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 > Photographic Accessories


Photographic Accessories Discussion on other Photography related Equipment. Tripods, Luggage and suchlike.

Polariser problem

Reply
 
Thread Tools
  #1  
Old 21-08-11, 19:09
flatlander flatlander is offline  
Senior Member
 
Join Date: Nov 2008
Location: Essex UK
Posts: 109
Default Polariser problem

Hi folks , perhaps someone can advise on this question, while out yesterday I was taking some long range shots of some shipping with my Sigma 135-400mm lens and thought I would fit a polarising filter onto the lens to cut down any glare etc, however I could not get the camera/lens to focus sharply, I tried rotating the filter but still to no avail - On removing the filter - the lens autofocus etc worked perfectly, and I have tried it again to today in more controlled conditions with the same results - has anyone else had this happen to them, - I'm sure I have used this same filter on my 10-20mm with no problems - is this a telephoto thing or a dodgy filter? - hope you can help
Reply With Quote
  #2  
Old 25-08-11, 12:39
Don Hoey's Avatar
Don Hoey Don Hoey is offline  
Senior Member
 
Join Date: Dec 2005
Location: Norfolk
Posts: 4,462
Default

If I have the lens correct then at 135mm the largest aperture is f4.5 and at 400mm its f5.6.
The polariser will cut the light by up to 2 stops so a/f will struggle as its equivalent to using a lens with max aperture of f8 or f11. If using at long range ( infinity ) the best bet is to use manual focus. Easy if your lens has a hard stop at infinity mark.

Don
Reply With Quote
  #3  
Old 31-08-11, 14:07
petrochemist's Avatar
petrochemist petrochemist is offline  
Senior Member
 
Join Date: Nov 2010
Location: Clacton, Essex
Posts: 388
Default

I think the problem may be that you are using a linear polariser instead of a circular one. Many auto focus systems do not work with linear polarisers. A CPL has an extra stage to get round this.
__________________
Mike

Pentax K5ii & Panasonic G5 user (with far too many bits to list)
Member of North Essex Photographic Workshop
Also online with PentaxUser.co.uk, Flickr, MU-43, MFLenses...
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 02:42.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.