Hyper Focal Distance (HFD) Calculator Excel sheet .. help needed please

[Wail]

Richard is very right here. Quite a few times before I found myself in the same position as you are Wail trying to use f/8 as optimal aperture but it simply does not work that well all the times. From my limited experience, there are two practical ways out of this but both are not ideal.

First, you can use wider lens and get closer - they do have greater DOF. Ultrawides are not suitable to everybody and every subject so this approach is of course quite limited.

Second, you can get a tilt lens and try to extend DOF that way. The native Nikon/Canon TS lenses are really expensive. You can try a cheaper alternatives like buying TS adapter and MF lenses but there the choices of the focal length are more limited. Plus focusing tilt lenses resembles some form of an obscure voodoo practice .

Alexey,

I couldn't agree more; however, as I've already stated, I am not a big fan of ultra wide angel lens for landscape. As I use fullframe, I find that anything wider than 35mm to be too wide for my landscape style.

I've got the 20mm Voigtlander, but I use that for monuments mostly.

I've also got a couple of the Nikon PC-E lens (24mm and the 45mm). While I've never used the 24 for landscape, just way too wide for me and I use it primarily for architectural shots; the 45 is simply magic for landscape with my style, and I can't stress just how amazing it is for what I shoot and the way I shoot.

However, there are times when I can't use the T/S lens, and I end-up having to make do with the 24-70; also, I do have friends who come along with me on the odd hike and they often ask me how to maximise their DoF & sharpness ... hence why I am thinking along the lines of the HFD theory.

 

[Wail]

I guess what I will do, is to take all my lens, a long measuring tape and go spend a weekend out in the desert, measuring and shooting noting down all the details on to a notepad to come home and see the results.

That, while keeping my eye on the HFD and DoF meter should put this matter to rest, I hope.


But now I have another question ... what equation do I use to measure DoF? ... May be this is for another thread!?

 

[Deleted member 8670]

Going over f/11 is something I want to try and avoid as much as possible, for the simple issue of diffraction.

Have you been reading again?
Don't worry too much about diffraction, it's not that noticeable until you go well over f/16.

 

[dalex_257]

Have you been reading again?
Don't worry too much about diffraction, it's not that noticeable until you go well over f/16.

That depends on the lens optics and how large you will print. My now sold Sigma 10-20 (was a very sharp copy) I only noticed it slightly at f/22 but then again I have not printed anything larger than A3 from those shots.

 

[dalex_257]

But now I have another question ... what equation do I use to measure DoF? ... May be this is for another thread!?

The Ins and Outs of Focus have HFD formulas on pages 14-15...

 

[david1701]

Have you been reading again?
Don't worry too much about diffraction, it's not that noticeable until you go well over f/16.

That depends on the lens optics and how large you will print. My now sold Sigma 10-20 (was a very sharp copy) I only noticed it slightly at f/22 but then again I have not printed anything larger than A3 from those shots.

also massively dependent on pixel density

noticable @ f8 on a 7d

 

[HoppyUK]

also massively dependent on pixel density

noticable @ f8 on a 7d

Can somebody show me some actual evidence of this pixel-density-diffraction business? I'm intruigued - I understand the theory, as it has so far been explained to me eg on CambridgeInColour, but have yet to see any evidence of it. I'm not interested in hypothetical formulae

In fact, just the reverse has been the case. From what I have seen on the web and my own tests, pixel density has no significant effect on diffraction (which is primarily an optical/lens effect and nothing to do with the sensor).

For example, the 7D is sharper than a 40D, as you might expect with 80% more pixels. This is beyond doubt. And as far as I can detect, with the same lens on both cameras, diffraction begins to bite around f/5.6 - again as you might expect. On full frame, it starts to impact about one stop higher, around f/8 - again as I would expect.

I have found diffraction to be a major deterrant to critical sharpness, especially on crop format where it is really quite bad at f/16, and frankly unusable at f/22 to my eye. On full frame, I will avoid f/16 if possible, but not worry about it too much. It was always thus, even with film.

 

[david1701]

5dII is same px density as 40dso should behave similarly,I heard the theory knocking about and we tried on foxy's 7d and the 17-40L becomes UNSHARP (I was appalled) barely at 5.6 and noticeably if you look at f8 its a shmexy lens on the 5dII even if it is unbearably slow

 

[HoppyUK]

5dII is same px density as 40dso should behave similarly,I heard the theory knocking about and we tried on foxy's 7d and the 17-40L becomes UNSHARP (I was appalled) barely at 5.6 and noticeably if you look at f8 its a shmexy lens on the 5dII even if it is unbearably slow

Not convinced David

What I would like to see, for example, is identical side by side images shot with both a 40D and a 7D, with the same high quality lens, at a range of f/numbers. Lowest ISO, same processing etc, showing detail at both the centre and edges

In that way, the main difference between the two would be pixel density, ie 10mp vs 18mp, on the same size sensor.

BTW, my 17-40L on a 5D2 is outrageously sharp. TBH I can't see any difference between f/5.6 and f/8 at the centre, but what is absolutely true is that the edges keep getting better right up to f/11!

Which reveals another real world factor that the pixel-density-diffraction theorists have forgotten - that is, diffraction only becomes a limiting factor when the sharpness losses due to diffraction outweight the gains in sharpness made by the reduction of other aberrations as f/number increases.

All lenses behave like this to a greater or lesser extent, so if we are to say (accurately) when diffraction takes over, you have to say where exactly in the frame you are looking.

What I'm beginning to think this theory means, at most, is this. Higher pixel density dictates that the diffraction limited peak will be reached at a slightly lower f/number. However, the higher pixel density more than off-sets this with the result that it will still deliver a higher level of sharpness at the same f/numbers - not less, which is what is being implied.

This at least fits with the theory, yet at the same time bears out what we see in practise

 

[Wail]

Have you been reading again?
Don't worry too much about diffraction, it's not that noticeable until you go well over f/16.

Yup, this is what I do when I am not out shooting! Thanks to an ailment, I am in bed a lot these days and end up reading a lot ... which just confuses the chicken out of me

That depends on the lens optics and how large you will print. My now sold Sigma 10-20 (was a very sharp copy) I only noticed it slightly at f/22 but then again I have not printed anything larger than A3 from those shots.

Thankfully, I never print nor display any of my work. However, a few good friends always come asking about how to get that bit of extra sharpness and I am trying to understand the "science" behind it so that I can better explain things to them.

The Ins and Outs of Focus have HFD formulas on pages 14-15...

Thank you for the link, I've downloaded the two papers and am trying to go over them. I will come back, I am sure, with a lot of questions

 

[Wail]

also massively dependent on pixel density

noticable @ f8 on a 7d

From my experience, I only notice "significant" and "bothersome" diffraction one I go beyond f/16 .. be it on FX or DX. May be it's my ageing eyes, or may be it's a mixture of other things (including my eyes).

Incidentally, I do notice it to be more prominent when using non-high-end lens, and it creeps in at lower f numbers. With high-end lens, I tend to find the whole situation more tolerant.

Can somebody show me some actual evidence of this pixel-density-diffraction business? I'm intruigued - I understand the theory, as it has so far been explained to me eg on CambridgeInColour, but have yet to see any evidence of it. I'm not interested in hypothetical formulae

In fact, just the reverse has been the case. From what I have seen on the web and my own tests, pixel density has no significant effect on diffraction (which is primarily an optical/lens effect and nothing to do with the sensor).

For example, the 7D is sharper than a 40D, as you might expect with 80% more pixels. This is beyond doubt. And as far as I can detect, with the same lens on both cameras, diffraction begins to bite around f/5.6 - again as you might expect. On full frame, it starts to impact about one stop higher, around f/8 - again as I would expect.

I have found diffraction to be a major deterrant to critical sharpness, especially on crop format where it is really quite bad at f/16, and frankly unusable at f/22 to my eye. On full frame, I will avoid f/16 if possible, but not worry about it too much. It was always thus, even with film.

There is a huge difference between the theory vs. the actual physical shot. The amount of issue with diffraction is a lot dependent, I've come to conclude, on the audience viewing the pictures, as well as the person who has just captured the shot.

I think in 99% of the time, most people just don't pay much attention; like pixle-peeping and chimping, only die-hards get to such details. May be it's just my own excuse to try to lift-up my skill to another hypothetical level :shrug:?

Not convinced David

What I would like to see, for example, is identical side by side images shot with both a 40D and a 7D, with the same high quality lens, at a range of f/numbers. Lowest ISO, same processing etc, showing detail at both the centre and edges

In that way, the main difference between the two would be pixel density, ie 10mp vs 18mp, on the same size sensor.

BTW, my 17-40L on a 5D2 is outrageously sharp. TBH I can't see any difference between f/5.6 and f/8 at the centre, but what is absolutely true is that the edges keep getting better right up to f/11!

Which reveals another real world factor that the pixel-density-diffraction theorists have forgotten - that is, diffraction only becomes a limiting factor when the sharpness losses due to diffraction outweight the gains in sharpness made by the reduction of other aberrations as f/number increases.

All lenses behave like this to a greater or lesser extent, so if we are to say (accurately) when diffraction takes over, you have to say where exactly in the frame you are looking.

What I'm beginning to think this theory means, at most, is this. Higher pixel density dictates that the diffraction limited peak will be reached at a slightly lower f/number. However, the higher pixel density more than off-sets this with the result that it will still deliver a higher level of sharpness at the same f/numbers - not less, which is what is being implied.

This at least fits with the theory, yet at the same time bears out what we see in practise

I will need to get back to this when I am a bit better; the pains are playing with my brains.... or what's left of the couple of brain cells .

 

[dalex_257]

Thank you for the link, I've downloaded the two papers and am trying to go over them. I will come back, I am sure, with a lot of questions

You don't have to read it all - just that chapter since it has the formulas you need ;-)