Large Format Photography to Grand Format Printing

Hi All, I'm glad i found this forum, looks like just the job.
We are a company that print digital Wallpaper Canvas Rollerblind or (Window Shades) and now Flooring. We have a world wide Patent Pending on a new vinyl cushion floor product. Basically my question is, if i can print a wall from a digital camera of about 12 million Megapixle, what quality am i going to get from scanning from a 4 x 5 negative? I need to shoot a series of images to use as flooring, like Grass, Sand, Water, Cobbles, snow, Etc. I'm guessing that the quality of large format photography is second to non, so is this the route i should be looking at or should i stick to digital and maybe get the images shot on a 50 + million megapixle camera?

I forgot to say, "the printer that we are printing the floor on is 5 Meters Wide, but we can tile the width with an artwork overlap, so the images could be blown up to any size".

Kind Regards
Kristian

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Originally Posted by Print2

Hi All, I'm glad i found this forum, looks like just the job.
We are a company that print digital Wallpaper Canvas Rollerblind or (Window Shades) and now Flooring. We have a world wide Patent Pending on a new vinyl cushion floor product. Basically my question is, if i can print a wall from a digital camera of about 12 million Megapixle, what quality am i going to get from scanning from a 4 x 5 negative? I need to shoot a series of images to use as flooring, like Grass, Sand, Water, Cobbles, snow, Etc. I'm guessing that the quality of large format photography is second to non, so is this the route i should be looking at or should i stick to digital and maybe get the images shot on a 50 + million megapixle camera?

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Well, a 4x5 transparency can be scanned to produce the equivalent of a 250 Megapixel image. :D

Cheers for that info.

If you are going to shoot 4x5 or larger yourself, you should be aware that while the "potential" for 250 megapixel resolution is there, to achieve the ultimate in resolution requires good camera technique. Shooting with Large Format is not nearly as easy as shooting a Digital SLR. You will have to practice and practice to get best results.

Hi, Thanks for the tip, I was going to commission the job to a Professional LF Photographer. I fully understand its not as easy as "pick up" or "mount the camera in this case" and shoot. The idea is to get the perfect viewing distances also. We view grass from and average of 5 feet so for the image to look realistic we will have to do a good few test prints to get this one spot on. Thanks so much for your advice.

There's more to this than just the size of the sensor/film, and the degree of enlargement.

The perception of "quality" will also be higher or lower, depending on favorable lighting, skillful placement of the camera, and ideal arrangement of the subject.

But while we're on the subject, an image made on an 8x10 camera will have 4 times the number of megapixels of a 4x5 image. They call it... Large Format.

Hi Ken, I was reading some of your other posts and replies earlier.

8 x 10 is something i have been looking at. Basically the floor gallery will start with ideas like grass etc, but when the designers get there head around the fact that there's no end to the idea that you could put onto a floor like coffee beans, sweets etc I think the hi res gallery could grow into something quite nice and different. Do you have any more info on 8 x 10?

The perception of "quality" will also be higher or lower, depending on favorable lighting, skillful placement of the camera, and ideal arrangement of the subject. I fully get this and understand that this has to be a job for a LF pro.

Thanks Again.

If your business can afford it, you might consider a digital back for a 4x5 camera. Go to betterlight.com, where they offer backs into the hundreds of megapixels. It would probably merge into your workflow nicely and be useful for other applications as well.

Thanks Mark, That looks like a good idea, i don't think i have the flair or knowledge to pull this one off. I think no matter how much i would love to set this up in my current place of work i also don't want to get it wrong, all the ideas i have in my head i can direct but not shoot. I will take a look at the digital backs though, it will give me a good idea of what I'm talking about when we come to shoot all this.

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Originally Posted by Print2

I will take a look at the digital backs though, it will give me a good idea of what I'm talking about when we come to shoot all this.

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Forget LF digital backs; they are horrendously expensive compared with an LF camera and a scanner. Kristian, did you get either of my PMs to you? If so give me a call; I can pop over as soon as is convenient.

I wonder whether it would be profitable to offer customers the option of sending in (via a digital file,) their own artwork to be printed?

Mike

Hi Mark, That is a very good question. The gallery that we are putting together is just a taster for designers and photographers. The real funky ideas will come from people like yourself that start thinking about the concept. There is no end to this concept apart from file size, so if it can be shot L F and the lighting and focusing is spot on you can do what you like. To answer your question yes people can use their own image and yes it will be profitable.

I think you will get the best possible quality using a digital scanning back. As you are not intending to do the photography yourself I would suggest contacting a Betterlight owner here in the UK. Richard Kenward at Artisan Digital (http://www.artisan-digital-services.co.uk) is very knowledgeable and has the right equipment, I'd give him a ring if I were you.

David Whistance

The lab where my wife works does something of this sort. They have capability to do large graphics (the sort you see on public transportation buses and the like) and can print on fabric, so she had a drapery made of one of her MF images of trees. The target resolution isn't quite as high as you might have in a print but it turned out really well. Negs are scanned on either the Sigma or drum scanner.

Hi , Yep same idea really, we concentrate on interior design products only. Because the flooring spaces can be so big is why I started looking at L F Photography. If you scan a 8 x 10 what file size could I expect?

If you're hung up on high resolution final images then you can scan using something like an Aztek and end up with perhaps 4 Gb files, or larger, from 8X10. BUT the necessity for such a large file would be contingent on the intrinsic quality (resolution) that was captured on 8X10 film. This sounds like a project that requires a fairly thorough plan from image capture through transfer to your product. I'd recommend a close coupling between the photographer and the digital scanner, at least. I assume your equipment can utilize digital data directly in some conventional format.

Nate Potter, Austin TX.

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Originally Posted by Print2

Hi , Yep same idea really, we concentrate on interior design products only. Because the flooring spaces can be so big is why I started looking at L F Photography. If you scan a 8 x 10 what file size could I expect?

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With an Aztek Premier, you could get a file as large as 24 Gigabytes. That would be 80,000 pixels wide, or 5,120 megapixels. You could make a full resolution print at 360 dpi at 222 inches, or 18.5 feet. You would want some good computing power to manage this. However, its doable. I've done it before...

Lenny

I would try a few samples before getting to hung up on size, super large files might prove to slow for the workflow needed to do this profitably. The material you are printing on will have a big effect on resolution you see, as will how the scans are made. You might find the 12mp camera is the practical and commercially sound solution even if not the ultimate quality. If you get busy, shooting 10x8, scanning and printing large files might be a bit of a choker. LF is great providing your equipment can handle that size of quality without grinding to a holt, if it can't smaller will be as good.

Kevin

Hi Lenny, Thanks for the info.

Hi Kevin, Take your point also, large files will slow workflow, I’m thinking that we may be able to do this 4 x 5. But thanks so much for taking your time out for all this information. Thanks everyone for all your replies up to now, please keep it coming as all points have been valid.

The reference to grass, coffee beans, etc. leads me to think that images may be tiled in the final output, so not necessarily a need to scan to produce a resolution capable of output of several feet across. Rather, produce an image and alter it such that when joined with itself is seamless. Then a final image of any size may be produce continuously.

Sounds like a great idea-

a small point-
will you expect to be paying for the use of images,
and on what basis might that be calculated?

The whole industry has been hit badly by the explosion of interest in photography,
and people will often accept the flattery of being selected for publication as payment in full-

Obviously, as a business, you'll be interested in minimizing costs, and maximizing profits, and a photography is often viewed as a costless item...

Apologies for rearing the ugly head of commercialism-

j

Hi Jim, Thanks for your info, you are correct in what you say about taking the image and then join the image with itself. The problem with doing this with smaller images or tiles is when you tile, mirror, flip, seam it, call it what you want, if the image is too small, although seamless you will spot the patterns repeating in some kind of way. It will look more natural if we can start with a larger file/image and then start to tile images together.

Hi Joseph, We will be paying for images, as of yet we have not worked out license agreements or deals for images, we will be putting agreements together over the next week or so. I fully understand your comments about the explosion of interest in photography, but I think the proof will be in the images, I can’t and people or some photographers can’t make images, dance, jump, sing, when shot. True pro’s can.

See the new site soon at www.print2group.com

I can't help but get the feeling that you may not need to print at some of the resolutions discussed-
a print on the floor is maybe six feet away, and while I can see some of the members here dropping to their knees and fumbling for their loupe, for the most part, something like 72dpi might be sufficient for your market-

Also, printing at that resolution might mean that tiling might never have to be an option-

I've done prints up to 6 x 2.4m- wallcoverings in an office environment- and the big picture is probably more important than the finer details-

In my opinion, of course- but also those of the client-

j

Hi Joseph, You are correct in what you say. In some cases just for work flow images are turned down to 72 Dpi, and will be in the future. I need the option to offer the client if need be, because there will be times when a client starts to talk about clarity. So my idea was to start with the large file and then have the option to turn it up and down. Thanks for your input on this one.

If you ever need a wallpaper printer in the future let me know. I can offer you some great rates and some fantastic textures.

Regards
Kristian

Thanks Kristian-

Just before Christmas, I was quite interested in printing directly onto glass-
but it proved to be too problematic, involving transfers-
Perhaps some research material for another patent for you?

Unfortunately, I don't have the throughput at that sort of size-
only 3 big ones last year-
and with the media talking down the economy, (cart? horse?)
they might be the last ones for a while...

j

As mentioned previously, before you get too caught up in file size, you should instead pursue the IQ you desire...

There is some posters on this list that will mistakenly advise you 4x5 scanned film contains 200 - 320 MP of data.... the realists are in the 30 - 50 MP range, which supports basic imaging fundamentals. It's not unusual on these forums for numbers to be off by a factor of 10x. You may want to glance at this current thread if your interested in a better understanding of the "recorded Mega Pixels" subject...

http://www.largeformatphotography.in...ad.php?t=44797

As for how to capture the images that end up on your Grand printer...... the first question I would ask is..... are the subjects static? If they are, you can simplify your life by using relatively low cost DSLR's and a decent rotating head... take MANY shots, then allow the power of PHotoshop to merge the montage into a seamless image. There is no way you can improve the IQ, and there is NO way you can get file sizes this small. You will have benefited greatly from digital technology.

The other question as mentioned previously, what view distance for each wall / floor. This determines how much resolution the shot should contain. Then from there, if you really want to push it further, you can back track, at that distance, what the eye can resolve, and then offer any level of detail from 10% to 100%. Its not as complex as it sounds. A simple formula will answer the question for each application. Based on this, you will properly assess the capture method required for each application.

If the subjects you want to capture are NOT static, than you are in a different league.... more complex, more expensive, lots of gear, etc. etc.

Hope this helps you with your initial orientation ...

bglick,

I was just thinking of you when reading this thread...

As from your previous pos, the maximum resolution a lens theoretically can resolve in lines per mm (lpmm) by averaging wavelengths is 1500/f-number. So, for common f-stops, the diffraction limits to resolution are:

f/stop : max lens resolution : max lens/film resolution

• f/2.8: 536 lpmm : 80 lpmm
• f/3.5: 429 lpmm
• f/4.0: 375 lpmm : 90 lpmm
• f/4.5: 333 lpmm
• f/5.6: 268 lpmm : 95 lpmm
• f/6.5: 231 lpmm
• f/7.7: 195 lpmm
• f/8: 188 lpmm : 100 lpmm
• f/9: 167 lpmm
• f/11: 136 lpmm : 95 lpmm
• f/16: 94 lpmm : 80 lpmm
• f/22: 68 lpmm : 70 lpmm (should be 68 lpmm)
• f/32: 47 lpmm
• f/64: 23 lpmm

Those are theoretical maximums, but no LF lens performs at 429 lp/mm at f/3.5. Also, Chris Perez quotes from his website the maximum film/lens combined resolutions at various f-stops. Bryan Guyer says that maximum film-resolution increases as f-stops are increased:

>"However, film resolution has also been shown to vary appreciably with
>aperture, and resolving power is always highest when the light source
>area is minimized, to retard dispersion. This presents a troubled
>dichotomy: Best lens resolution is achieved when shooting wide open, but
>best film resolution is at ~ f22 (or smaller)!"

I'm not sure I understand that, but he does quote the maximum lens/film combination as being 100 lpmm at f/8 (I quote these film/lens combination max's above).

Best Lenses Wide Open

Some of best lenses wide open, like the Xenotar 135/3.5 or 150/2.8 have been measured to get 20-30 lp/mm wide open at f/3.5 (I don't know about the Carl Zeiss ones); they've been measured at 60-70 lp/mm at f/8. Both of these are at center; outside of center, resolution drops to 10 wide open and 30 at f/8 for both lenses. The Kodak Ektar 203/7.7 has been measured at 67 lpmm average from 0-20 degrees from the axis, and 78 lpmm average from 0-10 degrees from the axis (calculated from the table at the bottom of this page).

Wide open, and even at f/8, these lenses would most likely be doing portraiture work, where relative center is the most important. So, assuming human eyesight of 5 lpmm, maximum enlargements from 4x5 are as follows (for apertures f/11 and below, I assume it is used for portraiture or other isolation work, and that the middle part of the image is most important, thus discard edge-resolution; for the Xenotar 135/3.5 and Kodak 203/7.7, I assume full-use of the film from center to edge after f/11).

• Schneider Xenotar 135/3.5 (~$400 - $800)
  
  • @ f/3.5: 20 lpmm / 5 lpmm = 4x (20" x 16" portraits) [5 megapixels]
  • @ f/8.0: 60 lpmm / 5 lpmm = 12x (60" x 48" portraits) [46 megapixels]
  • @ f/11: 40 lpmm / 5 lpmm = 8x (40" x 32" portraits) [20 megapixels]
  • @ f/16: 58 lpmm / 5 lpmm = 11.6x (58" x 46.4" portraits or landscapes) [43 megapixels]
  • @ f/22: 54 lpmm / 5 lpmm = 10.8x (54" x 43.2" portraits or landscapes) [38 megapixels]
  
  
• Schneider Xenotar 150/2.8 (~$1500)
  
  • @ f/2.8: 30 lpmm / 5 lpmm = 6x (30" x 24" portraits) [11 megapixels]
  • @ f/8.0: 70 lpmm / 5 lpmm = 14x (70" x 56" portraits) [63 megapixels]
• Kodak Ektar 203/7.7 (< $150)
  
  • @ f/7.7: 78 lpmm / 5 lpmm = 15.7x (78" x 63" portraits) [78 megapixel print]
  • @ f/11: 75 lpmm / 5 lpmm = 14.9x (75" x 60" portraits)* [72 megapixels]
  • @ f/16: 67 lpmm / 5 lpmm = 13.5x (67" x 54" portraits or landscapes) [58 megapixels]
  • @ f/22: 57 lpmm / 5 lpmm = 11.5x (57" x 46" portraits or landscapes) [42 megapixels]

It seems like the Ektar 203/7.7 would be an excellent portrait lens if you can compose with f/7.7, and if that doesn't provide too much dof. Also an excellent "normal" lens. Likewise, the Xenotar 135/3.5 and 150/2.8 seems excellent for portraiture and landscape.

* Measured aerial resolution for the Kodak Ektar 207/7.7 at f/11 was 103 averaged from 0 to 10 degrees from axis, as done by Larry and Linda Whatley; but 64 lpmm as done by Chris Perez (ctr + mdl).

I have heard, but not seen any test results, some people say that the Kodak Aero-Ektar f/2.5 resolves hundreds of lp/mm wide open; but this is apparently at infinity focus, whereas at portraiture focus, it is much much softer (it didn't measure as sharp as the Xenotars). Maybe a good lens for astrophotography? (if you can tolerate the color).

Nikon Nikkor-SW 90/4.5 or 90/8

I assume these lenses effectively have the same optical performance (but data is from the 90/8):

• @ f/11: 80 lpmm / 5 lpmm = 16x (80" x 64" portraits) [83 megapixels]
• @ f/11: 73 lpmm / 5 lpmm = 14.6x (73" x 19" portraits or landscapes) [69 megapixels]
• @ f/16: 65 lpmm / 5 lpmm = 13x (65" x 52" portraits or landscapes) [55 megapixels]
• @ f/22: 56 lpmm / 5 lpmm = 11.2x (56" x 45" portraits or landscapes) [40 megapixels]

Maybe a good environmental portraiture lens, but of course it's designed with landscape photography in mind, for which it is perfect.

Diffraction Limits at f/32 and f/64

Assuming all of the above lenses are diffraction limited at f/32 and f/64 (this is reasonable as the Kodak Ektar 203/7.7 pulls in 46 lpmm at f/32, just under the 47 lpmm diffraction limit), the maximum print size will be:

• @ f/32: 47 lpmm / 5 lpmm = 9.4x (47" x 38" portraits or landscapes) [29 megapixels]
• @ f/64: 23 lpmm / 5 lpmm = 4.7x (23" x 19" portraits or landscapes) [7 megapixels]

By contrast, a Phase One P45 39-megapixel P45 back is 7216 x 5412 pixels. That corresponds to a 57" x 43" print at 5 lpmm. Of course, this is a favourable estimate, as it assumes any lens on the P45, no matter the f-stop, will actually resolve the full 39 megapixels. But the above estimates of maximum print sizes for LF were also favourable, as they didn't account for the film part of the 1/R equation.

But yea, all of that kind of pretty much confirms what you said. The equivalent megapixels of a 4x5 range from 5 to 83 megapixels. If the numbers for the fast Xenotars wide open are representative of most Xenotar 135/3.5 and 150/2.8 samples, then if you need to shoot portraiture in low-light situations and can't have longer exposures, then you're probably better off with a DSLR (like my E3 + 58/1.2)...unless you want that uber uber narrow DOF (58/1.2 on an Oly E3 is very narrow dof...135/3.5 on LF is equivalent to 18/0.47 on Olympus 4/3rds, or 36/0.93 on 35mm in dof).

If you're doing portraiture where you can stop down a little bit, to f/7.7 (and compose there for the Kodak Ektar), f/8, or f/11, then large-format will deliver absolutely stunning resolution (if you really want that much detail) that will be superior to the best MF backs.

Landscapes where you can get everything you want in focus via tilts at f/11 or f/16 will be superb; more likely is f/22 which will also be great; if, due to the 3-dimensionality of your picture, you need f/32 even with tilts, then large-format will be equivalent to 29 megapixels. If you need to stop down to f/64, you might as well use a DSLR; enormous hit.

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Originally Posted by bglick

As mentioned previously, before you get too caught up in file size, you should instead pursue the IQ you desire...

There is some posters on this list that will mistakenly advise you 4x5 scanned film contains 200 - 320 MP of data.... the realists are in the 30 - 50 MP range, which supports basic imaging fundamentals. It's not unusual on these forums for numbers to be off by a factor of 10x. You may want to glance at this current thread if your interested in a better understanding of the "recorded Mega Pixels" subject...

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bglick,

Given that the maximum resolution one gets from 4x5 under optimal conditions is 80 megapixels (maybe 150 with black-and-white), how deep do you think one should scan the film? I.e., to get the full resolution out of it, how much does one have to over-scan it?

> but no LF lens performs at 429 lp/mm at f/3.5.


Absolutely correct.... and if you notice, I tend to only use the apertures the LF lenses are optimized for, at those apertures, lenses are much closer to diffraction limited. For LF lenses, the reason you see f3.5 - f5.6 is strictly for bright viewing of the GG, NOT for usage. The ground glass resolution is so low, that even the worst aberated lens will produce a nice clean bright image on the gg. As you stop down on LF lenses, specially after f22, the resolution threshold for the lens to meet becomes much less, hence why they become diffraction limited much easier vs. at wider apt. lenses.... that doesn't make them deliver more aerial resolution than lower f stops, but it delivers a higher % of max. diffraction limited value.


In some cases though, the lens is only optimized in a very tight f stop range....this is why its valuable to read the MTF curves for a lens, as it gives you an idea of where its sweet spots are at.... then, you can more accurately predict the recorded resolution. If you have no MTF curves, a simple film test will advise you.... Anyway, as you can see, this is where you have to apply a little common sense to the math.


But lets not forget the obvious, these issues only degrade the MP's issues you provided above, not improve them... driving the "real" MP's even lower than calculated values, hence why I always "max. possible". In all fairness, most modern LF lenses will reach their diffraction lmtd values, as well as MF lenses, specially Mamiya 7 lenses.



> Bryan Guyer says that maximum film-resolution increases as f-stops are increased:


ONLY if the lens is highly aberrated at the lower f stops, which is sometimes the case, specially in LF. But many people confuse this with some type of phenomena....instead, the lens was NEVER designed to be used at those lower f stops, they are highly aberrated and only exist for ground glass viewing. This is not the case with Digitar or very high end 35mm lenses....


> Best lens resolution is achieved when shooting wide open....


this is not always true....its a result of people getting carried away with 1500 / fstop. This can be tested quite easily by placing a ~ 3mm focal length astronomy eyepiece behind a lens, and view targets, you can easily see the aerial resolution of the lens.... when on film resolution is lower at wider f stops, its due to the aerial resolution being less, due to a highly aberrated aerial resolution at those wide apertures. This varies greatly with the lens type and format size....


Also, keep in mind, I think the lens tests you refer to are from Perez's site? If so, these are for B&W film, NOT color film....you are aware of that? I trust Chris's work, he has been testing lenses for years. But if you re run the numbers for color film, you will not see this level of recorded resolution. I did not check check your math on your examples, but it seems you have the hang of this. If you shoot color, you may want to reverse engineer the calculations for color film, 50 - 60 lp/mm.... I am glad someone has embraced these fundamentals !


Your are correct though, many lenses are optimized quite well for one focus distance and one f stop. This is where a vintage lens can still perform well. It was always easier to design a lens to perform ONE task very well.... the complexity of lens design comes into play when the designer wants a lens to do many tasks, and expect great performance in all areas, i.e. different f stops, different focus distances, varying fl's for zooms, etc. This is why you see some 35mm lenses with 15 - 20 elements these days, often with a few aspherical elements as well.... LF lenses are much more limited in their application, hence why you need so many of them :-(



>* Measured aerial resolution for the Kodak Ektar 207/7.7 at f/11 was 103 averaged from 0 to 10 degrees from axis, as done by Larry and Linda Whatley; but 64 lpmm as done by Chris Perez (ctr + mdl).


At f11 103 lp/mm is close to diffraction limited for the aerial resolution.... are you referring to Perez test results of 64 lp/mm on film, or aerial rez? I think Perez only shows on film resolutions, right? If so, 64 lp/mm to film, using 120 lp/mm MTF for the film, and the numbers work out perfect again... i.e. 1/R = 64 lp/mm....



> By contrast, a Phase One P45 39-megapixel P45 back is 7216 x 5412 pixels. That corresponds to a 57" x 43" print at 5 lpmm. Of course, this is a favourable estimate, as it assumes any lens on the P45, no matter the f-stop, will actually resolve the full 39 megapixels


NO! Not sure if you were writing this, or quoting someone else..... see my other posts on 1/R.... at best, you can resolve about 1/2 the native pixel count.... Digital capture is NOT immune to 1/R. The other thread has this in more detail, I can't keep re-writing this stuff....



> The equivalent megapixels of a 4x5 range from 5 to 83 megapixels.

Just keep in mind, you have color neg. on the low side, and high resolving Tmax B&W on the other side of the equation.... then you have GREAT lenses at low f stops, such as the SSXL's, 110, 150mm, and you have vintage lenses that were never even designed to be used for enlargements....they imaged directly onto paper inserted in the camera, before the days of film. This is why the numbers can be all over the map with LF, but its a simple formula, just build a model and its all quite predictable. But knowing a bit about the lens is critical, as many of your examples are for vintage lenses.... often with NO MTF data, so testing is your only means of trying to back track the lenses performance characteristics....


> If you need to stop down to f/64, you might as well use a DSLR; enormous hit.


You are really getting the hang of this..... Kudos.... One tip I mentioned previously.... lens tilt "can" be a miracle focal cure....but only when very little tilt is used.... as the MTF of a lens is based on parallel subject plane and image plane. When you tilt the lens, the two planes are no longer parallel.... now, the lenses aberations increase greatly... the more you tilt, the worse it becomes. As a general rule, if you can keep tilt under 8 degrees, and save 2 f stops (or more) by tilting, you will surely improve IQ....



> Given that the maximum resolution one gets from 4x5 under optimal conditions is 80 megapixels (maybe 150 with black-and-white), how deep do you think one should scan the film? I.e., to get the full resolution out of it, how much does one have to over-scan it?


This is where the quality of the scanner comes into play. Because now you are re-imaging an existing image. Also, the answer is highly dependent on the spatial frequency recorded on the film. The lower the spatial frequency, the more efficient the scanner, remember, the scanner too is confronted with 1/R.... as the process of scanning also involves a subject plane, a lens, and an image plane.


I will try to answer your question with two extremes.... with very low spatial frequency on the film.... and a very good scanner (high end flat bed or a drum), you can probably scan at 1.2x the highest frequency on the film. At higher frequencies, maybe up to 1.5x....


lower end scanners, you can double these values.


This is the real value of high end scanners - smaller files to work with. This can all be easily tested, by shooting targets, and scanning the film targets, and seeing how deep you must scan to resolve what you know is recorded on the film.... which you can clearly see with a good loupe and bright light box. Be sure the loupe has sufficient magnification, so it does not become the limiting factor.... Often in the 20 - 80x range. Make sense?

I'm really learning a lot from trying to keep up with the discussions on this thread- and the other main one-
as they say in internet land, thanks for sharing...

Just hope Jim Galli is following it too-

j

Quote:

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Originally Posted by dh003i

Kodak Ektar 203/7.7 (< $150)

• @ f/7.7: 78 lpmm / 5 lpmm = 15.7x (78" x 63" portraits) [78 megapixel print]
• @ f/11: 75 lpmm / 5 lpmm = 14.9x (75" x 60" portraits)* [72 megapixels]

[/list]

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These numbers are not correct. I did not realize that the Kodak numbers I was quoting were aerial resolution numbers here. The actual results at f/11, as C. Perez tests for f/11, and 1/R calculations for f/7.7 are:

Kodak Ektar 203/7.7 (< $150)

• @ f/7.7: 47 lpmm / 5 lpmm = 9.5x (47" x 38" portraits) [29 megapixel print]
• @ f/11: 64 lpmm / 5 lpmm = 12.7x (64" x 51" portraits)* [53 megapixels]

For all cases, switching to color means that, in the worst case (actually the best case), resolution is cut in half. This happens when aerial resolution is very high, so that the change from going from b&w to color becomes

Rbw / Rcolor = (1/60 + 1/Ra) / (1/120 + 1/Ra) => (1/60) / (1/120) = 120/60 = 2, so black and white is, in the best case, 2x sharper than color (and in the best case, color is 0.5x as sharp as color). I say "in the best case", because if Ra was 0, then here would be no difference between color and black and white final images (you'd just have no resolution).

Modifying my prior results to represent color resolution, they are as follows

[LIST][*]Schneider Xenotar 135/3.5 (~$400 - $800)

• @ f/3.5: 20 lpmm / 5 lpmm = 4x (20" x 16" portraits) [5 megapixels] (tested on color film, so no change)
• @ f/8.0: 60 lpmm / 5 lpmm = 12x (60" x 48" portraits) [46 megapixels] (tested on color film, so no change)
• @ f/11: 30 lpmm / 5 lpmm = 6x (30" x 24" portraits) [12 megapixels]
• @ f/16: 39 lpmm / 5 lpmm = 7.8x (39" x 31" portraits or landscapes) [29 megapixels]
• @ f/22: 37 lpmm / 5 lpmm = 7.4x (37" x 30" portraits or landscapes) [18 megapixels]

And so-on and so-forth...the equation is Ra = 1/(1/Rbw - 1/Rfbw)...then the new Rcolor = (1/Ra + 1/Rfcolor).

> For all cases, switching to color means that, in the worst case (actually the best case), resolution is cut in half. This happens when aerial resolution is very high, so that the change from going from b&w to color becomes


Glad you made these corrections, I thought you were crossing aerial vs. recorded rez. And yes, this is correct above.... but as you suggest, at low aerial rez, the lens becomes the limiting factor. This is the basic premise behind 1/R, it will never allow you to exceed the weak link in the optical chain....


A few other other comments..... first, not all B&W films are ultra high resolution film.... typically the sharpest B&W films are used for target tests, as they are the easiest to view under a loupe. So don't over generalize B&W film, they run the gamut in resolution... most people shoot B&W don't shoot the highest resolving films, as they are after other features such as tonality, Drange, etc. Color film also runs gamut... for example from my experience, some c41 color neg. films have a bit more than half the MTF of Velvia (the king of high resolving color film) In general, color neg film is not as easy to determine MTF data as chrome film is..... long story behind this... but part of the problem is the scanning process.....scanners love chrome film. In the darkroom, an enlarger is not partial....


> @ f/8.0: 60 lpmm / 5 lpmm = 12x (60" x 48" portraits) [46 megapixels] (tested on color film, so no change)


What color film was this tested on? Seems a bit high to me? Its possible if the lens is diffraction limited and Velvia was used.... 1/R = 56 lp/mm, close enough, as this is subjective. I have no experience with this lens, but I would be amazed if it produced this level of detail.... specially at that cost..... if it was a single purpose lens, than its very possible.



> And so-on and so-forth...the equation is Ra = 1/(1/Rbw - 1/Rfbw)...then the new Rcolor = (1/Ra + 1/Rfcolor).


I am not following what you are suggesting here? Can you explain?

[QUOTE=bglick;431602]> For all cases, switching to color means that, in the worst case (actually the best case), resolution is cut in half. This happens when aerial resolution is very high, so that the change from going from b&w to color becomes

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Glad you made these corrections, I thought you were crossing aerial vs. recorded rez. And yes, this is correct above.... but as you suggest, at low aerial rez, the lens becomes the limiting factor. This is the basic premise behind 1/R, it will never allow you to exceed the weak link in the optical chain....

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This of course makes intuitive sense. It would easily be understood if we consider looking at the world through the eyes of a 120 year old person who can barely recognize her own children from 5 feet. It doesn't matter how much detail you throw at her eyes, she still won't see any higher than the resolution of her eyes. (not to pick on nearly blind 120 year olds)

Quote:

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A few other other comments..... first, not all B&W films are ultra high resolution film.... typically the sharpest B&W films are used for target tests, as they are the easiest to view under a loupe. So don't over generalize B&W film, they run the gamut in resolution... most people shoot B&W don't shoot the highest resolving films, as they are after other features such as tonality, Drange, etc. Color film also runs gamut... for example from my experience, some c41 color neg. films have a bit more than half the MTF of Velvia (the king of high resolving color film) In general, color neg film is not as easy to determine MTF data as chrome film is..... long story behind this... but part of the problem is the scanning process.....scanners love chrome film. In the darkroom, an enlarger is not partial....

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Yes, but those numbers are upper limits then. I was using the 120 lpmm figure you provided, and the 60 lpmm for color.

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> @ f/8.0: 60 lpmm / 5 lpmm = 12x (60" x 48" portraits) [46 megapixels] (tested on color film, so no change)

What color film was this tested on? Seems a bit high to me? Its possible if the lens is diffraction limited and Velvia was used.... 1/R = 56 lp/mm, close enough, as this is subjective. I have no experience with this lens, but I would be amazed if it produced this level of detail.... specially at that cost..... if it was a single purpose lens, than its very possible.

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Well, this lens is designed to be sharp wide open. The film was as follows

Testing was done using Charles Sleicher's resolution chart, with a Canham 4x5/5x7 wooden field camera, on expired Kodak Ektachrome E100SW or EPP transparency film, with indirect light in my cramped living room, and read using a 1950s American Optics Microscope at 100x. Exposures, metered at ASA 125, were usually: f/2.8@1/8 second, f/4@1/4 second, et cetera.

It appears he did use lines per mm, not line pairs per mm, so it isn't the case that the numbers are really half of what I said. (btw, the convention of saying "lpmm" is really awful, as is "mpg" (miles per galon; all standard science uses a "/", so it should be l/mm for lines per mm, or lp/mm for line pairs per mm).

Quote:

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> And so-on and so-forth...the equation is Ra = 1/(1/Rbw - 1/Rfbw)...then the new Rcolor = (1/Ra + 1/Rfcolor).

I am not following what you are suggesting here? Can you explain?

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I'm just backing out the aerial resolution of the lens from the resolution as measured on black-and-white film, and the assumed resolution of the black and white film of 120 l/mm. Then I use that aerial resolution to calculate what the measured resolution on color film should be, assuming a color film resolution of 60 l/mm.

> It doesn't matter how much detail you throw at her eyes, she still won't see any higher than the resolution of her eyes.


never thought of this analogy, but I gotcha :-)




> Yes, but those numbers are upper limits then. I was using the 120 lpmm figure you provided, and the 60 lpmm for color.


To be clear though, IIRC, you can find some B&W films that are as low as color film in MTF...so be careful generalizing.




> (btw, the convention of saying "lpmm" is really awful, as is "mpg" (miles per galon; all standard science uses a "/", so it should be l/mm for lines per mm, or lp/mm for line pairs per mm).


There is actually a reason for this.... before MTF became vogue, say early 70's, the optical world revolved around spot sizes or airy disc diameters....which equates to lines per mm.... then, MTF had uniform expression of spatial frequency - as line pairs per mm, (lp/mm) so through the years you can see any iteration of:

lp/mm (line pairs per mm),
lpmm (lines per mm),
lpmm (line pairs per mm, missing the "/")
l/mm (lines per mm)


Add in all the typos that often occur and the mis use of the unit of measure, and it's a mess reading through optical literature through the years, so beware of this....




> I'm just backing out the aerial resolution of the lens.....

Ok, understood....



Since this has become such an involved thread..... I will introduce a new caveat, so some are not too surprised when it surfaces. Through the years, lenses were designed / built with spherical elements only. Recently, aspherical elements are becoming more commonplace, as they add levels of correction not possible with spherical elements. In 4x5 / 8x10 lenses, I think there is only a handful of aspherical lenses, such as the Super Symars XL's and I think a few Rodenstocks.... not sure, I never read through all the literature...but aspherics are more common place now on 35mm.


With spherical lenses, the aerial resolution typically will be degraded as you stop down. The exception is, very FAST lenses, where wide open, the lenses are quite aberated - so the aerial rez over all the f stops forms a bell curve. This is generally true of all normal to wide lenses in 35mm.


However, some of the more recent aspherical zoom lenses I tested actually have a straight line resolution between f2.8 and f11. This defies what we are used to seeing....but it makes sense. The lens design uses the aspherical elements to level out the resolution over many f stops, vs. the common bell curve profile. Of course, apt. diffraction is never surpassed....it's the mid f stops paying a penalty for keeping the wide open apertures from being too aberrated - as shooting wide open is a great marketing point to sell lenses. We all want fast lenses. Using ashperics is almost mandatory when trying to design a single lens to have a 300% fl range, 7 stops of apt. and focus range from 2 ft to infinity. Gee, wouldn't that be nice in LF? :-) So with aspherics, you can see some puzzling aerial resolutions that don't follow the commonplace aerial rez profile.

Hi Guys, I’ve been away on business so I have not been keeping up to speed with this thread. I’m back now and all I can say is “WOW!” you guys have been busy talking about image size, files sizes, lenses, LF, Digital, viewing distances and the list goes on. Thanks for all your info. I’m days away from sorting out license agreements for LF photographers to make money of their images for the worlds fist Vinyl Cushion Floor.
Thanks for all your time taken out on this one, it has some great points. I think I may re-post it.