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Prime lenses with internal focus or rear focus?
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PostPosted: Wed Jan 13, 2021 4:25 pm    Post subject: Reply with quote

stevemark wrote:
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

I assumed not.
I have loads of retrofocus lenses but I don't think I have any 'rear focus'.
Before this thread rear focus is a term I'd not even heard of, am I right in thinking its focusing by moving the rear group independently of the remainder?

Most of my lenses are block focusing, but I do have some that are internal focusing, (and loads with no focus at all in the lens itself)...


PostPosted: Wed Jan 13, 2021 5:29 pm    Post subject: Reply with quote

55 wrote:


#1


I like where they are going here.

As a bonus, along with Internal Focus, this lens includes Bokeh.

Wink


PostPosted: Wed Jan 13, 2021 7:00 pm    Post subject: Reply with quote

Not to be a complete idiot or anything, but isn't Nikon's rear focusing a variant of internal focusing? The effect's the same and so is the underlying process. The lens focuses closer than infinity by reducing its focal length without changing extension.

Re prime lenses that are IF, don't forget the 200/4 MicroNikkor AIS. Early reviews of it characterized it as fixed focal length zoom lens.


PostPosted: Wed Jan 13, 2021 7:42 pm    Post subject: Reply with quote

Blazer0ne wrote:
55 wrote:


#1


I like where they are going here.

As a bonus, along with Internal Focus, this lens includes Bokeh.

All the mumbo jumbo PR/marketing nonsense aside the Samyang 50 f1.4 is a fine lens: https://www.flickr.com/photos/131684321@N03/albums/72157714844267418
Wink


PostPosted: Wed Jan 13, 2021 10:25 pm    Post subject: Re: Prime lenses with internal focus or rear focus? Reply with quote

redimp wrote:
Hello everyone, I am on a lookout for lenses that feature internal focusing and rear focusing.!


You are looking for a lense with IF and RF ?
That's right?

Rear focus (RF) is a variation of internal focusing (IF).
The opposite construction is the Fixed Rear Element Extension. Here, only the front lens or the front elements are extended, the rear element remains rigid.


PostPosted: Thu Jan 14, 2021 1:19 am    Post subject: Reply with quote

tomasg wrote:
All the mumbo jumbo PR/marketing nonsense aside the Samyang 50 f1.4 is a fine lens: https://www.flickr.com/photos/131684321@N03/albums/72157714844267418
Wink


Excellent, tomasg. Like 1


PostPosted: Sat Jan 16, 2021 6:27 pm    Post subject: Reply with quote

DConvert wrote:

I have loads of retrofocus lenses but I don't think I have any 'rear focus'.
Before this thread rear focus is a term I'd not even heard of, am I right in thinking its focusing by moving the rear group independently of the remainder?


Yes, exactly. You may check the Minolta patents on their AF 2.8/24mm and 2.8/20mm lenses, or Haruo Sato's article on the Nikkor AF 2.8/80mm (https://imaging.nikon.com/history/story/0023/index.htm).

S