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Do single focus solutions change the focal length of the lens?


wallpaperviking
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4 hours ago, wallpaperviking said:

Hi Ken, 

              Thanks for the response and very interesting looking modification :)

When using a "fixed" diopter, like my Tokina 0.4, this does change the focal length right?  Any idea what the maths is?


tito probably could do the math  in his sleep, maybe he'll poke his head in otherwise google tito and  anamorphic i'm sure there might be something on his website

'

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I heard "diopters" and was summoned here. ;)

I personally haven't published much on how diopters work besides what's in my original guide - www.tferradans.com/anamorphic

But I have a ton of research and drafts expanding on the subject.

Most vari-str diopters (single focus solutions) act as a wide-angle adapter when close focused (Rectilux is 0.9x for example, I have notes on the others too, but not by memory), and regular diopters alter focal length a tiny little bit (you should disregard it).

Here's a great article by Jay Holben on diopters - https://ascmag.com/blog/shot-craft/deep-focus-diopters

and an instagram post by the author of the article, expanding on depth of field and the things it sounds like you're looking for:

 

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On 9/21/2019 at 6:37 AM, Tito Ferradans said:

I heard "diopters" and was summoned here. ;)

I personally haven't published much on how diopters work besides what's in my original guide - www.tferradans.com/anamorphic

But I have a ton of research and drafts expanding on the subject.

Most vari-str diopters (single focus solutions) act as a wide-angle adapter when close focused (Rectilux is 0.9x for example, I have notes on the others too, but not by memory), and regular diopters alter focal length a tiny little bit (you should disregard it).

Here's a great article by Jay Holben on diopters - https://ascmag.com/blog/shot-craft/deep-focus-diopters

and an instagram post by the author of the article, expanding on depth of field and the things it sounds like you're looking for:

 

 

Awesome!  Thanks so much for chiming in!  

The reason for the query was that I was hoping to attach one to a large format lens for use on a custom camera I am (attempting) to build, in an attempt to reduce bellows draw...

 

https://www.eoshd.com/comments/topic/38127-zev-hoover-8-x-10-camera-variable-diopter-work-with-it/

 

Do you think this might possibly work on a "fixed" lens, like my Goerz Daor 305mm?

 

Also, the reason for the question regarding whether "fixed" diopters affect focal length is in the table listed below...

http://www.subclub.org/fujinon/close-up.htm

To me, if those values are true, then that would affect the focal length enough to change what I am trying to achieve....

 

Am hoping that I can attach a "single focus attachment" to the lens and get focus from infinity to 1 metre without having to draw the bellows out too much (and still retain movements).  Possible?

 

Thanks again!  

 

 

 

 

 

Screen Shot 2019-09-22 at 3.18.35 PM.png

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On 9/21/2019 at 11:41 PM, wallpaperviking said:

The reason for the query was that I was hoping to attach one to a large format lens for use on a custom camera I am (attempting) to build, in an attempt to reduce bellows draw...

Do you think this might possibly work on a "fixed" lens, like my Goerz Daor 305mm?

If you have a Tokina 0.4 that should help you, but you'll be coming from infinity to very close focus. It will kill bellows draw, but you'll be doing a lot of leg exercise moving from one place to the other to keep subjects in focus and finding your framing.

On 9/21/2019 at 11:41 PM, wallpaperviking said:

Also, the reason for the question regarding whether "fixed" diopters affect focal length is in the table listed below...

To me, if those values are true, then that would affect the focal length enough to change what I am trying to achieve....

That's beyond my comprehension. I never notice a difference in field of view when using diopters. But, when going up in strength so hardcore like a +10, it's hard to get ANYTHING in focus.

On 9/21/2019 at 11:41 PM, wallpaperviking said:

Am hoping that I can attach a "single focus attachment" to the lens and get focus from infinity to 1 metre without having to draw the bellows out too much (and still retain movements).  Possible?

A single focus solution is likely to work well, better than fixed diopters and bellows. The problem I can imagine is the size of your front element being bigger than the back of a single focus solution. Try SLR Magic's rangefinder, they are dirt cheap on B&H these days.

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On 9/24/2019 at 6:55 AM, Tito Ferradans said:

If you have a Tokina 0.4 that should help you, but you'll be coming from infinity to very close focus. It will kill bellows draw, but you'll be doing a lot of leg exercise moving from one place to the other to keep subjects in focus and finding your framing.

That's beyond my comprehension. I never notice a difference in field of view when using diopters. But, when going up in strength so hardcore like a +10, it's hard to get ANYTHING in focus.

A single focus solution is likely to work well, better than fixed diopters and bellows. The problem I can imagine is the size of your front element being bigger than the back of a single focus solution. Try SLR Magic's rangefinder, they are dirt cheap on B&H these days.

Amazing!  Thanks so much for taking the time to help me out!  Much appreciated! :)

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