Article on Scheimpflug in latest View Camera

[Nathan Potter]

Yeah Steve, this article is rather complex and I've been trying to understand what Schiempflug didn't say as explained by the author. The problem is that the terms are not clearly defined as pointed out above. On the other hand these kinds of technical articles require a lot of work on the part of the reader even when they are easily intelligible. I for one like the challenge though so keep a few coming - much appreciated. Great issue - thanks.

Nate Potter

[Jeff Conrad]

I've analyzed the Scheimpflug principle extensively (as Leonard can attest), and think I understand it quite well, yet I can make no sense whatsoever of this article. Some of the photos and later diagrams are interesting, but like Bruce, I didn't want to invest the time wading through the material at the beginning.

[Leonard Evens]

I've now finished the article, but I still don't see its point.

Be that as it may, I did find that while struggling through it I started to think about some geometric issues that I had previously ignored, and I did find that useful. I mentioned one in my previous remarks. Another concerns what happens to the relation between the frame and the region of lens coverage when you tilt. The article makes an oversimplified calculation, which ignores the actual geometry . In reality, when you tilt, the cone of lens coverage intersects the image plane in an ellipse, the size and shape of which depends on the tilt angle and bellows extension. Where you can fit the frame within that ellipse through rise/fall depends on the dimensions of the frame and whether it is in portrait or landscape orientation. There is also a lower level in the image plane below which you can't image any points in the exact subject plane, which might limit further where you can place the frame. It becomes even more interesting if you do some additional ray tracing for points in the DOF wedge about the plane of exact focus. It should be an interesting problem to do the calculations. So reading the article wasn't a waste of time.

There is supposed to be a follow-up article. Perhaps that will say something interesting. Maybe he will even get to the hinge line which as far as I can tell didn't appear is the first article.

I've done some google searching for the "Rules of Optical Rectification", but I couldn't find very much on the subject. The author describes the Scheimpflug principle as Rule II in that subject. I'm curious what the other rules might be. I think the subject area in which this might all fall is photogrammetry, but I wasn't able to find out much about that on the web. If I have time I might go to my University's Library and try to see if I can find anything on the subject in a book.

I'm considering writing an article myself which summarizes various things which have cropped up in our discussions here, but I am deterred by the difficulty of producing adequate diagrams. Also, I would need a crew of volunteers to assess how understandable it is. It is alwasy difficult to get the right balance between comprehensibility and precision.

[Helen Bach]

Aside from the general geometric confusion, there seem to be quite a few optical terms used in the article that do not have the meanings I understand them to have. The principal planes, for example. How much peer review is there for these technical, or pseudo-technical articles?

Best,
Helen

[cotdt]

I didn't understand this article either. But I'm new to large format so that's understandable.

[Capocheny]

Hi Leonard,

Of all the people on this forum (and, probably, ANYWHERE,) who could pen an understandable article on Scheimpflug, IMHO, it would be you.

I'm sure it would be terrific (and comprehensible!)

Cheers

[Michael Kadillak]

I am with 100% with Steve on this one. If someone takes the bull by the horns and writes an article, at least he should be given credit for accomplishing what others only contemplated. Plus, he should be at least given an opportunity to be involved in the discussion here to defend his position to the degree necessary. It is wonderful that this evolved into a discussion on the subject, but there is a lot of Monday morning quarterbacking goig on here.

The lesson here is that if you have considered sharing some of your photographic knowledge or experience on a particular subject then reach our for assistance along these lines and/or get on the keyboard and get it done. I procrastinated for a log time myself and am working on several articles as we speak. You would be surprised at the assistance that this gracious audience would provide in all aspects of the process as necessary if you would only take the first step.

Cheers!

[phil sweeney]

Hi Michael,

I agree and hope my post is only seen as idle chatter.

[Helen Bach]

The act of assistance that I would consider as being the most valuable to an author of a technical article is a thorough peer review. This is something that can distinguish printed material from personal pages on the internet.

In a way, participation in forums like this one is a process of open peer review - we are sharing our photographic knowledge and experience, and allowing it to be contradicted, discussed, criticized and even ridiculed. Taking refuge in a monologue with no opportunity for counter argument is not what some of us wish to do. I have great respect for those authors who do write articles for their websites and then respond to technical comment. You can do that with a live thing like a webpage, but once something is in print it's pretty much done. The review needs to be done before publication.

Finding someone willing to review work properly and intelligently is not easy - it may be more difficult than finding someone to write the article in the first place. People who have a desire to craft an article that is accurate and clear will have to put a lot more effort into it than someone who is content with muddy, inaccurate confusion.

I hope that Michael is not accusing Leonard of Monday-morning quarterbacking. Leonard has made significant contributions to the community, and put considerable effort into those contributions.

Best,
Helen

[Scott Knowles]

I guess after reading the article and the responses, I'm curious what happened to the pre-publication peer review? The problems I saw in the article was its complexity not easily explained in the text and the presentation which added confusion to the text. What it may have had in a qualified peer review for technical merit, it thoroughly lacked in a lay review for presentation and understanding. It may be that there is simply too much in it to describe and explain in the alloted pages, and it should have been reduced to some initial or general ideas with suggestions for later Website or publication articles.

In short, to me, it lost the perspective for its audience, and anyone not knowlegeable about Scheimpflug's rule will simply find it a place to park the coffee cup so you don't ruin the other pages of the magazine. Just my thoughts.