Miami 0 #1 February 12, 2005 So I went and got a .3 from Way Cool (the red eye). Mounted it on my PC110, everything looked good. Decided to throw my .42 made by Bower (cheap-o) that I normally use on my TRV17 for tandems on the 110 to see just how much wider the .3 is. Well, it isn't. They are exactly the same. Now I know different lenses measure differently, and I would assume my nice new expensive lens is much closer to its stated magnification than my cheap older one, but how the hell do you tell what the exact magnification really is? Here's what I'm thinking to figure that out... Take the camera without lens, place it a certain distance away from the wall, measuring from the wall to the face of the lens. Measure the width of the wall captured in the lens. Then put the wide angle lens on, place the camera the distance away from the wall needed so the face of the lens is the same distance away from the wall as before and measure the width of the wall captured. Divide the first measurement by the second and you get the magnification. Is that right? And then on another note...anyone had any experience with the black eye or black eye X? Thanks for the help...Miami Quote Share this post Link to post Share on other sites
ltdiver 3 #2 February 12, 2005 Quoteto see just how much wider the .3 is. Well, it isn't. They are exactly the same. Welcome to the wonderful world of wide angle lens un-uniformity. ltdiver Don't tell me the sky's the limit when there are footprints on the moon Quote Share this post Link to post Share on other sites
diablopilot 2 #3 February 12, 2005 2 points. 1. They are not magnifying lenses as they do not enlarge the subject.2) The advantage to the .3's isn't really Field of View, it's the fact they are only a 3rd the length or so. Very low profile. Quote....and I would assume ..... Don't do that!---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
Miami 0 #4 February 12, 2005 Quote1. They are not magnifying lenses as they do not enlarge the subject. Well what ever it is... I was going off of the idea that a telephoto being 2X magnification makes everything 2X as big, therefore .3X magnification would make everything .3 times as big. Quote2) The advantage to the .3's isn't really Field of View, it's the fact they are only a 3rd the length or so. Very low profile. But shouldn't the field of view be at least a little close to what they say it is? And how do you calculate that field of view? Very frustrating...Miami Quote Share this post Link to post Share on other sites
Miami 0 #5 February 15, 2005 So using the method I talked about above it looks like my .42 and my .3 are both actually giving me a field of view of about .407. This is with the lenses mounted on a pc110, face of the lens 3ft from the wall, the width of the picture without a lens of 24in, width of the picture with the .3 of 59in. Anyone care to input as to whether that is the right way to figure the field of view? Also does anyone have the black eye (.25), preferably mounted on a pc110, and have any idea what the actual field of view of it is? Thanks,Miami Quote Share this post Link to post Share on other sites
Zee 0 #6 February 15, 2005 This is how I do it – I don’t know if it’s the actual scientific way of calculating it but it works for me. Start with the focal length of the built in lens on your camera. For the PC110 it is 4.2mm - 42.0mm. Multiply that by the conversion factor of your new lens and you’ll get you the focal length with your conversion lens FL x .3 = New FL or 4.2mm x 0.3 = 1.26mm -(12.6mm) To get the difference in image width you have to divide the original focal length by the new focal length. 4.2/1.26 = 3.33 Take the 3.33 and multiply it by the size of your CCD chip (PC110 is ¼”) and you get 3.33 x .25 = 0.835 This is your multiplication factor for the new lens If your original image width was 10 feet at a specified distance your new one will be 10 x 1.835 = 18.35 feet at the same distance. If you do the same calculations with a 0.42 you’ll come up with 0.595. I’ve measured it with my Kenko .42 high grade and it was pretty damned close.. Hope it helps, Z Action©Sports Quote Share this post Link to post Share on other sites
Miami 0 #7 February 19, 2005 I'm pretty sure I follow but it doesn't match up with the ol' tape measure. At 10ft without the lens I would get 24.6ft with the .3 (which actually comes out to about .407). Wouldn't a true .5 turn a 10ft wide picture into a 20ft wide picture? Thanks again...Miami Quote Share this post Link to post Share on other sites
indyz 1 #8 February 19, 2005 QuoteWouldn't a true .5 turn a 10ft wide picture into a 20ft wide picture? Thanks again... I think you are assuming that there is some sort of standard for conversion lenses (distance from the fixed lens, that sort of thing). There isn't. Every manufacturer does things a little differently. Therefore, than can never be a true .5, unless it is designed specifically for a certain model of camera. Quote Share this post Link to post Share on other sites
racine 0 #9 March 21, 2008 Quote 2 points. 1. They are not magnifying lenses as they do not enlarge the subject.2) The advantage to the .3's isn't really Field of View, it's the fact they are only a 3rd the length or so. Very low profile. Quote ....and I would assume ..... Don't do that! saying that you can't have magnification below 1.0 is like saying you can't have negative acceleration... it's simply untrue. Also, lens magnification is a function of both lens shape, and distance between lens and subject, as well as lens and viewer (CCD in this case). whether the lens is lower profile is based on manufacturing and design practices, not it's magnification rating. Pretty much any highschool or college level general physics book will have a good section on the math behind lens applications. I suggest checking one out and get yourself some baseline knowledge before taking the word of Joe Blow on the forums. Also, check your local public library for books on photography. If it's published, it's more likely to be based in fact vs. hearsay.Think, then type. Quote Share this post Link to post Share on other sites
diablopilot 2 #10 March 21, 2008 1) what's your point? Your post seems to have very little to do with mine. Did you mean to reply to me? 2) you are right about not taking "Joe Blow's" word for things. Learning all you can for your self is the best course. However with well over 1000 video/photo jumps and having owned and used quite a collection of equipment, I believe I have some valuable advice to offer anyone who wants it.---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
DSE 3 #11 March 22, 2008 This is a regurged thread from 3 years past, not that it matters, as your post is still cogent. I'm not exactly sure why an old thread was dredged up other than to make a comment. unless someone has something to actually offer the thread, it'll likely end up at the back of the line where it was. Quote Share this post Link to post Share on other sites
