Focusing question

[marcg]

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I've had a vague sense that the rangefinder is not completely accurate.

 

Today I have been mucking around taking pictures of my striped socks – while I am wearing them!

 

When I focused using live view, the picture is absolutely sharp.

 

When I focused using the rangefinder, the picture was considerably less sharp – in fact not really in focus.

 

I had imagined that there was some correlation between the rangefinder and the focus peaking – but this seems not to be the case.

 

I'm thinking about going down to my local store tomorrow to have the rangefinder adjusted – but can someone with an understanding of how it all works confirmed to me that this disparity between the two focusing systems is possible – and how it all works.

 

Thanks

[hunta]

The two are independent, and to make matters worse the lens is as well! So long as those elements you use align you'll be fine. Without additional bodies or lenses to hand it's difficult to know what is 'incorrect'.

[jaapv]

Socks are not the ideal test object for focussing accuracy...

[Jared]

It is definitely possible for the rangefinder to show a different point of focus than the EVF.  Since the EVF is reading off the chip, it is, by definition, correct.  

 

The problem is that rangefinders are both finicky and complex.  You can run into situations where they are accurate at close focus, but not accurate at longer distances.  You can also run into the opposite situation.  You can also see differences between lenses, either because the lens itself needs some adjustment or because the lens has different points of best focus at different apertures (generally referred to as "focus shift").

 

Here is what I would recommend:

- If you have more than one lens, try it with all your lenses not just one; the problem could be with the lens not the camera

- Try it at 2m and 10m to see whether your results are consistent. 

- Using the EVF, check to see whether your lens has focus shift.  That is, if you focus at f/2 and then stop down to f/2.8 or f/4 does the image become less sharp.

 

If you aren't happy with what you are seeing, you'll have to take it to your local dealer and explain the problem.  If you don't have a local dealer, you'll need to contact Leica directly.  I wouldn't recommend having anyone other than Leica take care of the issue since your warranty would likely be voided if you tried to get an independent camera repair person to fix this.  Also, it's not an easy adjustment to make, and the tolerances are very small indeed.  If your camera is brand new, I'd recommend you just ask for a replacement rather than a repair.  That is assuming the problem is visible in more than one lens, indicating the issue is with the camera not the lens.  If you end up having to send the camera in, I'd recommend sending all your lenses at the same time.  Leica will calibrate them all together.

 

- Jared

[Jared]

Jaap is right, by the way. The classic test object to use would be a ruler oriented diagonally to your line of site.  That way you can tell whether the camera is front focusing or back focusing, and by how much at a given subject distance.  

 

- Jared

[marcg]

The two are independent, and to make matters worse the lens is as well! So long as those elements you use align you'll be fine. Without additional bodies or lenses to hand it's difficult to know what is 'incorrect'.

 

Thanks. It hadn't occurred to me that the lens needs to be queried as well.

 

If it turns out to be the lens, then how difficult is that to get adjusted?

 

Socks are not the ideal test object for focussing accuracy...

 

Actually the lines on my socks reminded me very much of the old television test cards.

 

I'm thinking of putting up some of my old socks on eBay as Leica focusing aids or even selling the idea to X-Rite to go with their colour passport.

 

Anyway, although you have over 47,000 posts, How many socks have you focused on in your life?? I beg to suggest that I may be a greater authority on focusing on socks than anyone else on this forum   .  I might even have focused on more socks than Thorsten   

 

Or maybe I should just get out more.

[Ko.Fe.]

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Socks are not the ideal test object for focussing accuracy...

 

Yes, stockings are! 

[Tailwagger]

It is definitely possible for the rangefinder to show a different point of focus than the EVF.  Since the EVF is reading off the chip, it is, by definition, correct.  

 

Perhaps a bit off topic, but I'd amend this a bit as I haven't found things to be quite this simple in terms of relying on the EVF being more accurate than the OVF in the field. The res of the EVF is great but not infinite and both subject to noise or glare depending on conditions. And with focus peaking enabled, while the edge might claim to be in focus, it isn't necessarily at the optimal focus point particularly when  the lens is stopped down. The OVF, assuming proper alignment, isn't subject to that issue.  If, for example, you forget to open the lens fully when relying on zoom/focus peaking, its easy to misjudge or more accurately be misled into thinking things are spot on only to realize in post that shot is soft as while the point you choice was outside the CoC, it wasn't at the precise dot you intended, just somewhere in the vicinity.  And of course, if you eschew focus peaking and/or zooming, you do have to ensure that the Visoflex diopter adjustment is spot on, which, IMO, is a particular pain as AFAICT there's doesn't seem to be a way to lock it in place.  I find the adjustment moved off its intended mark nearly ever time I pull the camera from the bag.  So when using EVF, I've gotten in the habit of checking everything, focusing initially with the OVF, glancing at the zoomed EVF, fine tuning if necessary when in shallow DoF situations. Otherwise, when I expect to be stopped down I depend on the OVF as I find it more precise and far less error prone.   

[Jared]

Perhaps a bit off topic, but I'd amend this a bit as I haven't found things to be quite this simple in terms of relying on the EVF being more accurate than the OVF in the field. The res of the EVF is great but not infinite and both subject to noise or glare depending on conditions. And with focus peaking enabled, while the edge might claim to be in focus, it isn't necessarily at the optimal focus point particularly when  the lens is stopped down. The OVF, assuming proper alignment, isn't subject to that issue.  If, for example, you forget to open the lens fully when relying on zoom/focus peaking, its easy to misjudge or more accurately be misled into thinking things are spot on only to realize in post that shot is soft as while the point you choice was outside the CoC, it wasn't at the precise dot you intended, just somewhere in the vicinity.  And of course, if you eschew focus peaking and/or zooming, you do have to ensure that the Visoflex diopter adjustment is spot on, which, IMO, is a particular pain as AFAICT there's doesn't seem to be a way to lock it in place.  I find the adjustment moved off its intended mark nearly ever time I pull the camera from the bag.  So when using EVF, I've gotten in the habit of checking everything, focusing initially with the OVF, glancing at the zoomed EVF, fine tuning if necessary when in shallow DoF situations. Otherwise, when I expect to be stopped down I depend on the OVF as I find it more precise and far less error prone.   

 

 

You are correct that if your lens has a less-than-flat the EVF might be misleading, especially if you recompose and zoom.  The rangefinder would be misleading as well, of course, under these circumstances and for the same reason.  It's also true that focus peaking will only get you so close, and with certain lenses and distances may be less precise than the rangefinder.  I agree with you that I wish the Visoflex let you lock in a particular diopter adjustment.  I have simply taped mine.  Not elegant, but perfectly functional.  

 

All that said, I stand by my assertion that the EVF allows for the greatest accuracy of focus for this situations where extreme accuracy is required.  It's just showing you what the CMOS chip is actually recording.  That makes the EVF useful, though I certainly wouldn't use it as a replacement for the rangefinder.  For most of the pictures I take I would rather use the rangefinder, and it is more than accurate enough in the majority of situations.  They each have their benefits.  Need critical focus with a narrow depth of field with my 75mm?  Or 90mm? EVF.  Need to focus an R mount lens that isn't rangefinder coupled?  EVF.  Macro shot?  EVF.  Need critical control over the composition?  EVF.  Shooting a lens wider than about 24mm?  EVF.  Street shooting?  Rangefinder.  Shooting any lens between 28mm and 50mm?  Rangefinder.  Shooting the 75mm or 90mm stopped down a bit?  Rangefinder.  Snapshots and vacation pics?  Rangefinder.  I much prefer the rangefinder experience as a whole or I wouldn't own an M10, but there are certainly areas that are better suited to the EVF.  I'm glad we have a competent EVF available for the M10 so I can use whichever is more appropriate for the situation. 

 

- Jared

[marcg]

Update: I had it checked in my local shop – and it's perfect.

 

I was given the advice that socks are not the best thing to use to test a range finder's accuracy.

 

Pacé JAAP

[Foxtwo]

Update: I had it checked in my local shop – and it's perfect.

 

I was given the advice that socks are not the best thing to use to test a range finder's accuracy.

 

Pacé JAAP

Depending upon your height, and whether your were standing or sitting, could you be right at, or inside the min focal distance?

 

You were wearing the socks, right?

[marcg]

Yup - socks.

 

I was over the min focusing distance.  

I think that for the moment, I'll just put it down to user error.

[microview]

I'm thinking of putting up some of my old socks on eBay as Leica focusing aids or even selling the idea to X-Rite to go with their colour passport.

 

Anyway, although you have over 47,000 posts, How many socks have you focused on in your life??

   

[marcg]

 

I'm thinking of putting up some of my old socks on eBay as Leica focusing aids or even selling the idea to X-Rite to go with their colour passport.

 

Anyway, although you have over 47,000 posts, How many socks have you focused on in your life??

   

 

 

I think that my medication must have been wearing off.  Sorry.

[Tailwagger]

You are correct that if your lens has a less-than-flat the EVF might be misleading, especially if you recompose and zoom.  The rangefinder would be misleading as well, of course, under these circumstances and for the same reason.  It's also true that focus peaking will only get you so close, and with certain lenses and distances may be less precise than the rangefinder.  I agree with you that I wish the Visoflex let you lock in a particular diopter adjustment.  I have simply taped mine.  Not elegant, but perfectly functional.  

 

All that said, I stand by my assertion that the EVF allows for the greatest accuracy of focus for this situations where extreme accuracy is required.  It's just showing you what the CMOS chip is actually recording.  That makes the EVF useful, though I certainly wouldn't use it as a replacement for the rangefinder.  For most of the pictures I take I would rather use the rangefinder, and it is more than accurate enough in the majority of situations.  They each have their benefits.  Need critical focus with a narrow depth of field with my 75mm?  Or 90mm? EVF.  Need to focus an R mount lens that isn't rangefinder coupled?  EVF.  Macro shot?  EVF.  Need critical control over the composition?  EVF.  Shooting a lens wider than about 24mm?  EVF.  Street shooting?  Rangefinder.  Shooting any lens between 28mm and 50mm?  Rangefinder.  Shooting the 75mm or 90mm stopped down a bit?  Rangefinder.  Snapshots and vacation pics?  Rangefinder.  I much prefer the rangefinder experience as a whole or I wouldn't own an M10, but there are certainly areas that are better suited to the EVF.  I'm glad we have a competent EVF available for the M10 so I can use whichever is more appropriate for the situation. 

 

- Jared

 

In the first sentence of your reply, I think you misinterpreted something in my previous post or I'm misunderstanding your point. As I take the situation you describe, I'd assert that EVF, on the M10 at least, has potentially superior value because, unlike OVF, you can reposition the focus point, zoom in and adjust without having alter the compositional plane and recompose. 

 

Regardless, I suspect you may be thinking that I'm arguing against the value of EVF.  Quite the contrary, I wouldn't own a camera without it, but not particularly for any narrow DoF focusing benefits. That's welcome, but not strictly essential in my view, at least when the RF and lens are properly adjusted. Rather, its precision in framing, ability to mitigate parallax issues in symmetrical compositions, visual feedback regarding the amount of lens distortion, exposure preview in tricky high DR situations, etc.  I don't equate one or the other with particular focal lengths, rather my reliance on OVF/EVF is alternately dictated by a greater desire for speed versus a stronger requirement for compositional precision. Beyond the native glass, that, for me, is the beauty of an M body. Its the only FF that provides a choice to use one, the other or both as circumstance dictates. 

 

What we see does indeed comes from the sensor, but you've omitted the fact that it undergoes significant downsampling and is only an approximation of whats being recorded.  If what I see coming through the EVF when zoomed at 10x in average light was what I wound up with in post, I'd dust my old Rebel XT off, stomp down to Leica Boston and demand my money back.  With the M10, the EVF resolution is more than good enough when DoF is thin and your just trying to hone an edge. No one would or should argue that EVF isn't inherently more reliable in those instances.  But as DoF increases, and particularly on the wider end where everything is kinda in focus, there isn't enough resolution to critically judge where the central point of focus is. Its very easy to think you're on the mark, particularly with peaking enabled, when a quick glance in the OVF will show, you actually are way, way off.  And if you fail to perform this check, alternately by at least opening the lens wide, what seemed fine at the time, can be quite disturbing in post. As this had caught me out at times and as there are many new first time Leica owners showing up these days, I mention this not to be argumentative, but purely to caution others. That scenario might not fit some folks model of what constitutes greatest accuracy, but in my work precision of focus point in a complex, deeper DoF scene, is just as critical as if I were trying to lock in on an eyelash with the Summliux 75mm wide open.

[M11 for me]

What is the final outcome now? Did you put your M10 on a tripod and tried to focus now properly a subject that is NOT moving?

 

My range finder is absolutely perfect. I never used the EVF so far. My pictures are very sharp.

[willeica]

If your camera and lens are perfectly matched then the RF is the most precise way of focussing. Focus peaking can lead to incorrect assumptions about the point of focus and it is a less precise tool. It can be useful, however, for telephotos where the frame area is quite small on the RF and also as a 'one size fits all' viewfinder with wide-angles such as the WATE. I used my WATE with the M10 at a car show last Sunday and stayed with the Frankenfinder. The EVF stayed in my bag. The useful thing with the Frankenfinder is that you can see inside and outside the frame and decide how best to frame a car at a show. This is particularly useful for avoiding too many other spectators in photos. I must admit that I got fed up changing the menu and the settings on the Frankenfinder and in the menu and switched to a 24mm Elmar for my last few photos. I used the RF for focussing throughout. The M10 itself was perfect.

 

William

[Foxtwo]

Yup - socks.

 

I was over the min focusing distance.  

I think that for the moment, I'll just put it down to user error.

Could be that your camera’s focus is accurate, but your legs are too short?

[Jeff S]

For calibration checks I always use live view, with camera on tripod and clear target (like that provided with LensAlign kit or similar). Best to minimize variables prone to error.

 

Jeff

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Hallo,

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[marcg]

Could be that your camera’s focus is accurate, but your legs are too short?

 

No. It's definitely not that.

 

My legs are a perfect length – they reach exactly to the ground and I have no difficulty walking.