Paperman you know EXACTLY what I mean when I said "resolution". You need to accept that not everyone will agree on "resolution", "sharpness", "video", "bokeh", etc. etc. This thread was suppose to be about D5100 impressions and you guys took it way off course.

Then you must consider the second part of my sentence :

" ... And I'm sure he would have noticed in his visor if the lens reached infinity at a mark earlier than infinity . ( He's obviously not using the infinity marking on the lens to find focus but looking thru his visor ) ".

---------

I was sure but I did go and check focus marks on my old FF lenses ( one Af , one MF ) - if the measured distance matched the focused distance marking on the lens ( on my D300 ) . They all did ; 50cm was 50 cm , 3 m was 3m , 7m was 7m on both of them .

So old FF lens on cropped D300 - correct distance reading as I expected .

DOF part of the argument is true but cropped sensor has no effect on marked distances on FF lenses.

Paperman said:
And I'm scratching my head to say why it doesn't make sense .

Vidrazor has a problem of not being able to reach infinity focus when he runs to the end of the lens. ( he needs to be able to go more ) . So he can't go past it anyways to a mark past the infinity mark . And I'm sure he would have noticed in his visor if the lens reached infinity at a mark earlier than infinity . ( He's obviously not using the infinity marking on the lens to find focus but looking thru his visor )

It is actually shorter focus not beyond infinity. Crop brings the image in closer.

TaoTeJared said:
I'm scratching my head - running out of ways to describe it. You line up the infinity focus on the aperture points. Make since?

And I'm scratching my head to say why it doesn't make sense .

Vidrazor has a problem of not being able to reach infinity focus when he runs to the end of the lens. ( he needs to be able to go more ) . So he can't go past it anyways to a mark past the infinity mark . And I'm sure he would have noticed in his visor if the lens reached infinity at a mark earlier than infinity . ( He's obviously not using the infinity marking on the lens to find focus but looking thru his visor )

And Nikodoby , I know our stars will never align :-) .... However ,

- the subject was not resolution at all but diffraction ( at what aperture it starts )
- but we are way past discussing that as well . TaoJaRed is suggesting how to get the focus right on the D5100 with the manuel lens - the exact subject . And I am just not aggreeing with that.

Niko - Can you move the hyperfocal discussion to a new thread? It's a good piece of info. :)

Here we go again! Why can't we ever have a resolution discussion in this forum without turning it into a long back and forth. Back on topic, a.k.a the D5100.

Paperman said:
I see what you mean ... But again it's got to do with DOF and not with the actual focus point.

I'm scratching my head - running out of ways to describe it. You line up the infinity focus on the aperture points. Make since?

I see what you mean ... But again it's got to do with DOF and not with the actual focus point.

I meant not to stop the aperture down, but the alignment of the DOF for the infinity symbol to be aligned on the lens.

It should only be a problem when the scales on the lens are used for DOF calculation. Todays's Hyperfocal & DOF calculators require one to add the crop factor as one of the variable's in addition to distance,focal length and aperture information.

It is the exact focus point vidrazor seems to be not finding ; he's not suffering from the "should be in focus " part within the DOF range. So I don't see how his problem can be relevant .

I don't get the last part at all - focus shifting with aperture ?

We may have jumped way off but in doing so, I think we may have an answer to OPs question. Clicking through reference items to the article you reference I found a piece of info all of us have missed.

It's not the depth to the sensor, it is the crop of the sensor. (Makes since - it is the only variable that changed.)

The Crop Factor's Effects on Hyper-focal focus. (This will make your heads hurt!)

Now comes the problem: the sensor of the M8 is cropped. How does it affect the hyperfocal distance and depth of field in general? A bit of mathematics will help us here. The DoF of a particular camera can be approximated in different ways, but we find particularly useful this expression:

DoF = (2 * H * s2) / (H2 - s2) for H > s

The DoF depends on the hiperfocal distance (H) and the distance to the subject (s). The hiperfocal distance is the focus distance that maximizes the DoF. The hiperfocal distance and the deph of field have an inverse relationship. When s approaches H, DoF tends to infinite. We can calculate the hiperfocal distance from

H = L2 / (f * CoC)

Where L is the focal length, f is the aperture number and CoC is the circle of confusion. The circle of confusion is a conventional value. It depends on the size of the sensor, the size of the print and the particular vision capabilities and subjectivity of the observer.

Basically what the math tells you and what they showed with Leica's crop is that the hyperfocal distance changed due to the crop. (Leica shooters and many street photogs use the scales and noticed the shift.)

@vidrazor
- set your Infinity focus at 1.5 stops down, (i.e. f/11 (film markings) to about 7.5-7.75) and try that. F/8 would be at about f/5ish. (I'm rounding in my head so forgive me on not being precise.) I'll try to find the data and do the math tonight to see what the exact #s are. Oddly enough, this is almost at the IR mark if I'm not mistaken.

We are sliding off the topic but here is some more from me .

TaoTeJared said:
I enjoy Luminous Landscapes but sometimes their articles get a little dated ...

We are not allowed to provide links but the LL article ( do sensors outresolve lenses ? ) can be considered recent ; many of today's 15-25 Mp cameras are mentioned .

Even though most of the math is beyond a normal person's understanding, it is stated that the calculations are based on a diffraction free top class lens ( a CZ prime maybe ) and that results taken with other lenses will not reach these resolution figures . The rest of the assumptions are based on the accepted maximum capacity of the human eye / circle of confusion etc . They are all maximums !

So it can't really be argued that less diffraction & better results with other lenses are possible when the figures stated are theoretical & for best case scenarios.

Another link is from Nikon Rumors Guest posts - pls check http://nikonrumors.com/2010/11/27/guest-post-shooting-products-with-nikon-tilt-lenses.aspx/ . See how the images detoriate on a D3x at smaller apertures.

TaoTeJared said:

I couldn't find the tables but I see diffraction from my D50 6mp sensor at F/8 with my 50mm just as I do with my D300. ...

Your findings match exactly with the LL findings . Table showing Mpixel equivelant (table 3 )indicates that diffraction at f8 can only be detected in an APS-C size sensor camera at 13 Megapixels and over . Both the D40 and D300 are below that .

TaoTeJared said:
Sorry, but experience says "Ummmmm No". This is when you know the math is oversimplified and the article is dated. I like their newer examples taken with a 39mp Medium Format camera...

The math is not oversimplified and findings are not dated . And someone from LL has actually done his own diffraction test with a 39 Mp PhaseOne backed Linhof ( please look for "understanding lens diffraction , Luminious Landscapes " ).He has noted diffraction starting at f11 and that is with a Medium Format sensor ! His finding matches well with the Medium Format/ f11/ 31 Mp figure in LL diffraction table .

The fact that you are not picking any diffraction until f20 doesn't mean it is not there . Your work may not be requiring you to get too close into details & sharpness but make sure - it is there .

Maybe we need a diffraction subject :-)

It would be interesting to learn or hear from Nikon/Canon/Zeiss/Leica lens designers and how they design lenses to handle diffraction and a whole host of other items. The assumption of all the calculations is that all lenses and their elements & designs are constant - which we all know is not true. I enjoy Luminous Landscapes but sometimes their articles get a little dated and are based around Canon and other cameras. (Nothing wrong with that just interesting to see what Canon doesn't focus on that Nikon does and at other times it is difficult to relate with the gear used.)

I couldn't find the tables but I see diffraction from my D50 6mp sensor at F/8 with my 50mm just as I do with my D300. I'm guessing that is what they may test with. With my 105vr and 60mm macro - I don't see it until f/20+ due to the vastly different lens designs and how they handle CAs and diffraction. Lens designs make huge differences in what f-stop diffraction will appear. F/8 on most variable zooms are the optimum.

Paperman said:
At f16 , the equivelant quality of the resulting image is calculated to be 3Mpixel regardless of the Mp it is taken . And that is for the perfect lens ! If we are talking FF and not APS-C , it improves but is still around 7Mp ( according to luminous landscapes tables ).

Sorry, but experience says "Ummmmm No". This is when you know the math is oversimplified and the article is dated. I like their newer examples taken with a 39mp Medium Format camera. There are tons of articles out there usually written about the same time a new camera comes out, that goes along the lines of:
-"This is all you will ever need"
or
-"You don't need something new because these mathematical equations I found (but really don't understand) tells me that your images just will not get better than this, and may actually become worse."

Then those articles sit out there for years, collect dust and are never updated by the original poster. I have actually see some of these, where the MP of sensors where the only things changed and re-posted 4 years later while leaving the old one up. And then people debated the two articles endlessly which "MP resolution was the limit". I thought they should have verbally strung up the guy who left the math and changed the MP numbers. (Oh and the Math really didn't make any since either.)

Either way, I don't think the OP's photos have diffraction so bad to make that much of a difference.

TaoTeJared said:
I have rarely if ever, seen diffraction at anything lower than F/16 and that is only on f/1.4 lenses that are optimized to shoot wide open.

A bit off the subject but believe me the diffraction is there . The diffraction calculations are made theoretically using circle of confusion / airy disks etc taking into account what the eye can detect . The lenses considered are "perfect" lenses - diffraction limited lenses meaning the quality loss in these lenses can originate only from diffraction .

So if all those diffraction tables point to diffraction starting at f8 for APS-C sensor size cameras ( detectable by a 13 Mp sensor ) , then it means that it is as good as it gets - that is the diffraction limit for the near perfect lens . From there unforunately , the only way is down depending on the lens you have .

As you know the diffraction is always there at anything smaller than the widest aperture ; the matter is how much of if it can be detected by the camera sensor used . Thus the lenghty complex calculations for determinig at what f-stop a sensor is prone to diffraction.

At f16 , the equivelant quality of the resulting image is calculated to be 3Mpixel regardless of the Mp it is taken . And that is for the perfect lens ! If we are talking FF and not APS-C , it improves but is still around 7Mp ( according to luminous landscapes tables ).

There may be a bit more play between bodies but I seriously doubt it. Almost every lens I have will focus a smidgen past infinity. I have noticed atmospheric and even temperature conditions can also play with what infinity truly equals and can been seen in distant objects. I never could see this with film but it does show with digital easily.

The plane can be calibrated but as you showed there is nothing wrong with your new lenses so I'm not sure what you want it calibrated too. If you are going to use the old lenses all the time, I would get them re-calibrated to your camera not the other way around.

>>I searched the rest of the internet. I saw thread after thread mentioning the 105mm f/2.5 and the 75-150mm not focusing at infinity on the Non AF bodies...<<

Interestingly the 105 was softer than the other optics, but all the MF optics were off-focus at infinity. Unfortunately this weekend was bad for infinity test shots here in the NYC area, but the next few days look good.

>>I have been shooing with a couple of my MF lenses today on my D300 and didn't see any issues with infinity focus.<<

My gut feeling is that this is a by-product of the cheaper bodies production. I'm convinced it's designed right into the mass-production process to get "close enough" at infinity focus and allow the AF optics to compensate.

I wonder however if the sensor plane position can be (re)calibrated after production.

I also believe the higher-end models are better calibrated for infinity focus, probably by virtue of having metal frames alone. The D300 is a step up in the Nikon food chain in this respect, so I'm not surprised you didn't have any issues with this. In addition to the tests I plan to do, I would love to test my optics (at least, the AI ones) on a higher-end body to see if the same issue arises. I believe it won't.

I have rarely if ever, seen diffraction at anything lower than F/16 and that is only on f/1.4 lenses that are optimized to shoot wide open.

vidrazor said:
As a general rule of thumb, 2-3 stops down from a lenses maximum aperture is the "sweet spot" of optimum aperture...

+1 F8 Should be good.

Oddly enough, I have been shooing with a couple of my MF lenses today on my D300 and didn't see any issues with infinity focus. Seeing this thread again, I searched the rest of the internet. I saw thread after thread mentioning the 105mm f/2.5 and the 75-150mm not focusing at infinity on the Non AF bodies (D40,40x,60,3000,3100,5000) and even the D70 series. I did run across one where it infinity was out of focus on a D40 but on his D200 it was fine. That was odd.

No real hard facts on anything except 2 lines (conveyed with slight differences) over and over.

"Infinity focus is only a guide - infinity does not mean everything is in perfect focus."
&
"Millimeters of focus change at long distances will make anything bury."

>>No horrid lens, the Nikon 24-70mm F2.8G starts to suffer from diffraction at F8 for example, as does the 35mm F1.4G.<<

As a general rule of thumb, 2-3 stops down from a lenses maximum aperture is the "sweet spot" of optimum aperture, and anything after that will start to induce diffraction. For example on both of the lenses I showed here, they were more or less in their optimum aperture.

PB PM said:
If you look at the mount there is a small tab sticking out. That tab is used with AI-S and AI lenses for metering purposes, it basically tells the camera what F stop the lens is set to. That is why you can input non-CPU lens data, and the camera knows what F stop is being used. Mounting a non-AI lens could cause that tab to break off or be damaged.

PB PM: Many thanks: a picture usually stands for more than thousand words :)

I guess you need to be "brute" in order to break that tinny tab. Now with your explanation, I know the limitations/features the D7000 has :)

A bit late in to this discussion.. but I agree that it is possible that the lens vs D5100 combo may be just that little bit off.. if you look at all the modern lenses they all focus past infinity. It would seem very logical to me that that was done to improve focus capability on focal planes that were slightly off. (would only need to be off by a few micro meters.) It would seem entirely possible to me that the modern manufacturing processes are much less exacting than in the old MF years as the cost to manufacture one of those old cameras was relatively many times more. It would seem logical to me that the modern systems compensate for this electronically and with lenses that focus past infinity.

Paperman said:
Couldn't find much in the PZ site on f8 diffraction - only some suggestions in forums . Don't get me wrong ; I'm curious because shooting only landscapes & always trying to find the balance between best DOF and minimum diffraction, I have been in time become a diffraction freak . I wouldn't mind taking in as much info as possible on what you said ; can point out what you are referring to? Are you talking about some horrid lenses ? I mean , if you are not safe at f8 , what are you safe at ?

In any case, we can't expect an f8 diffraction to cause the extensive "damage" in vidrazor's photo - if it were f22 , maybe .

No horrid lens, the Nikon 24-70mm F2.8G starts to suffer from diffraction at F8 for example, as does the 35mm F1.4G. The amount of diffraction is minimal, and as you pointed out it isn't a real issue until you are stopped way down. It wouldn't be enough on most modern lenses until F16 or more. With older lenses, being out resolved along with some diffraction could cause issues, but that doesn't seem to be the case here.

vidrazor said:
>>Diffraction is possible at F8, it depends on the lens. Some modern FX lenses suffer from diffraction at F8 (check photozone for examples) so there is no reason to believe the same cannot be true for old lenses as well. <<

True, but I get the same out-of-focus image at infinity at F5.6, 4, 2.8, and 2 (larger apertures depending on the optic). I haven't shot at smaller apertures yet. I'll see if I can do some more tests over the weekend.

Right, sounds like that isn't the problem then. I made that post because I never like to discount anything, just because it isn't normal.

PB PM said:
Diffraction is possible at F8, it depends on the lens. Some modern FX lenses suffer from diffraction at F8 (check photozone for examples) so there is no reason to believe the same cannot be true for old lenses as well.

Couldn't find much in the PZ site on f8 diffraction - only some suggestions in forums . Don't get me wrong ; I'm curious because shooting only landscapes & always trying to find the balance between best DOF and minimum diffraction, I have been in time become a diffraction freak . I wouldn't mind taking in as much info as possible on what you said ; can point out what you are referring to? Are you talking about some horrid lenses ? I mean , if you are not safe at f8 , what are you safe at ?

In any case, we can't expect an f8 diffraction to cause the extensive "damage" in vidrazor's photo - if it were f22 , maybe .

rbid said:
I'm here to learn as well...

Can you explain again, I guess the AI index is some mechanical or a contact.. Is this true?

Maybe this image will help (D700 used as an example).

If you look at the mount there is a small tab sticking out. That tab is used with AI-S and AI lenses for metering purposes, it basically tells the camera what F stop the lens is set to. That is why you can input non-CPU lens data, and the camera knows what F stop is being used. Mounting a non-AI lens could cause that tab to break off or be damaged.

The D40, D40x, D60, D3000, D3100, D5000 and D5100 do not have that metering tab, so they can mount non-AI lenses.

>>Diffraction is possible at F8, it depends on the lens. Some modern FX lenses suffer from diffraction at F8 (check photozone for examples) so there is no reason to believe the same cannot be true for old lenses as well. <<

True, but I get the same out-of-focus image at infinity at F5.6, 4, 2.8, and 2 (larger apertures depending on the optic). I haven't shot at smaller apertures yet. I'll see if I can do some more tests over the weekend.