Testing Focusing Accuracy

[tashley]

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What you would want to look at is if the arm that carries the connecting wheel of the camera is not slightly bent. It has been know to happen. The wheel must run exactly on the edge of the helix. If it is slighly out, it will be tilted by a fraction, producing exactly the kind of problems described here.

 

EDIT (having now read what you wrote correctly!)

 

I can't do this because both samples of the lens have been returned to Solms. In any event, Solms themselves say that the lens design means that it WILL behave as described, so it is a by-product of the ASPH construction at this focal length.

 

Best

 

Tim

[robsteve]

I posted this on the PhotoForum, but here it is again to show the M8 is capable of focusing fast lenses.

 

After all the talk on this forum about focusing problems, I though I would mount my Noctilux and shoot my son at the coffee shop this morning. These were at the near focus limit and shot at f1.2 and 640iso. I had to move my chair back a bit from the table to get far enough away to get it in focus. I find the Noctilux gets a bit better at these close distances if you stop down half a stop.

 

Nothing exciting, just an example to show the M8 can focus a Noctilux up close. In the second picture, with his tongue out, he was jumping and shaking his head to make it difficult to focus.

 

 

 

[Jamie Roberts]

Hey Tim--

 

Thanks for the kind words on the galleries, etc... They're coming mostly down, as my partner and I are all sick of them (we're always designing new sites!)

 

But I just finished a set of portraits--all taken with the 35 1.4--ranging from 1.4 to 5.6 and except where I completely messed up (low shutter, bad eyes) they're all right on the money (or eyeball, in this case).

 

So if you ever have any brainstorms for something I can try here, please let me know and I'll happily try it.

 

Someone did once tell me that there is a mystique around the build tolerances of the chrome lenses, and I completely dismissed the idea; I thought they must be wrong! And since I have a black M8, I would have gone for black, but this was a used lens....

 

And if you're ever here across the pond, near Toronto, let me know and we'll compare 35s over a pint

 

@ Rob--the problem Tim is describing, if I understand it correctly, is that the lens doesn't focus the same way when it's stopped down as it does wide open. Though I have to say I'm always amazed when you post something focused--at all--at F1.0...

[robsteve]

 

@ Rob--the problem Tim is describing, if I understand it correctly, is that the lens doesn't focus the same way when it's stopped down as it does wide open. Though I have to say I'm always amazed when you post something focused--at all--at F1.0...

 

The Noctilux focus shifts when stopped down too, but in practice, I have never noticed it.

 

I have a 50mm Summicron for when I don't need faster than f2. It seems to focus fine too and they are not known for focus shifts.

[tashley]

Hey Tim--

 

Thanks for the kind words on the galleries, etc... They're coming mostly down, as my partner and I are all sick of them (we're always designing new sites!)

 

But I just finished a set of portraits--all taken with the 35 1.4--ranging from 1.4 to 5.6 and except where I completely messed up (low shutter, bad eyes) they're all right on the money (or eyeball, in this case).

 

So if you ever have any brainstorms for something I can try here, please let me know and I'll happily try it.

 

Someone did once tell me that there is a mystique around the build tolerances of the chrome lenses, and I completely dismissed the idea; I thought they must be wrong! And since I have a black M8, I would have gone for black, but this was a used lens....

 

And if you're ever here across the pond, near Toronto, let me know and we'll compare 35s over a pint

 

@ Rob--the problem Tim is describing, if I understand it correctly, is that the lens doesn't focus the same way when it's stopped down as it does wide open. Though I have to say I'm always amazed when you post something focused--at all--at F1.0...

 

Thanks Jamie, you have been very kind throughout, though I have been lead to believe it's not possible to get a really good pint in Toronto...

;-)

 

I went to my dealer today with (and how anal is this?) a ruler, laptop and M8 and tried his 35 'cron. Solms said it would do the same thing and it does but this one at least did it far less than my Lux examples. I tried it on my M8 and the dealer's and the results were pretty much the same though the tolerances were within what I would consider acceptable, if not quite what you'd expect. I might take that lens, rather than risk using my 30% from Solms and getting a pup. It's a cute little thing, felt nice and perky. Then I can use the discount for a WATE and start whining about filters and hoods.

 

What this space!

 

:-)

 

Tim

[carstenw]

Tim, I also have a 35/2 Asph and it has been great for me, focusing really well. I am surprised to hear of all your trouble, and still tend to think that the camera must be out of whack. Oddly, I found that my 50 Lux Asph focused wrong and my 35 Cron Asph focused right, but when I tested them both after setting the camera to focus correctly at 1-2m (my near-far balance is out quite a bit), I found that they actually focused the same. I remain suspicious that your rangefinder near/far balance is a little out. Not enough to disturb most of your lenses, but enough for the 35 Lux Asph. Anyway, short of getting the rangefinder mechanism checked over by an independent, I don't see any way to properly resolve this.

[tashley]

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Tim, I also have a 35/2 Asph and it has been great for me, focusing really well. I am surprised to hear of all your trouble, and still tend to think that the camera must be out of whack. Oddly, I found that my 50 Lux Asph focused wrong and my 35 Cron Asph focused right, but when I tested them both after setting the camera to focus correctly at 1-2m (my near-far balance is out quite a bit), I found that they actually focused the same. I remain suspicious that your rangefinder near/far balance is a little out. Not enough to disturb most of your lenses, but enough for the 35 Lux Asph. Anyway, short of getting the rangefinder mechanism checked over by an independent, I don't see any way to properly resolve this.

 

 

Hi Carsten,

 

Thanks for your focus (no pun) on this.

 

Trust me, my RF is close to perfect: if it passes 'the test' at 24mm, 50mm and 90mm then an aberration at 35mm tells me something. Not only that, but Solms agrees, as the rest of these two threads show.

 

The 35 'lux will, for most people backfocus on an M8 as it stops down, the 35 'cron also but less so. I'm now probably going to buy the 'cron cos the issue is less evident... but I'd love to see what new lenses come down the pipe within the next 18 months as this stuff gets sorted.

 

Best

Tim

[d_brown]

Hello Tim,

 

Think carefully before you buy the 35 Cron. I am sorry to say that I followed that line of reasoning and now have three bad 35's. The first Lux has been at Leica for about two months and still no word as to the "repair price", let alone fixing it. Hard to understand why Leica would charge to repair something they did wrong. The 35 Cron is almost as bad as the first Lux. It sits here in the dark, unusable, waiting to have something done. The third Lux was sent to a third-party repair and after a few days is on its way back to me. He says he fixed it! I'll test it for focus as well as focus shift and let you know what happens. I also bought a 35 Zeiss Biogon to use in the meantime and it focuses perfectly at all stops and all distances. It is a very, very nice, very sharp lens. You might want to consider it as it is considerably cheaper. The other alternative would be to send your Lux to my repairman. Don't follow my example and spend $10,000 on one focal length!

 

Hope all ends well, and soon, for you.

 

Dale

[Jamie Roberts]

Dale--

 

Since I have the spooky 35 1.4 that actually focusses just fine, I'll be really interested to see how yours does when it comes back!

 

@ Tim--whoever told you there isn't a good pint to be had in Toronto, well.

 

There's just nothing for that but to show you where they are when you're here (and your source should try Cameron's Ale, brewed in Oakville and served on tap in a few rare Toronto establishments before they declare the city pint-less!).

[tashley]

Hello Tim,

 

Think carefully before you buy the 35 Cron. I am sorry to say that I followed that line of reasoning and now have three bad 35's. The first Lux has been at Leica for about two months and still no word as to the "repair price", let alone fixing it. Hard to understand why Leica would charge to repair something they did wrong. The 35 Cron is almost as bad as the first Lux. It sits here in the dark, unusable, waiting to have something done. The third Lux was sent to a third-party repair and after a few days is on its way back to me. He says he fixed it! I'll test it for focus as well as focus shift and let you know what happens. I also bought a 35 Zeiss Biogon to use in the meantime and it focuses perfectly at all stops and all distances. It is a very, very nice, very sharp lens. You might want to consider it as it is considerably cheaper. The other alternative would be to send your Lux to my repairman. Don't follow my example and spend $10,000 on one focal length!

 

Hope all ends well, and soon, for you.

 

 

Dale

 

Dale, that's fascinating and thank you. I will be very intrested to hear if your repair man has go the lux to work, that could be an interesting route to go down though as far as my understanding of optics goes, if your RF is correctly adjusted and the 35 lux focusses correctly wide open (mine both did) then any adjustment to the progressive stop-down back-focus would either blow your wide open focus or your infinity focus...

 

The good thing about the 'cron is that I actually got to try before I buy, so I know exactly what I'm getting, rather than the lottery of awaiting deliveries from Solms that are expensive to return!

 

Before Solms decided that my lux's backfocus was a design feature rather than a fault, they had offered to repay my 100 euro shipping bill for the return of the first lens. Of course, that is now 200 Euro since I've sent two back... and as a design feature (albeit not exactly gloated about in the marketing literature!) rather than a fault, who knows who is liable for the shipping!

 

What I really want is Jamie's Lux. I am going to go to Toronto on the basis of claiming a pint, get the poor lad totally sozzled and nick that lens. Oh yes siree!

 

Best

 

TIm

[marknorton]

Tim, I've lost track of what exactly was wrong with your lens and how much the focus shifted as you stopped down.

 

In my tests, looking down at a rule, I initially had trouble judging the focus point because the image from the rangefinder was tilted compared to the viewfinder image but with practice it was easy to focus on the reference line with the lens wide open. As I stopped down, the reference line stayed within the zone I thought of as being in focus, but very much at the back of that range, hardly any extension towards the camera and mostly away from it. I assume that in your case, even the back of the in-focus zone moved away from the camera.

 

I think close focussing any of the fast lenses - and the Nocti is worse - is a challenge and one thing you might think about is that the 35/1.4 is not ideally suited for such close focussing when wide open. If you want to go that close, maybe using your 50 is a better option.

 

I was flamed a while back for suggesting the 35/1.4 is due for a makeover. Lens historians will correct me here but I think it was a cut down version of the 35/1.4 Aspherical (as distinct from ASPH) which had 2 ASPH surfaces but was difficult and expensive to make. It was also one of the first lenses to have the concave front lens element and it was a ground-breaking lens at the time. Things move on though and I do wonder whether the lens is overdue for revision. Aside from the ELC legacy lenses, it's one of the oldest in the catalogue.

 

Have you thought about the 28/2?

[tashley]

Tim, I've lost track of what exactly was wrong with your lens and how much the focus shifted as you stopped down.

 

In my tests, looking down at a rule, I initially had trouble judging the focus point because the image from the rangefinder was tilted compared to the viewfinder image but with practice it was easy to focus on the reference line with the lens wide open. As I stopped down, the reference line stayed within the zone I thought of as being in focus, but very much at the back of that range, hardly any extension towards the camera and mostly away from it. I assume that in your case, even the back of the in-focus zone moved away from the camera.

 

I think close focussing any of the fast lenses - and the Nocti is worse - is a challenge and one thing you might think about is that the 35/1.4 is not ideally suited for such close focussing when wide open. If you want to go that close, maybe using your 50 is a better option.

 

I was flamed a while back for suggesting the 35/1.4 is due for a makeover. Lens historians will correct me here but I think it was a cut down version of the 35/1.4 Aspherical (as distinct from ASPH) which had 2 ASPH surfaces but was difficult and expensive to make. It was also one of the first lenses to have the concave front lens element and it was a ground-breaking lens at the time. Things move on though and I do wonder whether the lens is overdue for revision. Aside from the ELC legacy lenses, it's one of the oldest in the catalogue.

 

Have you thought about the 28/2?

 

 

Thanks Mark,

 

That's about an exact description of the problem: the selected POF moves OOF as you stop down, but not just close up - it happens at all distances apart from infinity. I have shots of buildings forty feet away where the edges are sharper than the center because they are slightly further away and are therefore in better focus. If I want to focus on something thirty feet away at F4 I have to actually focus on something more like twenty feet away.

 

It's clear from what I've read in all these threads that the 35 lux doesn't cut it on the M8 for quite a few people but that for some inexplicable reason (and it might be that the silver ones are better than the black) one or two people have examples that work. You are one of them!

 

The 28 is just a bit too close to my 24, so a good 35 is the right filler for me on the way to my 50 lux (the best piece of glass I have ever owned) so I guess it's going to be the 35 'cron for me, though it seems a lot of people have had trouble with that too. The one I tested at my dealer yesterday is _just_ acceptable!

 

Thanks for your help and advice,

 

Best

 

Tim

[Jamie Roberts]

{snipped} If I want to focus on something thirty feet away at F4 I have to actually focus on something more like twenty feet away.

 

It's clear from what I've read in all these threads that the 35 lux doesn't cut it on the M8 for quite a few people but that for some inexplicable reason (and it might be that the silver ones are better than the black) one or two people have examples that work. You are one of them!{snipped}

 

Tim--10 feet at distance?! Really? That's just *wild* to my way of thinking.

 

I've never owned any 35mm camera that was off by 10 feet at f4 that wasn't horribly defective (like, I dropped it), let alone a working Leica.

 

Heck, when my DMR dropped with a 35 Lux R on it, and got the mount bent out of shape, it was still not off by anything like a foot--more like 6 inches, and only visible wide-open (and it drove me nuts)--let alone 10 feet at 30 feet!!

 

Even a Holga would do better than that. My Panaleica 2MP superzoom snapshot camera does better.

 

Something is just wrong there; no difference between film and digital or philosophical wonky lens design implies that much error. There would be a lot of awful newspaper shots if that were the case, and hyperfocus would be ridiculous.

 

I'd bet a lot of (good) pints that you've really got a bad rangefinder; the fact that your other lenses work is a fluke or due to the internal rangefinder sensing. Perhaps the back of those lenses is slightly different.

 

Honestly, before you drop more $$ on another Leica 35, I'd be buying a CV or something "completely different," serviceable and cheap, first.

 

Remember--a 35 is supposed to be "easy" to focus. That kind of error is absurd IMO.

 

As for the Toronto pint, I'm thinking you need to borrow my M8, not the lens

[tashley]

Tim--10 feet at distance?! Really? That's just *wild* to my way of thinking.

 

I've never owned any 35mm camera that was off by 10 feet at f4 that wasn't horribly defective (like, I dropped it), let alone a working Leica.

 

Heck, when my DMR dropped with a 35 Lux R on it, and got the mount bent out of shape, it was still not off by anything like a foot--more like 6 inches, and only visible wide-open (and it drove me nuts)--let alone 10 feet at 30 feet!!

 

Even a Holga would do better than that. My Panaleica 2MP superzoom snapshot camera does better.

 

Something is just wrong there; no difference between film and digital or philosophical wonky lens design implies that much error. There would be a lot of awful newspaper shots if that were the case, and hyperfocus would be ridiculous.

 

I'd bet a lot of (good) pints that you've really got a bad rangefinder; the fact that your other lenses work is a fluke or due to the internal rangefinder sensing. Perhaps the back of those lenses is slightly different.

 

Honestly, before you drop more $$ on another Leica 35, I'd be buying a CV or something "completely different," serviceable and cheap, first.

 

Remember--a 35 is supposed to be "easy" to focus. That kind of error is absurd IMO.

 

As for the Toronto pint, I'm thinking you need to borrow my M8, not the lens

 

I was pretty shocked by that too but I told Leica and they said it fit the pattern. I only ascertained this by a few shots in a less than scientific trial (no rulers, tripods, smoke or mirrors!) and they have now gotten deleted which is extremely irritating as I'm guesstimating those distances from memory. I'd love to have that lens back for a day and run some more accurate tests at distance. I would say, however, that the focus at thirty foot was pretty reasonable just not perfect, and focussing a few feet nearer made it perfect.

 

We will never get to the root of this but I remain utterly convinced that my RF is close to spot on - like I said above, I tried a 35 'cron at my dealers yesterday and the results were identical on both mine and the shop's M8 bodies. So we'll just have to explore the myriad possibilities over that (no doubt winderful) pint!

 

So now I might even get the biogon 35mm if I can find anyone who has successfully hand coded one!

 

Best

 

Tim

[marknorton]

I expect the dealer was rather bemused by this unusual level of lens testing...

 

I took a break from photographing my desk lamp this afternoon and went out with my 35/1.4 to see if I could trip the lens up. I could not. All I saw was brilliant resolution all the way from minimum focus to infinity. I used the finder magnifier because at f1.4, focussing really does have to be spot on but at no time did I find what I was focussing on was de-focussed at f4 compared to f1.4.

 

So, it's a real mystery why Tim's lenses are not behaving.

 

Part of the problem is that when there's a focussing problem, we do not know whether it's body or lens and I think it would be useful if Leica were to introduce a bayonet which could set the roller to the defined positions for 0.7m and infinity focussing so that the rangefinder alignment could be checked. Of course, the rangefinder has to track every position in between but it would at least show whether the end points are correct.

 

With this as a benchmark, the finger of blame - lens or camera? - could be pointed in the right direction.

 

What does surprise me is that Leica seem to be saying "that's the way it's designed to work" and I wonder if Tim is receiving the best advice. Well meant, I am sure, but I wonder if Peter Karbe would be saying the same thing?

[Jamie Roberts]

Mark, I couldn't agree more. I can't trip up the 35 lux no matter what I do, and I find I don't even need the magnifier--not even in darkness. It's a 35, after all--it's easier to focus than a 50 or a 75!

 

Tim--I hope you're reading this thread.

 

http://www.leica-camera-user.com/digital-forum/18316-nokton-35-1-2-compatibility.html#post193055

 

If the Nokton 1.2 can be focussed well at f1.2, then I suspect someone at Leica wasn't telling you the right thing, here, at all.

 

PS--Tim--I sent you a PM, too

[tashley]

Mark, I couldn't agree more. I can't trip up the 35 lux no matter what I do, and I find I don't even need the magnifier--not even in darkness. It's a 35, after all--it's easier to focus than a 50 or a 75!

 

Tim--I hope you're reading this thread.

 

http://www.leica-camera-user.com/digital-forum/18316-nokton-35-1-2-compatibility.html#post193055

 

If the Nokton 1.2 can be focussed well at f1.2, then I suspect someone at Leica wasn't telling you the right thing, here, at all.

 

PS--Tim--I sent you a PM, too

 

Hi Jamie,

 

I didn't get any PM from you...

 

Best

 

Tim