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04-23-2015, 06:54 PM   #16
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I do not know how to respond to ??

---------- Post added 04-23-15 at 09:50 PM ----------

QuoteOriginally posted by unkipunki Quote
Focus point on bridge in distance or a street I cannot see in focus in this image? I like this shot as I see it by the way, just unsure us to which street you refer.


Thanks for liking the image.


Nothing special about the street being focus ground zero. I can see the street at 100% view in LV. Plus, this isn't the only lens I have tested at this location and that street fills more of the frame at 200mm so I am fairly aware of the street being there. Plus, the biggie - the street is in the exact center of the frame. I repeat this position as any testing protocol would call for. And lastly, I wrote the text before I embedded the image. This image posted is smaller than the image I intended to post (perhaps the forum puts a limitation on image size or I simply screwed up) otherwise, I think you would have been better able to see it.


But, my main point and that of the article too I feel is that focusing choices can be simplified by focusing on infinity (the full set of articles are easily Googled with the parameters Merklinger & Shutterbug and the entire series might give better context). In the OP's image, the easiest choice would be to place focus on the mountains and stop down. In my image, it could be anywhere in the frame since the entire frame is at infinity distance. I never got around to reading the whole series of articles myself. I was looking for an explanation of hyperfocal and when I ran across this alternative, I tested it hard and decided it produces repeatable results so there was no need for me to read further.

04-23-2015, 08:02 PM   #17
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QuoteOriginally posted by unkipunki Quote
Nothing within it explained how focusing on infinity (the mountains) could hope to bring the foreground into acceptable focus. Not absolutely saying it can't, but really asking how on earth can it?



Mr. Merklinger gets a bit wordy but essentially he says focus at infinity and stop down. The stopping down part is where he gets wordy and technical. Maybe skip the article and just try it. I'll recommend it to anyone using the 1/3 alternative to try this instead.
04-23-2015, 08:06 PM   #18
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100 years of photography is not likely to be wrong when it comes to DOF. If you want the very far to be absolutely the sharpest--then yes infinity is right, but if both near and far are to be in good focus--focusing at infinity wastes 1/2 of the potential DOF.

---------- Post added 04-23-15 at 08:55 PM ----------

QuoteOriginally posted by steve645z Quote
Last question: at f16, on a 55mm lens, on this camera, hyperfocal distance of 12.6 feet will show acceptable sharpness from 6.3 feet to infinity..
at f22, on a 55mm lens, on this camera, hyperfocal distance of 9 feet will show acceptable sharpness from 4.5 feet to infinity...
I did not check the hyperfocal values to verify they are correct--but yes that is the meaning of hyperfocal distance. You will be in (acceptable) focus from 1/2 the hyperfocal distance to infinity.

Here acceptable generally means for enlargement to about 8"x10" print. If acceptable isn't to your taste reduce or increase the f-stop when looking up the hyperfocal distance (e.g., taking at f/16, use the hyperfocal distance for f/11--to have finer detail). BTW this is what you do when using 35mm [film or FF] values (as on the lens) for the 1.5 cropped sensor; as the greater enlargement means less detail unless you use more stringent.criterion (it would be exactly 1 stop if it was a 1.414 cropped sensor--which is close enough to 1.5).

Last edited by dms; 04-23-2015 at 08:57 PM.
04-23-2015, 09:09 PM   #19
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QuoteOriginally posted by rfkiii Quote
I do not know how to respond to ?? [COLOR="Silver"]
i will try to tread lightly here, but I honestly thought perhaps you mis-typed what you meant to say.
I personally would never focus on the distant mountains and expect to capture a range of mid-distance elements in acceptable focus at only f/11 on a 645 sensor, that's all. I did not click on the link you posted so I may be in for some enlightenment, but I believe setting to infinity will lose valuable DOF in that case presented.
respectfully.

__________________________________________________________

OK, i read the Merklinger and remain dubious but willing to play with it. In considering my own compositional style, however, I generally have subjects well in the foreground of my field, much less often at the infinity range. To sacrifice all that close field to achieve ultimate sharpness on a mountain seems unreasonable to me.
No offense to all the mountains out there, but you are not likely the intended subject of my photo...not you clouds either.


Last edited by mikeSF; 04-23-2015 at 09:29 PM.
04-24-2015, 12:44 AM   #20
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QuoteOriginally posted by mikeSF Quote
i will try to tread lightly here, but I honestly thought perhaps you mis-typed what you meant to say.
I personally would never focus on the distant mountains and expect to capture a range of mid-distance elements in acceptable focus at only f/11 on a 645 sensor, that's all. I did not click on the link you posted so I may be in for some enlightenment, but I believe setting to infinity will lose valuable DOF in that case presented.
respectfully.

__________________________________________________________

OK, i read the Merklinger and remain dubious but willing to play with it. In considering my own compositional style, however, I generally have subjects well in the foreground of my field, much less often at the infinity range. To sacrifice all that close field to achieve ultimate sharpness on a mountain seems unreasonable to me.
No offense to all the mountains out there, but you are not likely the intended subject of my photo...not you clouds either.


I am still very new to MF and the 645z so I do not have the DoF ingrained yet. When I said to stop down to "f11 or so", I meant to stop down to whatever aperture would be appropriate for the format. I went on to give an example from my FF system so any specifics after that did not relate directly to the 645z.


My comments were directed at the specific composition the OP posted which had little of interest in the near foreground. One might still use f11 and crop a bunch of that out. If one shoots classic compositions with near objects and the desire for front/back deep focus, don't use this technique. This is more for the Grand Vista type compositions (within the way I use the technique).


By the way, mountains and clouds are important objects in my compositions.
04-24-2015, 01:25 AM   #21
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QuoteOriginally posted by dms Quote
100 years of photography is not likely to be wrong when it comes to DOF. If you want the very far to be absolutely the sharpest--then yes infinity is right, but if both near and far are to be in good focus--focusing at infinity wastes 1/2 of the potential DOF.


First, I will say that I always want the very far objects to be as photographically sharp as possible because that is the only way I can hope to see such detail. I use photography so that I can view detail I am unable to see with my own eyes and perhaps get to see what others with better eyesight can see and maybe take for granted.

One half of the potential DoF sounds like a lot but once I saw the actual loss, I wasn't as concerned. I've included a couple of DoF calculations and maybe you can help me with them. The calculation on the left is my best guess at the situation the OP faced (camera on 6ft tripod or handheld). Yes he loses 1/2 his DoF @f11 17-5 ft. vs. 8.85 ft. but with the 55mm, wasn't the FOV out past 17.5 ft to start with? Take a look at the 28mm. Again, if the camera is on a tripod or handheld, isn't the FOV thrown out past 4.5 ft to start with? This begs the question in my mind: is the near limit measured from the edge of the FOV or from the camera sensor?


Images from dofmaster.com.

---------- Post added 04-24-15 at 03:44 AM ----------

QuoteOriginally posted by algrove Quote
I use the "Program Line" in the menu to set DOF to deep or maximum. I use either the 25 or 28-45 which I consider both as being WA lenses and setting my DOF scale 2 stops less than the lens markings for a degree of safety, my images seem to come the way I like them with foreground and infinity in focus when I want that.

I never hear anyone talking about the "Program Line" option in the 645Z camera 4 menu. Does everyone use it set to "Auto"?


Mine is set to Auto because I did not know it was there. Possible stupid question: is this used in conjunction with P on the mode dial?
Attached Images
   

Last edited by rfkiii; 04-24-2015 at 01:31 AM.
04-24-2015, 06:16 AM   #22
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The calculator you show is wrong (or at best very confusing). If the hyperfocal distance is 4.6 feet--then the closest and furthest distances in (acceptable) focus are 2.3 feet and infinity. 2.3 to 4.6 feet are possibly a tree, a person, etc.

A bit of the math. The average (or midpoint) of the inverses of the distances before and after the focus plane is the DOF** (i.e., using inverse of DOF/2). A simple example--if it is 10 feet hyperfocal distance, then the midpoint of 1/infinity and 1/5 ft = 1/10 ft (i.e., [1/infinity + 1/5 ft]/2= 1/5 ft/2 = 1/10 ft. That BTW (when you put in the numbers) is why when doing macro (m~1) the depth of field extends equally before and after the focus plane.

And yes these distances are from the film/sensor--which is essentially the same as from the lens objective--as we are not in the close focus range,

I just noticed although the values of close focus given in the table are wrong--in the final figure showing the effect visually they have it correct as 2.32 feet.
_____________
**Sorry not as easy to explain as I thought. I what I meant to say is the midpoint or average of the inverse of the near and far focus distances from the camera is the inverse of the hyperfocal distance.

Last edited by dms; 04-24-2015 at 07:40 AM. Reason: Added some math/explanations--later added footnote.
04-24-2015, 07:38 AM   #23
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Try this

steve645z...

See whether you obtain deep DOF with acceptable sharpness using this method.
• Set your AF lens to (MF) manual focus
• Using the lens distance ring, align the middle of the infinity mark with the aperture f/16 on your lens DOF Scale. You could also use apertures of f/22 or higher because the 645Z has a "Lens Correction" feature that corrects Diffraction. This is an On/Off feature and is Off by Default.
• Set the appropriate shutter speed
• Take a picture at f/16 as well as f/22 and compare with other pictures that were previously taken using other methods.

Have Fun.


Last edited by PreSolCoh; 04-24-2015 at 09:00 AM. Reason: An ommission
04-24-2015, 08:56 AM   #24
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QuoteOriginally posted by rfkiii Quote
I am still very new to MF and the 645z so I do not have the DoF ingrained yet. When I said to stop down to "f11 or so", I meant to stop down to whatever aperture would be appropriate for the format. I went on to give an example from my FF system so any specifics after that did not relate directly to the 645z.


My comments were directed at the specific composition the OP posted which had little of interest in the near foreground. One might still use f11 and crop a bunch of that out. If one shoots classic compositions with near objects and the desire for front/back deep focus, don't use this technique. This is more for the Grand Vista type compositions (within the way I use the technique).


By the way, mountains and clouds are important objects in my compositions.
You were evaluating the OP's composition and concluding he did not want any of the near field in focus, thus you gave a recommendation getting the distant objects in focus. With respect to that objective, your answer certainly makes sense. Heck, if his sharpest aperture is f/8, then he should stay at f/8 and focus at infinity and expect to optimize the infinity range, forgoing all nearer elements.

However, OP said: " if you are shooting a landscape, how are YOU getting everything in sharp focus?"

I understood the question to include more than just the most distant objects, including the captured midground.
04-25-2015, 05:13 AM   #25
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QuoteOriginally posted by dms Quote
The calculator you show is wrong (or at best very confusing). If the hyperfocal distance is 4.6 feet--then the closest and furthest distances in (acceptable) focus are 2.3 feet and infinity. 2.3 to 4.6 feet are possibly a tree, a person, etc.

A bit of the math. The average (or midpoint) of the inverses of the distances before and after the focus plane is the DOF** (i.e., using inverse of DOF/2). A simple example--if it is 10 feet hyperfocal distance, then the midpoint of 1/infinity and 1/5 ft = 1/10 ft (i.e., [1/infinity + 1/5 ft]/2= 1/5 ft/2 = 1/10 ft. That BTW (when you put in the numbers) is why when doing macro (m~1) the depth of field extends equally before and after the focus plane.

And yes these distances are from the film/sensor--which is essentially the same as from the lens objective--as we are not in the close focus range,

I just noticed although the values of close focus given in the table are wrong--in the final figure showing the effect visually they have it correct as 2.32 feet.
_____________
**Sorry not as easy to explain as I thought. I what I meant to say is the midpoint or average of the inverse of the near and far focus distances from the camera is the inverse of the hyperfocal distance.


Thanks. This is the second online calculator whose results have been called into question in the past few weeks when I have referred to them. The other being the diffraction calculator at Cambridge in Colour.

---------- Post added 04-25-15 at 07:15 AM ----------

QuoteOriginally posted by mikeSF Quote
You were evaluating the OP's composition and concluding he did not want any of the near field in focus, thus you gave a recommendation getting the distant objects in focus. With respect to that objective, your answer certainly makes sense. Heck, if his sharpest aperture is f/8, then he should stay at f/8 and focus at infinity and expect to optimize the infinity range, forgoing all nearer elements.

However, OP said: " if you are shooting a landscape, how are YOU getting everything in sharp focus?"

I understood the question to include more than just the most distant objects, including the captured midground.


Fair enough.
04-26-2015, 04:43 PM   #26
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Test Results

Hi All,

First off, thanks so much for the feedback on this post. Really incredible and smart people here.

I decided to run a F-Stop test. Used a Pentax 645Z and a Pentax-D FA 645 55mm f/2.8 lens.

Shot from F-4 up to F22 using the hyperfocal marks on the lens barrel aligned to the center of the infinity mark on the lens. A bit hard to tell if I was perfectly aligned but all the shots seem focused so so far so good.

Here's what I did:

1) Used a tripod and shot across a bunch of fstops in AV mode.
2) Shot in RAW
3) Brought all the images into Photoshop Camera RAW and did an identical "auto adjustment" to all images.
4) Applied no sharpening anywhere (Camera RAW sharpening set to zero.)
5) Brought the image into photoshop and here's what I got.

LINK TO DROPBOX file where you can actually see this image.... It's resized as the master was over 1.5 GB as a TIFF. This is 44mb.

http://tinyurl.com/p6r9svg

Based on what I'm seeing, F22 looks pretty darned good. And to clarify, I literally didn't focus any of these shots with the LCD or viewfinder.... Just lined up the hyperfocal f-stop to infinity.

Plan on more testing. But F22 looks quite encouraging. Again, no sharpening was applied to any of the images.

And I'm not seeing a lot of diffraction at F22.

What do you think?

All the best!

S
Attached Images
 

Last edited by steve645z; 04-26-2015 at 04:46 PM. Reason: bad link
04-27-2015, 04:07 AM   #27
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Very nice results, diffraction doesn't seem as much of a problem, in fact the f/22 result seems every bit as crisp as f/16 but with the railing better defined.
04-27-2015, 07:57 AM   #28
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I just switched to f22

Been shooting a lot this past 2 weeks in the dark---too dark to manually focus, sometimes too dark for AF. So, had to resort to zone focus. Using the FA 45-85 for several reasons, especially that this series dictates shifts in FL, and fumbling around at night or early dawn with the light getting brighter by the second means changing lenses is just too much, considering 3 flashes and wireless triggering.

At 100%, I can't see any difference so far between f16 or f22, diffraction wise, or not enough that it makes one iota of difference in these shots I'm making.
04-27-2015, 10:22 AM   #29
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Sorry it's a bit tough to download the image.... Unfortunately, it's massive.

But if you can follow the dropbox link, it's really neat to see the difference.

I wish this lens had better hyperfocal markings on it... The Zeiss lenses are awesome in that regard.

But I did manage to get all the images in focus without any form of formal focusing. Which is quite encouraging for landscape work.

Will have to try this with a few other lenses. Just ordered an old-school 45mm Pentax 645 lens off of ebay. Will be curious how this performs.

Thx!

S
04-27-2015, 02:48 PM   #30
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QuoteOriginally posted by steve645z Quote
Sorry it's a bit tough to download the image.... Unfortunately, it's massive.

But if you can follow the dropbox link, it's really neat to see the difference.

I wish this lens had better hyperfocal markings on it... The Zeiss lenses are awesome in that regard.

But I did manage to get all the images in focus without any form of formal focusing. Which is quite encouraging for landscape work.

Will have to try this with a few other lenses. Just ordered an old-school 45mm Pentax 645 lens off of ebay. Will be curious how this performs.

Thx!

S
How far were you away from the railing with the camera?
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