Sensor size and focus stacking -- LOTS ABOUT FOCUS STACKING
- Thread starter Mike Buckley
- Start date
I'm no expert in this, but think the readout time from the sensor is very important. My camera can work at 60fps in the mode where it doesn't update the focus (except when focus stacking) so it is possible to take multiple images very quickly. These are 20MP images and can be simultaneously stored as raw or jpg. A large buffer means it takes a while before it has to slow up. This speed requires a very rapid transfer of image data from the sensor. I think the larger the sensor and the more pixels the long this transfer takes, so full frame can't yet match this.
This high readout speed allows special features like handheld focus stacking, handheld hi-res (only in the E-M1X model), and ProCapture (stores photos before you take them - like time travel - so slow human reaction time no longer matters).
However if you don't need handheld, then speed doesn't matter and there is no reason why full frame cameras can't do focus stacking. You just need enough memory and processor power.
Water drops take umbrage with that statement
With apologies to all water drops in the universe, my comment was in the context of cameras' capabilities, not content being photographed.
I don't know anything about this stuff but I wonder if by necessity the algorithm has to be different for each format to achieve equal results with all three formats.
There are several stacking algorithms. If you use a product such as Helicon Focus it lets you choose.
I can't see why different formats would require different algorithms. They might require different parameters though.
I've read the same thing about Zerene.
That is correct.
I think Helicon is regarded as the best.
I tried both Zerene and Helicon back when I was trying to choose. At the time I decided Helicon was the clear choice but I don't remember why now .
This input probably isn't all that relevant to this thread...but I expected to use the Focus Shift (focus stacking) feature a lot more than I actually do. And, I bracket a fair number of pictures for focus stacking.
Nearly all of my images are captured from a tripod, so I'm sure this plays into it. When stacking landscape or architectural pictures, I usually use Live View with focus peaking. I will generally set the focus to the closest object of interest...and fire. Then, I slowly turn the focus ring on the lens to something in middle range of the scene...and fire. Finally, I select an object in the distance and fire. Later, I bracket those using Photoshop...with pretty good success. Granted, I am introducing a slight risk of not having perfectly aligned images since I am rotating the lens...but I do use a cable release and also align the images in Photoshop before blending them.
Now, sometimes I will take a few more images in that sequence--depending upon the aperture selected and the range of the scene. Sometimes, two is sufficient.
This is so easy for me to execute that I often find myself simply avoiding guessing what increments the D850 will select...determining how many shots...and so forth. My approach would be very different if I were dealing with macro subjects that require tens of images, though.
Glenn
Nearly all of my images are captured from a tripod, so I'm sure this plays into it. When stacking landscape or architectural pictures, I usually use Live View with focus peaking. I will generally set the focus to the closest object of interest...and fire. Then, I slowly turn the focus ring on the lens to something in middle range of the scene...and fire. Finally, I select an object in the distance and fire. Later, I bracket those using Photoshop...with pretty good success. Granted, I am introducing a slight risk of not having perfectly aligned images since I am rotating the lens...but I do use a cable release and also align the images in Photoshop before blending them.
Now, sometimes I will take a few more images in that sequence--depending upon the aperture selected and the range of the scene. Sometimes, two is sufficient.
This is so easy for me to execute that I often find myself simply avoiding guessing what increments the D850 will select...determining how many shots...and so forth. My approach would be very different if I were dealing with macro subjects that require tens of images, though.
Glenn
Glenn,
With the D850, you can (I think) set a maximum increment of 10 for Landscape and Architectural Images, focus on the nearest point and just press OK. The camera will then fire away until infinity is reached and you do not have to touch the lens. The required number of shots is calculated according to the aperture and does not need any more input from you.
However, if you are saying that, in addition to the stacking considerations you are also bracketing exposure then that would create the necessity to go through the procedure multiple times with different Exposure Compensations and you might not get the exact initial/minimum focus right each time.
What are your thoughts on this??
DG
With the D850, you can (I think) set a maximum increment of 10 for Landscape and Architectural Images, focus on the nearest point and just press OK. The camera will then fire away until infinity is reached and you do not have to touch the lens. The required number of shots is calculated according to the aperture and does not need any more input from you.
However, if you are saying that, in addition to the stacking considerations you are also bracketing exposure then that would create the necessity to go through the procedure multiple times with different Exposure Compensations and you might not get the exact initial/minimum focus right each time.
What are your thoughts on this??
DG
That wouldn't pertain just to macro subjects; it would also apply to any tabletop photography where the entire subject can't be in focus with just one capture. As an example, I wish I had focus stacking available for use with my 35mm lens combined with an APS-C sensor.
Years ago when I first learned about focus stacking, my impression was that Zerene was generally regarded as the best but not by a wide margin. Both products were being used back then but I don't know about now.
That would certainly help automate the process. But, when shooting at wider focal lengths and using f8 or f9, I find it usually doesn't take more than 3 exposures to get everything in tack sharp focus. So, my manual method is very quick. The only drawback that I see is the risk of an alignment problem due to touching the lens...but that is somewhat mitigated by the aligning that Photoshop does prior to merging the files.
That being said, I should probably familiarize myself more with the feature.
Glenn
I probably should have written Closeup subjects rather than Macro subjects. I have photographed flowers using my manual method...but clearly it would be easier to use a more automated focus stacking approach if the subject required tens of images.
Glenn
Glenn, you could use the touch screen on the D850 to shift focus. I have a cheap iPad "pen" that is less intrusive and more accurate than my finger.
That's another thing that I need to start trying! I'm always concerned that it won't be as precise...but maybe that's because I haven't used it while zooming in enough. I tend to zoom in very tightly and then rotate the lens very slowly until I see the area that I want in the color of the focus peaking.
Glenn
With respect Glenn, don't change a thing!!
Whatever you are doing, you are doing right!!
I have some questions though, which are not directed at anyone in particular, so if you feel that you have an answer please jump in.
Image a scenario where you are taking a panoramic view (on a tripod) and want to bracket:
a. the focus
b. the exposure
....and also take 10-15 shots to cover the width of the panorama with the camera in portrait mode.
Which order do you takes the shots and which order do you process them afterwards? For each of the 10-15 shots in the panorama you would need to bracket exposure for each of the focus steps and if we assume that, at minimum, there are going to be three focus steps and three exposure steps for each of the focus steps, that makes a total of nine shots for each of the 10-15 panorama steps. So we now have between 90 and 135 images to assemble.
In what order??
When taking the images I would bracket the exposure for each of the focus steps. Using the Z6 (or the D850 / D780) this could be done semi-automatically by using settings for focus steps which would ensure that the lens would reach infinity after three shots and then stop. This would then have to be done three times at the three bracketed exposure settings. One difficulty I see is being able to reset the focus to the same point at the start of each sequence.
When you get these images (RAW) into Photoshop, where do you start? Exposure bracketing or focus bracketing. Or is Photoshop clever enough to just ingest 135 images and spit out a completed panorama at the end? It does HDR Panoramas successfully but I have never tried to include Focus Stacking/Shifting into the equation.
BTW, I looked at both Zerene and Helicon and dismissed them because (on the face of it) Photoshop, to which I am a subscriber, SAYS it will do it and I do not see any sense in paying more than once for the same facility.
This would possibly make a very interesting thread on its own, so if anyone wants to shift it please feel free.
DG
Whatever you are doing, you are doing right!!
I have some questions though, which are not directed at anyone in particular, so if you feel that you have an answer please jump in.
Image a scenario where you are taking a panoramic view (on a tripod) and want to bracket:
a. the focus
b. the exposure
....and also take 10-15 shots to cover the width of the panorama with the camera in portrait mode.
Which order do you takes the shots and which order do you process them afterwards? For each of the 10-15 shots in the panorama you would need to bracket exposure for each of the focus steps and if we assume that, at minimum, there are going to be three focus steps and three exposure steps for each of the focus steps, that makes a total of nine shots for each of the 10-15 panorama steps. So we now have between 90 and 135 images to assemble.
In what order??
When taking the images I would bracket the exposure for each of the focus steps. Using the Z6 (or the D850 / D780) this could be done semi-automatically by using settings for focus steps which would ensure that the lens would reach infinity after three shots and then stop. This would then have to be done three times at the three bracketed exposure settings. One difficulty I see is being able to reset the focus to the same point at the start of each sequence.
When you get these images (RAW) into Photoshop, where do you start? Exposure bracketing or focus bracketing. Or is Photoshop clever enough to just ingest 135 images and spit out a completed panorama at the end? It does HDR Panoramas successfully but I have never tried to include Focus Stacking/Shifting into the equation.
BTW, I looked at both Zerene and Helicon and dismissed them because (on the face of it) Photoshop, to which I am a subscriber, SAYS it will do it and I do not see any sense in paying more than once for the same facility.
This would possibly make a very interesting thread on its own, so if anyone wants to shift it please feel free.
DG
I have done quite a few panoramas, and also focus stacking, so I'm familiar with the basics.
See here for examples: Panorama collection
But I have never combined them.
First a point to clear up a common confusion. People often say they want to focus stack raw files. It is logically impossible to focus stack raw files, you can only use those algorithms on images. Programs that claim to do it simply convert the raw files to images and then stack them, so you lack control over the raw conversion.
I would probably do as follows.
Taking the photos
I estimate that it normally takes me perhaps 3 minutes to carefully take a 15 shot panorama, after deciding the composition and preparing the camera. Adding the focus stacking would add no more than 30 seconds to each shot, so it might take a total of 10 minutes.
Conversion of the raw files might take about 10 minutes with a decent computer. Focus stacking might take as much as 30 minutes in total. Making the panorama and final editing another 15 minutes. So you should be able to do the post processing in under an hour.
I hope this gives you some ideas.
See here for examples: Panorama collection
But I have never combined them.
First a point to clear up a common confusion. People often say they want to focus stack raw files. It is logically impossible to focus stack raw files, you can only use those algorithms on images. Programs that claim to do it simply convert the raw files to images and then stack them, so you lack control over the raw conversion.
I would probably do as follows.
Taking the photos
- I would scrap the idea of multiple exposures, I dislike the fake looking HDR look. But I would accept the idea of taking raw photos, to get a good dynamic range. I would not use a tripod. You don't need it and I wouldn't want to carry it.
- The camera must be set on manual, fixed white balance, fixed ISO.
- I would set the camera to take about 10 images at different focus positions from close to infinity. I would have experimented with the best increment to achieve this, and found a way to get a fixed close distance to focus the first photo in the sequence. For example I would aim the camera at my feet, focus, then aim it up and fire off the focus shifting sequence. As you said I would have the camera in portrait orientation. I would then swivel my upper body 1/3 of a frame to the right and repeat for the next photo. I find I need at least 15 (but sometimes as many as 30) small rotations from fully left to fully right. Don't waste time, the light can change.
- Process the 150 raw photos all at once using identical settings. This can be done using Adobe Bridge, Lightroom or other raw processing programs that can apply one setting across all images. I now have 150 TIFFs or JPGs.
- Use any focus stacking software on each group of 10 images. So I now have 15 images, each sharp from close to infinity.
- Use Photoshop or other software to make the panorama.
- (In my case) use Zoomify to turn the panorama image into something viewable on the web (see examples linked to above).
I estimate that it normally takes me perhaps 3 minutes to carefully take a 15 shot panorama, after deciding the composition and preparing the camera. Adding the focus stacking would add no more than 30 seconds to each shot, so it might take a total of 10 minutes.
Conversion of the raw files might take about 10 minutes with a decent computer. Focus stacking might take as much as 30 minutes in total. Making the panorama and final editing another 15 minutes. So you should be able to do the post processing in under an hour.
I hope this gives you some ideas.
Thanks Richard,
I agree with most of that.
I have just realised that there is a flaw in Nikon's implementation of this feature which is not present in Olympus's implementation (judging by your description). I think that Nikon assumes tripod mounting because the focus shift is initiated from the menu and not from the shutter release therefore composition would be hit and miss in a hand held scenario when trying to combine focus shift and panorama shots.
On a tripod, the way I make my panoramas, focus shift would not be a problem but would necessitate very carefully choice of focus point to ensure accurate return to the same focus for every set in the panorama sequence. I am thinking that a device for setting the minimum focus of the lens held a fixed distance from the front element would be required ☺ . I will not be trying it any time soon because of the weather here (as you know).
I agree with most of that.
I have just realised that there is a flaw in Nikon's implementation of this feature which is not present in Olympus's implementation (judging by your description). I think that Nikon assumes tripod mounting because the focus shift is initiated from the menu and not from the shutter release therefore composition would be hit and miss in a hand held scenario when trying to combine focus shift and panorama shots.
On a tripod, the way I make my panoramas, focus shift would not be a problem but would necessitate very carefully choice of focus point to ensure accurate return to the same focus for every set in the panorama sequence. I am thinking that a device for setting the minimum focus of the lens held a fixed distance from the front element would be required ☺ . I will not be trying it any time soon because of the weather here (as you know).
I'm sure Nikon assume all focus bracketing would use a tripod or stand or rail. Given the ability of software to align, this seems out of date.
My idea about focus on the feet each time should work quite well, provided the closest focus was always at least that far away. It doesn't need to be exact as with 10 frames provided the aperture is say 5.6 there should be plenty of overlap between feet distance and infinity. But I would test it carefully. I don't see why it matters if it is a bit different for each set of the panorama, provided everything is sharp. My feet are always a fixed distance away when I'm standing up...
My idea about focus on the feet each time should work quite well, provided the closest focus was always at least that far away. It doesn't need to be exact as with 10 frames provided the aperture is say 5.6 there should be plenty of overlap between feet distance and infinity. But I would test it carefully. I don't see why it matters if it is a bit different for each set of the panorama, provided everything is sharp. My feet are always a fixed distance away when I'm standing up...
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