When is 135mm not 135mm?

denniswilliams · 09-11-2014, 05:07 PM

When shopping at Samy's recently the sales person stated 135 is 135 is 135 when comparing between lenses made for specific formats. The discussion centered on my favorite lens in 67 was the 135 and the reply was very likely my favorite lens on a full frame 35mm DSLR would also be 135, since aspect ratio aside, I would generate same looking images.

Pentax states that the lens to use on a 35mm FF body to replicate the field of view of a 135mm in 67 format is 70mm.

Which is it? Thanks.

**boriscleto** · 09-11-2014, 05:20 PM

The horizontal FoV of 135 on 67 is 29 degrees. The horizontal FoV of 135 on 135FF is 18 degrees.

If you used the 67 135 on 135FF the horizontal FoV would be 18 degrees. If you want to replicate the feel of a 67 135 on 135FF you would need something like a 75mm lens. The FA* 77 is close, with a FoV of 26 degrees. On APS-C a 50mm would be closest.

Mistlefoot · 09-11-2014, 05:20 PM

Look at this link. It compares 3 different formats (none medium, but the principle is the same) and the difference in "output" you'd get with the same length lens (ie, 135mm for each). If you want the same field of view pentax would be right.

http://www.flickr.com/photos/rusticolus/2267435928/

alamo5000 · 09-11-2014, 06:41 PM

Field of view and focal length are not the same thing. Here is what I mean.

The focal length is the focal length. It does not add nor take away 'zoom' in different formats. There is no more or less magnification regardless of format.

What changes is the field of view, or what your camera sees laterally and vertically. The 'in and out' or 'zoom' does not change, but what can be included in the frame does change depending on format.

When you see all this 'crop' stuff or 'reverse crop' they are relating what your camera sees to the standard 35mm format.

normhead · 09-11-2014, 06:51 PM - **2 Likes**

You might wonder what kind of photographic training this Samy's dude has.

narual · 09-11-2014, 07:12 PM

Angle of View Calculator nice easy calculator there.

135mm field of view on 6x7 sheet film would be equivalent to a 45.13mm lens on a pentax dslr... so get a 16-45 and use it at the long end.
A 43mm ltd would probably be closest for a prime, while a 50mm is certainly much less expensive.

**dms** · 09-11-2014, 08:06 PM

The short practical answer is field of view (FOV) is usually what we are most interested in.

But it is also correct that from the same position a single focal length (e.g.,135mm) lens will provide identical near-far relationship and in/out of focus (within the particular FOV) on any film/sensor format--assuming the image circle covers the film/sensor and no enlargement (or same degree of enlargement).

denniswilliams · 09-12-2014, 10:51 AM

I appreciate everyone's time.

I am just looking to set down the 67 rig and without moving my feet, pick up a FF 35mm rig and take as close as possible the same images I am taking now.

**boriscleto** · 09-12-2014, 10:59 AM

Originally posted by denniswilliams

I appreciate everyone's time.

I am just looking to set down the 67 rig and without moving my feet, pick up a FF 35mm rig and take as close as possible the same images I am taking now.

Then you would probably want the FA 77 or the DA 70. The DA lacks an aperture ring, but it can be used on film bodies that set the aperture, so anything from the Super Program on.

Nicolas06 · 09-13-2014, 05:19 AM

Originally posted by dms

The short practical answer is field of view (FOV) is usually what we are most interested in.

But it is also correct that from the same position a single focal length (e.g.,135mm) lens will provide identical near-far relationship and in/out of focus (within the particular FOV) on any film/sensor format--assuming the image circle covers the film/sensor and no enlargement (or same degree of enlargement).

What one typically want is some framing and print it in a fixed size. To keep the same focal lens would need to go more near or more futher away from the subject to keep the framing. But this would change dramatically perspective too.

To keep same framing, same level of perspective distorsion (so what one may care for practical purposes) you need to change the focal lens as to what is explain in equivalences formulas. To have also the same deph of field, you would need to change apperture too.

And the dof, in/out of focus depend a lot of magnification. Smaller sensors come typically with more pixel density than bigger sensor... and for practical purpose the final viewing size is the same... Meaning small sensor offer much more magnification and details with the same focal lens (provided the lens is of enough quality) than bigger sensors.

narual · 09-15-2014, 09:46 AM

ohhh on 35mm film... then the 70mm is almost exactly it... it'd match a 136.1mm lens.

The 77mm would match a 150mm on your 67 -- you'd need to take a step back, but you'd gain the aperture ring and apparently some pixie dust.

zapp · 09-15-2014, 11:26 AM

I don't think you can replacte a 6x7 combo by an APS-C digital camera.
Depth of field will be quite different, film grain is not like pixels ... looks will be different.

Get some digital body and play around and you will get a feeling of what you want or not want.

**Lowell Goudge** · 09-15-2014, 02:38 PM

Originally posted by denniswilliams

When shopping at Samy's recently the sales person stated 135 is 135 is 135 when comparing between lenses made for specific formats. The discussion centered on my favorite lens in 67 was the 135 and the reply was very likely my favorite lens on a full frame 35mm DSLR would also be 135, since aspect ratio aside, I would generate same looking images.

Pentax states that the lens to use on a 35mm FF body to replicate the field of view of a 135mm in 67 format is 70mm.

Which is it? Thanks.

135mm is 135mm for all lenses irrespective of optical formula or sensor/recording medium format, BUT only for lenses when focused at infinitity.

Internally focused lenses may achieve part of their focusing by changing focal length when focused at closer than infinity. High ratio zooms especially are known for this

09-11-2014, 05:07 PM	#1
denniswilliams New Member Join Date: Sep 2009 Location: The American Southwest Posts: 13	When is 135mm not 135mm? When shopping at Samy's recently the sales person stated 135 is 135 is 135 when comparing between lenses made for specific formats. The discussion centered on my favorite lens in 67 was the 135 and the reply was very likely my favorite lens on a full frame 35mm DSLR would also be 135, since aspect ratio aside, I would generate same looking images. Pentax states that the lens to use on a 35mm FF body to replicate the field of view of a 135mm in 67 format is 70mm. Which is it? Thanks.

09-12-2014, 10:51 AM	#8
denniswilliams New Member Join Date: Sep 2009 Location: The American Southwest Posts: 13 Original Poster	Thanks . I appreciate everyone's time. I am just looking to set down the 67 rig and without moving my feet, pick up a FF 35mm rig and take as close as possible the same images I am taking now. Attached Images

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09-11-2014, 05:20 PM	#2
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,477	The horizontal FoV of 135 on 67 is 29 degrees. The horizontal FoV of 135 on 135FF is 18 degrees. If you used the 67 135 on 135FF the horizontal FoV would be 18 degrees. If you want to replicate the feel of a 67 135 on 135FF you would need something like a 75mm lens. The FA* 77 is close, with a FoV of 26 degrees. On APS-C a 50mm would be closest.

09-11-2014, 05:20 PM	#3
Mistlefoot Veteran Member Join Date: Jan 2013 Location: Nanaimo, British Columbia Photos: Albums Posts: 328	Look at this link. It compares 3 different formats (none medium, but the principle is the same) and the difference in "output" you'd get with the same length lens (ie, 135mm for each). If you want the same field of view pentax would be right. http://www.flickr.com/photos/rusticolus/2267435928/

09-11-2014, 06:41 PM	#4
alamo5000 Pentaxian Join Date: May 2012 Posts: 2,962	Field of view and focal length are not the same thing. Here is what I mean. The focal length is the focal length. It does not add nor take away 'zoom' in different formats. There is no more or less magnification regardless of format. What changes is the field of view, or what your camera sees laterally and vertically. The 'in and out' or 'zoom' does not change, but what can be included in the frame does change depending on format. When you see all this 'crop' stuff or 'reverse crop' they are relating what your camera sees to the standard 35mm format.

09-11-2014, 06:51 PM - 2 Likes	#5
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	You might wonder what kind of photographic training this Samy's dude has.

09-11-2014, 07:12 PM	#6
narual Veteran Member Join Date: Jun 2013 Location: South Bend (Notre Dame), Indiana Photos: Gallery \| Albums Posts: 1,988	Angle of View Calculator nice easy calculator there. 135mm field of view on 6x7 sheet film would be equivalent to a 45.13mm lens on a pentax dslr... so get a 16-45 and use it at the long end. A 43mm ltd would probably be closest for a prime, while a 50mm is certainly much less expensive.

09-11-2014, 08:06 PM	#7
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	The short practical answer is field of view (FOV) is usually what we are most interested in. But it is also correct that from the same position a single focal length (e.g.,135mm) lens will provide identical near-far relationship and in/out of focus (within the particular FOV) on any film/sensor format--assuming the image circle covers the film/sensor and no enlargement (or same degree of enlargement).

09-12-2014, 10:59 AM	#9
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,477	Originally posted by denniswilliams I appreciate everyone's time. I am just looking to set down the 67 rig and without moving my feet, pick up a FF 35mm rig and take as close as possible the same images I am taking now. Then you would probably want the FA 77 or the DA 70. The DA lacks an aperture ring, but it can be used on film bodies that set the aperture, so anything from the Super Program on.

09-13-2014, 05:19 AM	#10
Nicolas06 Veteran Member Join Date: Nov 2013 Posts: 4,854	Originally posted by dms The short practical answer is field of view (FOV) is usually what we are most interested in. But it is also correct that from the same position a single focal length (e.g.,135mm) lens will provide identical near-far relationship and in/out of focus (within the particular FOV) on any film/sensor format--assuming the image circle covers the film/sensor and no enlargement (or same degree of enlargement). What one typically want is some framing and print it in a fixed size. To keep the same focal lens would need to go more near or more futher away from the subject to keep the framing. But this would change dramatically perspective too. To keep same framing, same level of perspective distorsion (so what one may care for practical purposes) you need to change the focal lens as to what is explain in equivalences formulas. To have also the same deph of field, you would need to change apperture too. And the dof, in/out of focus depend a lot of magnification. Smaller sensors come typically with more pixel density than bigger sensor... and for practical purpose the final viewing size is the same... Meaning small sensor offer much more magnification and details with the same focal lens (provided the lens is of enough quality) than bigger sensors.

09-15-2014, 09:46 AM	#11
narual Veteran Member Join Date: Jun 2013 Location: South Bend (Notre Dame), Indiana Photos: Gallery \| Albums Posts: 1,988	ohhh on 35mm film... then the 70mm is almost exactly it... it'd match a 136.1mm lens. The 77mm would match a 150mm on your 67 -- you'd need to take a step back, but you'd gain the aperture ring and apparently some pixie dust.

09-15-2014, 11:26 AM	#12
zapp Pentaxian Join Date: Jul 2011 Posts: 2,388	I don't think you can replacte a 6x7 combo by an APS-C digital camera. Depth of field will be quite different, film grain is not like pixels ... looks will be different. Get some digital body and play around and you will get a feeling of what you want or not want.

09-15-2014, 02:38 PM	#13
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by denniswilliams When shopping at Samy's recently the sales person stated 135 is 135 is 135 when comparing between lenses made for specific formats. The discussion centered on my favorite lens in 67 was the 135 and the reply was very likely my favorite lens on a full frame 35mm DSLR would also be 135, since aspect ratio aside, I would generate same looking images. Pentax states that the lens to use on a 35mm FF body to replicate the field of view of a 135mm in 67 format is 70mm. Which is it? Thanks. 135mm is 135mm for all lenses irrespective of optical formula or sensor/recording medium format, BUT only for lenses when focused at infinitity. Internally focused lenses may achieve part of their focusing by changing focal length when focused at closer than infinity. High ratio zooms especially are known for this