Choosing Image Size Versus Print Quality?

Tojo_Ralph

OK, I'll try to keep this simple.

With a holiday coming up, I'm looking at what I need by the way of additional compact flash cards for a camera I'll possibly replace next year.

The question is, whilst I understand bigger (image wise) is better and more versatile when cropping and resising downwards, what do I really need to have the camera set on based on maximum image prints of say 6" X 8"?


Here is the camera image data...
http://www.steves-digicams.com/2003_reviews/a80_pg2.html

Based on this chart, and the numbers adding up, I assume the Canon cameras's "superfine" setting is in fact in reality "fine" (there is no raw setting)
http://www.frogprints.co.nz/help/compression.cfm

So if I plan to print at a maximum of 6" X 8" do I want to have the camera set at..

a) Medium1 (JPEG) 1600 x 1200 pixels Superfine
Or.....
b) Large (JPEG) 2272 x 1704 pixels Fine

The Large option will permit the odd larger print, but will I notice a marked difference in print quality on the smaller prints?
http://www.frogprints.co.nz/help/quality.cfm

Either setting will give me the guts of the 1,000 snaps I plan taking on a 1024MB card .... Or do I just buy two 1024MB cards and go with Large (JPEG) 2272 x 1704 pixels Superfine ?

espresso

Why don't you simply try various settings before your holiday. Asda prices are:

6"x4" - from only £0.10
7"x5" - from only £0.14
9"x6" - from only £0.25

I doubt if you would notice any difference on the smaller print sizes. :rolleyes:

I hope that you have got a couple of sets or NiMh rechargables if you are planning to take so many pictures!

Tojo_Ralph

Espresso... Three sets in fact... Taking no chances

It's just a question that has bugged me for a while, and as it is the difference between buying an extra card I don't plan on needing again (I guess I could sell it on EBay) I thought I'd take the time to ask the question from a technical standpoint, and for future reference.

paul_h

I would always take photos at the maximum resolution possible - you never know if you may want an enlargement in the future. Once the photo is taken at a lower resolution, there's no way to get the lost detail back!

Tojo_Ralph

paul_h wrote:

I would always take photos at the maximum resolution possible - you never know if you may want an enlargement in the future. Once the photo is taken at a lower resolution, there's no way to get the lost detail back!

I think I tend to agree actually, for the sake of a few quid.

Amazon have a cheap viking card (not sure about reviews) .... and I like the idea of having two cards (one card failing leaves one card OK)....
http://www.amazon.co.uk/exec/obidos/ASIN/B00025E05O/pricerunner-21/ref%3Dnosim/202-9785096-1977443

Then again, the Kingston 2GB Elite Pro Hi-Speed Compact Flash Card takes my fancy.
http://www.ebuyer.com/customer/products/index.html?rb=12917099267&action=c2hvd19wcm9kdWN0X3Jldmlld3M=&product_uid=75530

wolfman

Good point. Also don't just take resolution into account. There'll be a setting that'll allow you to adjust pixel compression, can't remember what it's called on my Canon Ixus. It's an important factor when publishing/printing.

I basically have compression off and the resolution at the highest possible. As a general idea though 1600x1200 at 180 pixels per inch will look ok on an A4 print. Ideally you want something nearer 2048x1576 at 180 ppi. That's what I generally use when printing all of my photos and they look fine.

*Ed - The A80 should easily be able to produce a large enough image to print at A4 size.

Tojo_Ralph

Wolfman, I assume your refer to superfine, fine, etc? (scroll down page to table)
http://www.steves-digicams.com/2003_reviews/a80_pg2.html

As for compression "off" I don't think the Canon A80 has a compression "off" setting, which I assume is the RAW setting I read about?

That said, I'll check the manual.

EvilMonkey

Tojo,

Not too sure if I'm teaching you to suck eggs here but...

You have 2 settings

1 - Resolution. Measured in terms of Medium, Large etc. or in exact sizes 1600x1200

2 - Compression. The jpg format has compression built in, you can increase this compression, but you increase 'artifacts' IE things that weren't there like halo's and blurring around edges.

For you camera you can adjust both independently, but only one is important for print sizes, resolution.

Before we move to that I'd just say that most photo's will look ok with jpg compression set to fine rather than superfine.

Resolution & print sizes. You talk about 2 settings, Medium @ 1600 x 1200 pixels and Large @ 2272 x 1704 pixels. This basically means you produce a picture THIS pixels wide by THAT pixels tall. Ok fairly obvious, so then we move onto printing, when these pixels are printed you can think of them as a dot of ink on the page.

Printing quality is measured in Dot Per Inch (DPI) the higher this is the better the quality. Its advised that photgraphs are printed out at a minimum of 300 DPI.

Taking what we know, at your medium setting we have a picture 1600 dots wide and 1200 dots tall. Divide by 300 (our recommended print setting) to get the maximum print size (1600/300=5 & 1/3, 1200/300=4) So at medium your looking at 5 & 1/3 by 4 inch prints. At large its a little over 7.5" by 5.5".

This is all at recommended minimum print settings. In actual fact I've found that you can easily get away with 250 DPI and possibly down to 200 DPI. Although at 200 DPI certain photo subjects (like cloud or things with low contrast) may look 'digital' at this setting. I really wouldn't recommend going too much lower than that.

As for your original question, personally I'd always take 2 cards (and swap them every now and then) as I've lost cards before. The other way to think about it is to maybe buy a second smaller card (512MB and lowercan be picked up cheap as chips). Start off at the higher settings then judge how much you're getting through as the holiday progresses (you can lower your settings to squeeze mroe shots out of the remaining space / second card.

One last thought, compact flash is one of the more common formats, so there's a reasonable possibility they might sell them where you're going (IE you can buy one if you need one) albeit not at the best price....

E.M

wolfman

I'd try not to confuse DPI (dots per inch) and PPI (pixels per inch).

A pixel is made up of a number of dots when printing. This is because the printer mixes the dots to create a colour, so the higher the number of dots for a pixel the more accurate it is likely to be in terms of tone/blending etc...

For example a 200PPI image printed at 600DPI would have 3 dots per pixel. DPI basically relates to print quality whereas PPI relates to image quality.

Think of it like this. If I had a 100x100 pixel image and printed it at 10 pixels per inch I'd have a 10" x 10" picture. If I printed it at 100PPI I'd have a 1" x 1" photo. The 10PPI image would probably be very jaggy/pixelated as it would only have 10 pixels along each inch of the print.

So for a set resolution (ie 1600x1200) the larger you print it the lower the PPI will be, and the smaller you print it the higher the PPI will be. You generally want a PPI of around 150-200 for good quality photos.

So to achieve 200PPI on a 10" x 8" print you'd need a 2000x1600 image. That works out as (2000/10=200 and 1600/8=200).

1600x1200 will still print 10" x 8" prints in good quality at 150PPI.

Tojo_Ralph

Wolf and Evil .... Appreciate the input.

For tonight, I'm going to leave the DPI and Pixel issues to one side and will get my head around it tomorrow. It's been a long day, it isn't over, and I've an early start.

What I'll say for now is that I went for the Kingston 2GB Elite Pro Hi-Speed Compact Flash card for a number of reasons as follows.

1. Whilst I would prefer two 1gb cards for guarding against failure of one card, the Kingston card appears to be ultra reliable (based on reviews), so rather than take two 1GB that are perhaps slightly more prone to failure (I did not consider the more expensive 1GB cards), I've gone with what appears to be a bombproof 2GB card.

2. I want max storage because I want max resolution (or whatever you call it) as there will be a few days of group occassions and I anticipate cropping 6" X 4" prints.

3. As back up, I'll have a 128MB and 32MB card that will give 150 Medium1 (JPEG) 1600 x 1200 pixels Superfine or 280 ish pics Medium1 (JPEG) 1600 x 1200 pixels fine.

4. The Kingston 2GB Elite Pro Hi-Speed Compact card has more longevity (ie at top end of card sizes and speeds) and IMHO represents excellent VFM.

5. The Kingston 2GB Elite Pro Hi-Speed Compact has a lifetime guarantee.

6. And last but not least, I'm gonna live dangerously ... ... I'm just so damn organised it's painful, hence I already have two universal battery chargers and 4 lots of 4 NIMH 2,000 batteries from my last "what if" trip ... So this time ... With most of my eggs in one basket in the memory card department, I'm gonna live life on the edge.

And failing all else, whilst I'm advised that the more remote areas of Sri Lanka are not the best place to find up to the minute technology, if the worst comes to the worst, from experience, I know I'll find something.

EvilMonkey

wolfman wrote:

I'd try not to confuse DPI (dots per inch) and PPI (pixels per inch).

Dagnammit! You're right, I think I've got DPI on the brain at the moment (I'm teaching a module about printing in school and I think I obsessed a little!)

wolfman wrote:

You generally want a PPI of around 150-200 for good quality photos..

This can be a bit of a personal choice, I'd not go down as low as this as I'd notice the difference in some photgraphs. Basically its worth getting them printed out at as high a PPI as you can manage. With a 2GB card you should have plenty of space too!

Have fun on your travels!

E.M.