Is this photo Critically Sharp and if not Why? :)

[ahawkins]

This was a nice overcast morning in Mill Creek WA. Great Blue Heron preening in the Penny creek. I have a bunch of other photos at lower shutter speed, but this one is what I'm wanting an opinion on. Is this photo "critically sharp"? And what happened?

Z9 + 600mm TC f/4 lens
Gitzo 45 series Monopod
RRS Monopod mount

-0.67 EV Exposure bias
Shutter 1/2500s
f/4
Auto ISO 400
Matrix metering
RAW High Efficiency, Quality Priority
Wide Area AF (S)
Bird Detection
VR ON-Sport
The image below is not cropped


I added the photo to my Onedrive here 20240919-MCCA-R9A_3514.NEF
This should be setup to allow anyone to view with a onedrive login.
below is just a snippet.

 

[ButlerKid]

How much is the image cropped? What is the ISO?

 

[ahawkins]

The full image in Onedrive is not cropped at all. ISO is 400

 

[John Navitsky]

a bit hard to say, but i *think* it _might_ be a bit back-focused*, although seems like it's in the ballpark.

* my reasoning is some of the bushes in the background are in focus. but, the log and top part of the bird also seem reasonably in focus. so my _guess_ is the focal point is kind of between those two points but the bird is still within the dof, but not centered in it.

as for why, not sure, although i'm wondering if i could be wrong about it being back-focused. i do think there might be some other things going on here like atmospherics.

 

[John Navitsky]

also, howdy neighbor

 

[Barbara]

I wonder whether there was some atmospheric effect in play. As an alternative "explanation," it sometimes seems to me that mirrorless cameras can miss critical focus on relatively low-contrast subjects. (Comments clearly worth less than 2 cents.)

 

[ahawkins]

also, howdy neighbor

Hello, when you say neighbor, do you mean Pacific Northwest Neighbor? or Mill Creek Neighbor?

 

[ahawkins]

I wonder whether there was some atmospheric effect in play. As an alternative "explanation," it sometimes seems to me that mirrorless cameras can miss critical focus on relatively low-contrast subjects. (Comments clearly worth less than 2 cents.)

I have a 2 piece Zemlin hood, with only half deployed. it was a pretty cloudy day so I didn't think heat waves would have been there. The lens had been on the camera and my shoulder for ~ 1 hour (no fogging). Thanks for participating.

 

[Whiskeyman]

Keep in mind that the presentation on a website can be less sharp than an image is capable of being. In addition, the lower contrast, resulting from the overcast lighting, can also make an image appear less than critically sharp due to decreased contrast. With that being said, I'd say that the image, as presented here, is not critically sharp. but it is good and a candidate for improvement.

Did you apply any post process sharpening? If not, give it a try and add some sharpening and increase the contrast of the image to see if it looks better.

 

[ahawkins]

Keep in mind that the presentation on a website can be less sharp than an image is capable of being. In addition, the lower contrast, resulting from the overcast lighting, can also make an image appear less than critically sharp due to decreased contrast. With that being said, I'd say that the image, as presented here, is not critically sharp. but it is good and a candidate for improvement.

Did you apply any post process sharpening? If not, give it a try and add some sharpening and increase the contrast of the image to see if it looks better.

I should have mentioned that I did NOT apply any post. I was just surfing my photos trying to find the ones that were the best candidates.

 

[Whiskeyman]

I should have mentioned that I did NOT apply any post. I was just surfing my photos trying to find the ones that were the best candidates.

Then, applying sharpening and other edits to the RAW image should improve it.

 

[John Navitsky]

Hello, when you say neighbor, do you mean Pacific Northwest Neighbor? or Mill Creek Neighbor?

thrasher’s corner

 

[John Navitsky]

for those commenting on the forum image, note OP provided a downloadable copy of the raw

 

[MrFotoFool]

Based on what I see on the sreen it looks plenty sharp to me.

 

[Len Shepherd]

As an alternative "explanation," it sometimes seems to me that mirrorless cameras can miss critical focus on relatively low-contrast subjects. (Comments clearly worth less than 2 cents.)

This type of comment, whether or not is worth less than 2 cents, seems very relevant to this image.

The significant posted crop relative to the RAW image is a potential complication.

There is more feather detail about 4 inches in front of the eye than surrounding the eye.

If the intention was to focus on the eye - it is obvious with reasonable eyesight even within the limits of web image reproduction this did not happen with the posted crop

Cropping an image (which has happened) has a depth of field effect similar to getting closer to the subject.

As a starting point a long time ago when Nikon used to regularly produce a book of all their products, in the 1996-1998 edition they quoted 6.49 to 6.51 metres (less than 1 inch) depth of field for a 600mm at f4 at the then 6.5metres closest focus distance.
The two Z 600mm lenses can focus around 50% closer - with an expectation of one quarter of the depth of field at around 4 metre rather 6.5 metres.

This seems to me a good starting point assumption for this image crop - and helps explain the sharpness detail difference between the feathers around eye and the closer feather detail is a depth of field issue.

I speculate the image crop is close to about a 10 inch wide subject.
As a separate detail the Nikon specification for the 600mm f4 Z seems to indicate a subject width of 10.7 inches wide at MFD.
As this is a cropped image focussing closer than the MFD is eliminated.

In the RAW file image contrast seems relatively low and the birds eye is small in the frame.
While I was not there my speculation is subject conditions (contrast, subject size in the frame etc) were not enough for accurate AF on the eye.

IMO the still slight softness in the best feather detail in front of the eye is most likely due to the significant crop and is possibly also slightly limited by web reproduction limitations.

Depth of field sharpness in dof tables seems to be based on a historical 1/100 of an edge blur being just acceptable when the whole image area is included in a 10x8 inch print viewed at a "comfortable" viewing distance of about 15 inches.

On this basis your cropped image is distinctly sharper than the basic dof assumptions - so relatively well done - especially as few remember image resolution reduces in lower contrast lighting.

Sharper detail IMO is possible - but only when you can get closer to the bird, preferable in sunlight.

 

[ahawkins]

If the intention was to focus on the eye - it is obvious with reasonable eyesight even within the limits of web image reproduction this did not happen with the posted crop



Sharper detail IMO is possible - but only when you can get closer to the bird, preferable in sunlight.

these are two good inputs.
I was trying to focus on the eye, but as it looks and many pointed out, the AF was a bit short of the eye. Even though the AF marker included the eye, that was not the best focus. So maybe use the single point focus and point it at the eye. Which I have some of those shots from this subject.

I went back to the scene today and measured the distance to the log and it was 38 yards. I thought I was actually close, but seems like close would be better.


I had plenty of light, albeit flat overcast light. Notice the 1/2500 shutter and ISO400. I had switched between 840 and 600mm several times. Sounds like I should have kept the lens at 840 f/5.6 and kept the frame "fuller"

Many thanks for all that posted.

 

[Len Shepherd]

I was trying to focus on the eye, but as it looks and many pointed out, the AF was a bit short of the eye. Even though the AF marker included the eye, that was not the best focus.

Clarification first.
In your original post you said the image IS NOT cropped rather than cropped.
The link you posted to the original NEF has very flat light lighting, is deliberately under-exposed by .67 stops, and implies a severe crop plus a lot of PP to get to what you posted.

Measuring 38 yards and using my 600 f6.3 gives me a lot, lot less subject magnification with our moderately smaller local grey herons.

So maybe use the single point focus and point it at the eye. Which I have some of those shots from this subject.
I went back to the scene today and measured the distance to the log and it was 38 yards.

Perhaps do more testing first.
ALL manufacturers explain in instruction manuals that AF - including eye AF - does not always focus as well as some presume.

In what seems to be the original NEF the birds eye would have been distinctly small in the frame even with a 600mm, is round in shape rather than oval as with a human eye, the iris area around the eye is a much smaller percentage of the eye area than a human eye and is at an angle rather than square on - a significant challenge for an AF system.

Further testing will help determine whether eye AF can or cannot work well for you in similar situations - assuming the link to the original NEF is representative of the scene.

I had plenty of light, albeit flat overcast light. Notice the 1/2500 shutter and ISO400. I had switched between 840 and 600mm several times. Sounds like I should have kept the lens at 840 f/5.6 and kept the frame "fuller"

Actually on topic - many say that judging depth of field in a viewfinder is impossible.

My response is that with good eyesight when changing aperture just half a stop the dof difference is easy to distinguish in the viewfinder.
New eyeglasses cost a small fraction of the price of the equipment you were using.
Sometimes a visit to an optician can help.

The AF should have (in under a second) identified the bird with a rectangle, then with a smaller rectangle the head and then with a very small rectangle the outline of the eye - if eye AF worked.
Can you recall if there was a tiny rectangle around the eye?
If not, eye detect did not detect the birds eye

If the image is not a crop then with good eyesight it should have been easy to observe in the viewfinder the sharpest feather detail was in front of the eye.

 

[Krishnakotti]

Below is the original image opened in FastRawViewer. This is sharp enough for me.

More than sharpness, I think the major issues are it was underexpose and subject is not parallel or image sensor and hence you depth of field issue.

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100% zoom

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Below is how it might look with bit of processing:-

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[Palouse]

@Krishnakotti shows exactly what I was thinking. If there is more separation between the top of the head and the background the bird will appear sharper.

 

[zemlin]

Looking at the RAW file, I also see no sharpness issues. Plenty of feather detail. A wee bit of noise. Heavy crop shown in OP.

 

[Hooligans Imagery]

YES, this is where Fast Raw Viewer comes in handy. I use it often to compare two high frame rate images that could both be a winner and sometimes I see marked differences in sharpness, especially in the fine detail. When I see fine detail around the eye like you have that is a good thing.

Contrast Edges

Fine Detail

 

[ahawkins]

YES, this is where Fast Raw Viewer comes in handy. I use it often to compare two high frame rate images that could both be a winner and sometimes I see marked differences in sharpness, especially in the fine detail. When I see fine detail around the eye like you have that is a good thing.

Thanks! This FastRawViewer looks like a tool I need. Seems to run quickly on the CFExpress cards! Gives good sharpness guidance.