Technical Camera vs View Camera

[Jon Warwick]

The relative ease of large film to not display every sin was eye opening when I looked at my drum scanned 4x5" negative yesterday. I'd used a wooden camera, and the lens board would always jolt a bit when I cocked the shutter!

But looking at the 40x50" image on my 27" screen, and having spent recent years looking at thousands of digital images only, this relatively imprecise film gear had produced a flawless image - not an aberration in sight, just a very large amount of natural-looking detail all across the frame. Sure, I was using very fine grained Acros 100 & admittedly good lens (110mm super symmar xl), and the 350mb drum scan cost a small fortune - but I suddenly thought it's been a while since I saw such detailed and impeccable image quality at that big 40x50" size (the Phase 100mp images on the Alpa website aside!)

 

[jlm]

i've always thought of a point image in this context as as a converging cone of focus, with a sort of radial gaussian density distribution. thicker emulsion, bigger cone base radius; basically a larger and more smeared image of the point

 

[MGrayson]

The cone is three dimensional in the emulsion. When projected, it is much denser around its vertex, no matter how deep that vertex is in the emulsion. So field curvature has less impact on film at the expense of some slight softening of the point image.

I did the calculation of projected density, and it's really pretty good even if the emulsion is VERY thick. The OOF portions of the cone are not nearly as bright as the neighborhood of the vertex. Of course, this only works if the ONLY aberration is field curvature. If the cone itself has an ill-defined vertex, the image will be smeared.

Here's what it looks like (ideally):

Matt

 

[Abstraction]

"Depth of focus" is not the same as "Depth of field", I was talking about the former. Depth of focus is the depth of field behind the lens, that is in the film/sensor plane and the formula is DepthOfFocus = 2*FNumber*CircleOfConfusion. That is the larger f-number the larger depth of focus. So f/22 is twice as thick as f/11.

Concerning parallelism on the smaller format, you're extracting a similar resolution out of a smaller format, if you make the same print size you are enlarging the smaller format more. The more you enlarge, the more you enlarge any error. Think of taking your 4x5" camera and shrinking it. Every movement must be smaller. Ground glass grain needs to be smaller, and loupe magnification to larger if you want to view with the same precision as the 4x5" ground glass of course.

Smaller format means shorter focal lengths means more precise tilt and swing angles. When focusing wide angles I set fractions of degrees, for example to get a hinge distance of 1.25m on a 35mm lens I set 1.6 degrees of tilt. On a 4x5" that would be a 90mm lens set to 4 degrees of tilt.

I think there is also a large psychological factor that with digital and pixel peep it's much easier to precisely inspect focus on your computer, and thus people have got more picky about focusing.

But the key technical reason is smaller camera, similar resolution. With film if you wanted more resolution you shot larger film, the whole camera became bigger. Now we make smaller pixels and sharper lenses. I guess you could say the new IQ3 100MP presents similar resolving power as 8x10" film (grain-free), but to make prints the same size you need to enlarge almost 5 times more so thus the precision requirement is higher for the smaller format.

Ok, that makes sense to me. So, if I understand you correctly, the reason these errors weren't seen in a roll film back attached to a view camera was because the resolution of the roll film didn't match the resolution of the 4x5 (naturally), but the digital back does and since it has to be enlarged much more than 4x5, these errors can be more readily seen.

However, a lot of photographers inspected their 4x5 slides and negatives with a 20x loupe. Yet, none of them had ever complained. Have we gotten pickier now? How sharp does it have to be? I've seen giant (8 feet x 6.5 feet) prints from 4x5 negatives and they looked incredible up close. That's quite an enlargement. Yet, I hadn't seen anything out of focus, even in the corners. Granted, I didn't inspect them with a fine tooth comb, but nothing jumped at me standing 6 feet away. I guess what I'm asking is whether this is really an issue or have we gotten so spoiled that we're splitting hairs?

 

[torger]

Thanks for the film emulsion explanation! Makes sense to me now.

 

[Geoff]

We are definitely splitting hairs. And then some.

 

[jlm]

Overshadowing the theory is the fact that film is only so flat; it is an emulsion on a plastic substrate, usually cupped and only held down along the edges

 

[Abstraction]

We are definitely splitting hairs. And then some.

Then, is there a compelling reason not to use the view cameras, other than the wide angle lens issue, which I agree is a big deal?

 

[Lars]

As I understand it, the critical parallel requirements between lens and sensor in an MFDB setup is not due to higher resolution as much as due to shorter focal lengths being used. If you think about the Scheimpflug principle, the shorter the distance from lens plane to sensor the more the impact of a tilt-swing. conversely, if you use a long focal length lens on MFDB then parallelism is not so critical.

 

[torger]

Then, is there a compelling reason not to use the view cameras, other than the wide angle lens issue, which I agree is a big deal?

People get used to more comfortable easier to use cameras. First everyone was satisfied without back screen and using light meters to figure out proper exposure. Then people wanted back screens with histograms, then with possibility to see the image, the with possibility to review the image at 100% to check sharpness, then with live view to compose directly on that instead of a viewfinder/ground glass.

It's pretty comfortable on a pancake camera to pick out a leica disto D5 measure the distance to the wall set it on the high precision focusing ring and now it will be spot on without even looking. Once used to that, looking on a ground glass may start feel insecure and uncomfortable. Many that use tech cams are 50+ and eye sight may not be as it used to be, making ground glass even more difficult and uncomfortable.

But say if you're used to 4x5" view camera with film and good at focusing that well and you don't feel insecure, you should be able to use it with digital, at least with longer lenses. If you do table top photography or other closer shots there will be zero issues, as parallelism is a non-issue there. View cameras tend to have being used for a long time and becoming old and sloppy and you don't want that kind of camera, it should be tight. Once you've used a "digital view camera" with all movements geared, it's hard to go back to ungeared movements, it's just more comfortable to work with and easier to make small adjustments on tilt with the shorter focal lengths.

With all that said I've heard many many users say they tried digital on view camera and it just didn't work out, images got unsharp, missed focus etc, and then they changed to a pancake camera and all started to work. The exact reasons why it didn't work out is unclear and probably differs from person to person and situation to situation, but it's quite clear that it's a common experience among many. That makes it hard to recommend 4x5" view camera for digital, and when I suggest a digital view camera I always add the disclaimer that they first should check if they can work with the ground glass, or use a live view back.

 

[bomzi]

I just thought I'd thank all the posters for this great analysis of tech and view cameras!

 

[Egor]

Agreed, great info on the tech cam vs view cam

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e

 

[dchew]

I missed this thread the first time up. There are two points I have: First, I think this tech vs view camera is different now that you can get MF backs with reasonable live view. Abstraction has framed the question around having a back with live view but that is a relatively recent addition to MF backs. Sorry I don't consider the IQ1-2 series CCD-based live view really useful for the majority of users. I think the availability of live view on CMOS backs changes the game a bit for this question. As Torger and others point out focusing and alignment were the major drawbacks of view-style cameras, and live view goes a long way in solving that, or at least makes it easier.

Second, this is another case where Abstraction uses the word "compelling" in his question.

Then, is there a compelling reason not to use the view cameras, other than the wide angle lens issue, which I agree is a big deal?

Previously it was the "Is there a compelling reason to use MF" thread. So looking up compelling, "evoking interest, attention, or admiration in a powerfully irresistible way; not able to be refuted; inspiring conviction."

Hell, I don't think there is a compelling reason to use any specific camera. Well, other than the one in our cell phones, because it is always with us.

Dave