The fallacy of 35mm "equivalent focal lengths"

Started 4 months ago | Discussions
tony field Forum Pro • Posts: 10,153
Re: The fallacy of 35mm "equivalent focal lengths"
1

tcg550 wrote:

Is this the topic that finally puts it all to rest?

I hope not! These threads are always good for a chuckle and a snicker on Sunday afternoons on chilly overcast days. in many ways it is more entertaining than watching television.

-- hide signature --

Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca

Lee Jay Forum Pro • Posts: 54,270
Re: Even though you're right, you're actually wrong
1

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.  You'll lose 8/9ths of your pixel count if you crop that much.

-- hide signature --

Lee Jay

 Lee Jay's gear list:Lee Jay's gear list
Canon IXUS 310 HS Canon PowerShot SX50 HS Canon EOS 7D Mark II Canon EF 70-200mm F2.8L IS II USM Canon EF 8-15mm f/4L Fisheye USM +23 more
Fresch Senior Member • Posts: 1,821
Re: The fallacy of 35mm "equivalent focal lengths"

tony field wrote:

tcg550 wrote:

Is this the topic that finally puts it all to rest?

I hope not! These threads are always good for a chuckle and a snicker on Sunday afternoons on chilly overcast days. in many ways it is more entertaining than watching television.

Rocky just became champion of he world!

OP Tony Beach Forum Pro • Posts: 11,961
Re: The fallacy of 35mm "equivalent focal lengths"

Gerry Winterbourne wrote:

Tony Beach wrote:

Gerry Winterbourne wrote:

Tony Beach wrote:

Many wrongly assume that if you double or halve the focal length the AOV (or FOV for a given distance) changes accordingly. It's easy to imagine the photographer saying she wants to zoom twice as "close" to the subject and having the lens designating degrees instead of putative millimeters facilitates rather than hinders that.

Which is precisely why using focal length in millimetres is the best method.

If I halve or double the degrees I will change the AOV (FOV of the subject at a given distance) by that much,

Read the numbers of your graph - what you say is clearly untrue. 12mm to 24mm (your factor of two) gives angles of 122 and 84 - a ration of about 1.5.

I'm terrible at math, but nonetheless here's what I see:

96mm to 48mm widens the AOV by 90%

48mm to 24mm widens the AOV by 73%

24mm to 12mm widens the AOV by 45%

which won't happen when just changing the millimeters by that much.

No, I'm afraid it does exactly that.

At longer focal lengths it does.

mamallama
mamallama Forum Pro • Posts: 55,227
Re: The fallacy of 35mm "equivalent focal lengths"
2

Tony Beach wrote:

mamallama wrote:

Tony Beach wrote:

mamallama wrote:

Tony Beach wrote:

Describing a lens as having an equivalent focal length is simply wrong. I can't make it any more concise than that.

Provide a concise precise technical definition of equivalent as you are using the term. That will save a lot of the round robin discussions that have taken place.

I just did.

Where?

Sorry, I should have been more clear.

If you have already stated it then copy and paste the precise definition of equivalent here.

My point is there is no such thing as an "equivalent focal length" because all focal lengths have their own unique characteristics. By invoking one limited aspect of a focal length as its used on a given sensor the other equally important aspects of that focal length are explicitly being disregarded.

It's more accurate to say a focal length when used on a particular format has a particular FOV.

Our learned folks here at DPR use the term equivalent focal length in discussions and in their lens specifications. They are very definite in the definition of how they are using the term equivalent. It is not a fallacy. It is how the whole industry uses the term.

Now you are coming along claiming it is a fallacy. That is why I want to know your definition of the term.

AOV.

In all of your words you have said nothing to show that equivalent focal length describing AOV is a fallacy.

 mamallama's gear list:mamallama's gear list
Panasonic Lumix DMC-GX85 +1 more
Gerry Winterbourne Forum Pro • Posts: 15,772
Re: The fallacy of 35mm "equivalent focal lengths"

Tony Beach wrote:

Gerry Winterbourne wrote:

Tony Beach wrote:

Gerry Winterbourne wrote:

Tony Beach wrote:

Many wrongly assume that if you double or halve the focal length the AOV (or FOV for a given distance) changes accordingly. It's easy to imagine the photographer saying she wants to zoom twice as "close" to the subject and having the lens designating degrees instead of putative millimeters facilitates rather than hinders that.

Which is precisely why using focal length in millimetres is the best method.

If I halve or double the degrees I will change the AOV (FOV of the subject at a given distance) by that much,

Read the numbers of your graph - what you say is clearly untrue. 12mm to 24mm (your factor of two) gives angles of 122 and 84 - a ratio of about 1.5.

I'm terrible at math, but nonetheless here's what I see:

96mm to 48mm widens the AOV by 90%

At 96mm it's 26.5 degrees; at 48mm it's 48.5 degrees. 48.5/26.5 =1.83; 83 is less than 90; and if what you said was true the number should be 100%. It isn't that in any of your comparisons.

48mm to 24mm widens the AOV by 73%

24mm to 12mm widens the AOV by 45%

About 1.5 ratio, which is what I said.

which won't happen when just changing the millimeters by that much.

No, I'm afraid it does exactly that.

At longer focal lengths it does.

As the lens gets longer the angular proportion gets closer to linear but never reaches it. The focal length proportion is always linear whether long or short.

-- hide signature --

Gerry
___________________________________________
First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

OP Tony Beach Forum Pro • Posts: 11,961
Re: Even though you're right, you're actually wrong

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.

This is the previously shown crop from the S95 taken at 22.5mm ("105mm focal length equivalent") next to a crop from the the NIKKOR 50/1.8D using my D800; both at 100%.

You'll lose 8/9ths of your pixel count if you crop that much.

More megapixels isn't what the S95 needs -- even at about double the MP its lens simply won't resolve as much detail as what the NIKKOR 50/1.8D resolves on my D800. Thus, if the lens on the S95 is a "28-105mm focal length equivalent" then (as I said and have now shown you) my NIKKOR 50/1.8D on my D800 is a "50-150mm focal length equivalent."

Lee Jay Forum Pro • Posts: 54,270
Re: Even though you're right, you're actually wrong
3

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.

This is the previously shown crop from the S95 taken at 22.5mm ("105mm focal length equivalent") next to a crop from the the NIKKOR 50/1.8D using my D800; both at 100%.

You've done something wrong. You've got 4.6MP vs 12MP and they are the same size. Can't be.

215mm at 16MP but with 5.6x crop on the left, 600mm at 20MP but with 1.6x crop on the right. So, that's 16MP at 1200mm equivalent vs 20MP at 960mm equivalent, and the size and resolving power are similar even if the tone and contrast are a bit different because of the different rendering engines.

-- hide signature --

Lee Jay

 Lee Jay's gear list:Lee Jay's gear list
Canon IXUS 310 HS Canon PowerShot SX50 HS Canon EOS 7D Mark II Canon EF 70-200mm F2.8L IS II USM Canon EF 8-15mm f/4L Fisheye USM +23 more
OP Tony Beach Forum Pro • Posts: 11,961
Re: The fallacy of 35mm "equivalent focal lengths"

Gerry Winterbourne wrote:

Tony Beach wrote:

Gerry Winterbourne wrote:

Tony Beach wrote:

Gerry Winterbourne wrote:

Tony Beach wrote:

Many wrongly assume that if you double or halve the focal length the AOV (or FOV for a given distance) changes accordingly. It's easy to imagine the photographer saying she wants to zoom twice as "close" to the subject and having the lens designating degrees instead of putative millimeters facilitates rather than hinders that.

Which is precisely why using focal length in millimetres is the best method.

If I halve or double the degrees I will change the AOV (FOV of the subject at a given distance) by that much,

Read the numbers of your graph - what you say is clearly untrue. 12mm to 24mm (your factor of two) gives angles of 122 and 84 - a ratio of about 1.5.

I'm terrible at math, but nonetheless here's what I see:

96mm to 48mm widens the AOV by 90%

At 96mm it's 26.5 degrees; at 48mm it's 48.5 degrees. 48.5/26.5 =1.83; 83 is less than 90; and if what you said was true the number should be 100%. It isn't that in any of your comparisons.

Look again, it's 25.4°, not 26.5°, so 90%.

48mm to 24mm widens the AOV by 73%

24mm to 12mm widens the AOV by 45%

About 1.5 ratio, which is what I said.

Yes, it's non-linear, so you really aren't very close to doubling your AOV when you halve your focal length.

which won't happen when just changing the millimeters by that much.

No, I'm afraid it does exactly that.

At longer focal lengths it does.

As the lens gets longer the angular proportion gets closer to linear but never reaches it. The focal length proportion is always linear whether long or short.

Going from 100mm to 200mm the AOV is reduced by 50.4%, so that's pretty close to what you would expect using the millimeters to calculate the relative AOVs. It's just that as you go wider and wider that you don't get the expected result (the AOV diminishes by 31% going from 12mm to 24mm, and to get twice the AOV of 50mm you would have to use a 20mm lens).

OP Tony Beach Forum Pro • Posts: 11,961
Re: The fallacy of 35mm "equivalent focal lengths"

mamallama wrote:

In all of your words you have said nothing to show that equivalent focal length describing AOV is a fallacy.

https://www.dpreview.com/forums/post/62469733

OP Tony Beach Forum Pro • Posts: 11,961
Re: Even though you're right, you're actually wrong

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.

This is the previously shown crop from the S95 taken at 22.5mm ("105mm focal length equivalent") next to a crop from the the NIKKOR 50/1.8D using my D800; both at 100%.

You've done something wrong. You've got 4.6MP vs 12MP and they are the same size. Can't be.

You missed the relationship between pixel density and focal length. The S95 has 2.4x as much pixel density as the D800, so 22.5mm on the S95 will result in a 100% crop equal to a 100% crop from a D800 using a 54mm lens.

215mm at 16MP but with 5.6x crop on the left, 600mm at 20MP but with 1.6x crop on the right. So, that's 16MP at 1200mm equivalent vs 20MP at 960mm equivalent, and the size and resolving power are similar even if the tone and contrast are a bit different because of the different rendering engines.

It's not a bad result.

mamallama
mamallama Forum Pro • Posts: 55,227
Re: The fallacy of 35mm "equivalent focal lengths"
1

Tony Beach wrote:

mamallama wrote:

In all of your words you have said nothing to show that equivalent focal length describing AOV is a fallacy.

https://www.dpreview.com/forums/post/62469733

That proves nothing close to a fallacy.

 mamallama's gear list:mamallama's gear list
Panasonic Lumix DMC-GX85 +1 more
OP Tony Beach Forum Pro • Posts: 11,961
Re: The fallacy of 35mm "equivalent focal lengths"

mamallama wrote:

Tony Beach wrote:

mamallama wrote:

In all of your words you have said nothing to show that equivalent focal length describing AOV is a fallacy.

https://www.dpreview.com/forums/post/62469733

That proves nothing close to a fallacy.

Great, so then you believe that my 50/1.8D is a "50-150mm focal length equivalent" lens.

Donald B
Donald B Forum Pro • Posts: 12,493
Re: User errors, not the camera

FingerPainter wrote:

Donald B wrote:

nothing wrong with good quality small cameras, oly xz1 and canon 5dmk2 at the same venue these are heavy crops and af used on both cameras.

Don

Another false comparison from you , Donald. The Canon shot would be much better if you used the same 1/60 shutter speed and -1/3 EC, and had focused properly. You admit below that you didn't know how to use the Canon. Why imply this shows a comparison of camera body capabilities if one of the images images hasn't been taken properly?

dslr are hopeless at accurate af period. i processed the the 500 images the other pro took in the studio and the af was all over the place, why i moved to em5 cameras.

Don

-- hide signature --

Olympus EM5mk2 ,EM1mk2
http://www.dpreview.com/galleries/9412035244
past toys. k100d, k10d,k7,fz5,fz150,500uz,canon G9, Olympus xz1 em5mk1

Lee Jay Forum Pro • Posts: 54,270
Re: Even though you're right, you're actually wrong

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.

This is the previously shown crop from the S95 taken at 22.5mm ("105mm focal length equivalent") next to a crop from the the NIKKOR 50/1.8D using my D800; both at 100%.

You've done something wrong. You've got 4.6MP vs 12MP and they are the same size. Can't be.

You missed the relationship between pixel density and focal length. The S95 has 2.4x as much pixel density as the D800, so 22.5mm on the S95 will result in a 100% crop equal to a 100% crop from a D800 using a 54mm lens.

No, what I missed was that the S95 was 105mm equivalent and 10MP instead of 120mm equivalent and 12MP like the S110 and S120.

215mm at 16MP but with 5.6x crop on the left, 600mm at 20MP but with 1.6x crop on the right. So, that's 16MP at 1200mm equivalent vs 20MP at 960mm equivalent, and the size and resolving power are similar even if the tone and contrast are a bit different because of the different rendering engines.

It's not a bad result.

-- hide signature --

Lee Jay

 Lee Jay's gear list:Lee Jay's gear list
Canon IXUS 310 HS Canon PowerShot SX50 HS Canon EOS 7D Mark II Canon EF 70-200mm F2.8L IS II USM Canon EF 8-15mm f/4L Fisheye USM +23 more
Donald B
Donald B Forum Pro • Posts: 12,493
Re: The fallacy of 35mm "equivalent focal lengths"

New Day Rising wrote:

Donald B wrote:

New Day Rising wrote:

Donald B wrote:

nothing wrong with good quality small cameras, oly xz1 and canon 5dmk2 at the same venue these are heavy crops and af used on both cameras.

Don

Both are pretty bad (I know you are a good photographer; you had dreadful lighting here). Did you take both?

The Canon shot is just awful - completely out of focus. In focus it would likely have been the better of the two. That model of Canon can definitely do a lot better than that in poor lighting.

I was asked to shoot this image with a 5dmk 2 I was covering the event with my k7 with a studio setup and the main photographer asked me to use her camera, I was interested in a comparison so I ran down stairs and got my xz1 for a quick test shot. the lighting was stage lighting only their was about 200 students on the stage and as I said this is like a %500 crop I processed all the images for the night and my k7 blew the canon away for the studio work and my little xz1 did the same the af on the canon was pathetic and this was the best shot I took with it. its why ive never bought a ff they just don't work for me and what I shoot. GB loves this image

Don

It was probably because you hadn't used the 5D before - there is no way it could have been such a successful camera if the autofocus really was that bad

I processed the 500 images taken with the 5d from the second studio setup from the other working pro and the af was all over the place. i moved to mirrorless for accurate af plain and simple. my k7 was good but my em5 cameras are on another planet for af accuracy.

Don

-- hide signature --

Olympus EM5mk2 ,EM1mk2
http://www.dpreview.com/galleries/9412035244
past toys. k100d, k10d,k7,fz5,fz150,500uz,canon G9, Olympus xz1 em5mk1

tony field Forum Pro • Posts: 10,153
Re: User errors, not the camera
5

Donald B wrote:

FingerPainter wrote:

Donald B wrote:

nothing wrong with good quality small cameras, oly xz1 and canon 5dmk2 at the same venue these are heavy crops and af used on both cameras.

Don

no Pro or  active amateur that I know would be this incompetent at focusing

Another false comparison from you , Donald. The Canon shot would be much better if you used the same 1/60 shutter speed and -1/3 EC, and had focused properly. You admit below that you didn't know how to use the Canon. Why imply this shows a comparison of camera body capabilities if one of the images images hasn't been taken properly?

dslr are hopeless at accurate af period. i processed the the 500 images the other pro took in the studio and the af was all over the place, why i moved to em5 cameras.

Don

Was he really a pro??

I really wonder what you mean by "hopeless at accurate AF"?

I have had no issues with accuracy of DSLR focusing going way back to the nikon d100,d1 etc, or the Canon 1d or 5d series. All of the cameras function splendidly for difficult shooting including theater, dance, figure and speed skating, show jumping, motorcycle racing Etc. Every Pro that I know have no issues with DSLR cameras even going back into history.

I really wonder why you use this as an excuse to brag about different camera systems.

I have never used and em5. I will accept your evaluation that it is superb (for what you shoot)

-- hide signature --

Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca

OP Tony Beach Forum Pro • Posts: 11,961
Re: Even though you're right, you're actually wrong

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

Tony Beach wrote:

Lee Jay wrote:

When I crop, my 35mm-equivalent FOV

Even a lens used on 35mm format can have its equivalent FOV changed. The issue then becomes how much latitude you have in doing that. Compared to my S95, my 50mm f/1.8D lens just became a 50mm-150mm equivalent lens.

No way.

This is the previously shown crop from the S95 taken at 22.5mm ("105mm focal length equivalent") next to a crop from the the NIKKOR 50/1.8D using my D800; both at 100%.

You've done something wrong. You've got 4.6MP vs 12MP and they are the same size. Can't be.

You missed the relationship between pixel density and focal length. The S95 has 2.4x as much pixel density as the D800, so 22.5mm on the S95 will result in a 100% crop equal to a 100% crop from a D800 using a 54mm lens.

No, what I missed was that the S95 was 105mm equivalent and 10MP instead of 120mm equivalent and 12MP like the S110 and S120.

Okay. In my OP I actually resized the 35mm focal length shot taken with the D800 and NIKKOR combo to match the 100% crop from the S95. In the above example the 50mm lens is resolving much better than the fully zoomed S95 lens, so a longer focal length and/or more pixel density might change the equation some, but my point was relative to the S95 my NIKKOR 50/1.8D on my D800 is now a "50-150mm focal length equivalent." Relative to a different DSLR and lens, and/or a different compact camera (such as the one I will be taking possession of this week), those "equivalent focal lengths" are subject to change and are only relevant in describing the maximum AOV of the lens.

OP Tony Beach Forum Pro • Posts: 11,961
Re: The fallacy of 35mm "equivalent focal lengths"

jrtrent wrote:

Tony Beach wrote:

Again, the only thing that is equivalent is the FOV.

If I crop an image made with a 50mm equivalent lens, then it loses that normal field of view, and the scene no longer looks as natural and realistic as it did before, so I don't crop.

Here's the thing. You could walk around with a 28mm lens attached to a 35mm format camera and crop down its files to whatever AOV suits you as long as you understand two things:

1.) Perspective -- so it's all about where you stand (or crouch, or whatever).

2.) Aperture size -- so if the 28mm is an f/2.8 lens then you have a 10mm aperture diameter. If your compact camera has an "equivalent focal length" of 55mm and it's an f/2 lens, but the actual focal length is 14mm that means you will have a 7mm diameter aperture, so you get shallower DOF and more light with the 28mm lens even after you crop the results to match the AOV of the two kits.

Disregarding the apertures and focal lengths involved, other considerations would be:

  • cost
  • weight
  • convenience
  • resolution

Much of that could well favor the compact camera, particularly if the light is decent.

ThrillaMozilla Veteran Member • Posts: 3,859
Re: The fallacy of 35mm "equivalent focal lengths"

Tony Beach wrote:

The fallacy of 35mm "equivalent focal lengths"

Sets up a straw man and imagines blowing it over with a single puff.

Look, it's good that you try to work through these problems in order to buy the right camera, but you haven't found a fallacy.  It's more useful to ask questions than to tilt at windmills.

I'm quoting this post in its entirety to take up as much of the remaining posting limit as possible.

Tony Beach wrote:

Preface

Ironically, even here at DPR equivalent focal lengths are often divorced from a complete understanding of what is or isn't equivalent.

There is this idea that if a lens covers a certain FOV on a given format then it is somehow equivalent to whatever focal length that would cover that FOV on a 35mm format camera.

[This is a good place to suggest to anyone that doesn't want to read a long post (I usually don't like reading long posts) that you might want to skip to the picture below and take a long look at it and draw your own conclusions. Just be prepared for me alluding back to the "Getting into the weeds" portion of this post if you have any questions or concerns about what I'm presenting.]

The reason for this post is that I got to thinking about "reach" the other day as I was researching a compact camera to give my girlfriend for her upcoming birthday. “Reach” is one of the factors I was considering, and I’ve settled on a Panasonic Lumix DC-ZS70 with (among other features I think will be valuable to have) its 20 MP sensor and a 30x zoom. However, I don’t for a minute buy into the “24-720 mm equivalent focal length” which is how the camera is marketed (for instance, here and here). Will this new camera get more reach than the Canon PowerShot S95 it will be replacing? Undoubtedly, but I will have more to say about that later this week when I have the new camera in hand. Will it get more reach than I have with my D800, NIKKOR 70-200/2.8 VR and TC-14eII? I'm thinking it should, but that too remains to be seen.

Getting into the weeds

There are three things that add up to reach:

1.) Optics -- which includes the actual focal length (and not the equivalent focal length), and just how good the optics are (I looked at a 70-300mm lens for my D800 and it was sent back because it didn't have any more resolution at 300mm than the 200mm lens focal length I already had).

2.) Pixel density -- which is essentially how many linear pixels in a mm of the image circle covered.

3.) Aperture diameter -- which is what true equivalence is all about. As it relates to reach small apertures have more diffraction, and because smaller apertures restrict light coming to the sensor the exposure ends up being noisier which in turn negatively effects resolution.

Given all of that, what is the actual “equivalent” focal length of the Canon PowerShot S95 compared to what I routinely get with my D800? After some testing with various lenses I concluded that at 35mm my NIKKOR 28-70/2.8D matches the longest focal length of my S95, so it's a third of the published 105mm "equivalent" focal length of that compact camera. I expect the DC-ZS70 to do better than the S95 with its 129mm lens rather than the 22.5mm lens on the S95, and with its 840 pixels per linear millimeter rather than the 490 pixels per linear millimeter on the S95.

Will the DC-ZS70 do better than what I get from my D800 with my longest current focal length? Well here's the math so far for the D800 compared to the S95:

At 35mm my D800 with its 204 pixels per linear millimeter beats my S95 at 22.5mm with its 490 pixels per linear millimeter. That's not true of all the lenses I tested, and some could possibly do even better, but I did test my old NIKKOR 18-70 DX kit lens and at 50mm it barely matched the S95. One might have expected the S95 having 2.4x as much linear resolution as my D800 at the sensor level would translate to its 22.5mm lens being equivalent to a 54mm lens, and while reasonably close to that it's only 65% of the way there (35mm rather than 54mm). Some of this is about optics, for sure; but as I will show in the visual examples below diffraction is also a factor.

Maybe I should break out my D300 and crop its final output to 4:3 aspect ratio, which would work out to 10.8 MP and be a bit closer to the 9.98 MP for the S95, but at 181 pixels per linear millimeter that's only a difference in linear resolution per millimeter of 12.5% more for the D800 (i.e., it's barely noticeable). The thing is when it comes to focal length equivalence (if you define that as reach rather than FOV coverage area) is that it's not about the sensor's format or aspect ratio, it's about the relative pixel densities -- so if I put one of my 105mm focal length lenses on my D300 you're going to have a hard time at the pixel level telling the difference between its output on that camera and its output on my D800 (the one thing that will be obviously different will be the FOV, but that's not reach).

Given all of that, I'm expecting the reach of the ZS70 at about 105mm to beat my current longest lens on my D800. I'll try to test that hypothesis next week. In the meantime...

A picture is worth a 1000 words (if not more)

Okay, so now comes the visual evidence to back up what I'm writing about here:

As always, it's important to view this at its "original size" or "100% zoom."

My final thoughts (for this post)

For me that upper right crop at f/22 says a lot. Why? Because the aperture diameter at f/22 for a 90mm lens is 4.09mm, and that's (essentially) the same aperture diameter as f/5.6 for the 22.5mm lens used on the S95 (4.02mm). The middle crops are basically "web size," which in this context is the full frame of the S95 file and the equivalent FOV of the D800 file both sized to 1080 vertical pixels in height -- and for all practical purposes that's enough for a lot of people, and if that's the case I could probably have taken a good 20mm lens and gotten "good enough" results on my D800 under these conditions.

 ThrillaMozilla's gear list:ThrillaMozilla's gear list
Canon EOS Rebel SL1
Keyboard shortcuts:
FForum MMy threads