The maximum aperture could stay constant if you could afford the bigger glass at the end of the lens. You have to have room in the barrel of the lens to allow the aperture to get larger, which also demands bigger glass unless you want to vignette.
Catch me at home, after work, if you need further explanation. What I'm saying is that they limit the size of the diameter of the iris diaphragm at the tele end to keep lenses economical. They do make lenses of sufficient barrel size and glass size to support a constant max aperture but they aren't really consumer lenses. 80-200mm f/2.8 is one of them. I wouldn't call it a consumer zoom, would you? Len --- -----Original Message----- From: Paris, Leonard [mailto:[EMAIL PROTECTED]] Sent: Tuesday, April 09, 2002 11:37 AM To: '[EMAIL PROTECTED]' Subject: RE: Using external lightmeter with a Zoom lens... Yes, you are missing something but I don't feel like going through the whole, long, involved explanation here at the office. I have other things to work on. Len --- -----Original Message----- From: Christian Skofteland [mailto:[EMAIL PROTECTED]] Sent: Tuesday, April 09, 2002 11:24 AM To: [EMAIL PROTECTED] Subject: Re: Using external lightmeter with a Zoom lens... If that's the case why doesn't the maximum aperture stay constant? In other words if I have a 60-300 f4-5.6 and I set it to 5.6 and zoom to 300 am I still at 5.6? No, I need to set it at 4 to be at 5.6. Likewise if I set it at f8 and zoom to 300mm will I still be at f8? I don't think so. I'd be at f11 right? The question is: what is my f-stop when it is set at f8 and I'm zoomed to 200mm? Answer: ?????? or am I missing something again? Christian who doesn't like variable aperture zoom or zooms in general.... On Tuesday 09 April 2002 12:08, you wrote: > Well, as long as you are using an aperture smaller than 3.8 (in this case) > say f4 or smaller, you won't have a problem using an external meter. If > you are trying to shoot at full aperture, you may be forced to compensate a > bit. For example, if you set the aperture at f/8, it will remain at f/8 > throughout the zoom range. > > Len > --- - 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 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 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 .
