Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-15-2013, 08:44 AM   #16
Veteran Member




Join Date: May 2012
Posts: 698
QuoteOriginally posted by SoftwareArtifex Quote
It's little enough calculation that it could be done practically but tediously by hand before computers were available.
Not quite so I think. True, they could do it manually back then but that is one of the reasons that today lenses can be made that could not possibly be designed back then.

For prime lenses with not too wide aperture and not too short focal length you can indeed design an almost perfect lens by hand. It is when you widen the aperture especially when combined with wide field of view that things start to get complicated and beyond what can be done by hand.

Zooms are even more difficult to the extent that any half decent zoom lens is practically impossible to desgin by hand calculation alone, which is why no zoom with more than 3x focal range existed before the advent of computer aided design.

Even then computational power is what primarily limited the performance of zooms for many years. As the ability to design good zooms improved (due primarily to more powerful computers) the ability to accurately manufacture according to the design (and at sensible cost) started to become the main limitation and is today actually the only limitation. Today one can, with the appropriate software and some knowledge, design a lens (even a high ratio zoom) at home that would in theory be better than any lens money could buy - the problem is that there would not exist the means to manufacture it accurately enough at a reasonable cost.

09-15-2013, 08:55 AM   #17
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 23,720
QuoteOriginally posted by lister6520 Quote
at home that would in theory be better than any lens money could buy - the problem is that there would not exist the means to manufacture it accurately enough at a reasonable cost.
If it doesn't lead to a practical design, does it really exist? The problem with designing a theoreticly "perfect " lens and not building it, is it's in theory perfect, but without empirical proof it can't be thought of as any more than theoretical. It begs the question, is your fantasy lens real or theoretical. A lens designed by a computer but not manufactured definitely falls in the category of fantasy. Since my fantasy lens is a razor sharp 10-500mm corrected ƒ 1.4 zoom that weighs less than 6 ounces, I doubt computers can design such a lens... if they can, I'll grind the sucker and polish it by hand.

In real terms, if the computer doesn't know how good the lens will be after the manufacturing process, and whether or not it will be reasonably priced, it's not really much use is it? NO point in having 5000 designs for perfect lenses if none of them can be cost effectively manufactured. That's why a doesn't replace a lens designer, it just helps them.

Last edited by normhead; 09-15-2013 at 09:01 AM.
09-15-2013, 09:00 AM   #18
Veteran Member




Join Date: May 2012
Posts: 698
@normhead
That is actually exactly the point I was making - that today it is not design but the technology of manufacturing that limits the quality and performance of lenses. That wasn't the case a few decades ago when the opposite was true.

Manufacturing has of course made huge advances as well, especially with regards to aspherical lenses with very unusual curvatures that were impossible to manufacture just ten years or so ago.
09-15-2013, 09:06 AM   #19
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 23,720
QuoteOriginally posted by lister6520 Quote
@normhead
That is actually exactly the point I was making - that today it is not design but the technology of manufacturing that limits the quality and performance of lenses. That wasn't the case a few decades ago when the opposite was true.

Manufacturing has of course made huge advances as well, especially with regards to aspherical lenses with very unusual curvatures that were impossible to manufacture just ten years or so ago.
That, when I was in school 40 years ago was a huge issue. People knew how to hand design great lenses that couldn't be manufactured. It's good to hear progress is being made. When I look at the specs of these new SIgma Lenses, prime like sharpness, and better than prime CA control in zooms, I wonder if Pentax is doomed. The most important lens for me is my DA*60-250, and to date no one's built anything like it as far as I can tell... but in the wider end of things, all my recent purchases have been Sigma, and with the 18-35 coming, there's no end in sight.

Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, lens, lenses, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pets Helping Mum do the Garden. eaglem Post Your Photos! 10 04-12-2013 03:28 PM
Having trouble putting on a Pentax Hand Strap. NecroticSoldier Pentax Camera and Field Accessories 22 04-10-2011 06:46 PM
Anybody: Lending Lens to digLloyd for Serious 645D Testing? leping Pentax Medium Format 43 01-19-2011 07:44 AM
Point & Shoot Contest #34 "A Helping Hand" ivoire Pentax Compact Cameras 29 10-13-2010 07:41 AM
Join me in helping change the world, one frame at a time? soccerjoe5 General Talk 10 09-06-2009 06:17 AM



All times are GMT -7. The time now is 10:13 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top