Best lens for multiple sibjects in focus with background bokeh on a Canon eos 500D?

[BillyThomson]

Hi guys,

I'm new here and I'm not a pro.

I've been using the Sigma 30mm 1.4f lens for a while, which is great in low light and produces some fantastic background bokeh blurring when I'm shooting a single subject, which has been great for taking shots of my son. The thing is it's near impossible to get two subjects in the same shot with the same focus in low light. One or the other is almost always slightly out of focus.

Capturing in low light is really important to me, as is capturing moving subjects - I have two kids under 4 and they never sit still for a photo. My goal is to get the same level of bokeh blur in the background as I currently get with my Sigma but with two subjects in perfect focus in the foreground.

Does anyone know of any lens that would provide this type of result with a budget of up to £1000? Obviously lower than that would be ideal, but I could stretch to that if I really had to and the results were good.

Thanks in advance for your time and help on this.

cheers,

Billy

 

[SCraig]

At f/1.4 your depth of field is very, very narrow. That is going to be the case with ANY lens because it's a function of the subject distance, aperture, sensor size, and focal length. NOT the manufacturer of the lens. Your best bet is going to be to learn to live within the restraints of your depth of field, or manipulate it so it it is usable, or use supplemental lighting such as a speedlight. It's all about light, not lenses. Simply buying another lens is not going to improve the light so you have to learn to work with what you have or add additional light.

 

[weepete]

What SCraig said. And making sure you set up the shot to get a good distance between your foreground subjects and the background helps a great deal

 

[Big Mike]

Welcome to the forum.

I've been using the Sigma 30mm 1.4f lens for a while, which is great in low light and produces some fantastic background bokeh blurring when I'm shooting a single subject, which has been great for taking shots of my son. The thing is it's near impossible to get two subjects in the same shot with the same focus in low light. One or the other is almost always slightly out of focus.

Capturing in low light is really important to me, as is capturing moving subjects - I have two kids under 4 and they never sit still for a photo. My goal is to get the same level of bokeh blur in the background as I currently get with my Sigma but with two subjects in perfect focus in the foreground.

The reason that lens is good in low light, is because it has a large maximum aperture (F1.4). That large aperture allows more light into the camera, which in turn, allows you to use a faster shutter speed which helps to freeze the movement (of camera and subject) and thus get better photos.

The aperture is (for the most part) what controls the Depth of Field. The larger the aperture (lower F number) the more shallow your DOF will be.

So it seems that your problem is that your DOF is too shallow...and that can be easily fixed by choosing to use a smaller aperture (higher F number). You will likely have to be in Manual or Aperture Priority mode for this. To know just how small to make the aperture, you could consult a DOF calculator. They are available on-line or as an app for a smart phone etc.

It's not as simple as that though. If you use a smaller aperture because you want more DOF...that will be letting less light into the camera. You must therefore compensate by getting more exposure from either your shutter speed or your ISO. If you need to get more exposure via the shutter speed, that will mean longer (slower) shutter speeds...which will be more likely to give you motion blur in the photos.
So if you can 'stop down' your aperture and still get a fast enough shutter speed, then you're good to go. But if you that causes your shutter speed to be too slow, then the only other option left to you, would be to crank up the ISO. The higher the ISO, the less light you need for a good exposure...but the trade off is that the higher you set the ISO, the more digital noise you will see in your photos.

It's always going to be a compromise....and keep in mind that shooting in low light, is always going to make it harder.

There are some things that can help to tilt the odds in your favor, so to speak. For example, the farther you are from your subject (as you focus on them) the deeper your DOF will be. Also, the shorter/wider your lens, the deeper your DOF will be. That doesn't really help with a prime (non zoom) lens, but it's good to know.

 

[KmH]

Here in the US the Canon 500D is known as a Canon T1i.

Bokeh is a non-adjustable property of a lens design. Depth-of-field (DoF) is adjustable by controlling the lens aperture, point of focus distance, and lens focal length.
Your query is about DoF, and does not have any elements that are related to bokeh.
The notion that bokeh and DoF are somehow the same thing is a very common misconception.

A sharply focused subject in front of a blurred background, also known as 'selective focus', results from controlling DoF.

Using the online DoF calculator at Online Depth of Field Calculator, we see that a 30 mm lens on your T1i, set to f/1.4 and at a focus point distance of 8 feet (2.4 m) has a total DoF that is only 13.9 inches (35.3 cm) deep.
At a focus point distance of 5 feet the total DoF is reduced by almost 2/3 to only 5.4 inches (13.7 cm)

How deep DoF is determines if multiple subjects are in the plane of acceptably sharp focus.
The camera can only have 1 plane of sharp focus, and it is generally parallel to the plane of the image sensor in the camera. so if the camera is slightly tilted up/down or left/right so is that plane of acceptably sharp focus.

Understanding Depth of Field in Photography
Canon Professional Network - Depth-of-field
Understanding Camera Autofocus
Tutorials ? Sharpness

 

[bratkinson]

You're definitely 'caught up' in the exposure triangle battle. Faster ISO? Bigger aperture? Slower shutter? It's a low-light battle I have been waging since I started taking pictures without flash of various events at my local church about 12 years ago. I still use an external, bounced flash somewhat, though, just to 'guarantee' a decent number of 'keepers'. Don't be concerned with bokeh (the out of focus 'quality' of the background) just yet. Get the kids in focus and properly exposed. That's what counts.

While I haven't owned a 500D/T1i, I'm guessing you'll find the 'usable' high end ISO speed probably about 800 or 1600 before you get an unacceptable amount of noise in the photographs. Whatever that high end is, you'll want to set that in your camera. Having the f1.4 lens works great for low light, but wide open, the DOF is measured in inches when you're fairly close in. With multiple subjects, they will either have to be 'lined up' or one of their faces will be out of focus. So, your next (and only option unless you have more light), is to slow down the shutter speed to 1/60th or thereabouts and 'offset' that by shooting at f2.8 or even smaller aperture to increase DOF. Unfortunately, at that slow speed, subject movement-caused blurring is common. Unless your camera is on a tripod or monopod, your own hand motion (heartbeat!) may cause blurring as well. What I've done in situations like those is to take 8-10 shots and hope that one, yes, one, of them is usable.

As finances have allowed me, I've upgraded my kit lenses to all f4 and faster. I'm also on my third DSLR camera to get improved ISO. You've already got a good fast lens for low light. That's a great starting point. My next step would to purchase a monopod. While a tripod would be great, it would definitely get in the way when photographing kids unless you are outside. The monopod will provide improved stability (especially if you are sitting or leaning against something) needed for slower shutter speeds. An external flash would help, too, to get extra light so you can shoot at or near wide-open with decent shutter speed. Lastly, consider upgrading your camera to something close to current...perhaps a T5i or the new 70D. They should both give significantly better results at higher ISOs with less noise than you're getting with the 500D.

As for bokeh...as indicated by other respondents, that's dependent upon the lens, the aperture, and the distance between the subject and the background. Once you've gotten the exposure triangle 'under control' in your shooting, then you can 'add' bokeh to what you are trying to achieve use camera settings wisely to acheive that AND desired focusing.

 

[Gavjenks]

If you are already aware of ISO and such, and have tried all that, and the light is still too low to use a smaller aperture for broader depth of field focus, then your cheapest option is probably to add artificial light. For candids of kids indoors, a speedlight bounced off of a wall or ceiling would look just fine in most cases once you get the knack for it. Perhaps with a gel attached to make it tungsten colored if that is the dominant ambient light color and you plan to use flash + ambient.

And if you want to mix a flash and ambient light together at shutter speeds fast enough to capture motion, then you will need HSS high speed sync capable flash. The cheapest that will work well being this:
Amazon.com: Yongnuo YN-568EX TTL Flash Speedlite HSS For Canon 5DIII 5DII 5D 7D 1100D 1000D (ETTL / i-TTL, M, Multi Mode) By Ghope: Camera & Photo


Or if you want to use Canon-only products, then a 430 or a 580 flash.

The other option is a full frame sensor or new generation sensor crop, but these will all go beyond your budget significantly.

 

[BillyThomson]

Fantastic information guys, thanks very much. I know my way around the ISO settings and I always work in AV shooting mode, but I've never really played with the aperture setting as more often than not I end up with really slow shutter speeds which results in blurred pictures.

It sounds like I really need to look into getting a decent flash and working with that to get the desired results.

Sorry to keep asking questions, but do you have any suggestions for what would be the best ones to look at for my camera? I've only got the Yongnuo one on my options list right now.

 

[SCraig]

Fantastic information guys, thanks very much. I know my way around the ISO settings and I always work in AV shooting mode, but I've never really played with the aperture setting as more often than not I end up with really slow shutter speeds which results in blurred pictures.

It sounds like I really need to look into getting a decent flash and working with that to get the desired results.

Sorry to keep asking questions, but do you have any suggestions for what would be the best ones to look at for my camera? I've only got the Yongnuo one on my options list right now.

It is my understanding that AV is Canon's nomenclature for aperture priority automatic mode. If so you really NEED to learn to "play with the aperture setting" since that is what is the controlling factor in that mode. If, for example, your aperture got set to a very small diameter and you don't adjust it when in a low light situation then this is WHY you are having to shoot at slow shutter speeds.

Aperture, shutter speed, and ISO are directly related to each other as far as the exposure goes, which is why they are referred to as the "Exposure Triangle". For every "Proper" exposure there is one and only one exposure value that will give a proper exposure, however there are frequently many combinations of aperture, shutter speed, and ISO that will yield that proper exposure value. If you change to a faster shutter speed you have to open the aperture and/or use a higher ISO to compensate. If you use a wider aperture you have to use a faster shutter speed and/or lower ISO to compensate. Each choice has pros and cons and it is the responsibility of the photographer to understand how that choice will affect the photograph.

Some excellent tutorials Here. Take a look at the one entitled "Understanding Camera Exposure: Aperture, ISO and Shutter Speed".

 

[grafxman]

All of the info here looks pretty good. I would just like to add 2 things. If possible, after you close down the aperture you might try focusing somewhere in between the 2 kids. If you focus on one and the other one is some distance away then the faraway child may be out of focus. However if you focus in between the children they just might be both in focus with the lens stopped down to a small aperture. If you set your camera up to focus with the back focus button only then it will be easy to focus somewhere in between them, say on the floor, and then your focus won't change when you go to take your shot. As for the flash, if you are shooting any video with your camera then I would suggest the Canon Speedlight 320EX flash. It comes with a built in video light.

 

[Fitch]

I have read this thread with interest. Studied it would be more accurate. I'm in much the same boat as the OP so I hope this fits with the thread and adds discussion useful to the OP.

I happen to have a T3i with the two kit lenses but with grand kids and grand-nephews to take pictures of. They are seldom not in motion - more like molecules in a hot gas. I find myself using the sports setting (with lighting adjustment) and taking multiple exposures to capture the moment at family gatherings.

I'm also a total absolute novice trying to learn. Most of the discussion in this thread involves f-stop, ISO, and light. After playing with the DOF calculator, it seems like there is another variable, namely focal length, that might be a big help indoors at in room distances. Using the calculator, the DOF for 24mm and 20mm lenses @ f/2.8 is much better at in room distances like 5' to 10' than 30mm. A person could take advantage of that, and with the high MP rating of today's cameras crop to the desired frame and still have a picture that will print well in an abum, or look good on a frame that displays pictures one by one on the kitchen counter.

I'm specifically looking at the EF 20mm f/2.8 USM and EF 24mm f/2.8 USM lenses for the same type of indoor pictures as the OP.

I've taken pictures at 55mm, f/5.6, 1/100 sec, ISO 3200 of the baby to capture his facial expressions (they change at lightening speed) that we love to look at - but the grand-nephews (2, 3, and 4) seem to always come out best with around 20 to 24mm zoom as wide open as the lens gets.

Am I missing something?

Thanks
Fitch

 

[KmH]

Cropping means throwing pixels away, which also reduces resolution.

But I agree that for desktop size prints, the resolution loss will usually not be an issue.
It could become an issue if the original image is made as an in the camera JPEG and additional post process editing other than just cropping is attempted.
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