Lens resolution question

df cardwell · Aug 29, 2006

Sparky said:
Actually - the lenses on those puppies aren't THAT much to write home about resolution-wise. They just have a known (and specified) distortion. That's all you need to do metric work.

Yes, Linhof select Apo Symars are well-known dogs.

Still, a vacuum back, electronic relase, and rigid body do take care of a couple otherwise crippling problems.

Sparky · Aug 29, 2006

df cardwell said:
Yes, Linhof select Apo Symars are well-known dogs.

Still, a vacuum back, electronic relase, and rigid body do take care of a couple otherwise crippling problems.

ohhh... they are? Most of the Rollei ones are planars (I thought). Anyway - I'm just sayin' - they don't NEED to be high res to do metric work. There's no really compelling reason to have used those over another lens other than distortion measurement. I'm sure it's a great camera. I miss MY old apo-symmar (it was a rollei 150mm)...!

Dan Fromm · Aug 30, 2006

Sparky said:
Yeah, it's weird huh? How do you think they're getting the resolution? Maybe a betterlight back and they do separate aerial passes for each of R G and B...!

Short answer, $$$$$$$$$$.

And for many military applications, lower resolution images delivered much faster beat higher resolution images delivered with a considerable delay.

Claire Senft · Aug 30, 2006

I would suppose that any lens on an SR 71 Blackbird would qualify as being quite fast when the plane get up to speed.

Claire Senft · Aug 30, 2006

I am just curious. If the client wishes this type of detail to be present, just how big of a print is being planned?

Is the client asking for detail to fine to be visible?

m_liddell · Aug 30, 2006

Dan Fromm said:
Um, er, ah, before we go overboard patting each other and film on the back, be aware that digital image capture has pretty well displaced film for military aerial photography. At least in the first world, i.e., NATO. Why do you think so many Agiflite cameras have been sold off as surplus?

Indeed. NATO have the huge budget required to get giant sensors made that contain no defects. These just isn't economical for sensor manufacturers to sell.

Claire Senft · Aug 30, 2006

The more I think about this project the goofier it sounds. If the area in width is 4 miles then there will be very considerable height involved. If what is being contemplated is a very narrow height for a vey long print, then I would suspect that the print will have a considerable viewing distance.

Lets assume that you have been able to capture the detail and print it.

Is the detail on the print so fine that nobody can see it?

When viewed from the closest that the print can be appreciated, if the detail is visible in a handheld print, will it be visible from the viewing distance used in display?

I guess I would ask some questions of the client. Depending upon the answers, I might advise the client that they are wasting their money.

BrianShaw · Aug 30, 2006

Claire Senft said:
The more I think about this project the goofier it sounds. ...
I guess I would ask some questions of the client. Depending upon the answers, I might advise the client that they are wasting their money.

... or maybe they should be spending it in different ways if they really need/want to pull off htis project.

There is a lot of space-based imagery that is now available that might meet htis type of need. Zillow.com (and others) uses it. Both optical and radar images can be bought. Would that be a reasonable alternative? That's one way to gain access to DOD and commercial technology investments that are generally out of reach for us common folk.

felipemorgan · Aug 30, 2006

Claire Senft said:
The more I think about this project the goofier it sounds. If the area in width is 4 miles then there will be very considerable height involved. If what is being contemplated is a very narrow height for a vey long print, then I would suspect that the print will have a considerable viewing distance.

Claire, thank you for replying. You may want to go back to my two original post and re-read it to see what I am actually attempting to do vs. what you assume I am attempting to do. The end result needs to be a high-resolution digital file. I am posting on APUG because I intend to use a film camera and because the depth of knowledge here on APUG is deep indeed.

The client showed me several 600dpi scans of reference prints of the subject (they need updated photographs made from the same viewpoint to depict changes in the land use. They could see this from space but it makes comparison to the reference images much harder). The images were made in the late 80's using a Tachihara 4x5 on Kodak Vericolor VPN using a 135mm f5.6 Nikkor or Rodenstock Sironar of the same FL, a tripod and polarizer, and printed on a Mitsubishi paper.

So what I attempting to do better than is: a single 4x5 photograph, made using careful technique, of a vista about 3.5 miles wide. In the scan of the print of this image, you can see houses and they appear as white fuzzy rectangles. The client will be happy if the houses appear as rectangles with sharp edges and with the ability to distinguish a roofline, a window, a chimmney, etc from the rest of the structure.

Since the location is subject to winds and less than favorable atmospherics, my main concern is becoming getting the shot. Thanks to the input from this group I am beginning to believe that with:

The best medium format optics
The sharpest medium format color slide film
Immaculate technique
Ideal weather/light conditions
High quality film scanning
Effective use of software sharpening tools

I can acheive a result that betters the original shots, meets and maybe exceeds the client expectations. Testing will confirm or deny my lunacy!

Thanks to all the on-topic contributions! I've learned a lot already and my initial tests will be more likely to succeed thanks to your contributions. BTW, for my initial tests I've decided to attempt the stitched image approach first and I will be testing 2 vertical shots with my Fuji GW690III and then a grid of 6 frames (2hx3w) using a borrowed Mamiya 6 w/ 150mm lens; Provia film; 4800dpi scans.

--Philip.

David A. Goldfarb · Aug 30, 2006

Sounds like the original was done with nothing extraordinary. Why not just shoot it in 4x5"? Using similar equipment and modern film will give you a better result by itself, and you could improve on that with a more solid camera, and perhaps a more modern lens.

If you're concerned about wind, shield the camera with an umbrella while you make the shot, or just wait for a lull, which is what I usually do.

Film size makes a huge difference. It will be much harder to improve on the results of a 4x5" shot with medium format, than it will be to improve on the results of a 4x5" shot with 4x5".

felipemorgan · Aug 30, 2006

David A. Goldfarb said:
Film size makes a huge difference. It will be much harder to improve on the results of a 4x5" shot with medium format, than it will be to improve on the results of a 4x5" shot with 4x5".

I partially agree, and if my initial tests show the need for more film acreage, I will go that route (I am planning on stitching together several MF images, so that negates one of the potential benefits of the 4x5 format while introducing additional logistical complications...). I have heard about the umbrella wind shield trick but never tried it, so I'm glad to know that's an option. I guess I just think there's less to go wrong with MF and that makes it my first choice but I do realize I am pushing hard against the limits of physics, technique, and luck!

--Philip.

Claire Senft · Aug 30, 2006

I think that using a camera with 4x5 sheets and vacuum back with Velvia and a 135mm Zeiss Planar might be a very good solution. If this photo is being taken from ground level then using a high resolution b&W film with color separation filters would do much to sharpen the edges. I would go for the fastest shutter speed that would allow a f5.6 or 8 opening. TMAX100 would do a very nice job.

jimgalli · Aug 30, 2006

felipemorgan said:
I will be testing 2 vertical shots with my Fuji GW690III and then a grid of 6 frames (2hx3w) using a borrowed Mamiya 6 w/ 150mm lens; Provia film; 4800dpi scans.

--Philip.

I think you're dead on. My bet goes to the Fuji. A fixed lens camera guarantees good lens to film plane registration and I've seen what those little fuji's can do before. Hope you'll let us in on the test shots. Still the extra magnification of the 150 may win out.

Dan Fromm · Aug 30, 2006

felipemorgan said:
<snip>
The client showed me several 600dpi scans of reference prints of the subject (they need updated photographs made from the same viewpoint to depict changes in the land use. <snip>

In the scan of the print of this image, you can see houses and they appear as white fuzzy rectangles. The client will be happy if the houses appear as rectangles with sharp edges and with the ability to distinguish a roofline, a window, a chimmney, etc from the rest of the structure.

<snip>BTW, for my initial tests I've decided to attempt the stitched image approach first and I will be testing 2 vertical shots with my Fuji GW690III and then a grid of 6 frames (2hx3w) using a borrowed Mamiya 6 w/ 150mm lens; Provia film; 4800dpi scans.

--Philip.

That gear might do it, more likely with the 150 than with the 90, especially since you've relaxed the requirements from counting windows to counting houses. Consider trying E100G as well as RDP III.

Good luck, have fun,

Dan

felipemorgan · Sep 9, 2006

jimgalli said:
I think you're dead on. My bet goes to the Fuji. A fixed lens camera guarantees good lens to film plane registration and I've seen what those little fuji's can do before. Hope you'll let us in on the test shots. Still the extra magnification of the 150 may win out.

Well, I've conducted a comparison of my Fuji GW690 III against a borrowed Mamiya 6 MF with 150mm lens. I've written about it and I hope if you took an interest in this thread you'll take a look at the test shots.

If there's a reader with drum-scanner experience who'd be willing to speak to how much improvement drums scans would make in this comparison, I'd love to hear from you. I understand the concept of diminishing returns as it applies to film scanning, I'm just not sure where that graph line tapers off...

--Philip.

Dan Fromm · Sep 9, 2006

Philip, thanks for the update.

You did something that seems to have become conventional and that continues to baffle me. You scanned before comparing. Why do that when you can find a microscope and see what's in the negatives with no intermediate steps? In this case digitization strikes me as considerably illegitimate.

Cheers,

Dan

joeyk49 · Sep 9, 2006

Dan Fromm said:
........

Draw the triangle. Opposite leg = 1.75 mi. Adjacent leg = 4.0 mi. Tan(half the angle) = 1.75/4. So the angle your lens needs to capture to do it all in one shot is 2 arctan(1.75/4) = 47 degrees. Basically you'll need a normal lens to capture the scene in one shot. 80 mm if you're shooting 6x6.

Resolution needed? 2 feet is to 4 miles as 2 feet is to 21000 feet is as x mm is to 56 mm. So x = 112/21000 = .005 mm. 1/.005 = 200. So you need a lens-film combination that will resolve 200 lp/mm if you're going to do the job with a 6x6 camera.

You're cooked, even before we start worrying about atmospherics........

Dan

I almost followed Dan's explaination to the end and I kinda understood it...which pretty much astounds me...

I can't possibly help you with this....but if someone proposed the job to me (which they wouldn't), my response would be, "You've gotta be f*****G kidding?! Go talk to NASA..."

I almost wish I paid more attention in my algebra and geometry classes in high school...almost...

HerrBremerhaven · Sep 9, 2006

felipemorgan said:
Well, I've conducted a comparison of my Fuji GW690 III against a borrowed Mamiya 6 MF with 150mm lens. I've written about it and I hope if you took an interest in this thread you'll take a look at the test shots.

If there's a reader with drum-scanner experience who'd be willing to speak to how much improvement drums scans would make in this comparison, I'd love to hear from you. I understand the concept of diminishing returns as it applies to film scanning, I'm just not sure where that graph line tapers off...

--Philip.

Hello Philip,

I work with scans on a regular basis. However, rather than scanning I think your first test should be a 10x loupe to view the film, and make sure there is some detail there. Ideally you would have a 20x to 50x microscope. Worst case you might have an 8x loupe, but that is a start. You can use a macro bellows set-up as an alternatice, basically something that allows you to view very fine detail on the film.

Based upon your original target resolution, seems that you would need a 6000 dpi scan. You're not going to accomplish that on any scanner you could buy at Best Buy nor Office Depot. In fact, if you don't have experience with high end gear, have a good lab do it for you. If you want to PM me off list, since this is sort of off topic, I can recommend some minimal specification gear that will get you close to the results you want.

Ciao!

Gordon Moat
A G Studio

sanking · Sep 9, 2006

HerrBremerhaven said:
Hello Philip,

I work with scans on a regular basis. However, rather than scanning I think your first test should be a 10x loupe to view the film, and make sure there is some detail there. Ideally you would have a 20x to 50x microscope. Worst case you might have an 8x loupe, but that is a start. You can use a macro bellows set-up as an alternatice, basically something that allows you to view very fine detail on the film.

Based upon your original target resolution, seems that you would need a 6000 dpi scan. You're not going to accomplish that on any scanner you could buy at Best Buy nor Office Depot. In fact, if you don't have experience with high end gear, have a good lab do it for you. If you want to PM me off list, since this is sort of off topic, I can recommend some minimal specification gear that will get you close to the results you want.

Ciao!

Gordon Moat
A G Studio

I agree with the above. The resolution of both lenses used in this comparison, at f/11 and given the conditions of the test, should be well above the maximum potential in lppm of this Epson scanner, which is probably no greater than about 25 lppm.

Sandy King

felipemorgan · Sep 10, 2006

Thanks for the calls to sanity from Dan, Gordon, and Sandy. I placed the comparison shots in my MF Meopta enlarger (105mm El-Nikkor lens and glass carrier), cranked the head all the way up the column, put the aperture on f11, and took a look with my grain magnifier (unfortunately I don't have access to a microscope for even more exact and direct comparison.)

It's obvious that the scanner I used adds a heavy layer of artifacting that's not there on the film.
The difference between the two camera/lens systems is not nearly as marked as the scanner makes it appear.
The Fuji fares better in the enlarger comparison than in the scanner comparison. That leads me to believe that because the Mamiya slides show the subject with greater magnification, they do not suffer from the limitations of the scanner as much.
Both cameras produce a very sharp result on film. The Mamiya produces a bigger sharp result due to its longer lens. This can be an advantage.

--Philip.

felipemorgan · Dec 31, 2007

A very belated followup

Thanks to all who chimed in on this question. In very belated fashion, here's what happened with this photo project. I got the results required with my Fuji GW690 at f11, on a sturdy tripod, with Fuji Provia. Objects the size of a house about 2 miles are rendered with enough resolution to look like what they are.

Take a look at these scans of the film: http://www.philipmorgan.net/AltaWebPreview/

The scans were made on a Nikon Coolscan 9000 model, and some mild color correction and unsharp masking was performed on the files.

The files gave the client the resolution required for their purposes (overlaying imagery on the pictures to show the visual effect of proposed land development).

dpurdy · Dec 31, 2007

Oh no!!! They are going to put a bunch of housing developments along the Columbia Gorge!!? On the Washington side no doubt but that is bad enough. I hope there is a public debate over it and a vote. Probably already was and nobody showed up. Horrible news.

felipemorgan · Dec 31, 2007

dpurdy said:
Oh no!!! They are going to put a bunch of housing developments along the Columbia Gorge!!? On the Washington side no doubt but that is bad enough. I hope there is a public debate over it and a vote. Probably already was and nobody showed up. Horrible news.

I don't know the full story on this, but the photos I made were (indirectly) for the Friends of the Columbia Gorge who were wanting to graphically depict the effects of the type of development you mentioned so that the public could have information on the changes to the view that development would bring. I don't know ultimately what became of the pictures I made, but hopefully they aided the effort to preserve the beauty of the Gorge.

dpurdy · Dec 31, 2007

thank you for clearing that up. I already reversed the everlasting curse I was putting on you. Now good karma follows you.

Lens resolution question

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