The 2 things you have to remember are that both the aperture and focal length of the lens are rounded off by the lens maker. Nobody advertises their lens is a 192mm F2.53, they all say 200mm F2.5. Kent Gittings
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Knut Kampe Sent: Friday, November 09, 2001 12:59 PM To: [EMAIL PROTECTED] Subject: Re: 200 f2.5 question, how can filter ring be 77mm? At 09:18 09.11.01 -0600, you wrote: >Lets not forget in this discussion of the maximum f/stop of a >lens that the f/stop measurement is taken from the relationship >of the entrance pupil and the focal length. The actual diameter >of the front element is not part of the equation. >William Robb How can the entrance pupit be BIGGER than the the actual front diameter? I don't think that this is possible (the opposite is sometimes the case). Knut - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org . ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com ********************************************************************** - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
