fursan Posted October 29, 2007 Share #1 Posted October 29, 2007 Advertisement (gone after registration) maybe a dumb question, but related to my previous focusing thread, i want to get this right. how ( where ) does one set a leica lens for the infinity point manually? 1. in the center of the infinity symbol 2. begining of the infinity symbol 3. end of the infinity symbol 4. anywhere within the infinity symbol i ask because in my previous thread related to back/front focus, folks seem to set the lens to the infinity point, look at a distant object and then use a 2mm hex key adjustment till the images in the vf coincide/overlap. where should the focus index on the lens be for correct infinity focus in this instance from the alternatives mentioned above. what does it mean if the infinity symbol is overshot to bring image into focus? Grateful for your help to this rf newcomer nearing desperation ( not there yet:) Regards. Link to post Share on other sites More sharing options...
Advertisement Posted October 29, 2007 Posted October 29, 2007 Hi fursan, Take a look here how do you set the infinity point?. I'm sure you'll find what you were looking for!
robsteve Posted October 29, 2007 Share #2 Posted October 29, 2007 You need to set the lens at its infinity stop. In other words move it towards the infinity position until it hits a stop and will move no further. If the image goes past aligning, you moved the adjustment made with the 2mm allen key too far. Make sure you use your longest lens to set this and a distant object a km or so away. If you have a Noctilux and set your camera using it, it may work fine with the Noctilux, but all the other lenses may now be out. A 90mm is considered one of the best lenses to adjust with. Robert Link to post Share on other sites More sharing options...
gwelland Posted October 29, 2007 Share #3 Posted October 29, 2007 Infinity should be the end stop of the lens with the infinity mark aligned with the DoF indicator on the lens body. In this position, the rangefinder should be aligned against a distant, and I mean distant, object like a tower or similar fine object that you can accurately gauge alignment against. Other camera systems sometimes have lenses that align past infinity slightly (my Mamiya 7 lenses come to mind). I've never noticed this with any of my Leica glass. To be honest, if you're not sure where infinity is on your lens perhaps you shouldn't be messing with aligning your rangefinder yourself ... Link to post Share on other sites More sharing options...
carstenw Posted October 29, 2007 Share #4 Posted October 29, 2007 I saw a difference in focus with a 35 Cron Asph between a couple of kilometres and several kilometres. I subsequently used a star in the night sky, to remove all doubt. Link to post Share on other sites More sharing options...
Hookeye Posted October 29, 2007 Share #5 Posted October 29, 2007 Fahim; I believe you have no guarantee that your lens actually does focus at infinity even though you have turned the lens to the infinity point. So your question is far from dumb. I suggest you take some photos of the moon or very distant object with your lens fully open. Try 3 - 4 settings on and close to the point where your focusing ring stops. Turn the ring about 2mm at the time. Transfer the images to your PC and examine them carefully at a 100% enlargement and decide which setting actually correspond with focusing at infinity. For instance, I have a Noctilux which provide the sharpest image of the moon when the focusing ring is turned about 4mm in from the infinity setting. I.e. the lens has an inherent back-focus independent of the rangefinder cam. I could have tweaked the rangefinder cam with an allen key to get the nocti to focus correctly, but that would have caused the rangefinder to be misaligned with respect to all my other lenses. My advice is to not mess with the rangefinder cam unless two or more long focus (50+) lenses are in agreement that it actually needs to be adjusted. But then I am not as experienced as e.g. Carsten, Rob, Mark, Guy and the other "heavyweights". Let us see whether they second my advice or disagree... Link to post Share on other sites More sharing options...
fursan Posted October 29, 2007 Author Share #6 Posted October 29, 2007 Robert, Thanks. exactly what i was after. shall bring out the 90mm. You need to set the lens at its infinity stop. In other words move it towards the infinity position until it hits a stop and will move no further. If the image goes past aligning, you moved the adjustment made with the 2mm allen key too far. Make sure you use your longest lens to set this and a distant object a km or so away. If you have a Noctilux and set your camera using it, it may work fine with the Noctilux, but all the other lenses may now be out. A 90mm is considered one of the best lenses to adjust with. Robert Link to post Share on other sites More sharing options...
fursan Posted October 29, 2007 Author Share #7 Posted October 29, 2007 Advertisement (gone after registration) Thanks Graham. Just wanted to confirm. one never knows what unknown mechanical esoterics lurk behind a leica infinity point! Infinity should be the end stop of the lens with the infinity mark aligned with the DoF indicator on the lens body. In this position, the rangefinder should be aligned against a distant, and I mean distant, object like a tower or similar fine object that you can accurately gauge alignment against. Other camera systems sometimes have lenses that align past infinity slightly (my Mamiya 7 lenses come to mind). I've never noticed this with any of my Leica glass. To be honest, if you're not sure where infinity is on your lens perhaps you shouldn't be messing with aligning your rangefinder yourself ... Link to post Share on other sites More sharing options...
fursan Posted October 29, 2007 Author Share #8 Posted October 29, 2007 carsten, the moon is on view here. i shall try with that. I saw a difference in focus with a 35 Cron Asph between a couple of kilometres and several kilometres. I subsequently used a star in the night sky, to remove all doubt. Link to post Share on other sites More sharing options...
fursan Posted October 29, 2007 Author Share #9 Posted October 29, 2007 Hans, thanks. I am going out now and try what you have suggested with the moon as a target and the 90/2.8. let me see how it goes. whoopee! the chase is on again! Fahim; I believe you have no guarantee that your lens actually does focus at infinity even though you have turned the lens to the infinity point. So your question is far from dumb. I suggest you take some photos of the moon or very distant object with your lens fully open. Try 3 - 4 settings on and close to the point where your focusing ring stops. Turn the ring about 2mm at the time. Transfer the images to your PC and examine them carefully at a 100% enlargement and decide which setting actually correspond with focusing at infinity. For instance, I have a Noctilux which provide the sharpest image of the moon when the focusing ring is turned about 4mm in from the infinity setting. I.e. the lens has an inherent back-focus independent of the rangefinder cam. I could have tweaked the rangefinder cam with an allen key to get the nocti to focus correctly, but that would have caused the rangefinder to be misaligned with respect to all my other lenses. My advice is to not mess with the rangefinder cam unless two or more long focus (50+) lenses are in agreement that it actually needs to be adjusted. But then I am not as experienced as e.g. Carsten, Rob, Mark, Guy and the other "heavyweights". Let us see whether they second my advice or disagree... Link to post Share on other sites More sharing options...
carstenw Posted October 29, 2007 Share #10 Posted October 29, 2007 Hans, I agree somehow, but if you turn your lens to the infinity stop, and the moon is not sharp, it is time to send it in. Link to post Share on other sites More sharing options...
Hookeye Posted October 29, 2007 Share #11 Posted October 29, 2007 Carsten, I will send it in eventually. But for the time I have learned to just tweak the ring about four mm after having focused through the rangefinder. It works fine if you are not stressed and have to work fast . I do not use it all that often anyway. My message to Fahim is that it is nice to know whether it is the Lens or the Rangefinder which actually needs to be adjusted before one proceeds with the allen key.. Link to post Share on other sites More sharing options...
artur5 Posted October 29, 2007 Share #12 Posted October 29, 2007 I saw a difference in focus with a 35 Cron Asph between a couple of kilometres and several kilometres. I subsequently used a star in the night sky, to remove all doubt. Carsten you are really a hawkeye !. Focusing from infnity to 2 kilometers moves the summicron 35 optic group 0.0006 mm. forward ! Link to post Share on other sites More sharing options...
fursan Posted October 29, 2007 Author Share #13 Posted October 29, 2007 Hans, unfortunately I don't have access to another M8 to eliminate the lens/es or the M8. The dealer here maybe moves 3 or 4 Ms in a year. At least that is the impression i get when i once walked into the shop. the one staff was surprised when i enquired about an M8 back in june. he was leafing thru photocopied sheets of paper to find about the M8. never went back in again. he has a very good price on a brand new M7 + 'cron 50 system though! Carsten, I will send it in eventually. But for the time I have learned to just tweak the ring about four mm after having focused through the rangefinder. It works fine if you are not stressed and have to work fast . I do not use it all that often anyway. My message to Fahim is that it is nice to know whether it is the Lens or the Rangefinder which actually needs to be adjusted before one proceeds with the allen key.. Link to post Share on other sites More sharing options...
rob_x2004 Posted October 29, 2007 Share #14 Posted October 29, 2007 Is rangefinder alignment at infinity important? Does its correct set effect other points of focus? Link to post Share on other sites More sharing options...
carstenw Posted October 30, 2007 Share #15 Posted October 30, 2007 Carsten you are really a hawkeye !. Focusing from infnity to 2 kilometers moves the summicron 35 optic group 0.0006 mm. forward ! That may be, but I am talking about the twist on the focus ring. There was a small, but distinct gap between the two. Link to post Share on other sites More sharing options...
giordano Posted October 30, 2007 Share #16 Posted October 30, 2007 Carsten you are really a hawkeye !. Focusing from infnity to 2 kilometers moves the summicron 35 optic group 0.0006 mm. forward ! I'm torn between admiring Carsten's precision vision and Leica's precision engineering. With an effective rangefinder base length of about 50mm, the difference between 2km and several km is about 4 seconds of arc. I think that's roughly equivalent to distinguishing between 4 inch and 6 inch drainpipes on a building a mile away. Link to post Share on other sites More sharing options...
carstenw Posted October 30, 2007 Share #17 Posted October 30, 2007 Yeah yeah wise guys I am not talking about seeing things out of focus in the results, but seeing that a church spire perhaps 2km away did not match up at the infinity stop, but one perhaps 5km came closer. That was when I decided not to use objects for focus tuning which were closer than (almost) infinity, and started using stars at night. If you want the rangefinder to line up at the infinity stop, you need to do this, even if you can't see the difference in the result. Link to post Share on other sites More sharing options...
Hookeye Posted October 30, 2007 Share #18 Posted October 30, 2007 Hans, unfortunately I don't have access to another M8 to eliminate the lens/es or the M8. Fahim, you do not need a second M8 body to find out. If your LENS produces a sharply focused image of the moon when the focus ring is set at the infinity stop (for this test you should ignore the rangefinder), then the lens is probably OK. After you have verified the lens can go on to check your RANGEFINDER. Does the split image of a star coincide precisely when the focus ring of the lens you just tested is placed at the infinity stop, then the rangefinder is probably also OK. If, howwever, you see a double image of the star, then the rangefinder needs adjustment. This would be the time to get out the allen key.. Link to post Share on other sites More sharing options...
giordano Posted October 30, 2007 Share #19 Posted October 30, 2007 Yeah yeah wise guys I am not talking about seeing things out of focus in the results, but seeing that a church spire perhaps 2km away did not match up at the infinity stop, but one perhaps 5km came closer. That's what I understood you to mean. I can't see that difference myself, but can just manage to believe that you can. Link to post Share on other sites More sharing options...
germanlaws Posted October 30, 2007 Share #20 Posted October 30, 2007 In my supinion you have a problem only wih your distance-meter. Recalobrate it with the Inbus2 as told above. The D-meter seems to change sometimes during using the M8. I took the largest lens (4.0/135mm) and calibrated it by Try&Error. It´s realy not difficult, if you are able to refill the washwater in your car. lg Dieter Link to post Share on other sites More sharing options...
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