Author Topic: micro-nikkor Z  (Read 21749 times)

MEPER

  • NG Supporter
  • **
  • Posts: 1051
  • You ARE NikonGear
Re: micro-nikkor Z
« Reply #90 on: June 08, 2021, 23:33:08 »
It seems some expensive cinema lenses compensate for focus breathing by implementing a small zoom in their primes.
It is demonstrated here about 6 min. in the video. Nice lens....

https://www.youtube.com/watch?v=q1n2DR6H7mk&t=915s

David H. Hartman

  • NG Member
  • *
  • Posts: 2778
  • I Doctor Photographs... :)
Re: micro-nikkor Z
« Reply #91 on: June 09, 2021, 00:56:49 »
In other words, using "focus breathing" to fix "focus breathing" :o :)

I'm getting confused here! If I understand correctly a classic unit focusing lens has a longer as used focal length rear focus distance and therefore a narrower field of view as it focuses closer, e.g. a 105/4.0 Micro-Nikkor has a focal length of 105mm at infinity but a focal length rear focus distance of 210mm as used when focusing to 1:1 (helical plus PN-11). ???

It would seem that a little focus breathing is good, no focus breathing is bad and much focus breathing is really, really bad. Am I close?

Dave

I hope "rear focus distance" is the term I stumbled to find. I'm not sure the paragraph above makes any sense at this point.
Beatniks are out to make it rich
Oh no, must be the season of the witch!

Roland Vink

  • NG Supporter
  • **
  • Posts: 1523
  • Nikon Nerd from New Zealand
    • Nikon Database
Re: micro-nikkor Z
« Reply #92 on: June 09, 2021, 02:49:09 »
The focal length of unit-focusing lenses such as the 105/4 micro does not change when focusing. The focal length remains at 105mm whether at infinity, or 1:1 (with PN-11) or any other distance.  The reason the angle of view gets narrower when focusing closer is that the optical center of the lens gets further from the image plane. At infinity (no extension) it is 105mm from the image plane. At 1:1 the distance increases to 210mm (105mm of the lens itself, plus 105mm extension). That's where the 210mm comes from. Since the lens is further away from the sensor, the angle of view is narrower.

The point I was making is that the term "focus breathing" is used to describe two different things (which is confusing!) For still photography, when a lens focal length changes drastically when focusing, it is known as focus breathing. It usually shows as a reduction in focal length when focusing close, which means the framing is wider and the magnification is less than expected. For example, compare the 28-300 zoom @300m at close range, compared to a 300mm prime.

Video photographers usually want the framing and subject size to stay constant when focusing. If the framing expands or shrinks that is also known as focus breathing. This effect is not usually of concern in still photography. If a unit-focusing lens is used for video, the framing will change as explained above. To counter this, the lens focal length needs to change to compensate. So to fix focus breathing (video) you need a lens with focus breathing (stills)

It would be useful if we used different terms for these effects since they are quite separate...

Jack Dahlgren

  • NG Member
  • *
  • Posts: 1528
  • You ARE NikonGear
Re: micro-nikkor Z
« Reply #93 on: June 09, 2021, 04:30:19 »
The focal length of unit-focusing lenses such as the 105/4 micro does not change when focusing. The focal length remains at 105mm whether at infinity, or 1:1 (with PN-11) or any other distance.  The reason the angle of view gets narrower when focusing closer is that the optical center of the lens gets further from the image plane. At infinity (no extension) it is 105mm from the image plane. At 1:1 the distance increases to 210mm (105mm of the lens itself, plus 105mm extension). That's where the 210mm comes from. Since the lens is further away from the sensor, the angle of view is narrower.

The point I was making is that the term "focus breathing" is used to describe two different things (which is confusing!) For still photography, when a lens focal length changes drastically when focusing, it is known as focus breathing. It usually shows as a reduction in focal length when focusing close, which means the framing is wider and the magnification is less than expected. For example, compare the 28-300 zoom @300m at close range, compared to a 300mm prime.

Video photographers usually want the framing and subject size to stay constant when focusing. If the framing expands or shrinks that is also known as focus breathing. This effect is not usually of concern in still photography. If a unit-focusing lens is used for video, the framing will change as explained above. To counter this, the lens focal length needs to change to compensate. So to fix focus breathing (video) you need a lens with focus breathing (stills)

It would be useful if we used different terms for these effects since they are quite separate...

I have primarily heard "focus breathing" as a reference to angle of view changing while focusing. I believe this is what Nikon refers to as focus breathing as well. This is desired behavior for video, but also architectural photography or anything where subject framing is important. I have not heard the other use of the term, and would suggest that if a term is needed for that behavior it be something like focal length shift.

David H. Hartman

  • NG Member
  • *
  • Posts: 2778
  • I Doctor Photographs... :)
Re: micro-nikkor Z
« Reply #94 on: June 09, 2021, 05:19:37 »
The focal length of unit-focusing lenses such as the 105/4 micro does not change when focusing. The focal length remains at 105mm whether at infinity, or 1:1 (with PN-11) or any other distance.  The reason the angle of view gets narrower when focusing closer is that the optical center of the lens gets further from the image plane. At infinity (no extension) it is 105mm from the image plane. At 1:1 the distance increases to 210mm (105mm of the lens itself, plus 105mm extension). That's where the 210mm comes from. Since the lens is further away from the sensor, the angle of view is narrower.

This is a matter definition of terms. If you measure the 105/4.0 AI Micro when focused to infinity the focus distance from the rear principle point to the sensor is 105mm but it is only that when the lens is focused to infinity. When the 105/4.0 Ai Micro is focused to 1:1 the focus distance will be 210mm. Because the "focal length as used" has changed and the aperture's physical size has not changed the aperture ratio has to be recalculated. At infinity 105/26=4.0 and at 1:1 210/26=8.0. In my way of thinking the reason the angle of view is narrower when the 105/4.0 AI Micro is focused to 1:1 is because it is now a 210mm lens as used.

Dave

If at first you don't succeed change the subject: in days of old how did cinema photographers deal with focus breathing when using unit focusing lenses?   :)

Beatniks are out to make it rich
Oh no, must be the season of the witch!

simsurace

  • NG Member
  • *
  • Posts: 835
Re: micro-nikkor Z
« Reply #95 on: June 09, 2021, 09:16:30 »
Focal length is the distance from the optical center (rear principal plane to be precise) at which parallel incoming rays intersect. This does not change with a unit focusing lens. When the focal point is on the image plane, the lens is focused to infinity (from where light comes in parallel). If the focal length doubled as in your example while the lens is extending, it would still be focused at infinity!
Simone Carlo Surace
suracephoto.com

Erik Lund

  • Global Moderator
  • **
  • Posts: 6480
  • Copenhagen
    • ErikLund.com
Re: micro-nikkor Z
« Reply #96 on: June 09, 2021, 09:19:18 »
The Micro-Nikkor 105mm f/4 does not change focal length, the effective aperture changes as you focus closer, just like for the Bellows-Nikkor 105mm f/4
See the Nikon Instruction Manual here:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiuquqq_onxAhWi8-AKHRyLDvoQFjABegQIBBAE&url=http%3A%2F%2Fwww.nikonusa.com%2Fpdf%2Fmanuals%2Farchive%2FMicro-Nikkor%2520105mm%2520f-4.pdf&usg=AOvVaw0R2L7p-Xcb7KAFvu3qxmz0

And the Mir site for some nice details as well:

https://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/micronikkor/105mmicrof4.htm
Erik Lund

David H. Hartman

  • NG Member
  • *
  • Posts: 2778
  • I Doctor Photographs... :)
Re: micro-nikkor Z
« Reply #97 on: June 09, 2021, 12:15:44 »
What is happening inside the camera is the inverse square law of light in action. The lens is the light source for the sensor. If you double the distance of the lens from your sensor then the level of light falling on your sensor is 1/4 of what it was at the closer distance. The image projected by the lens covers 4/1 times the area when the lens is moved twice as far from the sensor. The image sensor crops 1/4 of the image projected.

The illustration at this site may help...

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/isql.html

Try thinking of r in the illustration as 105mm and 2r 210mm. The image sensor doesn't change size so it will sample only 1/4 of the area. I know the illustration is a section of a sphere and the sensor is flat but this is the best I can do.

...alternately you might scratch your head and wonder what is wrong with Dave. :)
Beatniks are out to make it rich
Oh no, must be the season of the witch!

simsurace

  • NG Member
  • *
  • Posts: 835
Re: micro-nikkor Z
« Reply #98 on: June 09, 2021, 12:56:15 »
Try thinking of r in the illustration as 105mm and 2r 210mm. The image sensor doesn't change size so it will sample only 1/4 of the area. I know the illustration is a section of a sphere and sensor is flat but this is the best I can do.

...alternately you might scratch your head and wonder what is wrong with Dave. :)

You are right about the reason for the lower brightness. It was just the claim that the unit focusing lens changes focal length when being extended that I (and also Erik) objected to. Actually, the unit focusing design is the only one that GUARANTEES that focal length will remain constant throughout the focusing range (all lenses including the focal point are just moving together as a unit) :).
Simone Carlo Surace
suracephoto.com

Bern

  • NG Member
  • *
  • Posts: 89
  • You ARE NikonGear
Re: micro-nikkor Z
« Reply #99 on: June 09, 2021, 15:30:01 »
This thread has been very informative.

My apologies if this question might go off topic a little... Is this version (105mm f/4 micro) the only one with a unit focusing design? The succeeding versions did not use the unit focusing design approach? Lastly, what information would be needed to somehow determine if focus breathing/ focal length reduction occurs in a particular macro lens?

Thanks,
Bern
Keep shooting,
Bern

simsurace

  • NG Member
  • *
  • Posts: 835
Re: micro-nikkor Z
« Reply #100 on: June 09, 2021, 15:34:12 »
Have a look at http://www.photosynthesis.co.nz/nikon/specs.html#105Micro

It seems that starting from the 105/2.8 Ai-s, which introduced CRC (close-range correction), the micro lenses stopped being unit focusing.

Quote
Lastly, what information would be needed to somehow determine if focus breathing/ focal length reduction occurs in a particular macro lens?
Without mounting it on the camera? It is theoretically possible to infer from the lens diagram, but would probably require a lot of practice or a ray tracing program.
Simone Carlo Surace
suracephoto.com

David H. Hartman

  • NG Member
  • *
  • Posts: 2778
  • I Doctor Photographs... :)
Re: micro-nikkor Z
« Reply #101 on: June 09, 2021, 23:07:49 »
The 55/2.8 AIS Micro-Nikkor introduced in 1979 was the first Micro-Nikkor to have floating elements. At least I'm not aware of any Micro-Nikkors before the 55/2.8 AIS that had floating elements, internal focus or other hybrid optical designs. I believe the 105/4.0 UV Nikkor from 1985 was the last unit focusing Micro-Nikkor. According to Roland Vink's site the prototype UV Nikkor was badged "Micro" while the production lenses were not.

Dave
Beatniks are out to make it rich
Oh no, must be the season of the witch!

Roland Vink

  • NG Supporter
  • **
  • Posts: 1523
  • Nikon Nerd from New Zealand
    • Nikon Database
Re: micro-nikkor Z
« Reply #102 on: June 09, 2021, 23:38:29 »
My apologies if this question might go off topic a little... Is this version (105mm f/4 micro) the only one with a unit focusing design? The succeeding versions did not use the unit focusing design approach? Lastly, what information would be needed to somehow determine if focus breathing/ focal length reduction occurs in a particular macro lens?
Almost any lens which has different groups of elements moving in relation to each other during focusing will have some change in focal length. That includes zooms and lenses with floating elements (close range correction), inner focusing, rear focusing, and front focusing (font groups moves for focusing while rear remains stationary - most kit zooms are like this)

The amount of focal length change varies from lens to lens, in some cases it is insignificant, in others it can be quite dramatic. The macro lenses from Nikon up to the 1970s, including the 55/3.5 and 105/4 are all unit focusing so have no change in focal length when focusing. All the macro lenses starting with the AIS 55/2.8 and AIS 105/2.8 have close range correction so have some focal length change. The AIS 55/2.8 is unusual in that the focal length increases when focused close.

MEPER

  • NG Supporter
  • **
  • Posts: 1051
  • You ARE NikonGear
Re: micro-nikkor Z
« Reply #103 on: June 10, 2021, 00:09:10 »
We discuss two topics now?
Change in focal length and focus breathing?

I put my AIS 105/4 micro on camera and this lens has focus breathing (I can see that even hand hold).
But I think that is quite obvious why it has focus breathing. It would need a change in focal length during focusing to avoid that like the cine lens "prime" which also zooms a bit when it is focused?

David H. Hartman

  • NG Member
  • *
  • Posts: 2778
  • I Doctor Photographs... :)
Re: micro-nikkor Z
« Reply #104 on: June 10, 2021, 01:36:55 »
The AF-S 105/2.8G IF-ED VR Micro-Nikkor is said to have serious focus breathing. I don't think I've ever used this lens on a tripods so I haven't noticed focus breathing as a problem. It's also large and bulky so I don't like it hanging off my camera while on a tripod. VR reduces the need for a tripod. I probably checked and confirm the focus breathing long ago. 8)

Lenses like the 105/4.0 AI and 105/2.8 AIS Micro-Nikkor can be used with a macro slider when on a tripod so breathing isn't so much of a problem. I use a long Wimberley C-30 Arca-Swiss style clamp with a lens plate or camera cross plate as a macro slider. The slider reduces the need to move your tripod. The image ratio is set first and then the camera and lens are moved together to achieve focus. It really helps to know the image ratio you'll need to fill the frame. A programmable scientific calculator or computer spread sheet can help, e.g. if your subject is 50mm long and you want it to be 25mm long on the sensor or film then you'll use a ratio of 1:2. You measure or estimate the subject size, determine how big it should be on the image sensor and let the program or spread sheet calculate the image ratio and subject distance.

I wrote a program for an HP-15C scientific calculator to make setting up a view camera easy. You would measure the subject and determine how large you wanted the image on film and the program would give you the bellows draw and lens to subject distance. The program also gave the exposure compensation needed when using a hand hand held light meter. You'd set your tripod and you'd almost be there. Only a little touch up would be needed.

Dave

Does anyone have the new 105mm Micro-Nikkor in Z mount?

I'm willing to be jealous.
I'm wanting to be jealous.
I'm waiting to be jealous.
Beatniks are out to make it rich
Oh no, must be the season of the witch!