Very interesting answer from Leica on 35mm 1.4

[sergiolov]

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Personally, I think we've done about all we can on this matter.

 

Nonetheless, I would make the following request:

 

Let's make a single type of test that is comparable to Tim's. The reason is that with older Leica lenses you could clearly see center/field/edge changes with prints up to 16 x 20, for example. All of today's lenses are superb compared to what used to be the case. Since Tim illustrated his problem in one way, all the other tests should be performed in the same way simply for clarity.

 

Check out his birdhouse photos. If Tim was at 10 feet, find an object at 10 feet for your test. (Something as detailed as Mark's teabox would be perfect.) Use the rangefinder to focus on it. WITH THE CAMERA ON A TRIPOD, change the pointing of the camera to put the same object into each of the four corners in turn.

 

Post the result.

 

The kind of tests Sergio and Bill have done prove that these lenses are excellent, but they DO NOT TEST Tim's contention. Their images show that there's very little difference over the lens's field of view; but the eye is misled by seeing a gradual deterioration as one moves outward over the frame. Not all record labels are equally clearly printed. Choose a single object and put it at the five locations mentioned.

 

Please, just try it. (I know it's easy for me to say when it's 75 F in Houston; but wait for a comfortable day and then try it.)

 

Please don't take offence. I'm not saying, "You did it wrong." All the tests you've done are good and illustrate the quality of the lenses. But they do not duplicate Tim's circumstances. As Sergio has clearly pointed out, turning the camera makes a difference. And that is what Tim did.

 

Just a request with the idea of putting the wrap on the matter.

 

 

Respectfully,

--HC

 

Howard,

You are right on the MTF. I was referring to the 1,4 , that is the lens that started it all.

Regarding the CoF , another time, but I think You'll find interesting that at 100% image size from the M8 is 36x54 inches viewed from a distance of 12 inches.

 

My first test with charts is related not to the mystery of the bird box, but to Tim's finding that closing the lens to f4 it goes out of focus. This is what I do not see, both with the test focus chart and with the resolution chart.

 

As the outside and inside temperature here in Italy is very favourable to perform test, it immediately follows.

Distance 10 feet, f4, tripod.

As you can see, the lens performs exactly as it should, with a sharp center and slightly less so corners. What to say more?

 

With all my appreciation for your kind and sensible attitude.

Sergio

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[wparsonsgisnet]

I will rerun the tests per Ho-Co's suggestion (post #239), but in effect I believe I have tested this with the foil picture (btw, it was taken in a cemetery, not to suggest that we have spent much time on this issue) in posting #234. In this pic, the leftmost side is about where the corner will be when I rotate the camera in place. In that pic, the focus point in the center of the image was about 3 feet away and the side is 4 feet away.

 

I expect to see that the corner is in focus at a smaller aperture (as in 234) and out of focus at a wider aperture. Something about physics, I believe, as discussed above.

 

I will test per Sergio's diagram (#227). And, I just might use the records again. Even tho they are printed with different degrees of skill (or maybe just attention to detail, what's this world coming to), they sound better than cd's. If anyone has a request, I'll listen to that recording while testing the limits of optics that even Leica cannot overcome.

[tashley]

Howard,

You are right on the MTF. I was referring to the 1,4 , that is the lens that started it all.

Regarding the CoF , another time, but I think You'll find interesting that at 100% image size from the M8 is 36x54 inches viewed from a distance of 12 inches.

 

My first test with charts is related not to the mystery of the bird box, but to Tim's finding that closing the lens to f4 it goes out of focus. This is what I do not see, both with the test focus chart and with the resolution chart.

 

As the outside and inside temperature here in Italy is very favourable to perform test, it immediately follows.

Distance 10 feet, f4, tripod.

As you can see, the lens performs exactly as it should, with a sharp center and slightly less so corners. What to say more?

 

With all my appreciation for your kind and sensible attitude.

Sergio

 

Hi Sergio,

 

I'm not logging in much while in Barcelona so sorry for the slow reply!

 

A questions: I am not sure in your test shots what is happening. Are they all at f4? If so, why are there so many of them? Where did you focus?

 

Best

 

Tim

[sergiolov]

Hi Sergio,

 

I'm not logging in much while in Barcelona so sorry for the slow reply!

 

A questions: I am not sure in your test shots what is happening. Are they all at f4? If so, why are there so many of them? Where did you focus?

 

Best

 

Tim

 

Hi Tim,

it seems that everytime i send you a message, I must start with a "you lucky man"!

 

In this test, requested by Howard to simulate your bird box example, the first shot is with the target in the centre, the others, rotating the camera, with the target in the four corners. All at F4.

 

I a preceding linked test, I tested the lens with a group of resolution targets all over the image field, from F2 to F8. Here is the link.

 

SUMMICRON 35 ASPH FOCUS SHIFT TEST

 

The result is that my cron 35 asph does exactly what we expect from it. It stays perfectly in focus, is sharper on center than in corners, corrners get better stopping down, and at 5,6 the image has a completely omogeneous and extremely high sharpness, outresolving the sensor everywhere.

 

At the same time, as we know, it extends the focus area on the rear when stopped down, but this is compensated by the fact that, full open, the focus plane is slightly in front of the focus area, but still perfectly inside it.

This is a very good compromise in calibrating the lens.

As I told before, if one works, ....all the others are misadjusted.

 

This one is ready to start a trip to UK at your order.

 

You lucky man!

Regards.

Sergio

[tashley]

Well Sergio, you and Jamie seem to have magic lenses! I just don't get it. There are so many out there that go OOF in the centre at 2.8 thru 5.6 that you either got lucky or the rest of us have ones with manufacturing errors - in which case, why did Solms tell me that this is just what they do?

 

I want to test your and Jamie's lenses. I do I do I do. I may travel...

 

;-0

 

Tim

[ho_co]

I will rerun the tests per Ho-Co's suggestion (post #239), but in effect I believe I have tested this with the foil picture

Bill--I agree. I think your test and Sergio's both show that a "Let's do the birdbox again" is unnecessary. For some reason, it looks as if your and Sergio's lenses are flatter field than Tim's, and that is beginning to interest me (don't you wish I'd just go away! )

 

And, I just might use the records again. Even tho they are printed with different degrees of skill (or maybe just attention to detail, what's this world coming to), they sound better than cd's.

You are right about attention to detail I was really fishing for a reason to say 'let's try it again'

 

And I agree that the warmth of vinyl is far superior to CD; but at least the listening will make the testing less a pain.

 

--HC

[ho_co]

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I will rerun the tests per Ho-Co's suggestion (post #239), but in effect I believe I have tested this with the foil picture

Bill--I agree. I'm beginning to think your and Sergio's lenses are flatter field than Tim's, and that is getting me interested. (Don't you wish I'd just go away? )

 

I just might use the records again. Even tho they are printed with different degrees of skill (or maybe just attention to detail, what's this world coming to), they sound better than cd's.

You caught me. I was really just fishing for a reason to request a re-shoot. (Not very subtle, huh?)

 

But I do agree that vinyl has a warmth that sounds better than CD's. I recently heard an audio engineer talking to another engineer about his recent work: "Man, it's so good, it sounds almost analog!"

 

 

One day soon, birds all over the world will be surprised to see Leicas armed with 35's shooting their boxes! Tim has started a revolution!

 

 

I've made one strange discovery: On this thread and this thread only, the forum software will not let me edit my posts. Once I've posted, when I click the EDIT button, I get the edit panel, but whether I click "save" or "cancel," nothing happens; the only other thing I can do is simply close the window, at which time the original post disappears. Forum software saying "Haven't you vented enough?" ??

 

--HC

[ho_co]

Okay, now the first post returned again.

I clicked EDIT, then DELETE--and again, the software didn't respond.

Sorry for the double post.

 

 

@Sergio--thanks for the test. You have indeed shown that these lenses do vary, and yours seems to work just as it should--and just as you said!

 

I bet Bill's will show the same--and as Jamie said, what, 88 posts ago?--we are going 'through the looking glass.'

 

And we've come full circle to what Michael Hußmann said in post #81.

 

 

I want to test your and Jamie's lenses. I do I do I do. I may travel...

Tim--just invite them to Barcelona!

 

Heck, I might even buy a 35 to make that trip if you invite us all! (And I'll bring my own birdbox.)

 

--HC

[rosuna]

And I agree that the warmth of vinyl is far superior to CD.

--HC

 

Well, I don't agree.

 

CDs are able to reproduce a far wider range of signal, without "noise". You can simulate the vinyl narrower dynamic range and random noise getting that "warmer" (noisier, louder, more compressed) sound, of course, but it isn't better. A CD played in a superb Linn player/amplifier, for instance, is an experience that the vinyl cannot provide.

[ho_co]

Rubén, I won't argue.

 

The audiologist says I'll soon need very strong hearing aids in both ears.

 

And even virgin vinyl does have the noise issue.

 

Maybe the important thing is that we enjoy our music?

 

I didn't mean to offend!

 

--HC

[tashley]

Okay, now the first post returned again.

I clicked EDIT, then DELETE--and again, the software didn't respond.

Sorry for the double post.

 

 

@Sergio--thanks for the test. You have indeed shown that these lenses do vary, and yours seems to work just as it should--and just as you said!

 

I bet Bill's will show the same--and as Jamie said, what, 88 posts ago?--we are going 'through the looking glass.'

 

And we've come full circle to what Michael Hußmann said in post #81.

 

 

 

Tim--just invite them to Barcelona!

 

Heck, I might even buy a 35 to make that trip if you invite us all! (And I'll bring my own birdbox.)

 

--HC

What a fantastic idea! You guys better get here quick though, I leave in two day's time!

;-)

T

[wparsonsgisnet]

Well, I don't agree.

 

CDs are able to reproduce a far wider range of signal, without "noise". You can simulate the vinyl narrower dynamic range and random noise getting that "warmer" (noisier, louder, more compressed) sound, of course, but it isn't better. A CD played in a superb Linn player/amplifier, for instance, is an experience that the vinyl cannot provide.

 

I would certainly like to hear a Lynn player.

 

Speaking in general, I think one must (1) spend in excess of US$2k for a CD player, and (2) play newer, better recorded (upsampled) CD's to equal what can be heard with a few hundred US$ record player and a decently made record.

 

The great frustration to me is that although there are recordists and record makers out there who have made magnificent recordings, most of the software sucks. The true problem is that the mass market is content with MP3's and they don't even equal the sonic level of poorly recorded CD's. Sigh.

 

The nail in the coffin was Sony's decision to make the CD fit a 5 1/2 inch space in a car radio.

 

That said, CD's are certainly quieter and more convenient.

 

This particular forum is one of the very few places that we can discuss superb instruments from a company that has a dedication to producing them for a long time.

 

Regards,

[msr]

I finally had the time to read all of this thread but after 11 pages I began to feel a bit numb & thought that I had heard most of the focussing/birdhouse discussion before.

 

A quick check of the Photo.net archives revealed the work of Martin Tai who, in 2002, dicussed the mathematics of focussing & recomposing with the Leica M. He even produced a small Excel file, Leica M Recompose Focus Guide, that could be printed and kept in one's bag to aid the photographer.

 

The thread can be found here: http://photo.net/bboard/q-and-a-fetch-msg?msg_id=002cCK

 

Apologies if this was pointed out on pages 12 or 13.

 

Malcolm

[ho_co]

Oh, shush, Malcolm!

 

I mean, man, after all the work we've put in rediscovering the wheel, you want to tell us it's been done?

 

Here I was thinking we'd all be going to Barcelona to check out the matter.

 

And, definitely, no, that link hadn't been posted here. Thanks for hunting it down for us. Want to buy a bird house?

 

--HC

[blakley]

I ran two tests tonight, both with the M8 on a sturdy tripod at ISO 320, Aperture-priority auto, JPEG fine, tungsten WB, chrome 35 Summilux ASPH with filter, focused at a little over 1 meter distance.

 

First test was the focus test chart (linked earlier) on the floor, shot from a 45-ish-degree angle (not measured) at full-stop increments from f/1.4 to f/11.

 

The second test was books in a bookcase, shot with the camera level and the sensor parallel to the plane of the spines of the books.

 

I'm not going to post the photos tonight because the light was dim-ish interior incandescent, which led to some camera-shake issues due to long exposures and the tripod being on carpet.

 

Still, to summarize the results, I found that while there was some backward migration of the plane of sharpest focus, the principal subject of focus was sharp (i.e. within a visually acceptable - to me - circle of confusion at "actual pixels" in Photoshop) in all the pictures.

 

I'll repeat the focus chart test tomorrow in daylight on the driveway to see if the results hold up after I minimize camera shake issues - and I'll post the photos.

 

It does seem to me, provisionally, that sample variation may be one of the factors here.

[blakley]

The daylight test may have to wait a day or two as we're having thuderstorms here...

[ho_co]

Interesting picture relevant to this thread on pp 8-9 of LFI 3/2007.

 

It's my impression that although the center of the image is sharp, the field is a bit less so, particularly on the left side. That would be in keeping with discussions here.

 

The photographer used a 35/2 ASPH with an M6.

 

That's the only picture in that story where I see the bit of unsharpness; but perhaps this was an effect already obvious on film, if we had looked.

 

??

 

--HC

[tashley]

Interesting picture relevant to this thread on pp 8-9 of LFI 3/2007.

 

It's my impression that although the center of the image is sharp, the field is a bit less so, particularly on the left side. That would be in keeping with discussions here.

 

The photographer used a 35/2 ASPH with an M6.

 

That's the only picture in that story where I see the bit of unsharpness; but perhaps this was an effect already obvious on film, if we had looked.

 

??

 

--HC

 

I see what you mean, though it could be that he has corrected perspective in PS. But one or two of the other shots in that series, all with the same lens, do look soft in the centre too. However without seeing the originals and not knowing other details we can't know. Tantalising though...

!!

 

Tim

[sean_reid]

That is a very interesting link and I thank you for it... very clear and detailed.

 

What it leaves unexplained is the Leica PDF for the 35 lux, which clearly shows the selected point of focus as remaining in focus as the F stop is reduced.

 

I can therefore conclude that either:

 

1) The marketing department has some say in the production of the DOF charts in the pre-sale information or...

 

2) There is something I have not understood - this is perfectly likely since I do not design lenses for a living, but I do test them, by using them or...

 

3) I have been sent two miscalibrated examples.

 

I may never know the answer but the questions interest me nonetheless!

 

Tim

 

One could also conclude that MTF, DOF etc. charts are not especially useful pieces of (electronic) paper.

 

Cheers,

 

Sean

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[sean_reid]

I got my new CV1.5 35mm pancake lens this morning as an attempt at finding a lens of this focal length that focusses well, and this lead to a little more testing and observations of the 35 Cron that I refer to in many of the above threads.

 

The good news is that the CV does focus correctly at all F stops, though like the 35 cron (

Tim

 

 

Just a quick clarification that the CV is a 35/2.5. In case people go searching.

 

Cheers,

 

Sean