WPF - World Photography Forum
Home Gallery Register FAQ Calendar Search Today's Posts Mark Forums Read

Welcome to World Photography Forum!
Welcome!

Thank you for finding your way to World Photography Forum, a dedicated community for photographers and enthusiasts. There's a variety of forums, a wonderful gallery, and what's more, we are absolutely FREE. You are very welcome to join, take part in the discussion, and post your pictures!

Click here to go to the forums home page and find out more.
Click here to join.


Go Back   World Photography Forum > Photography Equipment > Lenses


Lenses Discussion of Lenses

0.75X teleconverter

Reply
 
Thread Tools
  #1  
Old 13-04-06, 13:04
Canis Vulpes's Avatar
Canis Vulpes Canis Vulpes is offline  
Senior Member
 
Join Date: Dec 2005
Location: United Kingdom
Age: 51
Posts: 4,398
Default 0.667X teleconverter

Science fiction, but would it be great to have 0.667X TC (1/1.5X DSLR crop factor) This would allow 35mm SLR lenses to be used on digital SLR cameras but instead of loosing light, the TC would gain one stop by concentrating light and turning f5.6 into f4 but with f5.6 depth. Another gain would be full-frame usage from existing 35mm lenses.

I suppose it could be called a full frame converter.
Reply With Quote
  #2  
Old 13-04-06, 19:02
yelvertoft's Avatar
yelvertoft yelvertoft is offline  
Guest
 
Join Date: Dec 2005
Location: North Essex, UK
Age: 59
Posts: 8,486
Default

I can see that it would reverse the crop factor, but I can't see that it would give you a 1 stop light "boost".

Nice idea.
Reply With Quote
  #3  
Old 13-04-06, 19:10
Canis Vulpes's Avatar
Canis Vulpes Canis Vulpes is offline  
Senior Member
 
Join Date: Dec 2005
Location: United Kingdom
Age: 51
Posts: 4,398
Default

Light boost would come by concentrating light on a smaller area, like using a magnifying glass to start a fire from the suns rays. I expect one stop loss from 1.4X TC so the reciprocal should give one stop gain.
Reply With Quote
  #4  
Old 13-04-06, 19:15
yelvertoft's Avatar
yelvertoft yelvertoft is offline  
Guest
 
Join Date: Dec 2005
Location: North Essex, UK
Age: 59
Posts: 8,486
Default

OK, I can see that. I think it would con the camera into thinking that it was a "brighter day", giving you effectively 1 stop extra light, but the camera would still read the aperture correctly.
Reply With Quote
  #5  
Old 06-05-06, 17:33
GavinM GavinM is offline  
Guest
 
Join Date: Jan 2006
Location: Moscow, Russia
Posts: 70
Default

I wonder if this is possible, because I'd buy one.
Reply With Quote
  #6  
Old 06-05-06, 20:30
miketoll's Avatar
miketoll miketoll is offline  
Senior Member
 
Join Date: Dec 2005
Location: Suffolk
Posts: 7,477
Default

In a way its already done by Canon at least (and probably other manufacturers) who put a filter with millions of tiny lenses in front of their CMOS sensors to concentrate the light onto each pixel in order to decrease the amount of amplification needed hence reduce the amount of digital noise. The extra stop is in a sense shown by having higher iso's available without excessive noise.
Reply With Quote
  #7  
Old 07-05-06, 03:32
Tannin's Avatar
Tannin Tannin is offline  
Senior Member
 
Join Date: Dec 2005
Location: Ballarat, Australia
Posts: 288
Default

The micro-lenses serve (as I recall) two functions:

1: trap light that would otherwise fall in-between two pixels and be wasted

2: massage the angle at which light falls onto the sensor elements - because unlike film, a CCD or CMOS sensor isn't very sensitive to light which strikes it at an angle, only straight-on.
Reply With Quote
  #8  
Old 07-05-06, 07:50
miketoll's Avatar
miketoll miketoll is offline  
Senior Member
 
Join Date: Dec 2005
Location: Suffolk
Posts: 7,477
Default

Quote:
Originally Posted by Tannin
The micro-lenses serve (as I recall) two functions:

1: trap light that would otherwise fall in-between two pixels and be wasted

2: massage the angle at which light falls onto the sensor elements - because unlike film, a CCD or CMOS sensor isn't very sensitive to light which strikes it at an angle, only straight-on.
I'm sure you are right although one of the aspects of "digital" lenses apart from anti reflective coatings is to improve the angle of the light striking the sensor. I also recall reading what I said as well (in Amateur Photographer I think) complete with diagrams showing the front area of the micro lenses larger than the rear area so increasing the light gathering power. My mind just boggles at the thought of being able to manufacture the filter with millions of little lenses!
Reply With Quote
  #9  
Old 01-06-06, 09:06
Ant Ant is offline
Guest
 
Join Date: Dec 2005
Age: 34
Posts: 280
Default

I'd buy this, if it would still provide a 1 stop increse on 1.4 or 2x teleconverter.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 10:34.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.