I'm looking for an elementary introduction into multi-element optics. Specifically, something that would be useful for the tinkerer. I'm debating trying to adapt the lens from my Holga to my Mamiya 645, but this would require making the lens retrofocus to make room for the mirror. Also there are some ideas floating around in my head for LF optics. Suggestions for online guides or books one might find on Amazon would be much appreciated.
Go to amazon.com and do a search under "Rudolf Kingslake". Probably "Lenses in Photography. The Practical Guide to Optics for Photographers" would come closest, although "A History of the Photographic Lens" is (I think) the most useful and informative for large format users...
But most of his stuff is a bit dry and presumes a fair amount of basic knowledge. Kingslake was definitely more an optics expert than a writer...
"I love my Verito lens, but I always have to sharpen everything in Photoshop..."
Another possibility you might want to look at is the CD book "Exploring Simple Lenses" by John Evans. It's currently $19 and despite being mainly about single-element lenses it may be of interest. When I bought it a month or two ago it shipped from the UK in about a week.
Available from http://www.AlternativePhotography.com There's a short review posted there too.
Last edited by Bob Jones; 12-Jun-2007 at 17:39. Reason: added URL info
Online freebe http://www.mellesgriot.com/products/optics/toc.htm
A serious book on the subject is "Applied Photographic Optics" by Sidney Ray. It discusses in quite some detail every aspect of lenses and lens systems and how they work. Not a light read or an easy book but if you have mastered all the material there, you should be working for Schneider or Rodenstock. It won't be the first place you look to learn something about photographic optics but will probably be the last. It is expensive, you might want to have your library borrow a copy for you before you commit to buying it.
Cheers,
Dave B.
Thanks for the suggestions. The Holga/Mamiya mod is something I've been toying with for a while, and figure it's about time I actually start figuring out how to do it right. Now I just have to find a junked 645 lens to gut to graft the Holga lens into!
Hi !Originally Posted by David R Munson
If I understand well, the goal is to allow a mamiya 645 to focus with the Holga lens when the subject is located at infinity.
The first thing you can experiment easily is to mount the lens by any means in frot of teh camera body and see that you can actually focus at a certain distance. For this you do not need any book, you just need a piece of paper and may be a pocket calculator to compute the position of the image for a given position of the subject using Newton's formulae or similar classical formulae of paraxial geometrical optics.
Then you want to be able to focus at infinity with the Holga lens. This might no be possible as you mention, however taking into account that it is for experimental purpose, you can apply the principle of the retrofocus lens by adding a negative lens element in front of the Holga lens. I have no idea of the Holga lens design, if it is a single lens element, you'll have to play with a two element system.
You could find some help by using a real lens design software like Oslo® for which a free version, Oslo-edu® is available, the free version allows to design up to a 4-element lens. A group of my students in engineering just played with Oslo-edu they re-started from the 1902 tessar design patent and were able to re-compute everything with Oslo. they had absolutely no knowledge of lens design, however they did have some basic knowledge about single lens elements.
Oslo-edu is perfect to play with perfect single lens elements, just enter the focal length of each element and spacing between them and Oslo will compute everything for you.
No need even to know anything about Mr Snell's, (Descartes' in France) or Newton's formulae ;-)
Even if this is not at all a 'primer' and even if you have no use of the Oslo® software, I have found the (freely downloadable) Oslo Reference Manual to be an excellent reference textbook on optics.
Chapter 3 on paraxial optics contains the answer and basics about most things photographers can need when trying to adapt a 60mm Holga lens to a 645 SLR ;-)
http://www.lambdares.com/pub/Optics_Reference.pdf
"Chapter 3, Paraxial Optics"
Excellent info, guys. Many thanks.
David
If we do not care for aberrations, there is a simple solution to the problem by adding a negative lens element in front of the Holga lens.
The focal length of the coupound will be 75 mm and the clearance behind the holga lens increased to 88 mm.
Sure, the aberrations will be terrible, but with a Holga, as far as I know, this is part of the game ;-)
A good example of what Oslo-edu® can do, very easily, just playing with perfect lens elements.
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