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Dennis

Your Focusing experience for 75/90 lenses (OVF)

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Hi everyone.

These days I'm reading a lot about lenses with FL longer than 50mm, and I always find a common point: with 75/90/135 lenses is hard to focus on RF. Now I'm asking you: Why?

Is it because of the short focus throw range? Is it because it is hard to "confirm" the focus with small frame lines? Is the 75 easier than the 90?

My longest lens is a 50 Cron, so I never tried how hard can be. Is there a big difference between 50 and 75? Please enlighten me with your experience and tips

P.s. Of course, I'm talking only about to focus with the OVF, not EVF allowed in this post. 😉

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Posted (edited)

I use an Telyt apo 135 on my M10 and find focussing harder because of the framelines being about the same as the focussing patch. Harder than with the 50 Summilux. It takes a few seconds longer to focus, but 90-95% of the shots are in focus, so I hardly use LV. Confirming focus is not that difficult, it is more difficult to refrain from finetuning the focus (an extra small twist of the focus ring).  Having a calibrated lens and range finder is a must.

Edited by stephan54

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1 minute ago, stephan54 said:

It takes a few seconds longer to focus

it's a lot! It should be quick, right?

2 minutes ago, stephan54 said:

Harder than with the 50 Summilux

Why? Because the 1.4 aperture?

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It is not a quick lens, for me that is not a problem. I do manage to catch jumps by skateboarders-

I meant to say that the Summilux even at 1.4 is easy to focus. I seldom have a shot that is not in focus. Wearing glasses does not hamper working with the OVF:

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Got it. Maybe with this kind of FL we don't need to be SO fast, as it's mandatory for a 35 for example. For an unscripted street photography scene, speed is key. For a portrait or landscape, I guess we can wait one more second 🤔

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The longer the focal length, the shallower the DoF so the least focusing error is more visible. Especially true on sharp lenses at full aperture. 

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2 minutes ago, lct said:

The longer the focal length, the shallower the DoF

Correct! But with the Summarit 75 at f/2.4 for example, is much harder than a 50 at f/2? It should be similar... Unless that are more factors affecting, such as smaller frame lines and short focus throw range.

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Posted (edited)

With 75mm lens over 50mm, just gaining 50% of framing, depending on lens and mainly curvature of field in that particular lens,

curve field can be different in 50/75 which can enhance or dilute the "sharpness feeling".

I use along 2.5 or 2.8/50/75/90mm lenses without noting any difficulty in focus with OVF.

 

Large difference between 75mm Leica lenses.

First class focus ring with Summarit-M 2.5/75 for it's overall "feeling" (nice large grippy rubber ring, light and short throw ), comparing to Apo-Summicron-M 75mm, even worse with the otherwise very lovely Summilux-M 75mm which I can say it's difficult to focus with.

 

Edited by a.noctilux

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I guess it's the same for the new 75 Summarit 2.4, right? Is still first class? 🤔

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I have no problem focusing 75 & 90 (f2.5) lenses on my M10 - but then I started shooting sports with an M2 & 90 TE back in 1967 so I've had a lot of practice with moving subjects. Still like shooting action that way - seeing the action outside the frame lines.

The OVF still does pretty well for me with my 135 f4, but I prefer an SLR or EVF for that range. (Crossover point is 90mm for me.)

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Practice, practice, practice. Been doing it with a 90 & 135 for many years on M bodies. Nailing it takes a little longer, especially at wide apertures, but at f/8 - easy breezy.

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1 minute ago, spydrxx said:

Practice, practice, practice. Been doing it with a 90 & 135 for many years on M bodies. Nailing it takes a little longer, especially at wide apertures, but at f/8 - easy breezy.

Practice is a must, for everything, i Know. I can use a 75 or a 90 for many type of photography, but for portraits for example, my f-stop range would be 2.4-4 ... I would not use honestly a 90mm at f/8, besides the easy breezy 🤣

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1 hour ago, Dennis said:

I guess it's the same for the new 75 Summarit 2.4, right? Is still first class? 🤔

I don't know as I don't have the 2.4/75.

Same optical figure, so they must give same rendering .

Lastly, I'm pleased that the second hand market let me buy the 2.5 /75 which at first I wanted the 2.4/75 sh to try it out, as I use the two 75mm already , apo F/2 and F/1.4 since long.

With it's closer 70cm mfd the 2.4/75 may have less focus travel ring "balanced nice feeling" comparing to 90cm of the older 2.5/75.

 

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Posted (edited)

Practice ! And probably with a certain lens... I confess my fault in this : having lot of lenses (I'm not the only one, ok... 🙄), i tend to use them, too... and that's a problem, I feel; in my case, expecially  for the 90s... "oh, today I want to take the Summicron"... "oh well, it's some time I don't take my nice Elmarit-M..." "oh... Macro Elmar 90 is so compact to carry..." "well... to variate a little, today I could take the Summarit 75..."  😄 . Pleasant... but no good to really master  RF focusing... 😒 : probably stick with ONE 90  would be much better... anytime I take the Summicron and take a shot at f2 I am concerned.... it's so critical... surely I'd be  a better photog if I'd decide "THIS is my 90 to use, period". But... (and isn't so different for 50s 😉)

Edited by luigi bertolotti

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Posted (edited)
1 hour ago, lct said:

The longer the focal length, the shallower the DoF so the least focusing error is more visible. Especially true on sharp lenses at full aperture. 

This.

It's not rocket-science. If you wish to shoot long-focus / telephoto lenses wide-open then, as spydrxx mentions (and you agreed), skill really comes into the equation.

Broad generalisation, I know, but consider it this way; short-throw focus lenses are slightly faster to align but focus might be very slightly off if it's a really quick grab-shot. Long-throw focus lenses are easier to nail focus exactly but might take slightly more time to do so. If you are skilled / lucky you will be able to nail focus with a short-throw lens and very little tme. If you are less-skilled / unlucky you will miss focus-point / 'Decisive Moment' and with a longer focus-throw lens you will be running short of time as you try to nail focus 100%.

Then again; how much in 'perfect' focus do your snaps really need to be? A phenomenally spectacular image which is a bit soft is a million times better that a bit-of-a-dull image which is perfectly sharp...

I'm pretty sure you already understand all this, though, Dennis. I've seen your work and I've never yet checked on any image to see whether or not it was 100% sharp because the images are superb. And I'm being perfectly serious here. If any of them happen to be, in 'real-life', a tiny bit 'soft' it wouldn't matter one iota.

It might not seem terribly appealing for the purist but from a commercial point of view the most sensible approach is to adopt some sort of compromise in your mental approach. What follows is just In My Experience and bear in mind that my 75mm and 90mm Summarits are two of my four 'Essential Lenses'...

Shooting wide-open and expecting to nail focus 100% of the time any given 'grab shot' with, perhaps, 1/10 of a second's preparation is an approach likely to fail most of the time. Stopping-down a bit - a stop / stop-and-a-half - will lead to success most of the time. If it's a compromise between 100% superb image and 100% perfect focus then err on the side of the former. In which case marginally less D-o-F is worth it and a short-throw lens such as the Summarit would be a very good choice. It's exactly why I bought my two.

YMMV, of course, and Practice, Practice, Practice...

Philip.

Edited by pippy

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Posted (edited)

As usual, trying out is the best way to better know the gear.

While waiting ...

Images from Wiki to compare the 2.4/75 with 2.5/75 focus distance throw

(I think it's same throw on the two, not simple way as they don't match in ratio)

 

Edited by a.noctilux

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I have no problems in Focussing and I do not understand why people have them. 
I have 75, 90 and 135. And even with 135 I have a Hit Rate of 90-95%

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Posted (edited)
5 minutes ago, Gobert said:

I have no problems in Focussing and I do not understand why people have them.

I suspect that Dennis is more concerned about the speed needed to nail focus accurately wide-open when street-shooting than merely the actual, physical task of focussing a 75mm or 90mm lens which is pretty simplistic. At least that was my understanding of the post?

Philip.

Edited by pippy

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Just to echo other posters, the difficulty is that the depth of field is shorter (especially for close subjects) at a given aperture combined with the longer reach of the focal length.

Let’s say (just for example) that the DOF at 90/3.6 is as shallow as 50/1.4. Let’s also assume you want the subject’s face to fill the frame and the eye closest to you to be in focus. At 90mm, you’ll be working a lot harder to pick out the edge of the eye inside the the frame lines and focus patch, and it’ll be harder to control wobbles.

I’ll add a second vote to the Summarit 75 being surprising easy to focus. They did an excellent job on that one, it really is an under-rated lens.

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