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Largest photographic lens aperture size?
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PostPosted: Tue Jun 30, 2020 5:50 am    Post subject: Largest photographic lens aperture size? Reply with quote
My eyes were not really open (not enough coffee) and I mistakenly read 1000/2.5
Then I realized - no way.

But what is the largest?


PostPosted: Tue Jun 30, 2020 7:02 am    Post subject: Re: Largest photographic lens aperture size? Reply with quote
kansalliskala wrote:
My eyes were not really open (not enough coffee) and I mistakenly read 1000/2.5
Then I realized - no way.

But what is the largest?


Well the Carl Zeiss Planar 50mm f/0.7 must be one of the contenders I should think.
See:
https://en.wikipedia.org/wiki/Carl_Zeiss_Planar_50mm_f/0.7


PostPosted: Tue Jun 30, 2020 7:49 am    Post subject: Re: Largest photographic lens aperture size? Reply with quote
Oldhand wrote:
kansalliskala wrote:
My eyes were not really open (not enough coffee) and I mistakenly read 1000/2.5
Then I realized - no way.

But what is the largest?


Well the Carl Zeiss Planar 50mm f/0.7 must be one of the contenders I should think.
See:
https://en.wikipedia.org/wiki/Carl_Zeiss_Planar_50mm_f/0.7


Yes that one, plus there where plans for a f0,63 version:

http://www.marcocavina.com/omaggio_a_kubrick.htm


PostPosted: Tue Jun 30, 2020 8:54 am    Post subject: Reply with quote
http://allphotolenses.com/lenses/item/c_4301.html
Carl Zeiss 1700mm 1:4 So that has to has a 42.5cm aperture diameter.

Image dpreview:


https://www.dpreview.com/articles/3865393209/zeiss1700f4


PostPosted: Tue Jun 30, 2020 9:30 am    Post subject: Reply with quote
D1N0 wrote:
http://allphotolenses.com/lenses/item/c_4301.html
Carl Zeiss 1700mm 1:4 So that has to has a 42.5cm aperture diameter.


1000mm 1:2.5 would be smaller, only 40 cm?


PostPosted: Tue Jun 30, 2020 9:41 am    Post subject: Reply with quote
yeah a measly 40 centimetres :p


PostPosted: Tue Jun 30, 2020 10:37 am    Post subject: Reply with quote
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


PostPosted: Tue Jun 30, 2020 10:40 am    Post subject: Reply with quote
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


PostPosted: Tue Jun 30, 2020 10:59 am    Post subject: Reply with quote
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


You have to be careful with equivalency. 800mm is 800mm The number of degrees varies depending on image format. A 800/4 has a diagonal angle of view of 3.1° on 35mm and 6.25° on 6x7.


PostPosted: Tue Jun 30, 2020 11:00 am    Post subject: Reply with quote
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


PostPosted: Tue Jun 30, 2020 11:29 am    Post subject: Reply with quote
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.

Last edited by tomasg on Tue Jun 30, 2020 12:10 pm; edited 4 times in total


PostPosted: Tue Jun 30, 2020 11:31 am    Post subject: Reply with quote
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


Unless the image doesn't actually cover FF where the crop will give an indication of the minimum usable FoV.
Often you can get away with a bit more than the crop it's designed for, I've started noting the image circle of some of my lenses as crop factors. Some of my lenses designed for 110 film cover APSC (or even APSH) perfectly.


PostPosted: Tue Jun 30, 2020 11:35 am    Post subject: Re: Largest photographic lens aperture size? Reply with quote
kansalliskala wrote:
My eyes were not really open (not enough coffee) and I mistakenly read 1000/2.5
Then I realized - no way.

But what is the largest?


Do you include astro telescopes designed for photographic work some of these are seriously huge! Thank You Dog


PostPosted: Tue Jun 30, 2020 3:31 pm    Post subject: Reply with quote
tomasg wrote:
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.


Because the crop factor references FF, not 6x7.

800mm lens on 6X7 camera field of view is same as 400mm lens field of view on FF camera. FF calculation uses 6x7 camera crop factor of 1/2 for FF to calculate FF angle.

800mm lens from FF camera angle is identical to 800mm lens from 6x7 camera on FF camera because there is no crop factor to consider.

800mm is 800mm on FF camera no matter what camera format lens is originally. All 800mm lenses have identical field of view on FF; lenses frm smaller formats image circle may be too small to cover FF frame however.

800mm lens from APC-C camera field of view on FF camera is identical to 800mm lens from FF camera field of view on FF camera. The image circle may not be complete on FF.


PostPosted: Tue Jun 30, 2020 5:38 pm    Post subject: Reply with quote
I read someplace f/0.5 is the FASTEST possible, limited by refraction of glass.

LBT has the LARGEST aperture of 11.9 meters. https://en.wikipedia.org/wiki/List_of_largest_optical_reflecting_telescopes

The 125cm 57m Great Paris Exhibition Telescope of 1900 is the largest refractor lens. https://en.wikipedia.org/wiki/List_of_largest_optical_refracting_telescopes

Last edited by visualopsins on Tue Jun 30, 2020 7:59 pm; edited 1 time in total


PostPosted: Tue Jun 30, 2020 6:27 pm    Post subject: Reply with quote
visualopsins wrote:
tomasg wrote:
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.


Because the crop factor references FF, not 6x7.

800mm lens on 6X7 camera field of view is same as 400mm lens field of view on FF camera. FF calculation uses 6x7 camera crop factor of 1/2 for FF to calculate FF angle.

800mm lens from FF camera angle is identical to 800mm lens from 6x7 camera on FF camera because there is no crop factor to consider.

800mm is 800mm on FF camera no matter what camera format lens is originally. All 800mm lenses have identical field of view on FF; lenses frm smaller formats image circle may be too small to cover FF frame however.

800mm lens from APC-C camera field of view on FF camera is identical to 800mm lens from FF camera field of view on FF camera. The image circle may not be complete on FF.


Yes. And quite the same for DOF. That why a 400/2 lens @f/2 on FF would have the same rendering as a 800/4 @f/4 on 6x7 in termes of angle of view and bokeh (also DOF if I am right), apart from the different ratio (24/36 vs. 6/7) and the light transmission because f/4 is f/4 without matter of waht is used to capture the image.
That's why the 6x7 is a very interesting camera for "cheap" film portrait setup :
- 105/2.4 is approximatively equal to 50/1.2 on FF
- 150/2.8 is approximatively equal to 75/1.4 on FF
- 200/4 is approximatively equal to 100/2 on FF
I am not a fan of 200mm FOV (FF) so I use my 400/4 mainly on FF, but it would render as a 200/2 lens.
Wider lenses are not that interesting for 6x7, as we can find wider FOVs on FF.


PostPosted: Tue Jun 30, 2020 7:05 pm    Post subject: Reply with quote
visualopsins wrote:
tomasg wrote:
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.


Because the crop factor references FF, not 6x7.

800mm lens on 6X7 camera field of view is same as 400mm lens field of view on FF camera. FF calculation uses 6x7 camera crop factor of 1/2 for FF to calculate FF angle.

800mm lens from FF camera angle is identical to 800mm lens from 6x7 camera on FF camera because there is no crop factor to consider.

800mm is 800mm on FF camera no matter what camera format lens is originally. All 800mm lenses have identical field of view on FF; lenses frm smaller formats image circle may be too small to cover FF frame however.

800mm lens from APC-C camera field of view on FF camera is identical to 800mm lens from FF camera field of view on FF camera. The image circle may not be complete on FF.


My brain is going to explode Laugh 1

If i mount a 50mm lens on FF and then on micro4/3 and compare the two images, everything being the same (distance from object) i will get an image with a field of view of a 100mm lens on the micro4/3 camera, correct?

If i mount that 800mm 6x7 lens on a 6x7 film camera and then on a FF camera, everything being the same, i will get an image with a field of view of 1600mm on the FF camera (that s all i am saying, leaving out DoF), right or wrong?

I am completely aware that the focal length of the lens it s a physical property (as is the aperture) and doesn t change based on the size of the film or sensor behind it. But what changes by the combination of the two is the field of view of the image (again with the focusing distance being the same).

Ah, i finally think i got what you re saying. In the example i gave we have one lens and two cameras with different size sensors, in your "example" we have two lenses of the same focal lenght but one camera so the sensor/film size doesen t change.

Last edited by tomasg on Tue Jun 30, 2020 7:52 pm; edited 1 time in total


PostPosted: Tue Jun 30, 2020 7:07 pm    Post subject: Reply with quote
CarbonR wrote:
visualopsins wrote:
tomasg wrote:
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.


Because the crop factor references FF, not 6x7.

800mm lens on 6X7 camera field of view is same as 400mm lens field of view on FF camera. FF calculation uses 6x7 camera crop factor of 1/2 for FF to calculate FF angle.

800mm lens from FF camera angle is identical to 800mm lens from 6x7 camera on FF camera because there is no crop factor to consider.

800mm is 800mm on FF camera no matter what camera format lens is originally. All 800mm lenses have identical field of view on FF; lenses frm smaller formats image circle may be too small to cover FF frame however.

800mm lens from APC-C camera field of view on FF camera is identical to 800mm lens from FF camera field of view on FF camera. The image circle may not be complete on FF.


Yes. And quite the same for DOF. That why a 400/2 lens @f/2 on FF would have the same rendering as a 800/4 @f/4 on 6x7 in termes of angle of view and bokeh (also DOF if I am right), apart from the different ratio (24/36 vs. 6/7) and the light transmission because f/4 is f/4 without matter of waht is used to capture the image.
That's why the 6x7 is a very interesting camera for "cheap" film portrait setup :
- 105/2.4 is approximatively equal to 50/1.2 on FF
- 150/2.8 is approximatively equal to 75/1.4 on FF
- 200/4 is approximatively equal to 100/2 on FF
I am not a fan of 200mm FOV (FF) so I use my 400/4 mainly on FF, but it would render as a 200/2 lens.
Wider lenses are not that interesting for 6x7, as we can find wider FOVs on FF.


In terms of depth of field those relations are correct, however, a 105/2.4 6x7 lens doesn't have the same field of view as a 50mm lens on FF, not does f/2.4 suddenly become a f/2 lens. 105/2.4 6x7 lens field of view on FF camera is same as 105/2.4 FF lens on FF camera.
EDIT: Maybe what you say is true and I don't understand. I know you have 6x7 105/2.4 and M42 105/2.8. You could put those on your 5D then tell me they do not have same angle of view. Smile


PostPosted: Tue Jun 30, 2020 7:59 pm    Post subject: Reply with quote
visualopsins wrote:
CarbonR wrote:
visualopsins wrote:
tomasg wrote:
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.


Because the crop factor references FF, not 6x7.

800mm lens on 6X7 camera field of view is same as 400mm lens field of view on FF camera. FF calculation uses 6x7 camera crop factor of 1/2 for FF to calculate FF angle.

800mm lens from FF camera angle is identical to 800mm lens from 6x7 camera on FF camera because there is no crop factor to consider.

800mm is 800mm on FF camera no matter what camera format lens is originally. All 800mm lenses have identical field of view on FF; lenses frm smaller formats image circle may be too small to cover FF frame however.

800mm lens from APC-C camera field of view on FF camera is identical to 800mm lens from FF camera field of view on FF camera. The image circle may not be complete on FF.


Yes. And quite the same for DOF. That why a 400/2 lens @f/2 on FF would have the same rendering as a 800/4 @f/4 on 6x7 in termes of angle of view and bokeh (also DOF if I am right), apart from the different ratio (24/36 vs. 6/7) and the light transmission because f/4 is f/4 without matter of waht is used to capture the image.
That's why the 6x7 is a very interesting camera for "cheap" film portrait setup :
- 105/2.4 is approximatively equal to 50/1.2 on FF
- 150/2.8 is approximatively equal to 75/1.4 on FF
- 200/4 is approximatively equal to 100/2 on FF
I am not a fan of 200mm FOV (FF) so I use my 400/4 mainly on FF, but it would render as a 200/2 lens.
Wider lenses are not that interesting for 6x7, as we can find wider FOVs on FF.


In terms of depth of field those relations are correct, however, a 105/2.4 6x7 lens doesn't have the same field of view as a 50mm lens on FF, not does f/2.4 suddenly become a f/2 lens. 105/2.4 6x7 lens field of view on FF camera is same as 105/2.4 FF lens on FF camera.
EDIT: Maybe what you say is true and I don't understand. I know you have 6x7 105/2.4 and M42 105/2.8. You could put those on your 5D then tell me they do not have same angle of view. Smile


On the 5D they will have the same field of view, but shoot the 6x7 105/2.4 on a 6x7 camera and compare it to both the images from the 5D, the image from the 6x7 camera will have an field of view of 50mm, both the images from the 5d will have a 100mm field of view. The diagonal of the film on the 6x7 camera is twice of that on the sensor diagonal on the 5D, thus turning the field of view of the 105/2.4 lens into a 50mm field of view lens, on a 6x7 medium camera.

Last edited by tomasg on Tue Jun 30, 2020 8:04 pm; edited 1 time in total


PostPosted: Tue Jun 30, 2020 8:04 pm    Post subject: Reply with quote
tomasg wrote:
visualopsins wrote:
CarbonR wrote:
visualopsins wrote:
tomasg wrote:
visualopsins wrote:
tomasg wrote:
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


Wouldn t the lens have a 1600 mm field of view instead? Being 24x36 smaller?


Well, no, on FF 800mm lens has same field of view as any other 800mm lens on FF. Crop factor references FF, i.e. what would lens look like on other formats (aps-c crop is 1.5 or 1.6 angle on FF), FF crop factors do not apply when adapting TO FF.


If i use my Biometar 80mm lens on my Sony a7 and than on medium format P6 i bieleve, i have no experience with medium formats, wouldn t i get tow different FoVs? I always though that on medium format the Biometar has a field of view of around 50 mm.

I mean the op wrote that the lens was designed for 6x7, why doesn t the crop factor apply when adapting to FF (36x24)?

Ah, i now understand what the OP meant it was about "rendering", the combination of FL and speed, a 400/2 lens for 35mm would be a monster indeed. Mounting that 800/4 on FF would turn it into an apparent 1600mm in terms of field of view, but that s something different.


Because the crop factor references FF, not 6x7.

800mm lens on 6X7 camera field of view is same as 400mm lens field of view on FF camera. FF calculation uses 6x7 camera crop factor of 1/2 for FF to calculate FF angle.

800mm lens from FF camera angle is identical to 800mm lens from 6x7 camera on FF camera because there is no crop factor to consider.

800mm is 800mm on FF camera no matter what camera format lens is originally. All 800mm lenses have identical field of view on FF; lenses frm smaller formats image circle may be too small to cover FF frame however.

800mm lens from APC-C camera field of view on FF camera is identical to 800mm lens from FF camera field of view on FF camera. The image circle may not be complete on FF.


Yes. And quite the same for DOF. That why a 400/2 lens @f/2 on FF would have the same rendering as a 800/4 @f/4 on 6x7 in termes of angle of view and bokeh (also DOF if I am right), apart from the different ratio (24/36 vs. 6/7) and the light transmission because f/4 is f/4 without matter of waht is used to capture the image.
That's why the 6x7 is a very interesting camera for "cheap" film portrait setup :
- 105/2.4 is approximatively equal to 50/1.2 on FF
- 150/2.8 is approximatively equal to 75/1.4 on FF
- 200/4 is approximatively equal to 100/2 on FF
I am not a fan of 200mm FOV (FF) so I use my 400/4 mainly on FF, but it would render as a 200/2 lens.
Wider lenses are not that interesting for 6x7, as we can find wider FOVs on FF.


In terms of depth of field those relations are correct, however, a 105/2.4 6x7 lens doesn't have the same field of view as a 50mm lens on FF, not does f/2.4 suddenly become a f/2 lens. 105/2.4 6x7 lens field of view on FF camera is same as 105/2.4 FF lens on FF camera.
EDIT: Maybe what you say is true and I don't understand. I know you have 6x7 105/2.4 and M42 105/2.8. You could put those on your 5D then tell me they do not have same angle of view. Smile


On the 5D they will have the same field of view, but shoot the 6x7 105/2.4 on a 6x7 camera and compare it to both the images from the 5D, the image from the 6x7 camera will have an field of view of 50mm, both the images from the 5d will have a 100mm field of view.


Yes!!! Crop Factor is applied in one case not both!!!

CarbonR may be referring to DOF. Make photo with 105/2.4 on 6x7 camera. Make another photo with 50/1.4 on FF. Mask to 6x7 photo to show only 24x36mm frame. The DOF and framing will be the same.


PostPosted: Tue Jun 30, 2020 11:40 pm    Post subject: Re: Largest photographic lens aperture size? Reply with quote
Oldhand wrote:
kansalliskala wrote:
My eyes were not really open (not enough coffee) and I mistakenly read 1000/2.5
Then I realized - no way.

But what is the largest?


Well the Carl Zeiss Planar 50mm f/0.7 must be one of the contenders I should think.
See:
https://en.wikipedia.org/wiki/Carl_Zeiss_Planar_50mm_f/0.7


Topcon (Simlar at the time) also made an ultra fast lens, http://www.topgabacho.jp/Topconclub/lens8.htm

Quote:
During the Second World War, TOKYO OPTICAL experimentally produced TOKO5cmf0.7. In 1951, they designs it again, this most bright lens in the world was completed. This lens was designed by Mr. Shuji Maruyama who are the famous designer at that time. He moved to Norita Kogaku at the later time and designed various excellent lenses. By the way, this lens was not mass-produced regretfully and was made only 3 pieces. These 2 pieces were delivered to the South Pole expedition party of the Mainichi Newspapers.


https://camerapedia.fandom.com/wiki/Simlar
Quote:
Wartime Simlar 50mm f/0.7 Edit
The first Simlar[12] 50mm f/0.7 was designed by Maruyama Shūji (丸山修治)[13] — who later worked for Norita.[14] The development of an ultra-high aperture lens was ordered by the military towards the end of 1943, and the lens was completed in Summer 1944.[15] The most detailed account of the story is given in the December 1951 issue of Asahi Camera, reproduced below.[16] The lens was also mentioned in an article dated 23 Oct. 1951 of the daily newspaper Mainichi Shinbun, which mainly addresses the 5cm f/0.7 postwar evolution.[17] (Remarkably, the article in Asahi Camera makes no mention of the postwar lens.)

5019755641_240baaae4b.jpg
Article on the wartime Simlar f/0.7, in Asahi Camera December 1951.
It shows a portray of Maruyama Shūji, holding an example of the lens. (Image rights)
The lens has eight elements in four groups.[18] The angle of view is 30 degrees, and the coverage is good enough for 24×24mm exposures.[19] The lens was originally developed for night reconnaissance photography.[20] However, before it could be extensively tested for its intended use, the few examples made were claimed by the Aeronautical Engineering Institute of Tachikawa for X-ray medical photography.[21] The lenses would have been part of an experiment to learn about the effects of high acceleration on the human heart during the pull-out manoeuvre after dive bombing.[22] It seems that the rest of the equipment needed for the experiment was never built — perhaps not even the camera — and nothing came out of the project.[23]

The December 1951 article in Asahi Camera says that ten units were made until the end of the war, but their fate was unknown except for one example, still held by Maruyama Shūji at Tōkyō Kōgaku at the time.[24] The article in Mainichi Shinbun says that Life's reporter David Duncan wanted to borrow a Simlar f/0.7 at some point; the phrasing seems to imply that the story applies to the wartime version (maybe Maruyama's own example), and that Duncan did not actually obtain the lens.[25] Various later sources say that one or several examples were transferred to the U.S. forces after World War II;[26] all these seem to repeat a piece of information that was perhaps in Tōkyō Kōgaku's fifty-year history book, printed in 1982.

At least one surviving example of the wartime 50mm f/0.7 has been recently photographed;[27] it is very likely that this example was the one mentioned in Asahi Camera December 1951 and pictured in the hands of Maruyama Shūji. It has a large black barrel, 128mm long and 90mm in diameter, and weighs 1kg.[28] There is a fine screw thread at the base of the barrel, 66mm in diameter and 0.5mm in thread.[28] The flange-to-film register is 33.3mm, but the lens rear element is only 7mm away from the film plane.[28] The aperture ring is graduated from f/0.7 to f/8, and the diaphragm has 18 blades.[28] It seems that the lens has no focusing ring, but this is not entirely clear.[29] The surviving example has serial number 5,[30] and is engraved Simlar 1:0.7 f=50mm Tokyo Kogaku Nr.5 around the rim.[31]

Postwar Simlar 5cm f/0.7 Edit
The Simlar 5cm f/0.7 is a postwar evolution of the previous lens. The 1951 article in Mainichi Shinbun, already cited above, says that the lens design was improved by Maruyama Shūji after the end of the war.[32] These modifications were rather minor: the formula is the same as the wartime lens (eight elements in four groups), and the optical scheme looks very similar.[33] Lens coating, absent from the wartime lens, was applied to the postwar version.[34]

The Mainichi article goes on saying that three examples were made, two of which were used by the newspaper for an expedition to the South Pole.[32] No detail is known of the camera used in that expedition.

The Simlar 5cm f/0.7 lens was still listed in a catalogue of Tōkyō Kōgaku products showing the Topcon 35A, 35B and 35-S, dating c.1956.[35] No price is given in this document, but this is perhaps an indication that the lens was still available on special order, and that more than three were made after all.

At least one surviving example of the lens is known, with serial number 100002, either the second or third produced. Judging from the available pictures, it seems that this lens has hardly any traces of use;[36] it is likely that this example was not one of those sent to the polar expedition.

The lens weighs 2,500g, much heavier than the wartime version.[37] The barrel is 105mm in diameter and 123.7mm in length.[37] The lens is all chrome, except for a black beauty ring at the middle of the barrel, engraved Simlar 1:0.7 f=5cm Tokyo Optical No.100002.[38] The aperture ring, graduated from f/0.7 to f/8, is less massive than on the wartime lens, and the diaphragm only has thirteen blades.[37] The base of the barrel has a square plate with four screw holes, to attach the lens on a camera. The flange-to-film distance is 30.3mm, and the distance from the rear element to the film plane is 7mm, same as on the wartime design.[37] The lens reportedly has focusing ability from 3m to infinity, but this is unconfirmed.[39]

Besides the f/0.7 lens, it is said that a 50mm f/0.75 design was also computed,[40] but it seems that it was never made.


Column on the Simlar f/0.7 (Dec. 1951) by rebollo_fr, on Flickr


I try to spread the knowledge that Zeiss wasn't the only manufacturer to make a lens this fast, so when the Zeiss lens above is mentioned I will take the opportunity to spread the info to those that may not know about it, apologies to those that have seen my posts about it before.


PostPosted: Thu Jul 02, 2020 4:57 am    Post subject: Reply with quote
visualopsins wrote:

In terms of depth of field those relations are correct, however, a 105/2.4 6x7 lens doesn't have the same field of view as a 50mm lens on FF, not does f/2.4 suddenly become a f/2 lens. 105/2.4 6x7 lens field of view on FF camera is same as 105/2.4 FF lens on FF camera.
EDIT: Maybe what you say is true and I don't understand. I know you have 6x7 105/2.4 and M42 105/2.8. You could put those on your 5D then tell me they do not have same angle of view. Smile


I always meant the 6x7 lenses were used on 6x7. Lenses don't know on what they are mounted, they just produce the image, so the 6x7 105/2.4 and M42 105/2.8 produce the same image. One of these images will cover a greater part of the subject in front of the lens (and will be a 1/2 stop brighter), but the two images will have the same reproduction ratio (eg. your 1m80 tall subject will be reduced to 1.8cm).

tomasg wrote:

On the 5D they will have the same field of view, but shoot the 6x7 105/2.4 on a 6x7 camera and compare it to both the images from the 5D, the image from the 6x7 camera will have an field of view of 50mm, both the images from the 5d will have a 100mm field of view. The diagonal of the film on the 6x7 camera is twice of that on the sensor diagonal on the 5D, thus turning the field of view of the 105/2.4 lens into a 50mm field of view lens, on a 6x7 medium camera.


Yes, thats it Wink

visualopsins wrote:

CarbonR may be referring to DOF. Make photo with 105/2.4 on 6x7 camera. Make another photo with 50/1.4 on FF. Mask to 6x7 photo to show only 24x36mm frame. The DOF and framing will be the same.


In fact, 105/2.4 on 6x7 and 50/1.4 on FF will have the same framing, because both are the standard lens for the used format, which means that the focal lengh is about the the as the diagonal of the sensor.
I know that these subtilities are very technical and difficult to understand. The some optical courses I had during my studies may have helped me. Best thing to do is to try with this site : https://dofsimulator.net/en/ . You will see by yourself that 105@2.4 on 6x7 is approximatively the same (FOV, bokeh, DOF) as 50@1.2 on 24x36. The 24x36 configuration will still be f/1.2 so shutter speed will be different from the 6x7 but this is almost the only difference.


PostPosted: Thu Jul 02, 2020 9:44 am    Post subject: Reply with quote
CarbonR wrote:
Pentax made a 800/4 for the 6x7 format. Not the biggest but quite a respectable lens, that approximatively gives a 400/2 rendering (FL/aperture) on 24x36 format.


I misunderstood what you said here. You say on 6x7 800/4 frames same angle and has same dof as 400/2 lens on FF camera. I thought you said 6x7 800/4 lens on FF camera gives same angle and dof as FF 400/2 lens on FF camera, which is wrong.

CarbonR wrote:
...

visualopsins wrote:

CarbonR may be referring to DOF. Make photo with 105/2.4 on 6x7 camera. Make another photo with 50/1.4 on FF. Mask to 6x7 photo to show only 24x36mm frame. The DOF and framing will be the same.


In fact, 105/2.4 on 6x7 and 50/1.4 on FF will have the same framing, because both are the standard lens for the used format, which means that the focal lengh is about the the as the diagonal of the sensor.
I know that these subtilities are very technical and difficult to understand. The some optical courses I had during my studies may have helped me. Best thing to do is to try with this site : https://dofsimulator.net/en/ . You will see by yourself that 105@2.4 on 6x7 is approximatively the same (FOV, bokeh, DOF) as 50@1.2 on 24x36. The 24x36 configuration will still be f/1.2 so shutter speed will be different from the 6x7 but this is almost the only difference.


Yes, yes, you are correct. I don't know why I said to mask the 6x7 photo -- no mask!, entire frames are the same.

Tomasg asked about applying crop factor, why 6x7 800mm lens doesn't give 1600mm angle on FF, but he meant 800mm lens on FF camera gives same angle as 1600mm lens on 6x7 camera, which it does. Using the FF camera crop factor for 6x7 camera to determine angle equivalency, like using APS-C crop factor for FF camera to determine equivalency.

The gist is we are all in agreement about the dynamics of equivalencies, but sometimes misunderstand exactly what is being referenced.
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