> * Re: EOS Which 50 mm do you recommend and why? > Date: Wed, 19 Sep 2001 19:46:11 +0200 > From: "Daniel ROCHA" <[EMAIL PROTECTED]> > Subject: Re: EOS Which 50 mm do you recommend and why? > > Tests from Chasseur d'Images show that the Sigma > is better at full aperture, at f/16 for exemple. Have not seen the test, so I can't say much to that. Anyway, the Canons optical performance is better than current film anyway, why bother? > > Do you know that in some Sigma lenses a complete > > lens group is fixed with only adhesive tape? > > Do you know that a lot of lenses are very good ones ? > EX - HSM ones to be precise. I have no first hand experience with those, but I have experience with many of the cheaper Sigma lenses, presumably the ones people buy much more often. > A cheap lens stay a cheap lens, from all manufacturers. Agreed. > > The Canon needs the lifesize extender for that, right. > > On the other hand the extender is indeed a 1.4 extender, > > which results in far better working distance than with > > With less optical performances. Using the Macro with extender in 1:2 with and without extender the same at 1:2 does not show any differences in the slides. It does not affect the pictures, but it gives more working distance. Given that the range between 1:2 and 1:1 is very rarely used at all, many people might be fully content with the very compact yet at 2.5 still acceptable fast Canon. If 1:1 is really of importance, then the higher working distance might be crucial for illumination of the subject. A lens with better measured performance does not help if you don't get any light between lens and subject.... > Do you want to tell that the extender/lifesize extender > have no effect on the real aperture when it's placed on > the lens ?! No, not at all, but in order to achieve 1:1 you have to calculate the light loss due to extension as well. Just run the test with the Sigma, if you have it and find out for yourself. From infinity down to 1:1 you lose 2 f-stops, much more if you use a bellows. Since the Canon uses a mix of extension and longer focal length by Lifesize extender (which indeed is a dedicated 1.4x converter), it renders 2/3 of an f-stop more light in the viewfinder at 1:1. Which is dramatic. So, if you really need 1:1, the Canon is definitely the way to go because it leaves more room for working distance and illumination and it renders the far brighter viewfinder image. If ou can live with possible compatibility problems and don't really need 1:1 too often, you might as well buy the Sigma for budget reasons. -- Michael Quack <[EMAIL PROTECTED]> Again, this is very advanced technology. You will not see these pictures on any other channel. (CNN live coverage) * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
