Bob Holtzman wrote:
What is needed for 11x14?
I'd try the obvious, simple, test. Look up the cameras that you're interested in buying, go to their websites, download a sample image, take that to your local photo lab, and ask them to print an enlargement from it. Or do the same with your own printer, if that's how you're going to make prints.
You can also ask the photo lab their opinion about what's needed, but I've noticed that mine seems to find nothing wrong with some rather crap quality images. You need samples in your hands to scrutinise.
There's a reason professional portrait (and I include wedding) photographers use medium format cameras such as Hasselblads. They do that size easily.
On Wed, 2007-11-07 at 08:46 +0900, John Summerfield wrote:
There's a reason professional portrait (and I include wedding) photographers use medium format cameras such as Hasselblads. They do that size easily.
Not to mention having decent accessories (lots of them, and robust ones, too).
I still have a Kodak Brownie camera that used 127 film. Not a large format, but a medium format. Despite its rudimentary optics, it could produce reasonably good pictures because it used a very large negative.
'twas also the ultimate in point and shoot for a rank amateur. There was no auto focus to get things wrong, it had fixed focus, so focussing was instantaneous. ;-) It was always, almost, in focus. Likewise, there was no iris or shutter speed to work out. In daylight, it just worked. Press button, wind on film, rinse lather repeat... No batteries, no adjustments, nothing to go wrong. ;-) A good camera to learn on, all you had to worry about was framing, and having something worth taking a photo of.
My 35 mm SLR, just a middle priced enthusiasts semi-automatic Chinon camera, does very nice A4 enlargements, can do reasonably good A3, and acceptable A2 (for viewing from a distance). The optics aren't pro, so things suffer around those points. Cinemas may still use 35 mm to project onto huge screens, but you view them from far away, they use much better optics, and the randomness of film grain across moving frames gives you the impression of much higher resolution than a single frame can produce.
My 4 megapixel Canon compact digital camera just about manages a reasonably good A4 enlargement. I'm not game to try anything bigger. It's convenience factors almost outweigh my preferences for my Chinon.
On Wed, 2007-11-07 at 11:06 +1030, Tim wrote:
I still have a Kodak Brownie camera that used 127 film. Not a large format, but a medium format. Despite its rudimentary optics, it could produce reasonably good pictures because it used a very large negative.
This takes me back. As a pre teenager I used an old, small bellows camera (can't recall the make) of my father which used 120 film. The image quality was great, even when I did my own processing and contact prints. Again the large negative. The tiny pin hole in the bellows made for interesting effects if the sun was over my right shoulder. Quality on enlargement was better than prints from some new reasonably priced 35mm compacts bought in the last couple of years.
Konstantin Svist wrote:
Bob Holtzman wrote:
What is needed for 11x14?
If you know in advance that you're going that big (or bigger), don't use a digital camera. Use a lower-end digital camera to take a snapshot, find the settings you like by taking a few shots (the main appeal of digital cameras is instant feedback), then use an analog camera with same settings to finish the job. You can then get the film processed, printed and scanned onto a picture CD (here's your digital copy) and you keep the negatives which you can 1) blow up to a pretty large size, and 2) re-scan for higher resolution later on, if you wish to. All of this will cost less than having your digital photos printed out.
see http://www.kenrockwell.com/tech/free-digital-camera.htm
With digital, I'd say you need ~18MP to get the same quality as you would with 3MP for 4x5.
I tried the PhotoCD method and I will stick with my dSLR. Images were compressed to much. I did a better job of scanning the images from the prints. Images were the right size to send to Uncle and granny but not for post work.
I have found that if I am taking a few really critical shots, I use RAW. If I am taking lots of shots, I will use the highest resolution of JPEG. This is more to save post work.
When you have 300 photos that you have to process, then using RAW is just to time consuming.
The issue of printing is one that bugs me. I have printed out only 3 prints in two years. The cost of getting prints done at the local store is quite low. All are using the same kiosks so this is a minor difference only covered by costs.
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Tim -
Tony Nelson