johann_fuller Posted March 20, 2003 Share Posted March 20, 2003 I got round to making a more sophisticated 'baffle' for the rear of my 50 F2 Summicron ( 2584XXX) - 'Flare monster' (see previous thread) this one features a 3x2 ratio cutout and is glued (semi permenantly) to the offending (flare producing) inner ring and is hence non rotating and non corner of frame vignetting unlike the previous circular cutout. It works a treat!<div></div> Link to comment Share on other sites More sharing options...
lutz Posted March 20, 2003 Share Posted March 20, 2003 Johann, while I like your spirit of engineering and innovation (guess why...;o) I'm a bit uncertain in how far your baffle could possibly improve my 245xxxx Summicron which seems to be of the same built. Not that I'm seriously considering to follow your path as I have never experienced any flare problems with my lens - but still... From your pic the material (cardboard?) you are using appears to be at least as reflective as the matte black surface of the underlying ring of MY lens. Now, to better understand what you are covering on YOURS, could you post a "before" pic? Thanks! Link to comment Share on other sites More sharing options...
johann_fuller Posted March 20, 2003 Author Share Posted March 20, 2003 Posting a before pic is a bit difficult as I would have to unglue it. As for the material (thin card) having the same reflective qualities -this is true but the card only presents an edge to the light rays traveling out of the rear element where as the inner locking ring had a surface about 5mm in length parralel to the light rays - it is this I believe which reflects off light onto the film. The basic theory behind my device is that there is now no parallel surface between the lens and the film outside the image forming light path (a 3:2 rectangular cone) to create this particular vieling flare. Link to comment Share on other sites More sharing options...
john_collier2 Posted March 20, 2003 Share Posted March 20, 2003 Thanks Johann, Mine does have a problem with veiling glare and I will give your solution a go when I get it back from the chap I lent it too. Link to comment Share on other sites More sharing options...
henry_ting2 Posted March 20, 2003 Share Posted March 20, 2003 Interesting....so you have a hood on the front as well as the back. But I don't see how the back shade helps, because if the lens flares, the light would have bounced exponentially within the optical path internally, not after it exits the rear of the lens.....logically speaking of course. Link to comment Share on other sites More sharing options...
johann_fuller Posted March 20, 2003 Author Share Posted March 20, 2003 Henry, This is not the ordinary flare you get when shooting into the light - i.e aperture shaped ghosts across the frame. This is in effect a kind of fogging of the film caused by light bouncing off the inside of the lens barrel after it has left the rear element - often seen when you are shooting a darker scene with a bright object outside the field of view (typicaly the sky). Link to comment Share on other sites More sharing options...
lutz Posted March 20, 2003 Share Posted March 20, 2003 Okay, Johann. Now I got your point. Hmmm... You should see my thin Tele-Elmarit in comparison to the 50 cron, though. *That* is reflecting light from the inner barrel just after the last element - maybe a major reason for its bad reputation, flarewise...?! It would be harder, though, to offer a fix for that one. You would have to attach the baffle to the rear end of the bayonet itself. But - why not? Cheers. Link to comment Share on other sites More sharing options...
johann_fuller Posted March 21, 2003 Author Share Posted March 21, 2003 Lutz, I have never seen the inside of a 90 TE but have heard of it's legendary flare qualities. I have a VC 90 3.5 and this has a finely ribbed interior which is very resistant to light bouncing off it - is the TE's interior surface smooth? Link to comment Share on other sites More sharing options...
lutz Posted March 22, 2003 Share Posted March 22, 2003 Well, here you go. It's ribbed, but still... Even the backmost brass rim seems to be contributing to the flare.<div></div> Link to comment Share on other sites More sharing options...
johann_fuller Posted March 24, 2003 Author Share Posted March 24, 2003 Hum - you can definatley see some light bouncing off the black areas -not sure you should worry about the cam though but mount the lens on your M and open the back with the shutter open on B to check what you can see. Could still be worth making a bafffle - it's not going to cost you anything but time. Good luck Johann Link to comment Share on other sites More sharing options...
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