How many megapixels......?

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BlueSkyNick

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....... does a camera need, in order take a picture of boat which can then be blown up to say 24"x18", and mounted?

I know it is possible to sort out some aspects of the picture on the computer afterwards, light and colours for example, but the shot needs to be reasonable quality to start with.... doesn't it?

I am guessing my Sony digital snapshot camera at 5Mpixels, will not be good enough.

So how good does the camera need to be, for quality pictures to be framed and displayed? What other factors need to be taken into account?

(I am talking about boats sailing at 6-8kts, not high speed mobo's!)
 
How big a file you need is dependant on the resolution that you want to print at.....

So, newsprint and the web reproduces material at 72dpi, versus Vogue magazine which repro's at something like 300dpi....


Your camera has a file size of 15mb... (3 times the mega pixels)

If you were printing on newsprint you would need (72x24) x (72x18) pixel...ergo in theory you would need about 2.3 mb.... so the 15mb would do fine....

but it never seems to work out that way in reality......when we print at that size on Photobox, we send a 40mb file size, which we get by either shooting it on our 16.7mp (ergo 48mb) cameras, or upsizing from one of our other cameras.... We regularly up the file size from 17mb to the 40mb, and have no problems.....

So, I would up the file size using Genuine Fractals, to 40mb, send it off to Photobox and see what you get.......

Shoot the picture at a low ISO, no more than 200 ISO, preferably 100. (Those small chip cameras generate a lot of noise) if you can, save it as a RAW or TIFF file or worse, the largest JPEG you can, then go from there.....
 
[ QUOTE ]
which we get by either shooting it on our 16.7mp (ergo 48mb) cameras, or upsizing from one of our other cameras.... We regularly up the file size from 17mb to the 40mb, and have no problems.....

[/ QUOTE ]I was with you until this point ... how do you up the file size by using another camera? Not that I am going to do so myself but want to understand the principle, for the next bit.

[ QUOTE ]
So, I would up the file size using Genuine Fractals, to 40mb, send it off to Photobox and see what you get.......


[/ QUOTE ] I dont know what Genuine Fractuals is, but if I start with a 5Mp shot, ie 15Mb file as you explained, are you saying that each pixel goes from 3bits to 8bits in some way to get to a 40mb file?
 
From what I've seen, most snapshot cameras produce jpeg files. I don't think either of mine can produce raw format like an SLR. Likewise 7-10 MP seems to be the maximum until you move up into professional kit. I would have thought the ability to blow up to 24" was more dependant on the quality of the lens.
 
Sorry.. bit unclear that... if we know in advance we are gonna make a big print, we will shoot it on our big cameras....

If we get a request for a big print and the file was not shot on the big camera, we will "upsize" the file... the usual file size from our smaller cameras is 17.2 mb..... we "upsize" using a application called "Genuine Fractals" which uses a particularly good algorithm to interpolate the data needed to get to the larger file size.... You can upsize (or resize) using photoshop or a simular application, but it is not as good as GF....

Using GF I can produce nice prints at the size you need from our 8mp cameras, but your 5mp camera may be a bit marginal, as it probably does not produce as good a pixel as our cameras as well,,, which is why you should try to get the best file quality possible....

But your best bet is to resize the image, using GF if possible, if not try it in Photoshop, and see the result you get.... a print of that size from Photobox is only a few pounds...


Hope thats clearer...
 
never mind megapixels - are you taking the photo on the water? in which case you biggest issue is likely to be camera shake unless you have a very sunny day (use a tripod on land) + lens quality as per snowleopard
 
I'm only a dabbler, not even an amateur photog, so I'll probably get shot down in flames.....

Before thinking about megapixels, I would think about how you're going to get the image into the camera:

To avoid blur and/or camera shake (from your movement and the target boat's) I would imagine you'd be looking at 1/1000s shutter speed or better. To get the boat to fill the frame of your x000 MP camera, I would guess you'll be looking at something around 200mm focal length lens (in 35mm terms). This means your aperture needs to be F/4 for 100ISO on a generally sunny day, even if not full sunshine.

I've not kept up with where compact cameras have got to, but I would have thought that this alone put you into SLR territory

For a bit of background, I have a Nikon D50, which I'm extremely happy with. I think it's 6MP, but what genuinely amazes me, time and again, is that *if* I have done my bit right, I can zoom in and see that each individual pixel is a correct representation of its bit of the image. In contrast, most of the compact camera images I've looked at dissolve into a fuzzy mess long before you get to individual pixel level, and/ or become a bit of a mix and match of different colours, with none in particular being correct. I'm not saying it is what you need to have, just that the equation involves more than MP.

On a different tack, how far away from the finished image will you be when you look at it? SWMBO was getting some stuff printed for a trade exhibition stand, and threw in one of my photos to see how it came out. It was a 1.5MP .jpg file (~1.3MB). The resultant print is about 24"x36" and looks superb on the wall. If you get closer than about 12" you can start to see where the printers re-touched some of the sharp edges to avoid 'jaggies'(?), but even if you know that's there, it disappears if you move away. The 'natural' viewing distance is about 6'. I consider myself 'picky' on image quality, but I'm nowhere near professional standards, but I believe that a good picture with this camera would blow up to quite a pleasing 24 x 18. The interesting part is getting the *good* picture to start with!

And then there's image stabilised lenses - I've used a friend's and they really do work!

I would appreciate the professional's view on this, (even if it is shooting me down!)

Andy
 
Use a decent digital SLR with at least 8MP and you should be OK. Megapixels aren't the be all and end all - the sensor size plays a big part in picture quality too - so a mobile phone with 5MP on a tiny sensor won't produce as good a shot as 4MP on a bigger, better sensor.

I have an 8MP digital SLR (Canon 30D) which whilst now about 2 years out of date shoots at high enough resolution to blow up to the size you want. Snapfish do a very good service for this
 
An alternative view

To buy a digital camera that would provide the sort of performance you require would cost a fait bit - mid-level DSLR with a goodish lens.

For much less money you could buy a better camera with a lens of the same quality that would permit enlargement to that size and beyond.

But it would be a used film camera.

Really high-end analogue SLR's are ridiculously humbly priced for the quality of construction and the level of facilities they provide. The sort of camera that Beken was using 5 years ago could be yours today for somewhere in the region of what you'd pay for a pocket-sized toy digicam.

You'd have to spend more money on a lens, but the same would be true if you were buying a DSLR.
 
Re: An alternative view

Erm yes, really sorry about the fred drift but I have a Canon EOS50E that had about two films run through it! Standard lens. Superb camera but just don't use it. I'll go to "For Sale" now! /forums/images/graemlins/blush.gif
Nick, you need to just try it on yr camera. We had some superb results on quality but "Point n Shoot" Nikons, Olympus etc.
My son is photographing yachts and printing on canvas now and using a variety of cameras including DSLR.
 
Re: An alternative view

Thanks for all the very interesting and helpful feedback.

I have a Canon E300 35mm (I think) which I bought for holiday in Gambia about 6 years ago, used it for less than a year, then bought a cheapo digital.

Maybe I will dig it out of the drawer and give it a go. I know its not ridiculously high end to use Ken's expression, but its pretty reasonable.

I believe, but would like to be corrected, that I can use the same lense if I buy a digital body.
 
Re: An alternative view

The EOS50 certainly uses same lenses as the 350/400D, so it must be standard Canon fitting I guess. I know because my son has "borrowed" a couple of my USM lenses.... /forums/images/graemlins/ooo.gif
 
Re: An alternative view

Ok, so I've shot my load of 24shots or whatever and head for the photographic dept at Boots. (The only one I know in our High St).

I know they will produce the standard negatives but I think they will also convert to digital and give me a CD. Then I can stuff said CD into PC and to the business, as if its a digital shot in the first place.

Is that about it, or have I missed something along the way?
 
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