Bonsia ~ Testing Depth of Field

[PJcam]

The weather is abysmal, heavy rain and hail, strong winds and going to get much stronger. So as a 'beginner' I thought it was time to experiment with the camera and learn a little more, having done so, now it's time to ask for your comments.

The aim of this lesson I gave myself was to try get the best image I could, in bad light, without flash and with a narrow depth of field, from just before the bonsia to just past the blinds and glass which has rain running down. I included the vertical blinds at a slight angle, my thoughts were to include reflection from the blinds and also to fade the image behind the set field.

The image was in Raw format, converted to Jpg using instant Jpg from raw software, (Good Free software), but as it was to large to upload, just over 2mb, I resized it in Adobe Photoshop which crashed the image down to just over 800kb, I hope this doesn't spoil the image quality to mush. I am not sure what is the largest Jpg file we can upload on here?

I welcome comments good and bad. I realise I could have taken the image portrait instead of landscape, but this way showed a little more rain on the glass behind the blinds.

Camera - Canon EOS Rebel T6 1300D,
Lens - Canon EF-S 75-300 mm f/3.5-5.6
Settings - Shutter 1/200 sec, Aperture f/4.5, ISO 1600, Lens set at 130.00mm

 

[jcdeboever]

Good lesson. Your on the right track. Looks like it is pretty thin DOF. Keep track at what point the subject is all in focus with good separation. Know and understand where that threshold is, especially since a lot of lenses don't have the markings. Show us good, better, best. I'd post this in beginners forum moving forward. Some really smart people pay close attention to that thread to help you expedite the learning curve.

I have done this by placing white craft paper on a table, and with a sharpie, map out the distance points on the paper, and place objects in a row. There are DOF calculators online to help guide you as well, some lenses have the marks already on them.

P.S. @terri , I'd move this to the beginners forum.

 

[jcdeboever]

@PJcam, I have a real good lesson on DOF in a John Hedgecoe book. If I can remember, I will try and copy it for you and post in this thread when I get home tonight.

 

[PJcam]

Good lesson. Your on the right track. Looks like it is pretty thin DOF. Keep track at what point the subject is all in focus with good separation. Know and understand where that threshold is, especially since a lot of lenses don't have the markings. Show us good, better, best. I'd post this in beginners forum moving forward. Some really smart people pay close attention to that thread to help you expedite the learning curve.

P.S. @terri , I'd move this to the beginners forum.

Thanks jcdeboever, I did take a number of shots and recorded in my note book the settings of each, the first trial ran images with changed shutter speeds, aperture and ISO, the second set was taking a fixed aperture f/4.5 and changing the other two setting to see the field change. I soon picked up that the lower the F-Stop the tighter the depth of field, this is all new to me but very fascinating, and quite rewarding.

I will see if I can add some images as you have mentioned.

Being a 'beginner' there is so much to learn, and once I learn I realise comes practice, practice, practice, then experience with time and practice. To help me from what I read so far and seen on video I created this... I think I got right. I stuck it in the front of my note book for reference till it is all in my head.

 

[jcdeboever]

Awesome @PJcam. This really will expedite things along.

 

[PJcam]

Awesome @PJcam. This really will expedite things along.

I must admit the more I tried to learn Shutter Speed, Aperture and ISO, I kept confusing myself with the High and Lows of the F-Stops, compared to aperture openings, whilst also trying to get ,my head round which way the DoF worked, but I them found I had all tables the same way and ISO works opposite to the other two. I am getting there. The only way (for me) was sit down write it down and then make an image with notes for my note book. We all learn different ways.

 

[jcdeboever]

Awesome @PJcam. This really will expedite things along.

I must admit the more I tried to learn Shutter Speed, Aperture and ISO, I kept confusing myself with the High and Lows of the F-Stops, compared to aperture openings, whilst also trying to get ,my head round which way the DoF worked, but I them found I had all tables the same way and ISO works opposite to the other two. I am getting there. The only way (for me) was sit down write it down and then make an image with notes for my note book. We all learn different ways.

For ISO, I simply think of it as a way to gain shutter speed. I use it for low light, like to double the focal length so bumping the ISO will get me there (i'm pretty shaky at times). Or for sports when I want to freeze fast movement. Some lenses have stabilization that helps keep that double focal length thing less drastic. Of course you should really find out the threshold of what you deem acceptable as far as noise level. For example, I find my Fujifilm cameras acceptable up to ISO 6400.

 

[Ysarex87 81]

The weather is abysmal, heavy rain and hail, strong winds and going to get much stronger. So as a 'beginner' I thought it was time to experiment with the camera and learn a little more, having done so, now it's time to ask for your comments.

The aim of this lesson I gave myself was to try get the best image I could, in bad light, without flash and with a narrow depth of field, from just before the bonsia to just past the blinds and glass which has rain running down. I included the vertical blinds at a slight angle, my thoughts were to include reflection from the blinds and also to fade the image behind the set field.

View attachment 152294

The image was in Raw format, converted to Jpg using instant Jpg from raw software, (Good Free software), but as it was to large to upload, just over 2mb, I resized it in Adobe Photoshop which crashed the image down to just over 800kb, I hope this doesn't spoil the image quality to mush. I am not sure what is the largest Jpg file we can upload on here?

I welcome comments good and bad. I realise I could have taken the image portrait instead of landscape, but this way showed a little more rain on the glass behind the blinds.

Camera - Canon EOS Rebel T6 1300D,
Lens - Canon EF-S 75-300 mm f/3.5-5.6
Settings - Shutter 1/200 sec, Aperture f/4.5, ISO 1600, Lens set at 130.00mm

Practice practice -- very good for you.

A couple comments: The software you used to extract the JPEG did not convert the raw file. It simply extracted the embedded JPEG which was in fact created by the camera. All digital cameras create a JPEG whether you want one or not and whether you set the camera to save one or not. A copy of that JPEG is embedded into the raw file and used to preview the raw file.

Good job with the DOF exercise. As a DOF exercise the photo is fine.

If you want to consider the photo otherwise then I would suggest your background choice for the bonsai tree is poor and that the tree needs to be lit differently. Thinking in very basic terms we (humans) are drawn to light -- makes sense. We preferentially see light and bright objects and concentrate our interest on those over dark objects. That natural trait makes photographing dark objects against light backgrounds typically unsuccessful. You took a photo of the tree, but when I first look at the photo it takes me too long to make the subject recognition. Not only is the background light compared to the tree it's also very graphic which further demands attention. Re-photograph the tree, get some light on it and find a less graphic and darker background.

Joe

 

[Ysarex87 81]

Good lesson. Your on the right track. Looks like it is pretty thin DOF. Keep track at what point the subject is all in focus with good separation. Know and understand where that threshold is, especially since a lot of lenses don't have the markings. Show us good, better, best. I'd post this in beginners forum moving forward. Some really smart people pay close attention to that thread to help you expedite the learning curve.

P.S. @terri , I'd move this to the beginners forum.

Thanks jcdeboever, I did take a number of shots and recorded in my note book the settings of each, the first trial ran images with changed shutter speeds, aperture and ISO, the second set was taking a fixed aperture f/4.5 and changing the other two setting to see the field change. I soon picked up that the lower the F-Stop the tighter the depth of field, this is all new to me but very fascinating, and quite rewarding.

I will see if I can add some images as you have mentioned.

Being a 'beginner' there is so much to learn, and once I learn I realise comes practice, practice, practice, then experience with time and practice. To help me from what I read so far and seen on video I created this... I think I got right. I stuck it in the front of my note book for reference till it is all in my head.

View attachment 152296

Your chart raises a few red flags. You watched the toothpaste video and you're showing possible influences from the Triangle Cult. Triangle Cult first: ISO does not control noise in a photograph and increasing ISO does not increase noise. Increasing ISO (especially since you're using a Canon camera) reduces noise. The triangulars are confused about cause and effect. They've attached themselves to a spurious correlation and converted that over to a cause - effect. Noise in a photograph is primarily a function of exposure. Less exposure = more noise and more exposure = less noise. ISO is related: When we don't have enough light to, as JC noted, achieve a fast enough shutter speed then we have to reduce exposure. If we don't have enough light to achieve the aperture we require for DOF then we have to reduce exposure. The noise is a result of reduced exposure. ISO does two things. It biases our camera meter to allow the reduced exposure calculation and then it post processes the sensor capture and brightens the image to compensate for the reduced exposure. In this post processing function ISO typically reduces the noise caused by the underexposure. It may sound like a subtle distinction but it's important to keep cause and effect straight. You can't control noise in a photo with the ISO setting; you have to do that with exposure. Noise is a function of exposure.

Toothpaste: The toothpaste video isn't too bad but it doesn't simplify DOF; if anything it complicates it and confuses some important aspects. It fails to simplify because it doesn't consolidate the different variables into a final simply form that clarifies what's happening. DOF is a function of f/stop and magnification. That's arguably too simple but it's immensely helpful to get to that point for an overall understanding. Subject distance and lens focal length reduce to the variable magnification. From the camera position then f/stop is the only other control available. A critical aspect of DOF that the toothpaste video failed to note was the unequal distribution of DOF. There's more DOF behind the focus plane than in front of the focus plane (can also be expressed as magnification). Here's a graphic that helps:

Toothpaste didn't manage to work in the role of Coc (circle of confusion) in the graphics.

With a smaller aperture the DOF increases:

With the subject closer to the camera (increase magnification) the DOF decreases.

Joe

 

[ac12]

Bonsai

 

[PJcam]

For ISO, I simply think of it as a way to gain shutter speed.

Good thinking.

I use it for low light, like to double the focal length so bumping the ISO will get me there (i'm pretty shaky at times).

Although my hands are alright, I cannot stand for long and find I rock due to pain in my hips and back, I therefore use, tripod or monopod and a plug in lens button.

Some lenses have stabilization that helps keep that double focal length thing less drastic.

I just ordered this lens, Canon EF-S 10-18mm f/4.5-5.6 IS ST M due for delivery tomorrow, it has image stabilisation. Something else to learn and play with.

Of course you should really find out the threshold of what you deem acceptable as far as noise level. For example, I find my Fujifilm cameras acceptable up to ISO 6400.

All this will come with practice I think, to be honest I am new to all this, learning from scratch, this image was only the second one I have taken. I realise somethings are not what I would do in a proper photograph, it was just grab the camera on a dark, wet, horrible day, pick something up (the bonsai tree) take it into the conservatory, lightest room in the property, even though the black clouds were getting thicker by the minute and just aim to test what I learned regarding DoF.

Thank you for your help, suggestions and comments they are always appreciated.

 

[PJcam]

Practice practice -- very good for you.

A couple comments: The software you used to extract the JPEG did not convert the raw file. It simply extracted the embedded JPEG which was in fact created by the camera. All digital cameras create a JPEG whether you want one or not and whether you set the camera to save one or not. A copy of that JPEG is embedded into the raw file and used to preview the raw file.

Thank you for confirming this for me.

Good job with the DOF exercise. As a DOF exercise the photo is fine.

Thank you Joe, that is really all the exercise was, to make sure I understood how to control DoF. I think controlling DoF is just as important as all the other settings, it cn contribute to make or break a final image.

If you want to consider the photo otherwise then I would suggest your background choice for the bonsai tree is poor and that the tree needs to be lit differently. Thinking in very basic terms we (humans) are drawn to light -- makes sense. We preferentially see light and bright objects and concentrate our interest on those over dark objects. That natural trait makes photographing dark objects against light backgrounds typically unsuccessful. You took a photo of the tree, but when I first look at the photo it takes me too long to make the subject recognition. Not only is the background light compared to the tree it's also very graphic which further demands attention. Re-photograph the tree, get some light on it and find a less graphic and darker background.

Joe

A lot of what you say here I did expect to be honest, my only aim with this experiment was the testing DoF, first I shot 7 images, changing each of the triangle settings, the lowest number F-Stop was the best, this was compared when comparing the images, so my next trial was to use Av, set the F-Stop and change shutter speed and ISO, the image included was the best one. I realise the background could have been better, I wished the light was better but the storm was overhead so I though just try it and include these things to compare DoF, in front of the bonsai and between the blinds and through the glass. To many things and to lighter colours behind, all point to note, but DoF worked enough to confirm what was in my mind was right and I can look to create another image.

Being a 'total beginner' you may find I will share images that are not up to standard, you will LOL, but at this stage of learning I will be testing myself with little projects, possibly shooting anything to try out some of the settings and compare them against each other. I do not take any replies as criticism as they are all supplied to help beginners learn better and hopefully faster.

Many thanks for your comments Joe.

 

[PJcam]

Your chart raises a few red flags. You watched the toothpaste video and you're showing possible influences from the Triangle Cult.

Toothpaste: The toothpaste video isn't too bad but it doesn't simplify DOF; if anything it complicates it and confuses some important aspects.

Toothpaste didn't manage to work in the role of Coc (circle of confusion) in the graphics.

With the subject closer to the camera (increase magnification) the DOF decreases.

View attachment 152301

Joe

Well Joe, what can I say, we go from red flags, to Triangle Cults, to Circles of confusion and then include noise. I am glad you didn't put those in capitals. (Just joking).

I can see a little in what you say, but being a total beginner I need to hang on to what I learnt so far and put that into practice, practice, practice, before going deeper. That said I am always open to comments, that was why I posted the image, and even if I am maybe not ready for the extra depth of understanding yet, other readers may be.

For me at this stage, I have proved to myself and had it confirmed on here that as far as DoF is concerned in the image, which is all the test was for from my prospective, I have grasped the basics of controlling DoF. I now need to find other items and do things differently, probably testing other things, the more I learn by using the shutter speeds, aperture and ISO, one against the other the sooner I will get it to gel in the brain and then will become second nature, allowing the mind to concentrate on the items and light in the image, which way they come from, etc, etc. Sadly until the better weather I cannot get out, I cannot even hobble to the car when the wind is 20mph or more and at present gusts in the mid 60's are forecast. There is a nature reserve within 10 miles, I know my lens are not powerful enough for many of the birds at distance but it will be worth a visit when the weather gets better, there is plenty more items to shoot at not just the wildlife.

 

[Designer]

I can see a little in what you say, but being a total beginner I need to hang on to what I learnt so far and put that into practice, practice, practice, before going deeper. That said I am always open to comments, that was why I posted the image, and even if I am maybe not ready for the extra depth of understanding yet, other readers may be.

As a simple observation, it seems to me that you're making this way too complicated. I know you wrote that we each need to learn how we do it best, but learning DOF by experimentation seems the long hard way as compared with consulting a chart or website.

You learn your way, and I'll learn my way, but learning DOF wasn't exactly difficult for me, so I just accept it for what it is and move on.

 

[TCampbell]

Your chart raises a few red flags. You watched the toothpaste video and you're showing possible influences from the Triangle Cult. Triangle Cult first: ISO does not control noise in a photograph and increasing ISO does not increase noise. Increasing ISO (especially since you're using a Canon camera) reduces noise. The triangulars are confused about cause and effect. They've attached themselves to a spurious correlation and converted that over to a cause - effect. Noise in a photograph is primarily a function of exposure. Less exposure = more noise and more exposure = less noise. ISO is related: When we don't have enough light to, as JC noted, achieve a fast enough shutter speed then we have to reduce exposure. If we don't have enough light to achieve the aperture we require for DOF then we have to reduce exposure. The noise is a result of reduced exposure. ISO does two things. It biases our camera meter to allow the reduced exposure calculation and then it post processes the sensor capture and brightens the image to compensate for the reduced exposure. In this post processing function ISO typically reduces the noise caused by the underexposure. It may sound like a subtle distinction but it's important to keep cause and effect straight. You can't control noise in a photo with the ISO setting; you have to do that with exposure. Noise is a function of exposure.

Joe

Joe,

I'm wondering if I've misunderstood what you meant to write.

Noise is a tricky subject to tackle and I honestly don't know anyone who feels completely comfortable tackling all aspects of it. One of the reasons is that noise is caused by lots of contributing factors... not just one thing.

Noise is more noticeable as a result of amplification ... which is the gain applied as a result of dialing up the ISO setting. (Changing ISO does not alter the sensitivity of the sensor.) This gain (amplification) is either applied via analog means prior to analog to digital conversion (ADC) and is sometimes called "upstream gain", or it could be applied via digital multiplication after ADC and is sometimes called "downstream gain", or a combination of both. How it's performed varies by camera manufacturer and model.

But noise is caused by lots of other factors... heat build up (which does tend to increase in long exposure images), even quantum effects (that we can't control). One type of noise is "read noise" and this is an amount of noise inherent in a sensor (due to electronics) and that amount of noise is considered to be fixed.

We regard an image as "not noisy" not because there is no noise... but because we don't notice it. This is a result of the "signal to noise ratio" (SNR). So if "read noise" is fixed... but I can get more "signal" by taking a longer image, then it stands to reason that I will have a better SNR by taking a longer exposure image than a shorter exposure image. This supports the hypothesis that a longer exposure duration should result in less noise (which is what I believe you are saying). But this is primarily a function of read noise. But there are other types of noise.

This is why I started with "I don't know anyone who feels completely comfortable tackling all aspects" of noise.

I can say that as an astrophotographer (where shooting really long exposures at high ISO is pretty common)... it doesn't matter that I can take a really long exposure. We still get more noise at higher ISO levels (regardless of exposure duration). (Astrophotographers deal with this by taking loads of images of the same object and then using "stacking" software to integrate the images ... especially using statistical integration algorithms which do a pretty impressive job of knocking down the noise.)

If the hypothesis that noise is primarily just a function of exposure duration, then we should be able to predict that if, in addition to increasing ISO, we also increase the exposure time, then we should not see an increase in noise because we've maintained the exposure duration.

So for example:

ISO 100 at f/2.8 for 30 seconds ... compared to ... ISO 12,800 at f/32 for 30 seconds
(trading 7 stops of aperture for 7 stops of ISO so we can maintain the same 30 second exposure duration).

But if I do this test... I get no noticeable noise in the ISO 100 image, but loads of noise in the ISO 12,800 image.

The data does not support the hypothesis that noise follows exposure time (instead of ISO).

I could also shoot at ISO 12,800 but trade 7 stops of aperture for exposure duration (so f/2.8 at 1/4 seconds instead of f/32 at 30 seconds). This also results in a noisy image. There may technically be less total noise in the longer exposure due to the improved SNR ratio w.r.t. the "read noise" component of the total noise, but because this is being overwhelmed by other contributors to noise, I don't notice an obvious improvement to the image. The only way I do notice a dramatic and obvious difference, is to lower the ISO value.

In testing that I've done... noise primarily follows ISO setting (at least with my cameras). I have specifically tested the scenario where I set a low ISO with a long image duration (30 seconds) to get a representative sample of how much noise I get. Then used a very high ISO but still use the same 30 second exposure time (compensating by stopping down aperture) and can confirm that the long exposure does not help smooth out the noise problem in any meaningful way. The only way to get a meaningful reduction in noise from a single image is to use a lower ISO value.

There are loads of contributing factors to noise. And one major wrench-in-the-works is that accurately assessing a sensor relies on having information available which manufacturers do not share. We do (now) know that many manufacturers "cook" their RAW images (in other words the true read noise & shot noise is higher than they let on... but they de-noise the images ... and still tell us these "cooked" images are "RAW") and this makes it difficult to accurately assess the camera at a technical level.

In science, if we observe a behavior and try to ascribe a cause, we might be able to do that if there is only one cause. If there are multiple causes, it is difficult to understand how much of the observed behavior should be ascribed to one factor vs. another factor. If we can gain confidence that we thoroughly understand one of those factors, then we can more accurately understand the other factor (because it's responsible for whatever is left over). But if you have multiple factors (more than two) ... especially when you don't know how many factors you're dealing with (and some of it's trade-secret) it gets really hard to be able to say we understand or can accurately explain the observed behavior.

So I wont attempt to say "why" noise follows ISO (more than exposure duration). I can only state that testing the camera shows that it does.

Tim