How many megapixels do you need?

How many megapixels do you need to print on a specific paper size

I made this simple table for personal use, than I thought it may came in handy to others too, so here we are.

It sums up how many megapixels do you need to print on each of the more common paper sizes available.

Given that the level of quality requested varies according to the kind of image – a portrait will be more enlargeable without artifacts or softness than a detailed landscape, for example – I’ve set three thresholds at 200, 260 and 300 dpi.

Please note that here we are talking about PRINT resolution, not PRINTER one.

If you don’t have this point clear please read one of the basic introductions available online. Let’s suffice to say that normally you will have to “stretch” the megapixel of your picture onto the area you intend to print; to have a quality result you don’t want to stretch them too much, and that’s what I’m talking about.

Printer resolution, on the other end, refers to the way printers manage to actually create an image putting thousand of ink dots one after the other on a piece of paper.

While print resolution – how many megapixels you need to cover the area of a piece of paper – it is alway the same regardless of the device used to create the image on paper, printer resolution varies wildly between models, makers and technologies used.

Panorama multishot Olympus shift 35mm f/2,8 OM Zuiko

And now let’s look at the table. In the first column you find the paper format; in the seconds its size; in the third, fourth and fifth how many megapixels do you need for each print resolution, from the worst (200 dpi, in red) to the best (300 dpi, in green). You may pull it off with 200 dpi if the viewing distance for your print is not very close, especially if there is an actual physical impediment for the people to getting closer; otherwise everyone usually tends to stuck its nose to the print searching for more detail – and at 200 dpi this detail it will simply not be there.

In the last column I’ve listed how many shots you will need to use if you decide to join multiple frames in a matrix fashion to achieve a resolution of 300dpi with a 21-24 Megapixels camera* (first number is the total of shots needed, then how many shots rows x columns).


*With a 20% margin of juxtaposition to join the frames flawlessly


Paper format

Paper size
(mm / in)

200dpi260dpi300dpiN° of shots
[rows x columns]
A01189 x 841mm
46.8 x 33.1″
628914015 [ 5 x 3 ]
800 x 800mm
31.4 x 31.4″ 
3957899 [ 3 x 3 ]
A1841 x 594mm
33.1 x 23.4″ 
3145706 [ 3 x 2 ]
700 x 700mm
27.5 x 27.5″ 
304468 6 [ 3 x 2 ]
600 x 600mm
23.6 x 23.6″ 
223250 4 [ 2 x 2 ] 
A2594 x 420mm
23.4 x 16.5″ 
2235 2 [ 2 x 1 ]
500 x 500mm
19.6 x 19.6″ 
2235 2 [ 2 x 1 ]
A3420 x 297mm
16.5 x 11.7″
 11 17


How to: semi-stand development in Rodinal

Foma Fomapan 100 in Rodinal semi-stand 1+200

Full disclosure: I’m badly biased in favor of Rodinal.

If you don’t know it (but it has been around from the end of the 19th century…) it is one of the best black and white film developers out there, and these are its pros and cons:



Amazing tonalities with almost any film
Super-sharp results
Infinitely scalable contrast
It lasts years without spoiling
Ultra cheap – you need only tiny amounts of it


For the same reason of point 2 of the PROS list it will emphasize the film grain


The – only – con(s) needs a bit of explanation. First of all it depends quite a bit from your agitation scheme too. Secondly more than enlarging the grain the Rodinal tends to render it in a sharper and more “honest” way, giving the single grain clumps a peppery aspect.

Given that, like I said, this developer it is going around from the late 1800s the original Afga patent is long expired. So you can actually find “Rodinal” sold under a lot of different brand names, but almost every one will refer to it, somewhere in the description, with its original, “real” name. And if you want you can also make it yourself, in the best DIY spirit, starting with a bit of paracetamol (a hint: search the web for “Parodinal” if you’re interested in the recipe).

Shanghai GP3 in Rodinal semi-stand 1+200

I like to use this amazing jake of all trades of developer at almost any dilution, depending on the light on the scene, the film I’m using, how lazy I feel that particular day and so on.

At this regard I will publish in an upcoming post a list of films / developers combinations that in my opinion tends to produce really beautiful results, so stay tuned. But a combo is my bread and butter, the one to which I default more often that I care to admit.

I’m talking obviously about the one mentioned in the title: Rodinal semi-stand at a dilution of 1+200 – yes, it is not a typo, TWO-HUNDRED; I said it was ultra cheap to use! In practice you dilute 5 milliliters of Rodinal in 1 liter of water, and you’re set. With this amount you can develop up to 2 rolls of 135mm or 120.

The full procedure will be carried in semi-stand development, and in detail it is composed of the following steps:


Step by step

1  Pre-soak = 5 / 10 minutes (depending on the film you use)
Fill the tank with water and let it rest; change it a couple of times until it comes out clear

 Developer = 2 hours (yes, 120 minutes)
Agitate the first 30 seconds, and then again invert the tank a couple of times at the 60 minutes mark (this is to avoid the bromide drag, a border effect similar to a bad sharpening halo between high contrast regions)

3  Stop bath = 1 minute
Just plain water; it is an optional passage, mostly to prolong the fixer solution life

4  Fixer = 4 / 5 minutes (depending on the dilution you use)
Agitate the first 10 seconds and then 5 inversions every 30 seconds

5  Wash = use the Ilford archival method
Fill the tank and do 5 gentle inversions, then refill and do 10 inversions, refill one last time and invert the tank 20 times. This will guarantee – per Ilford research center – archival quality without wasting water

6  Photoflo (wetting agent) = 2 minutes
Use 2 / 4 drops of Photoflo – or of a neuter PH dish soap -, fill the tank agitating it for 1 minute to create foam and let it rest for another 30-60 seconds

7  Hang the film to dry

8  Scan the film


Shanghai GP3 in Rodinal semi-stand 1+200

What makes the semi-stand development in general, and in Rodinal more so, special is the enormous quantity of information you can pull out of your films. The semi-stand process act as a compensator, so you will be left with a huge, and vastly customizable after scanning, tonality scale on your negative. Just to be clear: a digital file, even an HDR one, doesn’t come near not even in the least. At the same time, though, thanks to the characteristics of the Rodinal, you will not sacrifice the details; quite the opposite.

Summing up: you will get the true, only and original “raw” file that, after careful scanning – preferably with an high end scanner or using a digital camera with my method -, you will be able to interpret to your heart content, sure that each and every light value you may need will be on film – so no more blown out highlights, blocked out shadow or stepped histograms!

And as added bonuses not only you will have a lot of room to spare at the time of the exposure, even if you like to “guess” the exposure or using the reference card inside the film boxes; but you will also get to enjoy the time you would otherwise have spent agitating the tank with your significant other / friends / children – take a pick!

Give it a try, and I’m sure you will be hooked.


How to scan films using a digital camera

Overview of the setup

If you’ve not read this previous post so far give it a skim:

Best film scanner: Canon 5D Mark II vs Drum Scanner vs Epson v700

You will see what level of (very high) quality you can expect using a digital camera as a scanner, as long as you setup everything nice and properly aligned – don’t worry, it’s really simple!


The setup

The nice thing about this technique is that you will be able to extract all the information on the film even with a low-res digital camera, as long as you can increase the reproduction ratio and get used to join multiple files in one, like when doing a panoramic image. For the details please take a look at the previous post linked above.

The setup, like I said, is really really simple: you will have to put you camera vertically on top of the film – taped on a slide viewer – using a metal lens hood that act as spacer / camera support / light screen. Then you’ll use the Live View to focus on the film grain, and the self timer set at 2 seconds or a soft shutter release to avoid vibrations.

The setup

Like I said the secret is taking multiple shots of each film frame, and joining them in a panoramic software.

How many shots will depend of:

> the reproduction ratio you (and your lens) will use

> how much detailed the picture is

> the resolution of your camera

> the sensor size of your camera (full frame, aps-c)

Generally I use a 1:2 enlargement ratio on medium and large format film and a 3:1 ratio on 35mm and I get more or less this results:

– 35mm = 4 / 6 shots
– 4,5×6 = 3 / 6 shots
– 6×6 / 6×7 = 6 / 8 shots
– 4×5″ / 13x18cm = 20 / 30 shots


How to take the multiple shots…

Multiple shots

…and the resulting image

 The resulting image

The shooting session lasts generally 15-30 seconds for each complete picture; how much time the computer will need to join the shots will depends by the computer processor power and amount of ram, other that by the number of shots to be joined. But for you to have a rough estimation: my 2011 iMac, with 24Gb of ram, generally takes 30-50 seconds to join 6 shots and up to 10 minutes to join 30 shots.

Using an higher reproduction ratio is more time consuming (you’ll need more shots to cover the same area), but as a result you will be able to get the most detail from the film. Just check this few examples, in which the Canon setup is used at various reproduction ratios and compared against a well respected flatbed scanner, the Epson v700:

Epson v700 scan     Canon multirow scan

Epson v700 sharpened scan     Canon unsharpened scan

Epson sharpened scan     Canon unsharpened scan     Canon unsharpened scan 3:1 ratio


The tips

This is all for the general guide, now some tips:


– don’t try to focus at full aperture; even an excellent lens like the Zeiss Makro Planar has its problems, and all your pictures will look like mush. Close the lens a couple of stops from the maximum aperture to focus (remember, set the Live View to compensate automatically for the light loss if you want to see anything at all!)

– if possible focus on the film grain, not on the details; this way you will be sure to extract all the information there is on film, and it is easier; if you don’t seem able to see the grain just look at a dark out of focus area, the grain will pop out!

– focus independently each frame; even if they are on the same strip of film they will require more often than not an adjustment in focus

– for maximum sharpness tape the film to the viewer, tensioning the film itself a bit to ensure maximum flatness; use painter’s paper masking tape, the one that leaves no residues


– if your computer is powerful enough shoot in raw; you will benefit not only from more detail, but also from extended dynamic range and better gray / colors

– close the lens a couple more stops from the one you used to focus – till f/8 or better f/11 – to take the shot. This way you will hit the best spot of your lens and avoid vignetting related issues

– take a custom white balance on the viewer surface, without the film. This way the colors will be almost perfect without the need to mess with the curves later in Photoshop or Gimp

– shot in manual mode, to have the same exposure and density on all sections

– “expose to the right”, i.e. overexpose until the histogram for all the colors almost touches the right side of its window; this will ensure that you will have less noise as possible and that you will exploit the entire dynamic range your camera is capable of. Be careful to not overexpose too much – another good motive to shoot in raw


– shot in some kind of order (clockwise, counterclockwise, whatever), to avoid forget same part of the film frame; after a while it will became routine, and you will become very fast

– to avoid scratching the negatives put them down with the shiny side up – it’s called “protective layer” for a reason; having the opaque side – the emulsion – in contact with the viewer surface will avoid the formation of Newton rings too

– if the picture you’re about to “scan” has got few details – vast areas of sky, water or out-of-focus zones – take closer knit shots to help the panoramic software identifying some meaningful “anchors” to use in the merge

– if you don’t have a slide viewer, but you’re comfortable around electricity, you can easily adapt to the same use an old scanner transparency adapter or build one of your own (plenty of DIY projects like this on the web)


The software

What panoramic software you want to use is your choice, there are hundred of them out there. The only important thing is that it has to let you join the files in a “matrix” fashion, not only in rows. Here some of the one I tried or use, and a few notes for each one:

– Adobe Photoshop function Photomerge: really good 90% of the times. Use the “reposition” option, because you are not shooting a panorama, so there is no parallax error to take care of. Its biggest downside is the lack of the possibility of manual corrections; on the bright side it is still one of the fastest panoramic software I ever used, and it was able to “digest” without a hitch even 110 files at once.

– ArcSoft Panorama Maker 5: really good for those 10% of the times in which Photomerge goes nuts. Its biggest drawback is the impossibility to maintain the 16 bit in the output tif. Quite cheap (13,99€ on the Mac App Store).

– Kolor Autopano Pro 3: as good as PhotoShop CS6 or slightly better. A lot slower, though. On the other hand it can batch process entire folders of files recognizing automatically which files to merge in which panorama. Not so costly, just 99€.

– PhotoStitch: this one comes free with every Canon digital camera. It would be really good, except that has a strong tendency to crash if used with 6 files or more (at least with Canon 5D mark II files, could also be some kind of incompatibility, I don’t know). Same problem of Panorama Maker, meaning that it doesn’t support a 16 bit output. Better, it supports 16 bit on paper, but the resulting tif files will be an ugly mess.

– Hugin: free and extremely complete. For the same reason a bit complex and intimidating at first, even if it’s present a sort of “assistant” that it’s supposed to guide you. Excellent for general panoramic photography, I found it a bit of an overkill for just join a few shots like in the technique discussed here.

Best film scanner: Canon 5D Mark II vs Drum scanner vs Epson V700

If you shoot film and you don’t are much into chemicals, or don’t have a basement in which to keep a gigantic 5×7″ enlarger, you’ll soon end up with the need of a way to import those beautiful pictures you’ve taken on the computer. What? Why I didn’t say straight on “you will need a scanner”? After all it’s not 1987 anymore, and scanners are common like toaster ovens.

Well, I didn’t say “a scanner” because this it’s not the only way you can digitalize those pictures. Indeed, turned out, even though it’s the first, and often, only way most people will think of, it is the most inefficient and time consuming. And it can loose a lot, i mean A LOT, of the quality of the original slide or negative.

But now there is a much better alternative…

Let’s cut to the chase: I’m proposing here to use a digital camera of high pixel count – full format / dx format doesn’t really matter – mated with a good macro lens to scan the film using multiple shots, like in a panorama. “A good macro lens” that it’s like saying “a macro lens” because, with the possible exception of some russian misassembled lemon, they all range from really good to exceptionally good. And if you have a bellows you can use, instead, an enlarger lens (an Apo-Ronar, for example, will put you back of only 60 / 70 euros).

But what about the quality you say? That it’s what this post is for!

First a brief overview of the contenders:

– Flatbed scanner: Epson V700

The film-holder height has been calibrated. I did not use fluid mounting, but I taped the films to the film-holder and / or used a glass to keep the films flat; so fluid mounting should only make a difference in terms of absence of dust, appearance of the grain clumps and, possibly, slight better tonality

– Drum scanner: Dainippon Screen DT-S 1045Ai

The films has been professionally scanned by an external service

– Camera + lenses: Canon Eos 5D Mark II + Contax Zeiss 60mm f/2,8 Makro Planar (for medium and large format); Canon Eos 5D Mark II + Nikon Nikkor 35mm f/2 O non-Ai version inverted (for 35mm films)

Given that the Canon 5D Mark II it’s the challenger we will compare it separately against each of the opponents.

So let’s check first how this setup fares compared to the Epson V700, an excellent flatbed per se (still a flatbed though).

Those are all 100% crops. First the “usual difference” between the output of the two systems: those crops belongs to a 4,5x6cm negative shot with an ultra-sharp Fuji GS 645, on a sturdy tripod and with a soft release. The Epson crop has been sharpened, the Canon one NOT (no kidding).

Epson 700v crop

Canon 5d marl II and Contax 60/2,8 Makro Planar

Yes, the Epson (or any other flatbed scanner, for that matter) here looks like an old man who is in desperate need of new glasses…

And now the best possible case (I saw the Epson behave so well only in rare occasions, like once or twice in a blue moon). Those crops have been shot on an Hasselblad 500c/m with mirror up, the standard 80mm f/2,8 Planar, tripod etc.

Epson 700V crop 02Canon 5d marl II and Contax 60/2,8 Makro Planar crop 02

Yep, you just witnessed the death of flatbed scanners as film-scanners. So buy the cheapest all-in-one or LIDE model you can get, just for bills and invoices, and be done.

But surely a drum scanner, a thing that costs more than many cars, whose scansions cost you 60 / 200 euros a pop, will put the Canon setup to shame. Let’s see. Those were shot on a Linhof Technika 13x18cm with a Symmar-S 240mm f/5,6. The drum image has been sharpened by the photo service, the Canon one is unsharpened:

Drum scanner Dainippon pre sharpened

Canon 5d marl II and Contax 60/2,8 Makro Planar crop 03

No, I’ve not made a mistake. Actually, I made one when I loaded the files in Photoshop. I gave both the same name – putting them in different folders – to make a sort of “blind test”. Well, I saw immediately that there was no contest, even though I made all the tests anyway. Boy oh boy I was up for a surprise…

This surprise came when I was saving the files: I used “Save as…” because I wanted to change back their names to something meaningful, and then I discovered that the file I was absolutely sure was of the Dainippon drum scanner, because obviously superior, was in fact the one shot with the Canon! I even double checked the exif, because I cannot believe my eyes.

The amazing thing is that I did NOT used the lens at 1:1 or, like I do on 35mm film, at 2:1 or 3:1 magnification. So, in exceptional cases of extremely sharp negatives – say ultra sharp lenses and microfilm like films – I would be able to pull out even higher resolution!

And, just to clear any doubt you may have, here the two crops above after a good dose of sharpening:

Drum scanner Dainippon with more sharpeningCanon 5d marl II and Contax 60/2,8 Makro Planar sharpened

To put things in perspective: those crops are from a 660Mb greyscale file; seeing it like this on a monitor it’s like peeping at a print of 5,20 x 3,70 meters. At 240dpi I could still print it as large as 2,30 x 1,65 meters!

Like I said going up with the reproduction ratio you can extract even more detail. See for yourself. All the following 100% unsharpened crops came from a 6x6cm negative shot like the ones before with an Hasselblad 500c/m with mirror up, the standard 80mm f/2,8 Planar, tripod. The last crop has been resized at the 50% (at 3:1 there is more grain than detail, so keeping a gigantic file is pointless). And please ignore the tonality; this is a shot from a color negative, and I’m struggling a bit to find a suitable curve:

complete image

Epson 700VCanon + Contax Makro PlanarCanon + Nikkor 35 inverted

I showed here only few examples, but I tested this thoroughly with many images, colors and black and white, slides and negatives, and I consistently found the same results.

Even the tonalities of the films were much better preserved with the Canon than with the scanners. And, as an added bonus, including the picture borders or importing into the computer some odd format shots – 6×17, for example – it’s a breeze.

Summing up: forget about scanners. Yes, if you have 3.000 euros laying around and you need to scan 100 shots a week by all means buy a Coolscan or an Imacon – but in this case for the sake of your own sanity go digital and lose film! Instead, if you need just to scan your best shots follow my advice and use this system.

Stay tuned: in the next post we will get in the specific of how to get the job done.

Large format crash course

Linhof Technika 13x18

1 ) Minimum requirements: a tripod (unless you are willing to use a Speed Graphic type camera in the Weegee style, handheld), a large format camera with a focus screen and a back, a bunch of film holders that fit both your camera format AND your film format (see below), a lens mounted on a shutter (again, unless you buy a Speed Graphic camera which owns an internal shutter), films in the chosen format, a loupe (the bigger the better, personally I use a 22x, even if an 8x it is ok to start with), a darkroom or a changing bag to load and unload the film holders (in a pinch you can also do it in your bed, under the blankets with the lights off and the window blinds shut, but it’s not very practical…)

2 ) If you chose 4×5″ than, possibly, make sure that your camera has a Graflock back (in 4×5″ it is the international standard back); it’s not imperative, but it will simplify your life

3 ) If you chose other formats make sure that the camera has a back compatible with modern, internationals, double-sided film holders

Linhof Technika III

4 ) There are many formats from which to chose, but the most common are (in parenthesis the european film sizes): 4×5″ (10×12, 9×12); 5×7″ (13×18), 8×10″ (20×25). For each US / European format the cameras are the same; what changes is the film holder that you have to use to load the film. So, if you want, you can use your 5×7″ camera with both 5×7″ and 13×18 films just buying the correct holders for each size of film

5 ) You could chose between studio cameras and field ones. The first have most movements and are usually cheaper (given the same features), but are bulky and uncomfortable to carry into the field; if you intend to use them close to your car this can not be an issue

6 ) When shopping for a camera watch for camera movements too: at least it should have frontal or back tilt and frontal rise; ideally even frontal and / or back swing. The “technical” cameras normally have more movements that others field cameras

Linhof Technika 13x18

7 ) The untold secret of large format reside in using the black cloth and a good ground glass, maybe fitted with a Fresnel screen (it will enhance the luminosity); this way you can focus and check the framing easily

8 ) You can mount lenses from every brand on every camera, just change the lens board

9 ) What you have to check in a lens, quality aside, is that it has enough cover for the format of your choice. The very reason to shoot in large format is to use camera movements, but you can do this only if the lenses that are you using have a larger coverage than the film format you are shooting on

10 ) For the previous reason (the coverage circle) usually it is better stay away from Tessar and Xenar schemes lenses; these, nonetheless, are often excellent lenses and quite cheap so they can be useful starting lenses in landscape photography, where the need for movements is less felt

11 ) To focus a view camera properly often you have to follow the Scheimpflug principle. Basically it says you have to make sure that subject, film and lens planes they all converge in some imaginary point in the space to achieve the best possible focus for a given aperture; and trust me, the theory may be awkward, but using it it is really simple once you understood the basics

Fujonon 150mm

12 ) The lenses are really simple: usually just the shutter times selection ring, a screwed hole for the remote shutter cable and four little levers. One of them is for opening and closing the shutter (you’ll need to close it before you’ll pull the film holder dark slide; you’ll need to open to framing and focusing). The others are for charging the shutter, select the apertures and shoot

13 ) Best way to start is to stick to one lens and one lens only. In any case you don’t need a lot of lenses, because especially with the larger formats there is a lot of space for cropping. If you really want more your best bet is to duplicate the three lens you most use in 35mm; to make the conversion multiply every 35mm focal length for 3,3 if you are using 4×5″, for 4,4 if you are using 5×7″ and for 6,5 if you are using 8×10″; likewise divide every large format focal length for the above coefficients to know what is its 35mm equivalent