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M8 backfocus test.


Guest guy_mancuso

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Guest guy_mancuso

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I was asked to run a back focus test on my M8's with the 35 , 50 lux and my 75 cron. I downloaded the focus chart that many have been using and carefully ran a full test on these lenses with both bodies. I have done a ton of testing focusing with the DMR and from what i read here on the M8 something sounded amiss. so after carefully running this i found that was i not only on, on all lenses BUT it was extremely easy to backfocus also if you are off just a hair and bam 3 inches out of focus going to the rear. i would suggest using the 1.25 magnifier on these lenses in practice running this test. It was so easy to be out when running it. So if you think you are having issue try several focus test . Try the chart and some other alternative's ways of doing this until you are consistent either way and use a tripod. Shooting at 1.4 the DOF is so narrow you need to be spot on here.

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I had the same results with the 90 Summicron wide open close in---kept on getting the focus point a little behind the eye. I tried the chart, and the lens and camera were dead on, but also amazingly unforgiving of even the slightest tweek of the focusing ring.

 

So today I went to the eye doctor, and although my sight is still good enough that I don't really need glasses, my shooting eye isn't quite perfect anymore. For me, perhaps a mild diopter along with the magnifier...

 

Clyde Rogers

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Guest guy_mancuso

Clyde i think that is the case here, i mean it is a hair difference . Folks also need to realize the extreme short DOF here also besides if your focus is off, if you move a touch or recompose it can throw things off at 1.4 with a longer lens. This is very true with the DMR and the 80 lux at 1.4 you really can't nail it but at f2 it is awesome when you do. I do like the magnifier on the M8 and for it stays on for everything butcan see clearly the frame lines from 28 on up and for the 21mm it stays on and use the external finder to frame. i shot a lot of 50 lux wide open shots in the Yosemite series and i was dead on everytime.

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yep, Carsten, you've got it right concerning the prices; the procedure with the diopter is like this: you fix it on the 1.25 magnifier or on the camera; if your glasses show, for example, +1 dpt for viewing objects in the distance, you should get a +1,5 dpt diopter since the M cameras come with a finder that already offers -0.5dpt

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I have found that my experience with focusing accuracy on the M8 to be similar to my experience with film M's, but that I am MUCH more critical. In the old old days, before scanning, I looked at very few images at the equivalent of our 100%. With scanning, I only scanned the best shots as best as I could tell with a loupe, and many of those taken wide open were basically OOF (focus missed). Now, of course, I can examine each image.

 

For me, the bottom line has bee exactly as Guy says. If shooting wide open, I must pay extreme attention with every shot. The huge advantage with the M8, of course, is that I can spend many more shots in "learning" mode; that is, learning how to increase the precision of the focusing because of the low additional cost per additional image and, more importantly, the speed of feedback.

 

Guy, although your sample here is only 2 or 3 cameras, do you have the sense that the focus point is the same for both? Is their variation between the two cameras?

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I noticed the slight focus difference, but find it most difficult to achieve on my 35/1.4/asph. The "knob" (is there a proper word for it?) that turns the focus ring makes it easy for slight pressure from the finger to overadjust. I find the smooth rings I can grasp on my larger lenses to be much more precise. On this lens I changed my grip to hold the base of the knob (on the lens body) and turn from there.

 

Anyone else have this difficulty?

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This is one important advantage of the M8 over the R-D1. The R-D1 rangefinder is adequate but the M8's is a much higher quality unit that's evolved over decades. I find that the M8s I've worked with have been able to focus spot-on. For those that are out of adjustment, or go out of adjustment, the adjustment can be made with well-known mechanical movements. In short, this RF is one of the best things about the camera.

 

Cheers,

 

Sean

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Guest guy_mancuso

Sean as a newbie to the RF world i have really have taken to this kind of focusing, it did take me some time to get the feel of it but the beauty in low light is awesome is that you can see so much better like this. And who ever was the guy that made the tab when on the bottom of the lens at 4.5 ft on all tabbed lenses was a freaking genius. I LOVE this feature

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Clyde i think that is the case here, i mean it is a hair difference . Folks also need to realize the extreme short DOF here also besides if your focus is off, if you move a touch or recompose it can throw things off at 1.4 with a longer lens. This is very true with the DMR and the 80 lux at 1.4 you really can't nail it but at f2 it is awesome when you do. I do like the magnifier on the M8 and for it stays on for everything butcan see clearly the frame lines from 28 on up and for the 21mm it stays on and use the external finder to frame. i shot a lot of 50 lux wide open shots in the Yosemite series and i was dead on everytime.
Guy Do you know of an external finder solution for the 24 2.8 on the M8 ? On the M6 I used the 21 and 28 with external finders and then went to the 35 using the std framelines. Never suffered from viewfinder cutoff. With a equivalent view of 32mm its a little wider than the 35mm or narrower than the 28mm. I have an almost new 24 with 6bit and the pre apo 21mm...so I am not looking to trade out yet.
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Just had a play around with the focus chart and the various lenses that I have. A couple of things worth noting. First, there seems to be a fair bit of focus shift between apertures with some lenses. I knew this was a 'feature' of the Noctilux (which I no longer own) but I was surprised to see how much focus shift there is with my 35/1.4 ASPH going between F1.4 and F4 (focussed in the close range). The second thing I'd note is that using these 45 degree focus charts close-up with a rangefinder is not all that easy. The distance between rangefinder windows means that the two lines being aligned in the rangefinder patch are not parallel with each other and there is plenty of scope for inaccurate focussing.

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Sean as a newbie to the RF world i have really have taken to this kind of focusing, it did take me some time to get the feel of it but the beauty in low light is awesome is that you can see so much better like this. And who ever was the guy that made the tab when on the bottom of the lens at 4.5 ft on all tabbed lenses was a freaking genius. I LOVE this feature

 

Hi Guy,

 

You know that I've been a rangefinder guy for a long time but, of course, I still work with SLRs for some projects. I've been testing a new set of alternate wides for the Canons (all MF) and boy do I miss that rangefinder when I'm testing them on a 5D.

 

Cheers,

 

Sean

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