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Old May 15, 2003, 9:03 AM   #1
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Default Aspect Ratio

I've been reading some reviews where this term is used and I want to confirm my understanding of it.

I think it means that it's the factor that you'd need to multiply the digital camera light detector by to make it the same size as a 36mm x 24mm negative. Am I correct ?

If I am then it would seem to me that a negative quality (a small format) is being sold as a positive (focal length multiplier).

The other question for me would be the resolving power that we are getting here. A fine grain film should be capable of printing up to about 20" x 16". A detector would need to hold 28.8 million pixels to do this at 300 pixels per inch.

The largest digital SLR I've found so far is the Kodak DCS Pro 14n at 13.5 million pixels, which suggests that the technology is getting there but hasn't quite made it.

Does this mean that the we are going to need more pixels on a 36mm x 24mm size detector or go for a larger format detector ?
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Old May 15, 2003, 10:55 AM   #2
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No, aspect ratio is merely the ratio of width to height. So a 1600x1200 pixel image has an aspect ration of 4:3 and a 6x4 print has an aspect ratio of 3:2. Reconciling the different aspect ratios of digital images and prints is a regular problem in these forums.

In the second part of your question, you imply that a quality print requires 300 pixels per inch. Why would this be so? Commercial printing is often done at 300 DOTS per inch - not necessarily the same thing.

I know that in theory a 35mm negative will contain more information than even the largest sensor. However, a lot of other factors come into play - some comparisons I've seen assume 25ASA film and a top-range Nikkor lens in excellent light at f11 1/1000th second and a sturdy tripod (and compare the result with a consumer digicam!). In practice, I swapped my Yashica SLR (400 when I bought it 15 years ago) for an Olympus 4000 (380 last year). The prints from the Yashica, done by a variety of processors, ranged from OK to lousy. The prints from the Olympus, done on my own Epson printer at sizes up to A4, are a delight. What's more, I can now do all my own colour processing without needing a darkroom. Like most people, I don't need 20x16s, so the camera's ultimate resolution is of little significance.

Extend the argument. No 35mm camera can offer the resolution of medium format. Is that a reason for everyone to carry around a medium format camera?
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Old May 15, 2003, 11:55 AM   #3
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Aspect ratio matters for 2 reasons: Creative look and feel of the scene, and the target output for your image capture. Look and feel is important for say landscapes. If you capture a native image at one aspect and output to print/monitor/plasma at another, you either end up losing part of the image and resolution by zooming to fit, or on a fixed aspect device such as a screen, parts of the screen will have black borders.

Spend a while watching a widescreen TV programme on a widescreen set. You will soon realise how much you have been 'conditioned' by 4x3 aspect tubes! The real view of the world is not the most compact shape of glass which can be made or fits our desktop.
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Old May 18, 2003, 2:55 PM   #4
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I think I've been using the wrong term (or one that gets used in some reviews). Other people refer to it as Cropping Factor.
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Old May 18, 2003, 4:46 PM   #5
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Just think of it as width divided by height as a ratio. E.g 640 X 480 (as square pixels) is 1.3333:1., Prints which are 6X4 without border are 1.5:1, so you see they don't match, so something has to go! That's why Fuji Frontier photo printers can do 6X41/2 prints (1.333:1) no cropping. We can get that service in UK at no extra cost.

It's interesting to check the aspect ratio of the ccd chip before buying (Kodaks can be 1.5:1) Because in reality, some of the cams megapix will be thrown away if you don't map to the same print aspect. Conversely, put most current 1.333:1 native uncropped pics on a widescreen plasma (1.7777:1) and you get big black bands either side!

I don't like the term 'crop factor' it gets me confused with 'proportional scaling' i'e when the aspect ratio stays the same and you have a smaller cut out of your original image.
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Old May 18, 2003, 9:11 PM   #6
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Thisisa massiv eissue .. i have taken a mountain of photos and at some stage i need to get tem printed. Now a few questions ...

a) Am i kidding myself otr id there a program that will convert a standard digicam aspect ratio to 4x6 size without distortion and without cropping???????????????????????? is this physically possible?

b) Does anyone make prints in the digicam size??? If so can one buy albums???
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Old May 19, 2003, 4:29 PM   #7
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a) No, it's not possible. You can do one of the following:

- crop your images
- squeeze (i.e. distort) them to fit the required ratio
- add white space on two edges to bring the image to the required ratio
- print them yourself at any size that suits you

Each of these requires you to do some work on the images with an editor. I believe some processors will print images without cropping on standard size paper, in which case you will again get a white space on 2 edges (but the lab will do it for you).

b) By "the digicam size" I assume you mean prints with the same aspect ratio as your digicam images. Unfortunately, they're not all the same! Different digicam, different ratio - albeit the differences are small. If you end up with non-standard size prints, you may have trouble finding an album of the slip-in envelope variety, but you can always use the old-fashioned sort with blank pages you stick the prints on to with photo adhesive. They look much better anyway.
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Old May 19, 2003, 6:04 PM   #8
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If you're going to get really bothered about it, just accept you've lost some of those pixels you bought in the pixel race and shrink your lcd by sticking black tape on it ! Oh! the lcd was a bit bigger than you needed as well.

The EVF is a problem until everybody locks on to the Aspect ratio pixel issue and gets selectable cage frames included as a viewfinder option.

But real camera people didn't worry about throwing away film area on their 21/4 square Hassels did they? Why should we worry about paying more for the sensor, preview displays and wasting memory and processing speed with incompatible output formats!

Quote:
Am i kidding myself otr id there a program that will convert a standard digicam aspect ratio to 4x6 size without distortion and without cropping???????????????????????? is this physically possible?
Imagine capturing a circle on your original sensor aspect. Change the aspect unequally horizontally or vertically afterwards, (other than cropping) and you'll never see a circle again!

If your cam sensor is 1.33333:1 then just get your local Walmarts with Fuji Frontier printers to get Fuji 6X41/2 paper, (like we get over here).
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Old May 20, 2003, 8:18 PM   #9
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Thanks guys, the use of tape on the LCD is a good idea I think ........... i like my 6x4's.

I hav ebeen against doing my own prints but i might have to and then use the magnetic photo albums as suggested so i can use any size print. i actually think the digican ratio is better than the 4x6 ratio but the allbums and print processors still use 35mm format.

You'd think that fairly soon print processors and album manufactuers will come out with products to suit the standard digicam aspect ratio.

Surely???? Matter of time??? Here's hopeing.
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Old May 20, 2003, 8:53 PM   #10
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Quote:
Originally Posted by Alfisti
You'd think that fairly soon print processors and album manufactuers will come out with products to suit the standard digicam aspect ratio.

Surely???? Matter of time??? Here's hopeing.
I think it will be the other way around...camera makers will add photo resolutions to their cameras, in addition to the computer resolutions they already have.

The problem was the digital camera was a convergence device...the first ones were based on video format rather than photo format. The first one I ever used, the Canon Xapshot (Q-Pix) wasn't even designed to be hooked up to a computer...its output was strictly video, it's resolution was video, it even recorded the pictures onto a proprietary disk in analog video format (not digital). If you wanted to bring in pics from that camera into the computer, you'd have to have a video digitizer (a rare thing on the PC, but then in those days people used Amigas for video and digitizers were comonplace on that device).

Getting back to today, the camera will remain a convergence device because if you throw away the computer resolutions and just have photo resolutions, the aspect ratio will look odd on a computer monitor...the old "six of one, half dozen of the other problem." At least with having computer resolutions on the cameras, it's easy to crop a bit off to get a photo resolution...not exactly the best solution but it works for now.

As for the tape idea, I personally wouldn't want to be limiting myself in that regard, especially when some pictures I take get put on the computer/web anyway. I want to look at a picture I want to make a print of on the computer and decide then and there how I want to crop for printing...I may want to go in tight, and if I had looked at the taped viewfinder I may have cut off too much to one side. I'd use clear tape (not that I'd do this at all) so you can still see what's underneath, but still have a line (of course trying to get the tape applied with any accuracy is a problem all its own).
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