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The lenses we use
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Lou Jost



Joined: 04 Sep 2015
Posts: 4071
Location: Ecuador

PostPosted: Tue Aug 14, 2018 8:12 am    Post subject: Reply with quote

You can turn any camera into a short-register-distance camera by glueing up the mirror and mounting the lenses on the inside of the lens mount. That's what I did with my Nikon D5300. I can use almost any lens on it.
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mawyatt



Joined: 22 Aug 2013
Posts: 2334
Location: Clearwater

PostPosted: Tue Aug 14, 2018 8:16 am    Post subject: Reply with quote

ray_parkhurst wrote:



I have a feeling that might change if I ever shift over to a camera with shorter register.


Ray,

Do I see a new Nikon Mirrorless in your future Shocked

Best,
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ray_parkhurst



Joined: 20 Nov 2010
Posts: 2483
Location: Santa Clara, CA, USA

PostPosted: Tue Aug 14, 2018 8:20 am    Post subject: Reply with quote

Lou Jost wrote:
You can turn any camera into a short-register-distance camera by glueing up the mirror and mounting the lenses on the inside of the lens mount. That's what I did with my Nikon D5300. I can use almost any lens on it.


I'm not sure I'd be brave enough to do that.

mawyatt wrote:
Do I see a new Nikon Mirrorless in your future Shocked


Either that or a D850, but my current interest is in automating the Stack and Stitch process. Should be fun!
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Justwalking



Joined: 10 Jun 2018
Posts: 137
Location: Russia

PostPosted: Tue Aug 14, 2018 11:26 am    Post subject: Reply with quote

rjlittlefield wrote:

I will say it one more time: when you image the same FOV at the same NA, on different size sensors, you get the same DOF and the same amount of diffraction blur. The Airy disk on the larger sensor is larger, but in exact proportion to sensor size. Everything scales together. If both sensors have the same MP, then you cannot tell the images apart.
--Rik


Rik, I totally agree about diffraction blur but sorry to say that you are missng with DoF again. Your DoF will be the same only in absolute size, but not relative to sensor's sizes.

Let's do remember your words:
Quote:

Nobody is debating whether the formulas are correct. The formulas are fine. I know them forwards and backwards and I use them often. All the formulas referenced by Justwalking are correct.

Well, lets take a count again with your expanded data (big thanks for it) with same NA and by the formula that you have been totally agree:

Dof=2*Feff*C/M^2

for FF: DoF[f] = 2*55*C[f]/(4.4*4.4) = 110C[f]/19.36 = 5.68*C[f], where C[f] - CoC on FF;
for crop DoF[c] = 2*10*C[c]/(0.8* 0.8 ) = 20C[c]/0.64 = 31.25*C[c], where C[c] - CoC on crop;

So in terms of their CoC DoF is different in inverse proportion exactly to crop size.

With the same NA crop (5.5) sensor have DoF is larger than DoF of FF exactly at 31.25/5.68 = 5.5 times ! In terms of their CoC and then also in terms of pixels on the 16MP picture.
Another thing why we can't see difference on both pic in your example - because both pics are so deep in diffraction field where it is no more visible borders of DoF. Overall sharpness to low to determine DoF.

Regards.
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Tue Aug 14, 2018 2:40 pm    Post subject: Reply with quote

Sigh...more popcorn...

Justwalking wrote:
Your DoF will be the same only in absolute size, but not relative to sensor's sizes.

Yes, of course. And that's a good thing, because DOF is measured in units at the subject. It's not supposed to be relative to the sensor size. This is just like FOV is measured at the subject, and NA is measured at the subject.

With same FOV at subject, same NA at subject, you get same DOF at subject -- sensor size doesn't matter.

Quote:
Another thing why we can't see difference on both pic in your example - because both pics are so deep in diffraction field where it is no more visible borders of DoF. Overall sharpness to low to determine DoF.

I assume you don't realize that what you just wrote is nonsense.

DOF depends on how fast the blur circles expand as you move away from perfect focus. The upper antenna is clearly burred, compared to the resolution chart. And it is blurred by the same amount in both images, which means that the rate of expansion is the same for both images. (Those images HERE.)

If your theory were correct, then because the magnifications are different by a factor of 9.5X, the rates of expansion would also be different by a factor of 9.5X. Such a large difference would be trivial to see.

Here, I can show you what that would look like. This is the same camera, with the aperture opened by about 9.5X. Less diffraction, less DOF -- the unavoidable tradeoff.



--Rik
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Justwalking



Joined: 10 Jun 2018
Posts: 137
Location: Russia

PostPosted: Tue Aug 14, 2018 3:51 pm    Post subject: Reply with quote

rjlittlefield wrote:
Sigh...more popcorn...
Yes, of course. And that's a good thing, because DOF is measured in units at the subject. It's not supposed to be relative to the sensor size. This is just like FOV is measured at the subject, and NA is measured at the subject.
With same FOV at subject, same NA at subject, you get same DOF at subject -- sensor size doesn't matter.


LoL. It is not good thing. It is a bad thing.
No matter only if you want to look this object directly by your eyes through the optics.
But it is mean that your DoF on FF will be smaller 5.5 times compared to whole frame on crop when you start to see whole frame on the screen. Dof is same in absolute size, but sensor with same 16 MP is 5.5 times large and you want to see projection or print the whole frame.

I'll answer to other part later, sorry. Must go now.
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Tue Aug 14, 2018 7:00 pm    Post subject: Reply with quote

LOL, indeed!

Justwalking, I marvel at the amount of faith that you place in your imagination.

But I suppose it is easy to maintain that faith, if you never take the time to check whether your assertions match reality.

I have not been so lucky. I am afflicted with the compulsion to experimentally confirm (or refute!) whatever I think the math is telling me, to make sure I understand the math correctly.

In the case of DOF, I have spent a lot of time over the last 13+ years, crosschecking theory with controlled experiments and side-by-side tests, using sensor sizes from 1/2.5" to FF, and where necessary exchanging email with the authors of published articles to resolve confusion.

Have you done any of that?

I expect not, but if you have, I would be interested to hear the nature of your experiments. Please provide data and post images.


I have to be offline for a few days starting very soon, so I will not be able to continue the discussion at this time.

I do have time to post one image.

This image was shot from my monitor screen, just as it appeared to my eyes. On the screen, the images that my eyes were seeing came from APS-C and 1/1.8" sensors (different by a factor of 3.07X).

For purposes of the controlled experiment, the aperture of the APS-C lens was set to two different apertures: one where the F# was scaled in proportion to the sensor size, and the other where it was not.

And what my eyes see, with the whole frame displayed on screen, is that the images from small and large sensors look the same when Feff was scaled in proportion to the sensor size.

This screen snapshot is of course quite small, just to show context. Interested readers can display the images on their own screen, and read the rest of the technical details and experimental protocol, by visiting http://www.photomacrography.net/forum/viewtopic.php?t=37669 ("A visual demo on the equivalence of small and large sensors").



By the way, this experiment was done 13 years ago, when I was still struggling to understand exactly what affected DOF. Fortunately those days are long past.

Now I just struggle to help other people understand.

This presumes, of course, that other people want to understand.

There's not a lot I can do for somebody who is committed to believing whatever fantasy their imagination creates.

--Rik
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Justwalking



Joined: 10 Jun 2018
Posts: 137
Location: Russia

PostPosted: Tue Aug 14, 2018 8:43 pm    Post subject: Reply with quote

rjlittlefield wrote:
LOL, indeed!

Justwalking, I marvel at the amount of faith that you place in your imagination.

--Rik


Rik, unfortunatelly doing irrelevant experiment
even 13 years ago is not help with the math. There more harm only.
Kodak with 1440 pixels on high and Canon with 2048. Then resized to different scale.
First of all it is not in the macro range and what happens there yoy can read at this link
https://www.bhphotovideo.com/explora/photography/tips-and-solutions/depth-field-part-3
Hope you will have time furter to do single shot of the safety match head at 4.4X Magnification on FF to compare.
Regards
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hero



Joined: 17 Jul 2017
Posts: 71
Location: California

PostPosted: Tue Aug 14, 2018 10:59 pm    Post subject: Reply with quote

There is nothing more to be gained by trying to explain basic mathematics and geometry to someone who is very clearly unable to comprehend what they are reading. Such rude, arrogant, and persistently incorrect responses is not worthy of anyone's time here.

Sometimes you have to know when to just cut your losses and move on. At this point, Rik has spent a substantial amount of time, energy, and patience to demonstrate why this individual's thinking is flawed, and all that he gets in response is incoherent "but 1440 pixels versus 2880" or "non-macro range" jargon. Continued investment of time will not be fruitful because this user is not open to admitting they could possibly be in error. As a former teacher, when a student is not willing to accept they are wrong, there is no further meaningful dialogue. Such people are cranks and crackpots--they believe they have proven it possible to trisect an arbitrary angle with straightedge and compass; or to have proven the twin prime conjecture, or P = NP.
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Macrero



Joined: 01 Sep 2011
Posts: 814
Location: Valladolid , Spain

PostPosted: Wed Aug 15, 2018 2:34 am    Post subject: Reply with quote

Wow Shocked this thread is going nowhere... How about leaving the formulas and maths apart for a while and spend that time on taking some nice pics? No matter the camera, sensor size, pixel size, etc, etc, etc...
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Wed Aug 15, 2018 5:03 am    Post subject: Reply with quote

I appreciate the discussion and the formulas even though the intended recipient is arrogant and stubborn and apparently can find an infinite number of excuses to maintain his beliefs against all evidence and math. Rik's discussion will be the go-to reference for anyone else who struggles with these issues. Thanks Rik for the patience to engage this individual.
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viktor j nilsson



Joined: 01 Mar 2013
Posts: 146
Location: Lund, Sweden

PostPosted: Wed Aug 15, 2018 5:04 am    Post subject: Reply with quote

Rik, just have to say that while your knowledge and empirical mindset are impressive, your patience is simply unbelievable. Continuing this discussion is clearly not going to advance Justwalking's understanding, but it has at least been very rewarding for me to follow. I'm an optics user that has not had a good understanding of these theoretical issues, but I've learned a lot from reading these 16 (edit: 19!) pages. So at least something came out of your efforts.
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Macrero



Joined: 01 Sep 2011
Posts: 814
Location: Valladolid , Spain

PostPosted: Wed Aug 15, 2018 6:24 am    Post subject: Reply with quote

Lou Jost wrote:
I appreciate the discussion and the formulas even though the intended recipient is arrogant and stubborn and apparently can find an infinite number of excuses to maintain his beliefs against all evidence and math. Rik's discussion will be the go-to reference for anyone else who struggles with these issues. Thanks Rik for the patience to engage this individual.


Lou,

the knowledge and information provided by Rik in this thread is much appreciated, as always. But after reading the whole thread, I think it has become a path that leads nowhere a long ago, given the commitment of certain user Rolling Eyes to refute almost all the info, formulas, etc. provided, believing to be the owner of the truth.

- Macrero
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rolsen



Joined: 01 May 2018
Posts: 144
Location: Finland

PostPosted: Wed Aug 15, 2018 7:25 am    Post subject: Reply with quote

Long time ago, in certain long forgotten nature forum we had this one guy. He had couple of "dogmas", like

1. You don't get sharp images in low light
- more light means sharper picture
2. You don't get sharp images from a distance
- the closer you get the sharper the image

We all did our best to show how these things work in real world, but no, nothing changed. This went on for years.
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Justwalking



Joined: 10 Jun 2018
Posts: 137
Location: Russia

PostPosted: Wed Aug 15, 2018 9:29 am    Post subject: Reply with quote

Lou Jost wrote:
I appreciate the discussion and the formulas even though the intended recipient is arrogant and stubborn and apparently can find an infinite number of excuses to maintain his beliefs against all evidence and math. Rik's discussion will be the go-to reference for anyone else who struggles with these issues. Thanks Rik for the patience to engage this individual.


Lou, if you think that "LoL" without reason in such discussion looks smart that is your own choice.
It's a shame that nobody from fans army of Rik's experience did not trying to help him bring me down and do just one single shot an 4.4 Mag at 16MP FF prefer instead to talk about anything else, but not about subject of the discussion.
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