All focus modes would improve if the subject is larger in the frame.
Shooting in Dx mode
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I actually observed this today. I was photographing a seagull flying around which was on the smallish size in the frame and the subject detection was only recognizing the whole bird's body and not the eye, so it was focusing on the body/wing area. I hit my button to swapped to DX mode and immediately the system started to focus on the eye and did so consistently in spite of the bird being no closer.
I'd say it does. As explained by apakett, the downsampling reduces several pixels into one. Depending on the method used to downsample it draws on data from neighboring pixels, so reduced noise and since dynamic range is based on the noise floor, also improved dynamic range.
Kuau
Member
So are you saying crop mode takes the full rez of the season then down sample it ? I thought it just cropped the image
apakett
Member
No, cropping throws away pixels. Downsizing where you have more pixels than the destination can use, downsamples the image.
I must be missing something or misunderstood the original post. Cropping and using the DX mode are not the same. (Yes sometimes they can be, but not always). DX mode collects only data from the DX area of the sensor. Cropping afterwards on the computer allows you crop different ratios and select which parts of the frame you like. I prefer not to use DX in the field if the bird is a reasonable size in the frame. I can always crop later.
If I encounter a rarely seen bird which is small in the frame and getting closer is not advised, I have no hesitation about flipping into DX mode. This is exactly what happened last week.
On a side note, I find the Z9 and the 180-600 5.6-6.3 produces very clean images in DX mode. This has surprised me more than once. For me the Z9 sensor and AF are a big factor. I don’t find I need extra noise reduction or sharpening. The lens may not be as sharp as my old 500F4G (which I still have) but it is producing better results and also allowing hand holding (it’s a much lighter lens).
In summary I have formed the view that I would rather flip into DX mode with the 180-600 than add in a 1.4TC. The results seem to be very good indeed. I think the extra stabilisation built into the Z lens is a big factor in making this a very usable lens. It is definitely much better value for money than I was expecting.
If I encounter a rarely seen bird which is small in the frame and getting closer is not advised, I have no hesitation about flipping into DX mode. This is exactly what happened last week.
On a side note, I find the Z9 and the 180-600 5.6-6.3 produces very clean images in DX mode. This has surprised me more than once. For me the Z9 sensor and AF are a big factor. I don’t find I need extra noise reduction or sharpening. The lens may not be as sharp as my old 500F4G (which I still have) but it is producing better results and also allowing hand holding (it’s a much lighter lens).
In summary I have formed the view that I would rather flip into DX mode with the 180-600 than add in a 1.4TC. The results seem to be very good indeed. I think the extra stabilisation built into the Z lens is a big factor in making this a very usable lens. It is definitely much better value for money than I was expecting.
No I'm not saying that. Crop mode is the same as cropping in post. Pixels thrown away. Here was apakett responding to scoombs, where the topic diverted a bit.
Shooting in Dx mode
I have been shooting more in Dx mode lately on my Z9 and 600 Pf. Positives for me : smaller file size , better AF. Negatives : smaller FOV I heard recently someone telling me that Dynamic range is smaller when shooting in DX mode: can anyone confirm this? When looking at Photons to Photos...
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Flyboy
Active member
Well...probably I'm a bit biased, but DX is what I have always shot, and my cameras both have the 1.3X on top of the DX crop factor. I don't use it a lot, but when I do, I take into account that it reduces the cameras' MP count to slightly more than my D 90 (12 MP) used to have. Could be I just didn't know or care about Dynamic Range but I never felt under gunned with that "small" MP count, and had no problem enlarging to my State photo competition's somewhat weird size requirements. If you have one of the Suuuuper Megapixel cameras, I wouldn't worry about a reduction in Dynamic Range, which may be all but unnoticeable.
apakett
Member
Dynamic range (noise) does not matter much as long as you have control over ISO. When you need to raise ISO due to either low light or a fast moving subject noise becomes an issue. It is less of a problem for Steve Perry and other professional photographers that shoot with a full frame camera and use long, fast lenses. They can also devote the time to wait for a subject to come to them.
The only question for me is can you see the difference in an A2 print or whatever the largest size your printer or print service does? My home printer prints to A2 size. I cannot really see any significant difference in the shots I take when I choose to use DX mode on the Z9. I rarely print at maximum size.
There are situations where the shot would benefit from cropping anyway. I can flip backwards and forwards between DX and FX. I am becoming equally happy to use either.
There are situations where the shot would benefit from cropping anyway. I can flip backwards and forwards between DX and FX. I am becoming equally happy to use either.
Like everything else in photography, the size of the viewed image, how far it is from the viewer, and the pixels dimensions all play a role. If I viewed an 8x10 paper print at arms length I would observe a certain impression of sharpness, noise, depth of field. If I cut out a 4x5 section of that same print and continued to view it at arms length it would have exactly the same sharpness, noise, and depth of field, since it is exactly the same print. However if I held it closer, enough to fill the same part of my vision that the 8x10 did, then I would in theory notice more noise, less DOF, and reduced sharpness. Same if I enlarged the 4x5 to 8x10 size, or reduced the 8x10 to 4x5 size.
What we call circle of confusion is not a fixed hard number, but varies with viewing distance and visual acuity of the viewer.
What we call circle of confusion is not a fixed hard number, but varies with viewing distance and visual acuity of the viewer.
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I understand what you are saying. It is correct but that’s not what i am saying. I am saying that taking a DX photo is already good enough. Thats it. I have been using my Z9 and long lenses for long enough to be very very clear about acceptable sharpness. The sharpness of the full frame Z9 image would probably reveal images at A1 size ( 23.39 x 33.11 inches) that look as good as a DX image at A2. I don‘t print that large. A2 is my maximum size. (16.53 x 23.39 inches.)
A DX image can be very sharp and very clear at the sizes I print at, you cannot tell which is which without looking up the metadata on the image. This means that looking at the image from the output I use is just fine. It is not necessary to shy away from using DX if that is the setting which has the subject in the size you want.
Using full frame may actually have better sharpness but you would need to print a huge image like an A1 to see the benefit of the full frame.
A DX image can be very sharp and very clear at the sizes I print at, you cannot tell which is which without looking up the metadata on the image. This means that looking at the image from the output I use is just fine. It is not necessary to shy away from using DX if that is the setting which has the subject in the size you want.
Using full frame may actually have better sharpness but you would need to print a huge image like an A1 to see the benefit of the full frame.
Sometimes we have to crop, we just don't have the reach. But if we did have the reach then for the same print size a downsized full frame with the subject filling the same part of the frame will be better. How much better to make it worth the bother is a matter of personal taste.
Piecat
Active member
Glad I saw this, I have a D500 right now. I’ve spent a lot on lenses in the past, but the tracking is just too slow for me (65). The a7RIV is the best I can do $$$. From what I can see 100-600 crops better for BIF. With the crop mode, it should be better right.
I do not own primes or F4’s. I really need tracking I can see. Would love your input.
Just out of curiosity I went into the table at the bottom of the dynamic range page of photons to photos and extracted the maximum PDR, the low light ISO, and the low light EV for several cameras in full frame and cropped mode. I guess it is as I expected, cropped is always less. I've heard folks say, maybe Steve and others, to square the crop factor and multiply that by the ISO to get the equivalent ISO when cropped.
Nikon Z 6 11.06 5132 10.68
Nikon Z 6(DX) 10.28 2480 9.63
Nikon Z 6II 11.28 5298 10.73
Nikon Z 6II(DX) 10.39 2467 9.6
Nikon Z 7 11.56 3973 10.31
Nikon Z 7(DX) 10.68 1903 9.25
Nikon Z 7II 11.60 4157 10.38
Nikon Z 7II(DX) 10.74 1937 9.28
Nikon Z 8 11.32 4224 10.40
Nikon Z 8(DX) 10.61 1994 9.32
Nikon Z 9 11.30 4144 10.37
Nikon Z 9(DX) 10.49 1893 9.24
Ahem.....
Canon EOS R5 11.85 5435 10.76
Canon EOS R5(APS-C) 10.89 2402 9.59
Nikon Z 6 11.06 5132 10.68
Nikon Z 6(DX) 10.28 2480 9.63
Nikon Z 6II 11.28 5298 10.73
Nikon Z 6II(DX) 10.39 2467 9.6
Nikon Z 7 11.56 3973 10.31
Nikon Z 7(DX) 10.68 1903 9.25
Nikon Z 7II 11.60 4157 10.38
Nikon Z 7II(DX) 10.74 1937 9.28
Nikon Z 8 11.32 4224 10.40
Nikon Z 8(DX) 10.61 1994 9.32
Nikon Z 9 11.30 4144 10.37
Nikon Z 9(DX) 10.49 1893 9.24
Ahem.....
Canon EOS R5 11.85 5435 10.76
Canon EOS R5(APS-C) 10.89 2402 9.59
My experience too. As you move up in sensor size, DR improves by about a stop per size (1" to MFT to APS-C to MF). There was a step-change improvement when BSI became a thing, but I actually don't think that stacked adds anything to the DR, just to readout speed. Strictly from DR/IQ perspective, still hard to beat a D850. DR hasn't been a priority for stills cameras as they raced to higher MP and faster readout and better AF.
Canon patented a 24 stop (!) 1 inch sensor last year and Arri has been selling an 18 stop S35 (APS-C) camera since '22. Red just introduced a 17+ S35 camera. So I think we'll see some improvements in hybrid cameras soon.
ViKan
New member
I too am confused about the lower dynamic range in dx mode. If the comparison was between something like 45mp FX vs a 45mp DX sensors it would have made sense. Maybe the gain is implemented differently when in DX mode or the raw files are not in 14bit ? If the DR loss is true , shooting in FX mode and cropping in post should be better .
When looking at FX vs. DX, the size of the sensor makes a difference. The photosites are larger or there are more small photosites with a full frame sensor. Whether you have large photosites like a 24 MP full frame camera, or small photosites but more of them with a 46 MP camera, the noise and dynamic range are around the same for a common output. When you crop, you have fewer pixels and the remaining pixels are larger with a common output. That makes noise more visible and dynamic range is reduced. Gain is essentially a form of noise reduction - the amount of energy captured by the photosite does not change. Any form of cropping - DX in camera or cropping in post - has the same effect.
ViKan
New member
Thanks Eric . I think I slowly getting a grasp of it.
Scenario 1 : I think this is what the photonstophotos plot is showing.
picture 1 - FX mode - fill the frame with the desired final composition , like filling the frame with a bird
picture 2 - DX mode - fill the frame with the desired final composition by either stepping back , compared to picture 1, or using a different focal length
picture 1 will have better DR and less noise because it has more pixels.
Scenario 2 : OPs case , if I understand it right
If the best you can do is fill the DX portion of the sensor with the final desired composition , because you can only get so close to the subject or the lens you have, shooting in DX mode or cropping the FX image in post should produce the same DR. Saves card space etc.
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Ever
Member
On another topic, if we find ourselves reaching for DX (or cropping in post), friendly reminder that it's not the same as using a lens to get that focal length. The latter would provide less DOF / more subject isolation.
I'm in the same position where the framing from DX tends to be "just right" with my current lens/bushcraft/fauna, but I'm trying to not get too comfortable with it as I like the look of isolation/small DOF.
Can also confirm what's already been stated: using DX (when the reach is needed) helps with subject detection.
I'm in the same position where the framing from DX tends to be "just right" with my current lens/bushcraft/fauna, but I'm trying to not get too comfortable with it as I like the look of isolation/small DOF.
Can also confirm what's already been stated: using DX (when the reach is needed) helps with subject detection.
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That's exactly right.
There are other benefits of DX mode for distant subjects. You just want to understand that poor dynamic range or noise loses about 1-1.25 stops, so if possible you might take a little more risk with a slower shutter speed or faster aperture so you can keep ISO as low as possible. At ISO 100-800 none of this is much of an issue, but if you're near ISO 3200 or higher, you probably want to consider your options. This is the kind of situation Steve refers to when he shoots at slower than recommended shutter speeds. You take more images and hope some will be good.
Cropping or using DX mode also reduces depth of field, all else being equal, assuming the crop is viewed at the same size as the uncropped. Sadly we don't get a free lunch from cropping.i still do it though.
Ever
Member
My understanding is if the desired outcome is to have a subject fill 50% of the frame (for example), achieving it through FL results in less DOF/increased isolation than achieving it via crop.
Said a different way, my understanding is that if a user stands 25ft from a subject and takes a photo using both a 500mm lens and an 800mm* lens, that the photos won't have the same DOF/isolation after the photo from the 500mm is cropped in post to 800mm*-equivalent. The same being said when using DX instead of cropping in post.
*using 800mm as a hypothetical example since I think it's roughly a DX-equivalent to 500mm. Google says DX is ~1.5x, so 500mm -> ~750mm
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Err I don’t think depth of field works the way you think it works. If nothing else changes (same distance, same aperture on the same lens, same shutter speed) going to DX on an FX body does not alter depth of field, I believe.
Check out this dof calculator. Keep all the same except compare a full frame like a d850 to a crop like a d500. I think the calculator assumes the size of the images will be equal.
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
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