SMF Posted June 21, 2007 Share #1 Posted June 21, 2007 Advertisement (gone after registration) Hi - I've been lurking here a while, and this is my first post - it's likely to be repeating something that someone's already thought of but I couldn't find anything in the archives I bought a CV15 following Sean Reid's review of the ultra-wides for the M8 and have been using scale-focusing and hyperfocal focusing . However, I've been occasionally frustrated that the item I thought I was focusing on isn't quite the point I was actually focusing on (i.e., my scale-focusing technique isn't great!). That's rarely a problem for smallish prints, but sometimes bothers me in anything larger than A4. So, I've been wondering whether there is any merit in the following. Would it be possible to mount a tab on the top of the rear element's barrel, such that it engaged the M8's focusing cam? This would couple with the rangefinder mechanism, although it would only be accurate at one point of focus - since the lens barrel does not move in and out as far as the normal focusing 'thing' (whatever it's called!) on a coupled lens. I was thinking of positioning the tab at the right distance for about 1.5m (which is where I seem to have the greatest incidents of misses). I could then use the rangefinder to make sure that I was at that distance from the thing I wanted to be in focus. Does this make sense? Stephen Link to post Share on other sites More sharing options...
Advertisement Posted June 21, 2007 Posted June 21, 2007 Hi SMF, Take a look here CV15 - making it rangefinder-coupled (sort of). I'm sure you'll find what you were looking for!
luigi bertolotti Posted June 21, 2007 Share #2 Posted June 21, 2007 I do not own a CV15, so, not having the possibilty to inspect the lens, cannot judge if fixing the tab you think of is easy, unintrusive, and can be done without risk of damaging some part of the lens (with tools, hand....). You'd have to "fine-tune" with care the tab for the proposed 1,5 m fixed distance, and computing the right measure is, I think, not so easy unless you have some nice tool (caliper) to be used on a standard lens RF coupled you set at 1,5 and then measure etc... Globally, not a difficult task for good mech amateurs but... do you think is worth ? Or better to try to exercitate yourself on distance evaluation: after all, if you say you had problem at 1,5 mt... is not so difficult to learn to evaluate on sight 1,5 or 2 meters...for 1,5 mt one can use some "body or object references" (1,5 mt = your arm + again the elbow to fingers distance about... standard desks are 80cm...1,5=desk+another less a little hand...) and after all is a 15... at f8 or 5,6 DOF is great also at 1,5 or so. Link to post Share on other sites More sharing options...
cme4brain Posted June 21, 2007 Share #3 Posted June 21, 2007 Hi - I've been lurking here a while, and this is my first post - it's likely to be repeating something that someone's already thought of but I couldn't find anything in the archives I bought a CV15 following Sean Reid's review of the ultra-wides for the M8 and have been using scale-focusing and hyperfocal focusing . However, I've been occasionally frustrated that the item I thought I was focusing on isn't quite the point I was actually focusing on (i.e., my scale-focusing technique isn't great!). That's rarely a problem for smallish prints, but sometimes bothers me in anything larger than A4. So, I've been wondering whether there is any merit in the following. Would it be possible to mount a tab on the top of the rear element's barrel, such that it engaged the M8's focusing cam? This would couple with the rangefinder mechanism, although it would only be accurate at one point of focus - since the lens barrel does not move in and out as far as the normal focusing 'thing' (whatever it's called!) on a coupled lens. I was thinking of positioning the tab at the right distance for about 1.5m (which is where I seem to have the greatest incidents of misses). I could then use the rangefinder to make sure that I was at that distance from the thing I wanted to be in focus. Does this make sense? Stephen Welcome to the forum. I, too, have the CV 15mm lens. I suppose Cosina did not RF couple the lens to save money and due to the fact that the depth of field is so huge that they figured even a poor guess with distance coupled to f/5.6 would give sufficent sharpness. I would like the lens to be RF coupled, but I would imagine that we will have to wait for Cosina to do this- like they have RF coupled their 25mm Color Skopar P lens (that I recently bought). I suppose in the mean time you could increase your ISO on the M8 so that you could use a smaller aperture. Link to post Share on other sites More sharing options...
sean_reid Posted June 21, 2007 Share #4 Posted June 21, 2007 Hi - I've been lurking here a while, and this is my first post - it's likely to be repeating something that someone's already thought of but I couldn't find anything in the archives I bought a CV15 following Sean Reid's review of the ultra-wides for the M8 and have been using scale-focusing and hyperfocal focusing . However, I've been occasionally frustrated that the item I thought I was focusing on isn't quite the point I was actually focusing on (i.e., my scale-focusing technique isn't great!). That's rarely a problem for smallish prints, but sometimes bothers me in anything larger than A4. So, I've been wondering whether there is any merit in the following. Would it be possible to mount a tab on the top of the rear element's barrel, such that it engaged the M8's focusing cam? This would couple with the rangefinder mechanism, although it would only be accurate at one point of focus - since the lens barrel does not move in and out as far as the normal focusing 'thing' (whatever it's called!) on a coupled lens. I was thinking of positioning the tab at the right distance for about 1.5m (which is where I seem to have the greatest incidents of misses). I could then use the rangefinder to make sure that I was at that distance from the thing I wanted to be in focus. Does this make sense? Stephen Hi Stephen, What you might want to consider is using a double shoe on the M8, one shoe holding the finder and the other holding an external rangefinder. Cheers, Sean Link to post Share on other sites More sharing options...
SMF Posted June 21, 2007 Author Share #5 Posted June 21, 2007 Sean - Thanks. I've been looking for a Fokos, but (surprisingly) there aren't any in London, UK at the moment (or at least I can't find any to go to look at). They do appeal to me - it would be like using the IIIf that I used to have! Dim and dirty, but it worked. Stephen Link to post Share on other sites More sharing options...
luigi bertolotti Posted June 21, 2007 Share #6 Posted June 21, 2007 The FOKOS is not rare...nice item... and do not make the error to buy the other RF WINTU ! It's horizontal...if you mount a double-shoe no space for the Finder... Link to post Share on other sites More sharing options...
SMF Posted June 21, 2007 Author Share #7 Posted June 21, 2007 Advertisement (gone after registration) Luigi - Thanks. I'd seen two Wintu and almost bought one until I realised where the mounting shoe was ... Link to post Share on other sites More sharing options...
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