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Author Topic: How many MP for 24inch print  (Read 5770 times)
Lou
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« on: January 01, 2006, 06:09:31 AM »
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Hello,

I'm looking at buying my first digital SLR camera and hoping to print images of approx 16 x 24 inches. The questions that I have is how many megapixels should I be looking for in the camera. Would 6MP be enough or should I be looking at the new Canon 5D (and more $$$) with 12.8MP and a full 35mm sensor??

Keep in mind that I will be using Photoshop to edit the images first, and then resampling to 24inches.

Thanks
Lou.
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Quentin
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« Reply #1 on: January 01, 2006, 07:37:13 AM »
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Hello,

I'm looking at buying my first digital SLR camera and hoping to print images of approx 16 x 24 inches. The questions that I have is how many megapixels should I be looking for in the camera. Would 6MP be enough or should I be looking at the new Canon 5D (and more $$$) with 12.8MP and a full 35mm sensor??

Keep in mind that I will be using Photoshop to edit the images first, and then resampling to 24inches.

Thanks
Lou.
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A full frame sensor is irrelevant for the purposes of determing sufficient resolution.  14mp is enough (Kodak 14nx that I use), for excellent prints at that size and a Canon 5D / 1Ds II or Nikon D2x would all give more or less equally good results.  I suspect the same would be true of a Nikon D200 (10mp), based on comments from a friend who has one and who raves about it.

More is better in most respects.  You can get great results at 24" 16" with a 6mp camera if rezzed up with care.

I'd be inclined to take 10mp as a base resolution for truly first class prints at your proposed size and work from there.

Quentin
« Last Edit: January 01, 2006, 07:38:20 AM by Quentin » Logged

Quentin Bargate, ARPS, Author, photographer entrepreneur and senior partner of Bargate Murray, Law Firm of the Year 2013
Tim Gray
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« Reply #2 on: January 01, 2006, 09:30:47 AM »
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I get very good prints at 17 x 25 from my Canon 1d2 (8mpx), but if you have the option, I agree with Quentin that 10 would start to give you a little breathing room.

If you have any kind of printer at all, you could get a sense - just download one of the many test shots on DPreview from the camera you're considering, res it up to the final print size you want, crop back to what your printer can handle and take a look.  This gives a sense only since the visual experience at 16 x 24 is different from 8x10.
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Dale_Cotton
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« Reply #3 on: January 01, 2006, 09:34:09 AM »
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Quentin: your 10 mp baseline works for me, but I'm just a little concerned about 16x24" from 6 mp under certain circumstances. I wondering if that might not be a little optimistic, given we don't know what subject matter Lou is intending.

I'm using a 6 mp camera myself, and find enlargeability depends dramatically on the subject matter. A head shot could probably be pushed that large; but in a class portrait there might only be two or three pixels per eye for the upsampling to work on. Ditto for certain types of landscape content. I've seen 16x24 landscapes done from 16 mp cameras hung in galleries that made me wince when I stepped in closer than several feet.

[You can skip the following paragraph, since Tim posted the same thing, almost word for word while I was typing:

Lou: given the amount of money involved, if you want to feel real secure about your decision, you might want to try this: Go to dpreview.com or similar site and download sample image files from cameras you are considering, samples in which the subject matter matches your intended usage. Enlarge as required to get to your target 16x24, then crop out an 8x10 chunk, then print on a decent letter-size printer (assuming you don't already have access to a large format printer). ]
« Last Edit: January 01, 2006, 09:36:04 AM by Dale Cotton » Logged
Lisa Nikodym
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« Reply #4 on: January 01, 2006, 09:57:53 AM »
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Another approach to answer this question involves a little basic math.  If you want professional gallery-grade prints, you'll need a resolution of about 240 pixels per inch; for less demanding uses (prints for your own wall, web images, newspaper pictures, etc.), about 180 ppi is OK.  You can upres a little without much image degradation, so estimate that you can start with about 210 ppi for gallery-grade or 150 ppi otherwise.  For a 16"x24" print, this works out to 3360x5040 pixels for gallery-grade, or 2400x3600 for other uses; that gives about 17 megapixels needed for gallery-grade or about 8.6 mp for other uses.

I currently use a 6 mp camera and print as big as 12"x18", which starts out at about 167 ppi.  At that starting resolution, it looks somewhat less sharp and detailed than a gallery-grade image, but still good enough that noone else notices.

(Of course, I'm still waiting for my 10 mp Nikon D200 to arrive so those 12x18's look even better    )

Lisa
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Jonathan Wienke
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« Reply #5 on: January 01, 2006, 09:59:17 AM »
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You will definitely be able to tell the difference between 6MP and 12MP at 16x24", no question. For most subject matter, the difference will be whack-you-in-the-face obvious at typical arms-length viewing distances. I'd highly recommend the 5D if you intend to print that large on a regular basis.

One other thing: If you use QImage for printing, up/downsampling to a specific print size is not necessary. QImage will do so on the fly well enough to make the effort of manually making and storing different-resolution files unnecessary. If I want a specific crop in a 4:5 aspect ratio, I'll make a cropped (but not resampled) version of the image, and have no qualms at all about printing that same image at 4x5, 8x10, or 16x20.
« Last Edit: January 01, 2006, 10:00:06 AM by Jonathan Wienke » Logged

61Dynamic
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« Reply #6 on: January 01, 2006, 12:40:19 PM »
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16"x24" is very possible with a 6 or 8MP camera. Several of my clients (who have switched over from MF) regularly shoot with a 20D (8MP) and make enlargements as bit as 24"x30." Granted a 12MP or more camera would make a noticeably better print at that size, they are quite happy with it.

I fully agree; 10MP is a good starting point for your print size requirement.

Whatever you go for, keep in mind you also have to have a computer to process the images that can match your camera. Raw vs Jpeg, 24/bit vs 48-bit editing, a few images per shoot vs hundreds per shoot, all are things to consider once you've settled on a camera and know how many megapixels it will be. If you computer is not up to the task, photo work will be miserably sluggish.
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Lou
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« Reply #7 on: January 01, 2006, 03:32:10 PM »
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Thanks to all who replied to my question. From the replies given it would appear that I could get away with a 6mp camera, BUT, image quality would be understandably less than a 10mp or 12mp camera.

The question I need to answer is how critical is image quality. Seeing that I occasionally sell my work (Landscape/Nature) I must answer that it is important. Having my work hanging on a customer's wall is a testament of my photographic attitude and an advert of my work to others.

So, I'll go with the 12mp camera, probably the Canon 5D. Now the only thing I have to do is sell my 35mm Minolta gear, probably for a fraction of what it originally cost..............Yuk!!    

Thanks again.

Lou.
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oldcsar
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« Reply #8 on: January 01, 2006, 09:58:43 PM »
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You can make 16x24 prints from less than 6MP images.

I don't think anyone really knows where the limit begins and ends, in regards to megapixels and enlargements. Some have claimed that they've seen fantastic 4 foot wide prints from 2 megapixel images, some have a very technical and rigid interpretation based on megapixels and ppi. Indeed, some specific images may resolve better than others on a technical basis, but it might be too much of a generalization to judge the quality of the output in regards to the megapixels and subject only. I agree with everyone who says that the bigger sensor would yield a more detailed print... but really, this is no more insightful than saying that the grass is green.

I'm not saying that anyone is wrong here. Everyone so far has been pretty insightful. I've had a 30x40 lightjet print done from a 5 megapixel image, which consistently manages to impress people... sure, it certainly has its technical limits, coming from a 5 megapixel source file... but it looks damn fine. If you want to make a big print, and you think your subject warrants it... do it!

One of the most important factors in making good enlargements is meticulous noise removal, using the best interpolation software available, and applying the optimum amount of sharpening with introducing little or no extra noise in the process. Just because you've seen a sub-par enlargement somewhere doesn't mean that it's technologically unattainable to produce a good print from a "low megapixel" file. Good ideas are sometimes executed badly. In short, good enlargements come from well-shot photos, shooting in RAW, efficient noise removal, good interpolation (such as Benvista Photozoom Professional), and applying the right amount of sharpening (PK Sharpener).

I believe all current DSLRs will make great enlargements. But one of the biggest factors isn't the amount of megapixels, but how skillfully you process the files. But... more megapixels will obviously give you more fine details.
« Last Edit: January 01, 2006, 10:01:14 PM by oldcsar » Logged

macgyver
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« Reply #9 on: January 01, 2006, 11:31:09 PM »
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I believe all current DSLRs will make great enlargements. But one of the biggest factors isn't the amount of megapixels, but how skillfully you process the files. But... more megapixels will obviously give you more fine details.
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If you don't mind a slight side question then, what is the most dramatic processing detail to effect such prints?  (I've been trying to improve my post skills as of late)
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oldcsar
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« Reply #10 on: January 02, 2006, 01:31:33 AM »
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If you don't mind a slight side question then, what is the most dramatic processing detail to effect such prints?  (I've been trying to improve my post skills as of late)
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That's really a tough one, because it always depends on the specific needs of each photo. If an image is very high ISO, then noise reduction would be most important, especially if it's low in megapixels... the more you enlarge the file, the more you enlarge the noise-- increasing your problems with image clarity.

I really want to say noise reduction is most important, but I would have to say that the proper level of sharpening is most important. If you sharpen too much, you'll bring out artifacts or noise present in the photo, and not enough sharpness will make your print seem out of focus to the human eye. The problem is that "sharpening workflows" seem to be recent inventions still, and this is seen by how few of us have a practical understanding of sharpening relating to print size, we usually have photoshop automaters (PK sharpener) or plugins do the whole process for us (nik sharpener pro 2, for example). Those programs are used successfully by several, it seems, but yet I still feel that many people have yet to truly understand the process. I could be speaking for myself, but I doubt it's just me... then again, I don't really need to know the inner workings of the process if I can plug in the proper parameters, according to output printer, etc.

I think the two are connected, noise reduction and sharpening. The key, I think, is that you must suppress the garbage (except in the event that you really want some grain for its artistic qualities, and this is really why sharpening takes first place... an image can be a little soft, but you don't want people cleaning their glasses and squinting  . There are very few cases, if any, where a photo shouldn't appear to have a decent level of sharpening, or focus) and bring the wanted detail to clarity... because they're that much more noticeable when you an enlarge an image.
« Last Edit: January 02, 2006, 01:55:25 AM by oldcsar » Logged

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