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Policar
30-Sep-2010, 13:07
Film vs. digital:

I've started shooting 4x5 instead of digital APS-C and right now I'm going for a "f64" look, mostly with longish lenses for the subject matter (primarily landscape). This means some serious stopping down. Sometimes. On a 300mm lens, f45 and f64 are sometimes necessary...

Since 4x5 is a little more expensive per shot ($6 vs free) than digital, I'm wondering if, with the next generation of dSLRs, 4x5 will offer no advantages--for my purposes.

Here's the hypothetical that bugs me:

Let's say I'm shooting the same scene with a Canon 7D and a 45mm tilt/shift lens as I'm shooting with a 300mm lens on 4x5. It's a pretty deep focus scene so I stop down to f64 with the 300mm lens.

On 4x5 I'm diffraction limited at 25lp/mm. And 25lp/mm*2 lines/line pair*120mm (width of 4x5 film)=6000 lines of resolution. Thankfully most film can resolve this just fine with acceptable contrast. Unfortunately, since diffraction also softens lower frequency detail than the absolute extinction limit indicates, these are 6000 fuzzy lines of resolution. This is being generous. I've read repeatedly that in real world situations no one ever gets above 25lp/mm, except maybe in the very center, at any stop in 4x5.

On the 7D, to get the same depth of field, I need to shoot at around f11. Now I'm diffraction limited at 141 lp/mm. And 141lp/mm*2 lines/line pair*23mm (width of 7d sensor)=6486. The difference between this and the figure for 4x5 film is just due to me using imprecise equivalents. It's really the same in both cases. Anyhow, since the 7D has a 5184 pixel wide sensor, we'd get 5184 semi-fuzzy pixels in this case.

The resolution of both images should be closer to identical.

With this generation of digital cameras, this problem only arises in extreme situations (300mm at f64, which is used but not often in landscape photography). It's still kind of humbling to think that an APS-C sized sensor matches 4x5 in some real-world cases, though.

Megapixel counts are still increasing at huge rates. Will the quality advantage of 4x5 over dSLRs still exist in four years? Before you cry foul, there are some lenses which are diffraction limited at f4-f5.6 and live view allows you to implement tilt/shift with per-pixel precision.

It seems digital sensors and modern lenses are getting so good that lens diffraction, not sensor size, will be the limiting factor in coming years, and instead of medium and large format we'll be dealing with full frame and APS-C digital virtually exclusively as "professional" formats.

But my non-inflammatory question is this: it seems there's a given resolution limit for a photo, irrespective of format, based solely on FOV and DOF....so why are my eyes so much sharper than a 1:1 print? Maybe they really aren't.

Bob McCarthy
30-Sep-2010, 13:58
Firstly, the lens on the 7D might have a theoretical resolution of 141 lpmm, but realistically you might actually achieve 60 to 70 lpmm. Complex lenses with many glass elements can not be designed and manufactured to theoretical book resolution.

The relatively simple lenses in large format will be very close to theoretical at the stops commonly utilized.

Major Point - I have to enlarge the digital crop camera rough 7 or 8 X before I get to 4x5 inches which would be equal to the coverage of a contact print (1:1) for a sheet film camera.

So the crop camera has a final resolution of 70/7 = 10 lpmm at the "final print equivalent" (and I'm being very generous).

So digital optical chain has less than 50% of the large format system, but you miss the point.



The great advantage of the view camera is we can conform the film plane to the subject so utilizing pure DOF to get everything sharp, is frequently not best approach. In almost everycase I can use a larger stop (area not numerical) so my actual resolution is many times your example. My most common f stop is f16 or f22. And I can certainly keep everything in focus in a landscape.

There is a reason large format is so beautifully microdetailed.

Being enlarged (roughly) 3X instead of 20x to make a 12x18 is why the tonality is so beautiful. Go bigger, the difference is even greater.

Gotta think differently with a camera that can adjust the plane of focus.

bob

BetterSense
30-Sep-2010, 14:32
Will the quality advantage of 4x5 over dSLRs still exist in four years?

Photographs have many qualities. Which qualties were you talking about?

Bruce Watson
30-Sep-2010, 14:38
It seems I've said this about a thousand times in this and other forums. There's more to a photograph than simple resolution. A lot more. If all you want to do is count line pairs on resolution charts, go for it. It's your life; do with it what you will.

But if you want to photograph in the real world, there's a lot to be said for control of the plane of focus through camera movements. And there's a huge amount to be said for image capture area. Especially if you like tonality, and smooth tonal transitions.

The best reason to use LF IMHO is that it forces you to move slowly, and to think about what you are doing. There is very little "spray and pray" in LF. Interestingly to me, LF forces you to learn how to compose without a camera. You learn how to look at a scene and evaluate it without a camera stuck to your face. You learn how to walk the scene without the camera, to find the right spot with the right perspective to make the photograph; as opposed to "composing with your feet" and that camera stuck to your face. You learn also how to realize your vision on the GG as a final step, not the first.

LF forces you to actually think about what you are doing; if forces you to understand why you are doing it. It can be the difference between snaps and art. If you have the talent and work your tail off.

theBDT
30-Sep-2010, 14:56
You have got to realize, each sheet of 4x5 film is basically like a 4x5-sized sensor. To elaborate:

I have a Canon Digital Rebel XT, which is 8MP. I have a friend with a 10MP point-and-shoot. While my dSLR is theoretically inferior by sheer resolution, the QUALITY of the 8MP is much higher than the 10MP point-and-shoot, mainly because of the sensor-size. The larger sensor affords better contrast and less noise.

Digital IS a cleaner, more efficient format than film. It's cold and crisp, and has a different feel well-suited to some things, and poorly-suited to others. But if you're just looking for a sheer resolution race, 4x5 black-and-white ISO100 film (especially Ortho film), scanned even on a simple Epson 700, can produce an acceptable "digital negative" between 80-100MP. Drum scan the negative and you have even more available resolution.

Likewise, I've scanned color 4x5 film, Portra VC160, at resolutions approximating 40-50MP. And HERE is where digital may soon at least catch up—in color MEDIUM FORMAT digital. Those crappy little APS-C sensors will fall apart with noise and poor contrast, even if you could cram 40MP into them! The large Kodak sensors in the Hassys, Mamiyas (sp?), etc., with sensor sizes measured in inches not millimeters, may soon be able to go toe-to-toe with 4x5 color film...

...assuming you want to sink $60,000 into an ultra-high-end medium format setup. $60K is a LOT of color film + processing + scanning... Just sayin'...

Of course, 5x7 is almost twice the effective "sensor size" of 4x5, and 8x10 is four times the size! It will be a long while yet before anything digital costing less than $100,000 will be able to TOUCH 5x7 or 8x10. And I feel as though it's safe to say it will be at least 10 years before digital quality catches up to 4x5 in the sub-$1,200 dSLR market, which is about the price-bracket for some of us "starving artist" types.

Oh, and let's remember, you also need a MASSIVELY powerful computer and the latest software to deal with these huge digital files. If you print out your 4x5 traditionally, the biggest processing/darkom problem you will have is dust...

Policar
30-Sep-2010, 15:36
I can't afford the digital camera I want...I'm just speculating that because digital sensors are so far superior to film over a given surface area, maybe maybe we'll see a massive shift from LF to digital among landscape photographers. Maybe we already have...

Anyhow, in theory every given FOV/DOF choice is equally diffraction-limited irrespective of sensor size, not taking shifts and swings (which are available, for a price, in small formats) into account. But the sensor can't always match that resolution. For the example I cited (gentle telephoto, extreme deep focus) 8X10 should have just slightly more resolution than a 7D. But it's an extreme example of diffraction limitation...

Just wondering what the future holds for current large format shooters. The same image quality (diffraction limited) may soon be available with tiny digital sensors, but not the same workflow or aesthetic.

Steve M Hostetter
30-Sep-2010, 15:46
I think large format shooters will continue to multiply...

Tobias Key
30-Sep-2010, 16:06
Thomas Kinkade's (http://www.thomaskinkade.com/) paintings are show a higher resolution than Van Gogh's (http://www.vangoghgallery.com/://). Is Van gogh a worse painter than Thomas Kinkade??? Given that Van Gogh paints in such low resolution does that make his pictures worse and of less value than any painter who paints with more detail? There is much more to a photo than resolution, although just for the record I have a 5d MkII as well as 5x4" I've never done any regimented testing because the resolution advantage of 5x4" is very obvious.

As an aside digital is not free unless you think that depreciation is not a cost. When I bought a 5d MK1 and in about 18 months it went from a 1600 purchase price to a 300 trade in value. Second hand large format barely depreciates if you buy well. So in the same time period if you spent less than 75 a month on film and developing you'd be ahead of the same digital purchase.

Sirius Glass
30-Sep-2010, 16:29
... I'm just speculating that because digital sensors are so far superior to film over a given surface area, maybe maybe we'll see a massive shift from LF to digital among landscape photographers.

Stop there! Fact: Digital sensors are so far inferior to film over a given surface area ...

By the laws of logic, if the hypothesis is wrong, ...

where will it lead you?? :eek:

There is no reason for me to read any further.

Steve

Policar
30-Sep-2010, 16:57
Okay I knew this would get me in trouble...although I still think digital is better per square millimeter (for color, not black and white):

1mm^2 from a Canon point and shoot:

http://home.comcast.net/~mwauhkonen/g12.jpg

1mm^2 of velvia (with a sharp lens and scan that resolved all the detail):

http://home.comcast.net/~mwauhkonen/35mm.jpg

Even the most generous estimate puts color 135 film at 25 megapixels or 80lp/mm. The 5mmx7mm sensor on that point and shoot outputs over 10 megapixels, somewhere around 300lp/mm. That's where dSLRs are going...

I guess I'm just frustrated by the concept of diffraction-limited resolution. You can't do anything about it no matter what format. (Except focus blending?) If my subject matter is going to be diffraction-limited maybe I'm wasting time with a bigger format?

Kevin Crisp
30-Sep-2010, 17:09
I am distraction limited.

Ben Syverson
30-Sep-2010, 17:10
If my subject matter is going to be diffraction-limited maybe I'm wasting time with a bigger format?
Well, you're certainly wasting time... :rolleyes:

BTW, "pro" cameras like the 5D Mark II are limited to around the same lp/mm as color film, so your argument has some obvious flaws. Unless you're really serious about comparing your 10 MP point and shoot to 4x5.

Bob McCarthy
30-Sep-2010, 17:24
When I see a 4x5 digital sensor, then I'll switch.

But to compare a tiny sensor less that 1 sq inch to film area of 20 sq in or 35 sq in or 80 sq inches makes no sense.

The lenses can not make up for the greatly required enlargement when outputting to a print of any appreciable size/

I suspect your correct when comparing film to sensor in a 1 to 1 comparison, but that is unrealistic when outputting to a permanent medium i.e. paper.

I have and use digital so I'm very familiar with the issues. There is no way a greatly enlarged sensor capture can even come close to a loafing large piece of film properly scanned into the digital realm..

Not even close.

And tilt/shift lenses have movement solely on the front end and are typically limited to one axis. Not the same as a view camera (useful, but not the equivalent).

bob

Sirius Glass
30-Sep-2010, 17:31
Okay I knew this would get me in trouble...although I still think digital is better per square millimeter (for color, not black and white):


If you are going for the highest cost for the lowest resolution, as you appear to be, maybe you should get an iPhone. :D

Color film and black & white film store images on the molecular level which is much smaller than any pixel will be for a long time. Newer is not always better.

Please do some more research before posting the pseudo triumphs of digital over film.There is a reason for last line of my signature. :eek:

Steve

Ivan J. Eberle
30-Sep-2010, 17:58
"I've read repeatedly that in real world situations no one ever gets above 25lp/mm, except maybe in the very center, at any stop in 4x5."

Sounds like horseshit to me. But then, misinformation oft gets repeated, sometimes seemingly endlessly, on the web.

If I wasn't doubling that 25lp/mm resolution with every one of my lenses, I'd long ago have thrown in the towel, myself. (Certain lenses like my Nikon SW 90mm, handily triple that figure. Real-world. Though not at f/64. And neither does your Canon, at f/22, incidentally).

And yes, some of us did come late to LF expressly due for the greater resolving power. My interest in it sure wasn't due to ergonomics, speed, or convenience.

Ben Syverson
30-Sep-2010, 18:26
And yes, some of us did come late to LF expressly due for the greater resolving power. My interest in it sure wasn't due to ergonomics, speed, or convenience.
Haha, exactly.

When digital can give me the tonality and sharpness of the attached image (second image is a detail), my interest will be piqued. Until then, it's a joke. Digital is fine for small prints and family snapshots, but you're not going to get a 40x50" print out of it.

Kevin Crisp
30-Sep-2010, 18:33
The think the 25 lp/mm argument is based on what paper can resolve.

Brian Stein
30-Sep-2010, 19:56
Film vs. digital:


On 4x5 I'm diffraction limited at 25lp/mm. .

At f64 yes pretty much (the old 1800/f stop routine). At larger apertures look at http://www.hevanet.com/cperez/testing.html.

Of course the other trick is not just to stop down to f64, but to use movements and a larger stop to get the best of both worlds. See http://www.largeformatphotography.info/fstop.html for examples. As discussed there John Sexton in one book used f64 ~5% of the time and f32 50% of the time. So in most of his pictures he was kicking in a 40-60 lpm resolution bracket.

And of course as previously been stated lpm is only one facet of many choices in making an image.

Ben Syverson
30-Sep-2010, 20:05
25 lp/mm is pretty good if you have enough mm.

Of course, I shoot at f/9-11, so I get a lot more than that.

Vaughn
30-Sep-2010, 20:14
I have a feeling that if I try to make a carbon print by contact printing a digital camera sensor, I won't get much of an image! LOL!

I enjoy using camera negative to make pt/pd prints and carbon prints. Problems of diffraction at f64 or f90 do not worry me. Never give it a second thought.

Edwin Beckenbach
30-Sep-2010, 21:00
Problem is that packing more and more pixels onto a sensor after a point only improves marketing brochures. It's hard to imagine APS-C ever performing up to 4x5 standards outside of special circumstances. Bigger pixels on bigger sensors is where it is at and Medium format digital, which basically performs on par with 4x5, is getting cheaper all the time but it still seems like it will be many years before its anywhere near affordable by any reasonable standard. The Pentax 645D is a big step in that direction. Look for a used one in five years.

rdenney
1-Oct-2010, 06:43
A Canon 5dII with a 24mm TSE II lens will make a very detailed image that will probably support a 16x24" color print at the capability of the printer and paper. That is pretty amazing from a 24x36 capture area, and it has tilt/shift capability (up to a point). Only the Live View makes it possible to adjust the focus plane really usefully for fine control of what is IN focus (other than for "artistic" effects of making things OUT of focus). And if you are going to use Live View, you are now on a tripod and spending real time on each image, so the convenience is lost.

Sure, we can stitch a million pictures made on a tiny sensor with an ultra-short lens that has huge depth of field so that we no longer have to focus. We could also hire a robot to make our pictures for us.

But the camera and lens together cost just shy of $5000. When people can enlarge those 5-micron sensor sites to the size of a pixel on their computer monitor, suddenly they see all the flaws in those lenses. Those flaws can be corrected, but only at a price.

And while digital cameras are depreciating, the lenses are not. I could routinely sell my 24mm TSE Mark I lens, that I paid $1100 for new two or three years ago, for $1000. And that lens is not a top performer like the Mark II. I could sell my 1987-vintage Canon 135mm soft-focus telephoto for $250-300, and it cost that new.

On the other hand, I replaced much of my large-format kit last year. I bought a Sinar F, an F2 front standard, a wide-angle bellows 2 (the camera came with the standard bag bellows and a standard pleated bellows), a 65mm f/5.6 Super Angulon, a 210 Sinaron (APO-Sironar-N), a 240mm Caltar Y, a 12" Ilex-Caltar, a Sinar Vario back, a Shen-Hao 6x12 back, a Maxwell screen, and a Sinar tilt-head. Nobody would complain about the quality of any of those purchases. I would have to add in all the lenses I already own (a 47mm SA, 90mm SA, 121mm SA, 180mm Symmar), plus tripods, spot meters, cases, focus cloths, film holders, and 10 years worth of film to add up to what that 5DII/24TSEII would cost.

And when you have scanned a 4x5" piece of film even on a lowly V750 flatbed scanner and printed it at 16x20, you will see what people are telling you. There is value in capture area. I get about 80 million useful pixels out of one of those scans.

Sure, there are ways to do it with digital camera with software. But that isn't the point of photography for most people, unless all they want is a documentary photo. And those purposes are what digital was made for.

Diffraction is less of an effect than being out of focus, and being out of focus is what most of any picture in the three-dimensional world is.

Rick "who worries about diffraction only when photographing test charts" Denney

jan labij
1-Oct-2010, 13:39
And it's not a boat, nor is it a ship---it's a brig! perhaps a hermaphrodite brig. But, that said, it's a nice picture--look great on a calender.

Mark Woods
1-Oct-2010, 18:09
I use older lenses with not CC coating stopped down to 64 all the time with my V8, and Chamonix 11x14. I like the look and the quality of the prints. I've been printing more and more 11x14 from both formats on Ilford MG IV FBW matte paper and love it. If you want digital on steroids, look at the Better Light equipment. The price is on steroids too. ;-)

Policar
1-Oct-2010, 21:21
Mark, so cool that you're a cinematographer! I am...an aspiring one. Shot a few really bad features and am now thinking of moving to LA, joining a grip union, trying to work my way up to better material. I have a friend who just graduated from AFI, awesome program, but I can't afford graduate school (plus I'm so good I don't need it, debatably...). My hero, Robert Richardson, went there, too! It's interesting that so many cinematographers shoot large format. It was my light meter (758 cine, guilty smile) that drew me away from dSLRs in the first place.

I have no money so it's going to be 4x5 all the way for me. Just need a better camera at the moment as my current one has a broken front standard. What does interest me is the idea that at a given FOV and DOF you're diffraction limited no matter the medium: large format film, medium format digital, even image stitching (unless you also stitch focus). It seems that at current pixel densities, medium format digital cameras are reaching diffraction limits for deep focus photography, and so the image quality larger formats offer is much less significant if that's the case... But then how do you do lens movements on a 645 digital camera? The sensor is way too small to focus by eye and tilt/shift lenses are limited.

I just wonder if this means large format film is here to stay (I can tell medium format film isn't by how quickly my lenses are losing value) or that image stitching is the inevitable future? As for 11x14, well, I can tell already it's not for me--but I'd like to at least try it some time.

Ben Syverson
1-Oct-2010, 21:41
Dude, if what you want is the infinite DOF look, and you have "no money," stitching is the way to go. Don't mess around with LF. You can make HDR multi-gigapixel images with a point and shoot that absolutely annihilate 4x5. Even if you just stitch a handful of DSLR shots, you'll beat the $40,000 MF digital stuff. (How big are you printing, anyway?)

Of course, stitching makes it a lot harder to shoot a scene with moving clouds, cars, water, or people.

If you're more interested in researching diffraction mathematics, you can read all about airy disks and such. "Airy disk" is one of those phrases like "circle of confusion" that is typically used by someone who is avoiding taking a photograph.

Dan Fromm
2-Oct-2010, 10:54
This discussion takes me back to the early 1970s, when H&W Company repackaged Agfa microfilm and sold it as H&W Control Film. They also offered a wonder-working developer that oxidized into uselessness within a few seconds after the bottle was opened. Very sharp but slightly unforgiving film.

The Leicanuts of the day were very pleased with it, asserted that with the wonder film and wonder developer they could make negatives that printed as large as the best possible from 4x5. And then they pissed the advantage, if real, away by shooting handheld, at too small apertures, at too large apertures, ...

Now comes young trolli, fresh from eating a herd of goats, to lecture us about the wonders of digital. What has changed since the early 1970s except the replacement of Agfa microfilm by silicon? The story's the same, advantage, if any, with perfect technique lost to imperfect technique.

Sirius Glass
2-Oct-2010, 12:17
I have no money so it's going to be 4x5 all the way for me.

If you have no money why are you screwing with digital.


It seems that at current pixel densities, medium format digital cameras are reaching diffraction limits for deep focus photography, and so the image quality larger formats offer is much less significant if that's the case... But then how do you do lens movements on a 645 digital camera? The sensor is way too small to focus by eye and tilt/shift lenses are limited.

But a REAL medium format camera [Read: Hasselblad] shooting film does not have these problems. If you want shift-tilt-swing look at Hasselblad's Flexbody and Arcbody.

Steve

John Whitley
2-Oct-2010, 13:25
We could also hire a robot to make our pictures for us.

Ask and ye shall receive: http://www.gigapansystems.com/ <cough> <cough>

I recall a Gigapan pano of President Obama's inauguration receiving some reasonable buzz on the 'net. I also recall thinking that an 8x10 (or 4x10) wide angle shot would likely have been better. At least it wouldn't have had mysterious disembodied legs and such... :p

Mark Woods
2-Oct-2010, 14:25
Hello Policar,

We think the AFI Cinematography program is pretty good. Our Cinematography Fellows work every week and we do more production that any school in the world to the tune of about $700K/year. Our alumni speak to our excellence. Was your friend in the Cinematography Discipline in the last 5 years? If so, s/he was in my class.

Thank you for your kind comments.

Policar
2-Oct-2010, 14:59
Hello Policar,

We think the AFI Cinematography program is pretty good. Our Cinematography Fellows work every week and we do more production that any school in the world to the tune of about $700K/year. Our alumni speak to our excellence. Was your friend in the Cinematography Discipline in the last 5 years? If so, s/he was in my class.

Thank you for your kind comments.

Yes, she graduated a couple years ago. I hear she loved the program but haven't heard from her since we competed for a gig...

I hate to be this guy, but would you be willing to look at my reel? It's two minutes long and I need some guidance. I've been considering grad schools, AFI included, but I don't know if I have the money to attend or the background to get in.

No hard feelings if you don't have the time. It's kind of a jerk move for me to ask but I'm on an opportunism kick lately having just lost a feature I was supposed to shoot this month (hence so much time wasted online...).

Mark Woods
2-Oct-2010, 15:59
Sure. Point me to the website or send a DVD. If you're considering Grad School and majoring in Cinematography, there's AFI, then all the rest. We joke about USC and UCLA may have the football teams, but we shoot their thesis films. If she graduated in the past 2-3 years, she went through my class. Do you mind if I ask who she is?

Mark

Steve M Hostetter
2-Oct-2010, 16:27
Ask and ye shall receive: http://www.gigapansystems.com/ <cough> <cough>

I recall a Gigapan pano of President Obama's inauguration receiving some reasonable buzz on the 'net. I also recall thinking that an 8x10 (or 4x10) wide angle shot would likely have been better. At least it wouldn't have had mysterious disembodied legs and such... :p

can I mount my 11x14 to that rig :D

engl
3-Oct-2010, 05:17
I believe you are right, if you need to stop down to F45-F64, there is no resolution advantage for 4x5 as compared to digital. The difference is that you can use camera movements to control the plane of focus, enabling you to shoot at bigger apertures, resulting in higher resolution.

This calculator at the bottom of this page is interesting for finding diffraction limited resolution, for a given sensor size and aperture, it will give you the number of megapixels needed to resolve detail up to the diffraction limit.
http://www.tawbaware.com/maxlyons/calc.htm
For 4x5 (127mm x 102mm), 16.5 megapixels is the diffraction limited resolution at F45. At F64, it is down to 8 megapixels.

Some here will tell you that resolution does not matter. It may not matter to them, but it is the main reason why I bother carrying around a 3.5kg camera :)

Policar
3-Oct-2010, 13:27
I believe you are right, if you need to stop down to F45-F64, there is no resolution advantage for 4x5 as compared to digital. The difference is that you can use camera movements to control the plane of focus, enabling you to shoot at bigger apertures, resulting in higher resolution.

This calculator at the bottom of this page is interesting for finding diffraction limited resolution, for a given sensor size and aperture, it will give you the number of megapixels needed to resolve detail up to the diffraction limit.
http://www.tawbaware.com/maxlyons/calc.htm
For 4x5 (127mm x 102mm), 16.5 megapixels is the diffraction limited resolution at F45. At F64, it is down to 8 megapixels.

Some here will tell you that resolution does not matter. It may not matter to them, but it is the main reason why I bother carrying around a 3.5kg camera :)

That's very interesting...seems like you lose 94% of your resolution between f11 and f45 (normal working stops for modern lenses on 4x5). Of course, the psychological impact of deep focus trumps sharper in focus areas in, but someone mentioned John Sexton shot most of his work at f32 or deeper. At that resolution, a 5DII with tilt/shift lenses would theoretically be as sharp, but of course digital black and white looks...much worse.

Maybe this is a good thing for sheet film's resilience to digital... A digital 4x5 sensor would be like a hundred thousand dollars and way too many megapixels to be useful if most of the time you're limited to fewer than 80 by optics. But it's too hard to do lens movements accurately on a 645 sensor so that's no replacement either. The professionals I know who shoot medium format have all switched to dSLRs but sheet film seems to have a unique workflow that separates it from other media beyond its impressive resolution...

I've also seen wall-sized enlargements from f45 negatives that look better to me than they should, so clearly diffraction is just one part of the equation.

Armin Seeholzer
3-Oct-2010, 15:21
I once was shoked because I used f 64 on my 8x10 and when I looked at the slide with a 8x loup it was just tak sharp, it was with my APO Ronar 360mm.
Since then I do not think much anymore about diffraction;--)))

Cheers Armin

Ben Syverson
3-Oct-2010, 15:54
Armin, how dare you contradict a random webpage calculator! :)

Steve Hamley
4-Oct-2010, 05:00
Needed depth of field trumps diffraction every time.

Cheers, Steve

Bob McCarthy
4-Oct-2010, 06:27
To understand it in the real world,

Work backwards from the eyeball. A healthy, young, well focussed eye can only resolve 5 lpmm up close.

So for contact prints examined up close, all you need is a "poor" quality lens for the most part.

For a 16X20 from an 8x10 (2X) you need a lens resolving 10 lpmm assuming you want to pixel peep. At normal viewing distances, half of that will do.

for a 16 x 20 from 4x5 (4X), 20 lpmm will do the job for those who have to put the tip of their nose on the print. A lens resolving 10 lpmm even looks OK at normal viewing distances.

Even below average large format lenses can do this with ease. Good lenses can go huge.



Now concider a full frame digital (24x36mm)

16x20 is a 16X enlargement (assuming you use every bit of the image and don't crop) so for an image that is capable of close inspection, we need at least 80 lpmm.

I used my Nikon digitals at f5.6, never more open than f8 to get this sort of resolution and DOF was often compromised.

Crop camera requires something like 25 to 30 X enlargement to make a 16x20.

F11 or higher, forget-about-it.



The one thing that saves our bacon is we don't put our nose on large prints, we stand off and the requirements go down.

However, digital shooters have a tendency to pixel peep and why I do not know.

A reformed digitalogapher (per Gen Singer) and long term filmie (as opposed to foodie).

bob

Ivan J. Eberle
4-Oct-2010, 06:37
f/64 is an 8x10 term.

Apples to oranges when comparing diffraction at f/64 effects on 8x10 sheet film (or larger) contact printed to 4x5, which with few exceptions tends to get enlarged rather than contacted.

Few today seriously using 4x5 will shoot at f/64, for much besides magazine page-size repro of food and other such product photography with a smallish final use. (In such commercial photography today film is typically supplanted by digital. Deep focus effect can be emulated by stacking multiple images with varying focal distances.)

Ed Richards
4-Oct-2010, 06:39
Bob has the right analysis of this problem. To get the maximum out of that digital sensor requires very good lenses, flawless technique, and not stopping down below f8. Those do not combine very well on many of the subjects we shoot.

Policar - I do not see any difference between digital black and white and film, as long as the digital image is properly exposed, is a suitable image for black and white, and is printed at a size appropriate to the sensor size:

http://www.epr-art.com/galleries/c1a-des-amis/photos/_DSC4241a.jpg

Mark Woods
4-Oct-2010, 11:32
Fun shot Ed.

Steve M Hostetter
4-Oct-2010, 11:46
I've got an idea..!! get you a digital camera and go shoot 1250 shots of the same subject so you can decide that you don't like any of them..???:D