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Prime lenses with internal focus or rear focus?
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PostPosted: Mon Jan 11, 2021 8:42 pm    Post subject: Prime lenses with internal focus or rear focus? Reply with quote
Hello everyone, I am on a lookout for lenses that feature internal focusing and rear focusing.

I found info about Nikon and Canon using IF and RF in their nomenclature to signify these. But I am nto sure how to even find lenses that work liek this.

For example the Nikon 24mm 1.4 ED lens is reaf focusing, and so is the 28mm 1.4. But they do not have the RF in their names.

Does anyone know of lenses from Nikon and Canon or other manufacturers, that would be internal or rear focusing? I am looking for 35-50 range at the moment.

Thank you!


PostPosted: Mon Jan 11, 2021 10:56 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
My Rokinon (Samyang) AS UMC 50mm f/1.4's elements move internally as a unit when focusing. The barrel length doesn't change.
https://www.pentaxforums.com/userreviews/rokinon-50mm-f14-as-if-umc.html


And I don't own Samyang's 35mm f/1.4 lens, but I'd expect it would also have internal focusing.
(My Samyang 8mm, 14mm and 85mm lenses also have internal focusing.)


PostPosted: Tue Jan 12, 2021 11:23 am    Post subject: internal focus Reply with quote
You asked about other manufacturers,

Angenieux made two internally focussing long lenses as the last ones before they ceased production for the amateur photo market. In spite of one critical opinion in the sum of French reviews at the time, I find the 180mm f2,3 "APO-DEM" quite good, but it is bulky and heavy. The internal focus system means that it is easy to focus even in minus 10C while the focus ring of their original 180 gets a bit heavy to turn in midwinter-

p.


PostPosted: Tue Jan 12, 2021 3:20 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
55 wrote:
My Rokinon (Samyang) AS UMC 50mm f/1.4's elements move internally as a unit when focusing. The barrel length doesn't change.
https://www.pentaxforums.com/userreviews/rokinon-50mm-f14-as-if-umc.html


And I don't own Samyang's 35mm f/1.4 lens, but I'd expect it would also have internal focusing.
(My Samyang 8mm, 14mm and 85mm lenses also have internal focusing.)


The Samyang 50 f1.4 is not a true internal focusing design (i own all the lenses i am mentioning), both the rear and front optical groups move as you focus, but it s true that the front optical group stays within the lens barrel. The 35 f1.4 is the same and it s also a floating design (the two optical groups move a different amount), same is valid for the 135 f2. The Samyang 85 f1.4 and the 24 f1.4 can be called an internal focusing design, only the rear group moves, the front group is static. The only true internal focusing Samyang is the 14 f2.8, when focusing nothing moves outside meaning some internal lens element are moved to achieve focusing.


PostPosted: Tue Jan 12, 2021 4:38 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
tomasg wrote:
55 wrote:
My Rokinon (Samyang) AS UMC 50mm f/1.4's elements move internally as a unit when focusing. The barrel length doesn't change.
https://www.pentaxforums.com/userreviews/rokinon-50mm-f14-as-if-umc.html


And I don't own Samyang's 35mm f/1.4 lens, but I'd expect it would also have internal focusing.
(My Samyang 8mm, 14mm and 85mm lenses also have internal focusing.)


The Samyang 50 f1.4 is not a true internal focusing design (i own all the lenses i am mentioning), both the rear and front optical groups move as you focus, but it s true that the front optical group stays within the lens barrel. The 35 f1.4 is the same and it s also a floating design (the two optical groups move a different amount), same is valid for the 135 f2. The Samyang 85 f1.4 and the 24 f1.4 can be called an internal focusing design, only the rear group moves, the front group is static. The only true internal focusing Samyang is the 14 f2.8, when focusing nothing moves outside meaning some internal lens element are moved to achieve focusing.


Amazing, thank you. Yes this is what I was asking for. I am looking for lenses that are longer then 30mm, and under 100mm to build a set of these for a very specific application. I would be happy with a 35, 50 and 85 for example.FLoating design is not what I'm interested, I need the front of the lens stay put, no matter if it focuses itnernally or via the rear group.


PostPosted: Tue Jan 12, 2021 4:45 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
redimp wrote:
tomasg wrote:
55 wrote:
My Rokinon (Samyang) AS UMC 50mm f/1.4's elements move internally as a unit when focusing. The barrel length doesn't change.
https://www.pentaxforums.com/userreviews/rokinon-50mm-f14-as-if-umc.html


And I don't own Samyang's 35mm f/1.4 lens, but I'd expect it would also have internal focusing.
(My Samyang 8mm, 14mm and 85mm lenses also have internal focusing.)


The Samyang 50 f1.4 is not a true internal focusing design (i own all the lenses i am mentioning), both the rear and front optical groups move as you focus, but it s true that the front optical group stays within the lens barrel. The 35 f1.4 is the same and it s also a floating design (the two optical groups move a different amount), same is valid for the 135 f2. The Samyang 85 f1.4 and the 24 f1.4 can be called an internal focusing design, only the rear group moves, the front group is static. The only true internal focusing Samyang is the 14 f2.8, when focusing nothing moves outside meaning some internal lens element are moved to achieve focusing.


Amazing, thank you. Yes this is what I was asking for. I am looking for lenses that are longer then 30mm, and under 100mm to build a set of these for a very specific application. I would be happy with a 35, 50 and 85 for example.FLoating design is not what I'm interested, I need the front of the lens stay put, no matter if it focuses itnernally or via the rear group.


I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


PostPosted: Tue Jan 12, 2021 4:54 pm    Post subject: Reply with quote
I believe the Super Yashinon-R 35mm f/2.8 that I used to have, focusses with the rear elements.


PostPosted: Tue Jan 12, 2021 5:01 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
tomasg wrote:

The Samyang 50 f1.4 is not a true internal focusing design . . .

Interesting. Thanks for the information, tomasg.


redimp wrote:

Amazing, thank you. Yes this is what I was asking for . . .

Glad to hear it. Good luck!


PostPosted: Tue Jan 12, 2021 5:30 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
visualopsins wrote:

I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


I don't think that is true. Nikon on their website clearly distinguishes between IF and RF lenses. They just don't list what actual lenses fall into each category, haha


PostPosted: Tue Jan 12, 2021 5:45 pm    Post subject: Reply with quote
Some of these lenses have internal focus.

http://www.adaptall-2.com/lenses/SP_Adaptall-2_LensIndex.html


PostPosted: Tue Jan 12, 2021 6:23 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
visualopsins wrote:
redimp wrote:
tomasg wrote:
55 wrote:
My Rokinon (Samyang) AS UMC 50mm f/1.4's elements move internally as a unit when focusing. The barrel length doesn't change.
https://www.pentaxforums.com/userreviews/rokinon-50mm-f14-as-if-umc.html


And I don't own Samyang's 35mm f/1.4 lens, but I'd expect it would also have internal focusing.
(My Samyang 8mm, 14mm and 85mm lenses also have internal focusing.)


The Samyang 50 f1.4 is not a true internal focusing design (i own all the lenses i am mentioning), both the rear and front optical groups move as you focus, but it s true that the front optical group stays within the lens barrel. The 35 f1.4 is the same and it s also a floating design (the two optical groups move a different amount), same is valid for the 135 f2. The Samyang 85 f1.4 and the 24 f1.4 can be called an internal focusing design, only the rear group moves, the front group is static. The only true internal focusing Samyang is the 14 f2.8, when focusing nothing moves outside meaning some internal lens element are moved to achieve focusing.


Amazing, thank you. Yes this is what I was asking for. I am looking for lenses that are longer then 30mm, and under 100mm to build a set of these for a very specific application. I would be happy with a 35, 50 and 85 for example.FLoating design is not what I'm interested, I need the front of the lens stay put, no matter if it focuses itnernally or via the rear group.


I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


Yes i know that, out of my head i also can t think of any other lens that moves only the rear group, i think that technically it s more correct when some internal elements are moved only, Samyang marks some of their lenses as internal focusing which in a way is also correct i guess. None of the Samyangs i own changes it s physical length as you focus, the distance between the mount and filter thread remains the same. The Samyangs construction is different than most vintage lenses, there aren t threaded helicoids but "tubes with grooves" (sorry for my english) the optical groups are moved via "rollers" like in zoom lenses, they are also very large for what they are, especially the 50 f1.4 for example.


PostPosted: Tue Jan 12, 2021 6:25 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
redimp wrote:
tomasg wrote:
55 wrote:
My Rokinon (Samyang) AS UMC 50mm f/1.4's elements move internally as a unit when focusing. The barrel length doesn't change.
https://www.pentaxforums.com/userreviews/rokinon-50mm-f14-as-if-umc.html


And I don't own Samyang's 35mm f/1.4 lens, but I'd expect it would also have internal focusing.
(My Samyang 8mm, 14mm and 85mm lenses also have internal focusing.)


The Samyang 50 f1.4 is not a true internal focusing design (i own all the lenses i am mentioning), both the rear and front optical groups move as you focus, but it s true that the front optical group stays within the lens barrel. The 35 f1.4 is the same and it s also a floating design (the two optical groups move a different amount), same is valid for the 135 f2. The Samyang 85 f1.4 and the 24 f1.4 can be called an internal focusing design, only the rear group moves, the front group is static. The only true internal focusing Samyang is the 14 f2.8, when focusing nothing moves outside meaning some internal lens element are moved to achieve focusing.


Amazing, thank you. Yes this is what I was asking for. I am looking for lenses that are longer then 30mm, and under 100mm to build a set of these for a very specific application. I would be happy with a 35, 50 and 85 for example.FLoating design is not what I'm interested, I need the front of the lens stay put, no matter if it focuses itnernally or via the rear group.


YW, the only thing i don t like about my Samyangs it s their size.


PostPosted: Tue Jan 12, 2021 6:49 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
redimp wrote:
visualopsins wrote:

I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


I don't think that is true. Nikon on their website clearly distinguishes between IF and RF lenses. They just don't list what actual lenses fall into each category, haha


and you know some RF designated lenses are for Rangefinder cameras...

Could you point to one of those Nikon RF pages please?


PostPosted: Tue Jan 12, 2021 7:34 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
visualopsins wrote:
redimp wrote:
visualopsins wrote:

I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


I don't think that is true. Nikon on their website clearly distinguishes between IF and RF lenses. They just don't list what actual lenses fall into each category, haha


and you know some RF designated lenses are for Rangefinder cameras...

Could you point to one of those Nikon RF pages please?


This is where they explai nthe terms https://www.nikon.co.in/en_IN/learn_and_explore/glossary.page#rf


PostPosted: Tue Jan 12, 2021 7:47 pm    Post subject: Reply with quote
Also to add to the comments above – Samyang is not internal focus for the 50mm fom what I see. The fact that barrel stays fixed does not mean internal focus, merketing people do misuse the term though.

What I am looking for is lenses in Normal range (not suepr wide, not tele) that focus with their front GLASS elements not moving at all.

Examples are Nikon 24 1.8 and 28 1.8 as described here https://photographylife.com/nikon-lens-nomenclature

Lenses from Nikon that feature rear focusing – 24, 28, 25 from this series: https://photographylife.com/reviews/nikon-35mm-f1-4g

Also all new Z series primes, and this 85mm https://photographylife.com/lenses/nikon-af-nikkor-85mm-f1-8d, also from what I see Batis lenses do it too https://photographylife.com/lenses/zeiss-batis-85mm-f1-8


PostPosted: Tue Jan 12, 2021 10:54 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
visualopsins wrote:

I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


The AF Nikkor 85mm 1:1.8 and its precedessor, the AF 80mm 1:2.8, both are rear focusing, as well as the Minolta (Sony) AF 1.4/35mm.

S

EDIT: Minolta AF 2.8/24mm and AF 2.8/20mm are rear focusing as well

Last edited by stevemark on Wed Jan 13, 2021 1:31 pm; edited 1 time in total


PostPosted: Wed Jan 13, 2021 12:31 am    Post subject: Reply with quote
...

Last edited by Blazer0ne on Tue Feb 22, 2022 7:06 pm; edited 1 time in total


PostPosted: Wed Jan 13, 2021 12:42 am    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote
stevemark wrote:
visualopsins wrote:

I don't know any any lenses which focus by moving rear group only. You know Nikon's terminology "RF -- Rear Focus" refers to what other manufacturers call "IF -- Internal Focus"?


The AF Nikkor 85mm 1:1.8 and its precedessor, the AF 80mm 1:2.8, both are rear focusing, as well as the Minolta (Sony) AF 1.4/35mm.

S


Laugh 1 That was then. This is now. Now I know of a few others too! Thank you!


PostPosted: Wed Jan 13, 2021 2:10 am    Post subject: Reply with quote
redimp wrote:
Also to add to the comments above – Samyang is not internal focus for the 50mm fom what I see. The fact that barrel stays fixed does not mean internal focus, marketing people do misuse the term though.
. . .


Yes, the elements in my Rokinon (Samyang) move about 1cm when focusing from infinity to minimum focus distance - even though the barrel doesn't change length.

And now I know "internal focus" means different things to different people. Wink
From the lens box of my 50mm, here's what the Rokinon marketers have to say about their lens:




#1


PostPosted: Wed Jan 13, 2021 2:28 am    Post subject: Reply with quote
Can IF & RF lenses be determined by optical design or elements/groups?


PostPosted: Wed Jan 13, 2021 3:05 am    Post subject: Reply with quote
visualopsins wrote:
Can IF & RF lenses be determined by optical design or elements/groups?


No. It is nearly impossible to determine from an optical design whether a lens has IF or RF, unless the optical diagram shows how the lens elements move during focusing. It is even more difficult to determine if only #E and #G are available.

CK


PostPosted: Wed Jan 13, 2021 3:35 am    Post subject: Reply with quote
ckshene wrote:
visualopsins wrote:
Can IF & RF lenses be determined by optical design or elements/groups?


No. It is nearly impossible to determine from an optical design whether a lens has IF or RF, unless the optical diagram shows how the lens elements move during focusing. It is even more difficult to determine if only #E and #G are available.

CK


Thanks ckshene. Good to see you here again.


PostPosted: Wed Jan 13, 2021 6:23 am    Post subject: Reply with quote
on a whim, i purchased an Accurar 35mm f/2.5 on ebay, because it was $10 and it looked cool, turns out it is one of the earliest japanese retrofocal lenses https://burntembers.com/2017/12/23/fujitar-p-c-35mm-f2-5-asahiflex-lens-test/


PostPosted: Wed Jan 13, 2021 11:56 am    Post subject: Reply with quote
benadamx wrote:
on a whim, i purchased an Accurar 35mm f/2.5 on ebay, because it was $10 and it looked cool, turns out it is one of the earliest japanese retrofocal lenses https://burntembers.com/2017/12/23/fujitar-p-c-35mm-f2-5-asahiflex-lens-test/

Nice lens! I believe this lens is quiet similar to the Enna 35mm f/2.5 I have.


PostPosted: Wed Jan 13, 2021 1:30 pm    Post subject: Reply with quote
benadamx wrote:
on a whim, i purchased an Accurar 35mm f/2.5 on ebay, because it was $10 and it looked cool, turns out it is one of the earliest japanese retrofocal lenses https://burntembers.com/2017/12/23/fujitar-p-c-35mm-f2-5-asahiflex-lens-test/


"Retrofocus" and "Rear Focus" is not the same ... !

S
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