What's the best way to focus the CV 15?

[rwchisholm]

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Probably a dumb question, but I would like to know any tricks or techniques for focusing the CV15, as it is not rangefinder coupled. I have been setting at infinity and shooting, but there must be a better way. Oh, and what f stop is giving the sharpest pics for this lens? thanks -rob

[jaapv]

Go hyperfocal. That is, look at the DOF scale, and set the furthest distance you want to have in focus on the aperture mark, or rather, two stops down because of the crop factor and various other considerations, so for instance if you want to be sharp to infinty and have the lens at f 11, set the infinity mark at 5.6. You'll see you are in focus to abou 60 cm.

[hdrmd]

Using the hyperfocal distance, as jaapv just said, then I find F6.3-8.0 to be very sharp indeed. DR

[stunsworth]

Don't use the lens at f8 or above. I've found apertures below this to be the sharpest.

[mike prevette]

Screw hyperfocal, just estimate the distances to your subject. You have two eyes, best damn rangefinder in the world till you hit about 150 feet. You will be amazed how close you can get with a little practice. and the 15 is pretty forgiving.

 

_mike

[Artichoke]

but I tend to avoid shooting above f8

take a look at the aperture when set at f11

it is tiny

I have found diffraction takes its toll at about f8 and has a great effect beyond that

as has been stated, the CV 15 is very forgiving, but it does not like being stopped down beyond f8

[jaapv]

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That it true, I used f11 as an example, Personally I tend to use the lens at 5.6.

[bradreiman]

i set it all the way to the left for short depth of field to shoot at 1 foot or all the way to infinity for most shots. if the subject is close (10-50 ft) i back off from infinity just a touch. Very sharp at 5.6 and at 1 foot i use f4.5 for more oof area. mine is super sharp even at 4.5 but i go to 5.6 because its tack sharp there. here are two examples, both at f4.5, one is focus all the way close (1 foot) the other is focus set to infinity. camera is sitting on the desert floor...brad

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[Jack_Flesher]

Funny. My copy is *really* sharp from f5.6 through f8-1/2, and still quite good at f11. I use hyperfocal; no sense wasting half the DoF by shoving the lens al the way the infinity stop. Re the scale on the lens, I personally use one stop smaller than it suggests --- IOW if I'm shooting at f8, I place infinity on the f5.6 mark.

 

Here is a shot from our recent Yosemite trip using the 15 on the M8. No filter, f8 focused at the f5.6 hyperfocal as explained above. In the full image, you can see the texture of the bark on the roots as well as the individual leaves in the tree on the far bank of the river. (Click the thumb for a larger view.):

 

 

Cheers,

[bradreiman]

Funny. My copy is *really sharp from f5.6 through f8-1/2, and still quite good at f11. I use hyperfocal; no sense wasting half the DoF by shoving the lens al the way the infinity stop. Re the scale on the lens, I personally use one stop smaller than it suggests --- IOW if I'm shooting at f8, I place infinity on the f5.6 mark.

 

Cheers,

 

im not sure i understand...how do i waste half the depth of field at infinity? the depth of focus is about 4 feet to forever. i calculate that to be about...negligible. i do lose focus for the first 4 feet or so, is this what you mean?

[Jack_Flesher]

im not sure i understand...how do i waste half the depth of field at infinity? the depth of focus is about 4 feet to forever. i calculate that to be about...negligible. i do lose focus for the first 4 feet or so, is this what you mean?

 

If you set the lens all the way to infinity, you have lopped off the half of the DoF BEHIND the plane of focus. By focusing closer than infinity, you utilize both halves of the DoF, the halves in front of and behind the PoF...

[bradreiman]

heres an example where the camera isn't sitting on the ground. lens set all the way to infinity, everything is razor sharp to me, this is at f5.6-now if im using a narrower lens like a 35 or 50 i always focus by rangefinder or try to be exact as possible but i don't see the need for this on the cv15. really interested to know the purpose of your method-im here to learn...B

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[bradreiman]

If you set the lens all the way to infinity, you have lopped off the half of the DoF BEHIND the plane of focus. By focusing closer than infinity, you utilize both halves of the DoF, the halves in front of and behind the PoF...

 

i understand this on a lens with short depth of focus say noctilux. but on a cv15 i dont get where im losing anything, the ground by my feet all the way to the moon is in focus in my experience-not bating you really trying to understand your theory in practice....B

[luigi bertolotti]

I know it'sn't right on topic, but I own a CV15 from 6 days, lot to learn, and many of you have experience I haven't : what about lens recognition/coding : did you test it's REALLY necessary with the 15 ? I'm on the point to order a Milich machined BM adapter, and like to be assured is a right thing to do... have a pair of old originals adapter, but they are of the "uncodable" kind...

[Vieri]

I know it'sn't right on topic, but I own a CV15 from 6 days, lot to learn, and many of you have experience I haven't : what about lens recognition/coding : did you test it's REALLY necessary with the 15 ? I'm on the point to order a Milich machined BM adapter, and like to be assured is a right thing to do... have a pair of old originals adapter, but they are of the "uncodable" kind...

 

Hello Luigi, I do think in order to avoid a very heavy cyan drift & vignetting it's very much needed to have the 4.5/15 coded and put a filter on it, too - I own both JM adapters and am very happy with the results I get. Here a couple of samples for you:

 

 

 

 

Good luck, and enjoy the 4.5/15!

[neelin]

the ground by my feet all the way to the moon is in focus ... really trying to understand your theory in practice....B

Not exactly. Someone more knowledgable, correct me if I am wrong. There is only ONE distance that is "in focus". The sharpness? deteriorates on either side of this focus. The "depth of field" is a subjectively defined standard of degradation of the image (circle of confusion?) as it moves out of focus. So if you focus on infinity, your near "depth of field" acceptable sharpness loss point is further than if you focused at the hyperfocal point, having the "other side" of the DOF, END at the infinity point.

 

So, your results "work" for you because you are not enlarging your results beyond your subjective "tack" sharpness definition, and there is nothing wrong with that.

 

Robert

(why use a half wave rectifier when you can use a full wave bridge?)

[Jack_Flesher]

Not exactly. Someone more knowledgable, correct me if I am wrong. There is only ONE distance that is "in focus". The sharpness? deteriorates on either side of this focus. The "depth of field" is a subjectively defined standard of degradation of the image (circle of confusion?) as it moves out of focus. So if you focus on infinity, your near "depth of field" acceptable sharpness loss point is further than if you focused at the hyperfocal point, having the "other side" of the DOF, END at the infinity point.

 

So, your results "work" for you because you are not enlarging your results beyond your subjective "tack" sharpness definition, and there is nothing wrong with that.

 

Robert

(why use a half wave rectifier when you can use a full wave bridge?)

 

Precisely correct, even with ultrawideangle lenses... The only difference with ultrawides, is as you go shorter on your focal length, the CoC drift is more forgiving; but the effect remains the same. Howver, whether or not the effect is strong enough to bother the artist or viewer remains subjective.

[bradreiman]

Not exactly. Someone more knowledgable, correct me if I am wrong. There is only ONE distance that is "in focus". The sharpness? deteriorates on either side of this focus. The "depth of field" is a subjectively defined standard of degradation of the image (circle of confusion?) as it moves out of focus. So if you focus on infinity, your near "depth of field" acceptable sharpness loss point is further than if you focused at the hyperfocal point, having the "other side" of the DOF, END at the infinity point.

 

So, your results "work" for you because you are not enlarging your results beyond your subjective "tack" sharpness definition, and there is nothing wrong with that.

 

Robert

(why use a half wave rectifier when you can use a full wave bridge?)

 

but at 100% I can look at a building half a mile away and see sharp details. i understand this theory at close focus but infinity is infinity and there is no area behind the plane of focus-the plane of focus is infinity right?

[Jack_Flesher]

I know it'sn't right on topic, but I own a CV15 from 6 days, lot to learn, and many of you have experience I haven't : what about lens recognition/coding : did you test it's REALLY necessary with the 15 ? I'm on the point to order a Milich machined BM adapter, and like to be assured is a right thing to do... have a pair of old originals adapter, but they are of the "uncodable" kind...

 

My roots shot above is uncoded and no filter...

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[bradreiman]

I know it'sn't right on topic, but I own a CV15 from 6 days, lot to learn, and many of you have experience I haven't : what about lens recognition/coding : did you test it's REALLY necessary with the 15 ? I'm on the point to order a Milich machined BM adapter, and like to be assured is a right thing to do... have a pair of old originals adapter, but they are of the "uncodable" kind...

 

i agree with Vieri. coding and ir filter are a must on this lens. other people certainly disagree but I can't express how pleased I was when i finally hand coded and filtered my cv15. the color is fantastic and with 1.33 crop this is a really great street lens when the ir is corrected properly...brad