We talked about it here:
Thread 'How does crop mode or cropping in post impact subject isolation/DOF?' https://bcgforums.com/threads/how-d...g-in-post-impact-subject-isolation-dof.16169/
Tele-converter or DX mode
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We talked about it here:
Thread 'How does crop mode or cropping in post impact subject isolation/DOF?' https://bcgforums.com/threads/how-d...g-in-post-impact-subject-isolation-dof.16169/
Dynamic range is not a pixel-event (leaving noise out of it, the two are confounded), it's a sensor size event; the larger the sensor, the more light (and light gradations) are captured leading to a higher dynamic range. Modern sensors/cameras are very good at reducing/not producing electronic noise, so dynamic range is most directly proportional to sensor's physical surface area. Lots written on the topic.
Yes..I’ve been saying for a long time that looking at 2:1 in LR on a hi res monitor or 1:1 on not one isn’t the right way to evaluate IQ. If you are going for screen output it’s gonna be most down sampled to 1024 or 1280(?) wide…and you need to look at those outpur resolutions on a screen…or for a print of whatever size look at it from the expected viewing distance based on print size.
If you do that…the vast majority of whatever O1 differences you think you see (or actually do see, lots of factors here)…simply get downsampled away…that’s just physics. That doesn’t mean the images aren’t different at output resolution…but the differences rent really in IQ any more…they’re differences in bokeh due to aperture or focal length or aperture or whatever and mostly the images are not better or worse but just…different…and which one ypu like will probably differ from image to image and viewer to viewer.
Once PP is finished…nobody ever looks at the image at 2:1 again…they look at output. I’ve done the comparisons…b7t only for screen as I don’t really print…and sharpness or detail or whatever your definition of IQ is doesn’t really show up at output resolution...as I said, it’s different and not better/worse.
Im not saying there is zero difference…just that the difference at output is a lot smaller than at 2:1…and every person needs to make their own determination of whether the various costs of the exotic lens, 2.8 aperture, TC or not, and crop or not makes sense for their actual needs. Some people simply want the best…no matter the cost and whatever field we are talking about…but far too few people stop to consider the better is the enemy of good enough principle and really rationalize why the various costs of the best mat or not make any actual difference.
Me…I would love a whole stable of 2.8 or 4 telephoto lenses and enough bodies to not need to swap, and a Sherpa or two to schlep them all around…but that’s in a perfect world and I don’t really live in that world. They would be wonderful…but weight and flexibility and several other considerations make good enough actually better than better.
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nmerc_photos
Well-known member
reading through this thread, the majority of users say that DOF remains the same when cropping, which is what makes sense intuitively.
Simon d'Entremont also mentions here (4:43) that "whereas cropping a photo tighter won't affect DOF or bokeh", and then shows an example
a quick google definition: "Depth of field is the distance between the closest and farthest objects in a photo that appears acceptably sharp. Now your camera can only focus ...".
I've never seen an instance with a photo where cropping changed the distance between the closest and farthest objects' sharpness.
Perhaps I'm misunderstanding, or we're debating something differently semantically?
This post is the best example I can find supporting that cropping DOES change DOF, but it also adds a caveat:
Cropping DOES change depth-of-field: Open Talk Forum: Digital Photography Review
Expert news, reviews and videos of the latest digital cameras, lenses, accessories, and phones. Get answers to your questions in our photography forums.
www.dpreview.com
"There are many people who think cropping an image doesn't change the depth-of-field. I admit that it's not all that intuitive that removing a portion of an image would change the DOF, but it does. The reason it does is because we almost always compare two images at the same final viewing size (the angle-of-view the final image occupies in our vision) and that means once we crop, we have to enlarge the remaining portion. That enlargement enlarges the blur along with the image detail, thus making the blur more visible. That changes DOF through a change in the circle of confusion (CoC) parameter used in the DOF equations."
so if you don't upscale the cropped image, DOF would not change.
even in the example where they did upscale the image though, it doesn't appear as though DOF changed... the distance looks the same
here's another poll where 52% felt cropping doesn't change DOF...
Straw poll - Do you think DoF changes when an image is cropped?: Open Talk Forum: Digital Photography Review
Expert news, reviews and videos of the latest digital cameras, lenses, accessories, and phones. Get answers to your questions in our photography forums.
www.dpreview.com
at best I am seeing that cropping affects "the perception" of DOF, but doesn't (and can't) change what's actually in focus.
"The basic definition of DOF is: the zone of acceptable sharpness within a photo that will appear in focus. In every picture there is a certain area of your image in front of, and behind the subject that will appear in focus.
This is measured from the camera and is expressed in distance units. M, cm, or ft. and I repeat, it is measured as distance from the camera lens. Not in a computer, not n a file, not on a print.
any cropping whatsoever in an image manipulation program, cannot change the physical distances that was to the camera lens during the shot, and therefore can not change the DOF, which will always remain the same as shot.
Having said that, your eye may be fooled sometimes when you strongly crop due to the enlargement effect, but this is an illusion only"
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Robert S
Well-known member
Things are obviously very complicated.
I thought I would go out and photograph a bird. The bird is on the deck of the granny flat, but to get a good angle of light I went across to the big house and photographed the bird from there. The sun was about 50 degrees in the sky and about 10 degrees away from my right shoulder. I include the first photograph to give an idea of the amount of crop on the following three. There is considerable PP of the final three to suit my taste. The photos were taken with an R7 and a 100-400 Mk2 with a Sigma 2x extender.
PS: I think we often forget just how good lenses are. Somewhere in all this chit chat and videos someone said that first of all you need a lens that is sharp. I now use Canon lenses a 70-200 f4 and the 100-400 Mk2. Both these lenses are old but very sharp. It seems to me that the Sigma Extenders are capable of good results. I'm not about to buy two Canon Extenders as I do not think the possible improvement would be worth while for me.
I thought I would go out and photograph a bird. The bird is on the deck of the granny flat, but to get a good angle of light I went across to the big house and photographed the bird from there. The sun was about 50 degrees in the sky and about 10 degrees away from my right shoulder. I include the first photograph to give an idea of the amount of crop on the following three. There is considerable PP of the final three to suit my taste. The photos were taken with an R7 and a 100-400 Mk2 with a Sigma 2x extender.
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PS: I think we often forget just how good lenses are. Somewhere in all this chit chat and videos someone said that first of all you need a lens that is sharp. I now use Canon lenses a 70-200 f4 and the 100-400 Mk2. Both these lenses are old but very sharp. It seems to me that the Sigma Extenders are capable of good results. I'm not about to buy two Canon Extenders as I do not think the possible improvement would be worth while for me.
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nmerc_photos
Well-known member
if it's a sensor size event, wouldn't cropping not matter? since the sensor size is the same?
I can visualize it like... the amount of DR is determined when the shutter is pressed, and then cropping is "throwing out" pixels, which has the potential to change the DR ratio if some of your blackest blacks or whitest whites are "thrown out", but doesn't necessarily guarantee it. it might be fair to say "cropping will likely reduce DR".
I've noticed in my own cropping that DR definitely changes, but I don't know that I've seen what I would call a reduction. Just a difference. (Perhaps I crop out the sky, and my image loses a lot of blue data)
if we DO add in noise (although you said to leave it out), I think the argument gets stronger. as you crop, you increase noise (which we know as a fact), and as noise increases, DR decreases (though I'm not sure how or why)...
also - is any of this enough to be measurable? does it matter?
I like the comparisons of cropping vs TC when it can be described in terms of "stops of light" or "stops of ISO" or something. from the DOF thing I posted earlier, it seems nobody is aligned on the issue - but I sure can't see a meaningful difference, let alone measure it.
just talking out loud at this point. thanks for sharing, I enjoy the reading
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There are (many) better descriptions of how it works online, so I won't try to explain. Empirically, you lose about a stop of DR as you change from FX to DX (or generically FF to APS-C). If you change sensor architecture, for example BSI to "standard" CMOS, other factors will come into play, but since all cameras except Canon use Sony sensors, that rule of thumb is close enough.
Does it matter? Not if you nail exposure and don't have to recover shadows.
My philosophy is I want all the data the sensor is capable of, which gives me the most pliable file to work with. That's why I shoot FF and MF, native ISO, highest bit rate, RAW, best optics I can buy.
nmerc_photos
Well-known member
thank you for indulging me in a brief explanation. I agree with you - I'm trying to move to better and more pliable files, which means shooting FF and MF, and particularly - I need to use longer lenses as I'm never filling the frame...
loving learning about the behind the scenes stuff and trying to weigh what is most important in getting a good photo at the end
There's actually no comparison. All DX mode does is crop your picture in your camera. It does ABSOLUTELY NOTHING to the focal length of your lens. Cropping ALWAYS adds noise.
A TC on the other hand actually changes the focal length of your lens, enabling a larger, closer view on your sensor. Yes, the TC may affect the crispness of your lens a bit, but at least in the Nikon world (the only world I can comfortably talk about) the difference, unless you create a huge print, will be negligible.
So go buy the converter!
A TC on the other hand actually changes the focal length of your lens, enabling a larger, closer view on your sensor. Yes, the TC may affect the crispness of your lens a bit, but at least in the Nikon world (the only world I can comfortably talk about) the difference, unless you create a huge print, will be negligible.
So go buy the converter!
John Navitsky
Well-known member
let’s look at this from a more practical perspective
i was shooting a dog show over the weekend and i used BOTH approaches
first, i was shooting part of the event with a prime that was perfect for most of the action, but a bit far for part of it, in these latter cases, i flipped to dx mode to retain optimal framing
in another part of the event i was using the 70-200 which was just a bit short for part of the action so i used the 1.4 and never touched the dx mode
basically just like “which lens should i buy?”, optimize for your shooting situation. you need to consider both you minimum and maximum shooting distance. so you can’t use that TC if you end up with a solution that’s too long, and while accommodating that minimum, you could be slightly short and the dx can be handy
ymmv
i was shooting a dog show over the weekend and i used BOTH approaches
first, i was shooting part of the event with a prime that was perfect for most of the action, but a bit far for part of it, in these latter cases, i flipped to dx mode to retain optimal framing
in another part of the event i was using the 70-200 which was just a bit short for part of the action so i used the 1.4 and never touched the dx mode
basically just like “which lens should i buy?”, optimize for your shooting situation. you need to consider both you minimum and maximum shooting distance. so you can’t use that TC if you end up with a solution that’s too long, and while accommodating that minimum, you could be slightly short and the dx can be handy
ymmv
fcotterill
Well-known member
Ah yes, yet again the equivalence debate returns
Ray Hennessy: Are Teleconverters Necessary for Wildlife Photography
Have been considering adding the Nikon 1.4x tele for extended reach on my 400 f/4.5 lens. Came upon interesting video from Ray Hennessy, in his opinion teleconverters on high resolution cameras such as the Nikon Z8/Z9 do not offer much of an advantage vs cropping as far as image quality is...
bcgforums.com
Focal length vs aperture IQ
After some testing between my 600 f4 with and without the 1.4 tc and 800 pf and todays denoise software I wonder which one really has the advantage when it comes to end result image quality. I feel like the closer you can get to your subject even if it’s a stop higher iso it’s a better image...
bcgforums.com
AUTO ISO: Issue to set lowest ISO setting (Z8)
I noticed that the Z8 is noisier than my old D500 at ISO 400. When I looked up how the noise performance of the Z8 is against the D500 (see attached chart which confirms high level of noise at low ISO) I came aware of the dual gain sensor behavior. Looking at the chart I am now convinced I do...
bcgforums.com
Depth of field for DX vs FX
If I put a DX camera and then a FX camera on the same lens, which one would have the greatest depth of field?
bcgforums.com
EricKlees
Well-known member
That is not correct. Cropping never, ever adds noise. It only enhanced it exposes the noise that is already in the photo.
The biggest problem with TC’S is loss of aperture, but sometimes you need more reach to get the shot with the lens you have.
How well a tc works also depends on the quality of the lens. High IQ primes tend to do better.
The loss of aperture is important because it affects the ability to soften and detune backgrounds. For instance the 600mm pf becomes an f9 when the 1.4x tc is added. The 800mm pf stays at f6.3 at 800 and it does a far better job with backgrounds Even though both lenses are f6.3 at the native focal length.
How well a tc works also depends on the quality of the lens. High IQ primes tend to do better.
The loss of aperture is important because it affects the ability to soften and detune backgrounds. For instance the 600mm pf becomes an f9 when the 1.4x tc is added. The 800mm pf stays at f6.3 at 800 and it does a far better job with backgrounds Even though both lenses are f6.3 at the native focal length.
Tomato, Tomahto.
EricKlees
Well-known member
Not really. When people don't know you start then down the wrong path with misunderstanding. They aren't the same thing said differently, just i correct and the other isn't.
Maximum available image resolution falls with either a DX crop (fewer pixels available) or a TC due to some degradation of the magnified lens image.
The reduced number of pixels available in DX crop reduce sensor resolution by about 33% - though as sensor resolution is not the only component of image resolution (on a test bench) a test bench resolution reduction of 12.5-15% is a reasonable starting point expectation compared to using a longer focal length lens without cropping.
I found the resolution reduction using a 1.4 TC for me was around 10% with F equipment - and a little less with Z equipment - though I resort to a stable tripod or monopod more ofter to achieve the increased subject magnification with either method.
I do crop in post when appropriate, especially with the 105 macro S that does not take TC's.
Using either method increases the camera shake effect due to the increased subject magnification.
There can be slightly increased internal camera flare effect if using a DX crop, usefully more AF points on the subject if using a TC, and slightly less efficient AF performance more so in low light conditions when using a TC.
There are many who regularly use TC's. I presume like me most have done testing comparisons to find out which works best for them and when.
There seems a wide consensus (and definitely my experience) using a Z TC on Z looses less image quality than an F TC on F mount lenses.
It matters little that using a TC or DX produce slight different image sizes being either a 1.4x or 1.5x change to the original subject size.
If one could crop without losing depth of field then we could throw away our macro lens and just shoot from a little farther away and crop to the same field of view as the macro. It would be cool if we could get a macro-like shot without losing depth of field, like magic, but there is no free lunch. Once the cropped image is resized to be equal size the circle of confusion changes. Plug in a full frame camera and a crop camera in a dof calculator, leave all other settings the same and look at the DOF results. For example try a D850 vs a D500 and keep all other settings the same. If you use the advanced calculator you see the impact on the circle of confusion.
www.photopills.com
www.photopills.com
Depth of Field (DoF) calculator | PhotoPills
This Depth of Field (DoF) calculator will help you get the creative control on the design of your photos. Decide the zone of sharpness you need to tell the story you want and get your message across.
www.photopills.com
Advanced Depth Of Field (DoF) Calculator | PhotoPills
Get the total control over depth of field. This calculator allows you to use an adjusted Circle of Confusion to calculate the adjusted depth of field values according to your desired print size, viewing distance, camera sensor size and viewer’s visual acuity.
www.photopills.com
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What I've noticed since the transition from film to digital, and now accelerating due to computing power and recently AI is the shifting of the final-image production from out-of-camera to post-processing. And I watched how my own worflow has changed. It's no longer "fix it in post," it's now "create it in post," and all I expect from my camera (and lighting equipment) is a great, detailed file. Data harvesting. If anything, my emphasis has shifted more to the quality of the optics (sharpness being one, but not even the most important attribute in my case).
Since I was accused of lying in a previous post, here is further support from photography life, with a link to the math to support it. If you stay in the same place with the same settings and just crop and resize it's the same as shooting with a smaller sensor, which is what the article is about. Quote:
4.3.1) Smaller Sensor = decreased depth of field (if identical focus distance, physical focal length and physical f-number).
photographylife.com
4.3.1) Smaller Sensor = decreased depth of field (if identical focus distance, physical focal length and physical f-number).
Sensor Size, Perspective and Depth of Field
photographylife.com
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nmerc_photos
Well-known member
can you demonstrate this macro example with pictures? or has anyone else done it?
I think I agree with you in theory, but everything I'm looking at shows that it matters a negligible amount in the real world. I can't imagine macro shooters are up in arms about how their DOF changes when they crop. or maybe my google search terms aren't pointing me in the right direction
John Navitsky
Well-known member
i think the conceptual confusion about dof, noise and all that comes when people add in an adjustment to keep the subject framed the same way
instead, visualize it without reframing. the dx crop is just the center of the image. it is literally no different
it’s the movement to reframe that changes things. i think if you think about it that way it’s clearer (at least that works for me)
instead, visualize it without reframing. the dx crop is just the center of the image. it is literally no different
it’s the movement to reframe that changes things. i think if you think about it that way it’s clearer (at least that works for me)
Same answer, just look at the dof calculator from the same distance full frame vs crop sensor. It seems to roughly track as the full frame depth of field divided by the crop factor to get the cropped depth of field. But in macro pupil magnification takes on a bigger role that is glossed over at normal distances.
Macro Depth of Field (DoF) Calculator | PhotoPills
Use this calculator to get more accurate depth of field values when shooting macro and close-up shots.
www.photopills.com
How many times has this horse been beat and it still lives...
DOF is perception. Or perhaps more accurately an attempt to measure perception. The only portion of an image that is actually in focus is that which lies exactly on the focal plane. Beyond that what is/isn't sharp lies purely in the eyes of the beholder. DOF calculators/calculations are a mathematically attempt to normalize/standardize "acceptable limits" of focus in front of and behind the focal plane. Which based on the amount of discussion that this topic always generates is a futile effort. Based on the mathematical description of DOF cropping does indeed alter it. It's not a topic of debate. It's mathematical fact. Based purely on subjective human perception it's been my experience that those who manage to fill the frame on full frame sensors believe strongly that cropping alters DOF. Those who shoot cropped sensors and or crop heavily swear that DOF is not affected. Go figure.
John Navitsky
Well-known member
nmerc_photos
Well-known member
Same answer, just look at the dof calculator from the same distance full frame vs crop sensor. It seems to roughly track as the full frame depth of field divided by the crop factor to get the cropped depth of field. But in macro pupil magnification takes on a bigger role that is glossed over at normal distances.
Macro Depth of Field (DoF) Calculator | PhotoPills
Use this calculator to get more accurate depth of field values when shooting macro and close-up shots.
charts and the little calculator are handy and all, but they don't illustrate anything in the real world. we can spend all day talking about how stuff works in theory, but I'm interested in what actually happens in practice. I'm asking if you (or anyone) has pictures that illustrate it
because from what I can tell, whether DOF does or does not change - the impact on the final image isn't significant
evidently decades of people debating it - and the reason people can't come to a conclusion is because it's not an impact that is easy to point out. a person will never know based on DOF, whether an image is fullsize or cropped - unless compared to a fullsize or cropped image of itself - which never happens outside of testing.
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