Your thoughts about manual focus lenses on digital bodies..is it a good idea?

[mike_halliwell]

I simply use the focusing screen. I don't see reason to use a DSLR if I don't use the focusing screen.

Mainly because it can be incorrectly calibrated. Contrast detect AF can't be.

[BeBu Lamar]

Mainly because it can be incorrectly calibrated. Contrast detect AF can't be.

I use the focusing screen like an old manual SLR. There is no AF involved. That's the real reason for a single lens reflex.

[mike_halliwell]

I use the focusing screen like an old manual SLR

For some reason I though fully MF cameras still needed the focusing screen's focus position adjusted too.

 

After-all there's still the 'assumption' that the lightpath distance off the mirror, through/onto the screen, is optically exactly the same as the path directly to the film once the mirror has flipped up? There's little screws, and shims and everything!

 

Seems like you can visually nail focus with/on the focusing screen but in reality what hits the film can be OOF.

 

That involves precise calibration, Contrast Detect doesn't.... even if you manually rotate the lens, thus MF.

 

In effect, focusing a large format camera with a ground glass screen, in place of the film (plane), and a loupe is 'human powered' Contrast Detect MF.

[BeBu Lamar]

For some reason I though fully MF cameras still needed the focusing screen's focus position adjusted too.

 

After-all there's still the 'assumption' that the lightpath distance off the mirror, through/onto the screen, is optically exactly the same as the path directly to the film once the mirror has flipped up? There's little screws, and shims and everything!

 

Seems like you can visually nail focus with/on the focusing screen but in reality what hits the film can be OOF.

 

That involves precise calibration, Contrast Detect doesn't.... even if you manually rotate the lens, thus MF.

 

In effect, focusing a large format camera with a ground glass screen, in place of the film (plane), and a loupe is 'human powered' Contrast Detect MF.

 

Sure but if the camera is adjusted correctly there is no adjustment needed for each lens also it can't be done with software.

[kevin_beretta]

Sure but if the camera is adjusted correctly there is no adjustment needed for each lens also it can't be done with software.

This is true for the Df. I can focus it simply by sight, even without a split screen. This is practically impossible with my D850 and was with the D700. Still, the micro adjustment you can create by a just-off-centre setting between the solid green dot and one of the arrows is easier and quicker to dial in versus trying it manually.

[rodeo_joe1]

That's the real reason for a single lens reflex.

Really?

I thought it was for parallax-free viewing, regardless of what lens is fitted, with the 'near enough for film' focussing being a secondary bonus.

 

What a gritty ground-glass screen definitely isn't good for is pixel-perfect focussing on a high-res digital camera. Especially in dim light.

 

It's also pretty useless with any lens that suffers from stop-down focus shift, which is a good many wide aperture (i.e. f/1.4) lenses.

Edited February 15, 2021 by rodeo_joe|1

[mike_halliwell]

It's also pretty useless with any lens that suffers from stop-down focus shift

I wonder if actually allowing a lens to focus shift may help with some complex designs because it really doesn't matter anymore?.....:D

 

Mind you, I'm not sure when in the sequence of taking a pic with a mirrorless camera the sensor actually 'sees' the stopped-down view and can focus on it?? The viewing aperture seems pretty random.

[Dieter Schaefer]

Mind you, I'm not sure when in the sequence of taking a pic with a mirrorless camera the sensor actually 'sees' the stopped-down view and can focus on it??

I think it depends on both the actual camera model's focusing modes as well as the actual aperture being used. I just can't keep track of which model does what under which circumstances :confused:. IIRC then stopping down beyond f/5.6 or f/8 on some mirrorless will not happen until just before the shutter release; so AF will be at f/5.6 or f/8 in that case - whether that's relevant for focus shift I believe is rather doubtful though.

 

A lot of things are different on mirrorless compared to DSLRs - and I personally find it rather hard to keep track of all the "buts" and "ifs".

[BeBu Lamar]

Really?

I thought it was for parallax-free viewing, regardless of what lens is fitted, with the 'near enough for film' focussing being a secondary bonus.

 

What a gritty ground-glass screen definitely isn't good for is pixel-perfect focussing on a high-res digital camera. Especially in dim light.

 

It's also pretty useless with any lens that suffers from stop-down focus shift, which is a good many wide aperture (i.e. f/1.4) lenses.

That's the only reason why I wanted an SLR and not a rangefinder. I can focus simply by looking at the focusing screen at any point of the image. There is no focus/recompose thingy. Parallax isn't a problem for me as I don't compose very tightly. I didn't like the rangefinder because you always have to focust with the rangefinder patch at the center of the screen and recompose.

I treat digital like film. If I focus sharp enough for film it's enough for digital. Besides these manual focus lenses were designed to be used for film any way. I guess I don't change.

[chulster]

- I set all manual lenses to -10 and adjusted from there so that the right arrow and the green dot would flicker on focus. Setting that was the easiest part of the whole day, to my surprise. Makes focusing the manual lenses a snap.

 

I'm puzzled by this. Are all of your manual-focus lenses chipped? In my experience, unchipped lenses are not affected by AFFT. Even the "Default" AFFT setting has no effect on my unchipped MF lenses. On the other hand, with my chipped MF lens, I can use a "Saved value" AFFT setting just as with an AF lens.

[kevin_beretta]

My main manual focus lenses are a 40 mm f/2 Voigtlander and a 50 mm f/1.4 Zeiss Milvus. Both have electronic contacts but no AF motor. It's with those two I set the focus as described above.

[petrochemist]

I'm puzzled by this. Are all of your manual-focus lenses chipped? In my experience, unchipped lenses are not affected by AFFT. Even the "Default" AFFT setting has no effect on my unchipped MF lenses. On the other hand, with my chipped MF lens, I can use a "Saved value" AFFT setting just as with an AF lens.

The behaviour of chipped lenses is very much dependant on the camera. I don't think any of my cameras require a chip for full operation, including metering & any focus aids...

Chips help with IBIS if they give the camera correct focal length info, (there's always been a manual means of entering that) other than that they are quite unnecessary on Pentax DSLRs, MFT mirrorless & Sony mirrorless cameras.

[chulster]

The behaviour of chipped lenses is very much dependant on the camera. I don't think any of my cameras require a chip for full operation, including metering & any focus aids...

Chips help with IBIS if they give the camera correct focal length info, (there's always been a manual means of entering that) other than that they are quite unnecessary on Pentax DSLRs, MFT mirrorless & Sony mirrorless cameras.

 

Interesting; I didn't know that. By contrast, some Nikon digital cameras will disable their meters when a chipless lens is mounted—which, it should go without saying, also disables any form of autoexposure. But even the ones that have pretty good support for chipless lenses will not allow the use of AF Fine Tuning with them.

[mike_halliwell]

Chips help with IBIS if they give the camera correct focal length info

That kinda implies a more or less approach depending on focal length.

 

Surely you can't have too much IBIS, can you?

[BeBu Lamar]

Interesting; I didn't know that. By contrast, some Nikon digital cameras will disable their meters when a chipless lens is mounted—which, it should go without saying, also disables any form of autoexposure. But even the ones that have pretty good support for chipless lenses will not allow the use of AF Fine Tuning with them.

As I understand it Nikon AF fine tuning is to tune the lens and not to compensate for error due to mirror position etc.. and thus it's not applicable to manual lenses.

[mike_halliwell]

So how does the little dot and <> arrows work with fully manual, unchipped lenses??

[Dieter Schaefer]

Surely you can't have too much IBIS, can you?

From what I've read, IBIS works best if it knows the focal length of the lens. Understandably, a 20mm focal length might need corrections different from a 500mm focal length.

So how does the little dot and <> arrows work with fully manual, unchipped lenses??

On my D810 - just fine. Doesn't matter whether or not there are lenses listed in the non-CPU lens menu. I can influence the behavior of the "green dot" (actually white) and the arrows by changing the AF fine tune default value (quite a narrow margin though) - but I can't save the value. My only chipped manual focus lens is the IRIX 15/2.4 - there I had to resort to setting the AF fine tune parameter to -20 (which can be saved) in order to get the "green dot" to be in line with what I see on the focusing screen. The lens can be manually adjusted and I had plans to do so (even purchased the necessary screw driver) but never carried out the adjustment.

[rconey]

The < o > focus notification system on my D850 works pretty well with unchipped lenses. Obviously, live view and magnification is better, but that generally means a tripod.

[kevin_beretta]

The < o > focus notification system on my D850 works pretty well with unchipped lenses. Obviously, live view and magnification is better, but that generally means a tripod.

I guess the question now is whether the D850 will allow the saving of an off-set AF value (say -15) without a chipped lens? Does it remember the lens by mere number or does it needs to be chipped to recognize/remember the lens? I'd try on my D850 but I don't have a non-chipped lens...

[chulster]

I guess the question now is whether the D850 will allow the saving of an off-set AF value (say -15) without a chipped lens? Does it remember the lens by mere number or does it needs to be chipped to recognize/remember the lens? I'd try on my D850 but I don't have a non-chipped lens...

 

I maintain that AFFT has no effect with unchipped MF lenses. I have proven this to myself with a simple experiment:

 

Put the camera on a tripod and point it at a good, immobile AF target. Adjust the focus ring so that the center dot is blinking alternately with the right-side triangle, indicating slight back-focus. (Try to get the dot and the triangle blinking with some consistency.)

 

Now set Default AFFT to -20. (As you know, negative values are used to correct back-focus.) Look through the viewfinder again. Has the blinking rate changed between the center dot and the right-side triangle? In my test, the blinking rate did not change, indicating to me that the AFFT setting had no effect.

[mike_halliwell]

I just tried an ancient 28mm f2 Vivitar on my D500 and to my slight surprise the arrows are the wrong way.

 

They usually point the direction to rotate the focus ring... but not on this one. I guess it doesn't know it's backwards...:confused:

[rodeo_joe1]

So how does the little dot and <> arrows work with fully manual, unchipped lenses??

Very badly?

[Dieter Schaefer]

I maintain that AFFT has no effect with unchipped MF lenses. I have proven this to myself with a simple experiment:

 

Put the camera on a tripod and point it at a good, immobile AF target. Adjust the focus ring so that the center dot is blinking alternately with the right-side triangle, indicating slight back-focus. (Try to get the dot and the triangle blinking with some consistency.)

 

Now set Default AFFT to -20. (As you know, negative values are used to correct back-focus.) Look through the viewfinder again. Has the blinking rate changed between the center dot and the right-side triangle? In my test, the blinking rate did not change, indicating to me that the AFFT setting had no effect.

For me, on a D810, there was a clear difference between the AF fine tune parameters 0 and -20.

[Dieter Schaefer]

Very badly?

On that we can agree. I certainly can't use it for any kind of critical focusing.

[rconey]

Oooooh, you mean like an f1.4 lens set to f1.4 and a medium distance subject say wanting the eyes in focus? Yea, that is pretty tough without live view.