Bought the wide angle - now a question about apetures

[DoleWhipDVC]

So I made my choice (with special thanks to Gdad, WDWFigment, ChiSoxKieth, and Zackiedawg for all the advice). I went with the Tamron 10-24mm for my wide angle lens. I picked it up yesterday and went out shooting today to check focus and function. The lens seems to work great, but now I’m curious about aperture settings. The lens is supposed to shoot 3.5 to 4.5 yet I can dial up to 22 in the AV mode setting on my Canon 40D. Isn’t that outside the spec range, or do I have my numbers crossed? I thought the larger the number, the smaller the aperture, right? So how can the camera allow a 22 aperture when the lens is only supposed to go to 4.5?? 22 is larger than 4.5 so… Help!!

Also, while shooting an interior room, I put the camera on a tripod, set the aperture to 3.5, ISO at 1600, and auto focus enabled. I shot with a remote to avoid camera shake. I took a capture at each of the main distance settings on the ring and as I adjusted the distance, the camera changed the aperture setting! In AV mode, isn’t the setting supposed to be “locked” at whatever you pre-set it at? I then rotated the aperture setting dial all the way to 22 and re-took the shots at the same distances. Again, the camera changed the aperture settings while on AV mode as I changed the distance of the shot. Don’t get me wrong, the pictures were rich and deep, but can anyone explain why the aperture setting changed when I had selected it in AV mode? I haven’t noticed this happening with my Canon 70-300 zoom or my Canon 28-135. Am I just very non-observant, or is this something inherent in wide angle lenses? I thought I had this basic stuff figured out, now I feel like I’m just starting out (or missing a simple explanation). Can someone please help without making me feel more like a total idiot than I already do!

 

[Theosus]

The two numbers aren't minimum and max. The smaller number is the max aperture at the most zoomed out...
The larger number is the max aperture when you are the most zoomed in.

I guess they print the max aperture, but not the minimum on there, because people don't care what the minimum is...

 

[My2Girls66]

I am sure someone will give a good explanation but it is normal for the aperture to change like that. The 3.5 is the aperture at the widest end and it gets smaller(larger #) as you zoom in toward the subject. So no worries there, it is working properly. A 2.8 zoom lens will stay at 2.8 throughout all the zoom lengths but you can still change the aperture to a higher # if you choose.
Have fun with the new lens!

 

[ukcatfan]

The two numbers aren't minimum and max. The smaller number is the max aperture at the most zoomed out...
The larger number is the max aperture when you are the most zoomed in.

I guess they print the max aperture, but not the minimum on there, because people don't care what the minimum is...

Correct, and to add to it, your other lenses do this but you just have not noticed. There are no constant aperture lenses at those focal lengths that I have ever heard about.

 

[ssanders79]

Also, while shooting an interior room, I put the camera on a tripod, set the aperture to 3.5, ISO at 1600, and auto focus enabled. I shot with a remote to avoid camera shake.

Why did you crank up the iso while shooting with a tripod?

 

[photo_chick]

f/22 is a smaller aperture than f/4.5. I know the numbers are counter intuitive, unless you know what they do. The f in f-stop stands for focal length. When you take the focal length and divide it by the aperture number you get the actual size of the opening. f/4.5 at 10mm is an opening of 2.22mm and f/4.5 at 20mm is 4.44mm. So even the aperture number is the same the actual opening changes at different focal lengths. (this is why longer focal lengths have a shallower depth of field at a given aperture)

Not all lenses can perform at all apertures at all focal lengths. Not sure why the aperture is changing on you in Av mode at f/22 though because I think that lens is supposed to be good from f/4.5 to f/22 at all focal lengths. Though it will change wide open because it can't open up to f/3.5 past a certian focal length.

 

[disneyboy2003]

So I made my choice (with special thanks to Gdad, WDWFigment, ChiSoxKieth, and Zackiedawg for all the advice). I went with the Tamron 10-24mm for my wide angle lens. I picked it up yesterday and went out shooting today to check focus and function. The lens seems to work great, but now I’m curious about aperture settings. The lens is supposed to shoot 3.5 to 4.5 yet I can dial up to 22 in the AV mode setting on my Canon 40D. Isn’t that outside the spec range, or do I have my numbers crossed? I thought the larger the number, the smaller the aperture, right? So how can the camera allow a 22 aperture when the lens is only supposed to go to 4.5?? 22 is larger than 4.5 so… Help!!

First of all, congratulations on your new ultrawide angle lens. I'm sure you're gonna have lots of enjoyment using this lens.

So, a couple things regarding the apertures listed on a lens. In your case, you've got the Tamron 10-24mm f/3.5-4.5 lens. What does this mean? First, it means that you have a variable aperture lens. In other words, the maximum aperture of your lens varies as you zoom in. When your lens is set to 10mm, the maximum aperture you can get is f/3.5.

On the other hand, when you zoom in your lens to 24mm, the maximum aperture you can get is f/4.5. When you're at 24mm, you *cannot* get an aperture larger than f/4.5 (ie. you can't get an f-number smaller than f/4.5). Specifically, at 24mm you cannot get an aperture of f/3.5. In variable aperture lenses, the maximum aperture gets smaller (ie. the f-number gets larger) when you zoom in.

There are other lenses out there that have a constant maximum aperture. For example, Tamron makes a 17-50mm f/2.8 lens. This means that the maximum aperture of this lens is f/2.8 throughout the entire focal length of the lens, regardless of whether you're at 17mm or at 50mm.

Usually, you pay a heftier price for constant aperture lenses.


Why are you able to dial your aperture all the way down to f/22? As you stated yourself, "the larger the f-number, the smaller the aperture." You are correct in that the number "22" is larger than the number "4.5". However, this means that f/22 is a smaller aperture than f/4.5. In other words, f/4.5 is a much larger aperture than f/22.

Here's a picture from the internet that demonstrates the relative sizes of different apertures:

Although f/4.5 isn't exactly listed in the above picture, you can imagine that f/4.5 is LOTS larger than f/22.

When reading apertures on lenses, photographers are usually concerned only about the maximum aperture. That's why they list only the maximum aperture on lenses. The camera can always make the hole smaller (ie. the camera can always make the aperture smaller). That's why you're able to go all the way down to f/22 in aperture size. However, you can't make a hole any larger than its maximum size (ie. you can't go larger than the maximum aperture).

Also, while shooting an interior room, I put the camera on a tripod, set the aperture to 3.5, ISO at 1600, and auto focus enabled. I shot with a remote to avoid camera shake. I took a capture at each of the main distance settings on the ring and as I adjusted the distance, the camera changed the aperture setting! In AV mode, isn’t the setting supposed to be “locked” at whatever you pre-set it at?

The reason the aperture changes in Av mode is because you've got a variable aperture lens.

You started off by setting the camera at 10mm, and it's maximum aperture at that focal length is f/3.5.

However, as you start zooming in, the maximum aperture of the lens changes. That's why you see the f-number change. By the time you get to 24mm, you probably noticed that the aperture was changed to f/4.5, even though you were in Av mode.

You are correct in that, in general, Av mode is supposed to lock the aperture that you set it at. However, if you've got a variable aperture lens and you set the aperture at the maximum f-number, the aperture WILL change when you zoom in with your lens.

On the other hand, let's say that you're in Av mode and you set the aperture to f/8. Because you're NOT at the maximum aperture (remember, f/8 is smaller than f/3.5 or f/4.5), the camera will always be at f/8, regardless if you're at 10mm or zoom in to 24mm.

Let's say you had a constant aperture zoom lens, like the Tamron 17-50mm f/2.8. If you're in Av mode and you set the aperture at its maximum f/2.8, then the camera will always stay at f/2.8, regardless of whether you're at 17mm or zoom in to 50mm.

I haven’t noticed this happening with my Canon 70-300 zoom or my Canon 28-135.

Yes, the same exact thing should also be happening with those 2 lenses. Both those lenses are variable aperture zooms, so their maximum apertures will vary, depending on the focal length.

For the Canon 70-300mm f4-5.6 lens, you start by setting up your camera at 70mm and f/4. Leave your camera in Av mode. When you start zooming in toward 300mm, you will notice that the aperture automatically changes to f/5.6.

For the Canon 28-135mm f/3.5-5.6 lens, you start by setting up your camera at 28mm and f/3.5. Leave your camera in Av mode. When you start zooming in toward 135mm, you will notice that the aperture automatically changes to f/5.6.


This "variable aperture lens" thing is a pretty confusing concept, and I hope I didn't make it more confusing with my long-winded explanation. I had to read through this explanation several times before it finally "clicked" for me.

Anyway, hope it helps.

 

[DoleWhipDVC]

Thanks to everyone who replied (and those who may still do so). This all makes sense now. I guess I was thinking I could adjust only between 3.5 and 4.5 at any length, not that those were settings for the longest and shortest lengths. Now if I just work with the lens and figure out which settings work best to not blow out the shot with too much light, I'll be all set.

Note to ssanders79, I cranked up the ISO because I was shooting in a dim room and just wanted to capture as much light as I thought I would need with each shot. I didn't want to change anything between captures myself (to observe the automatic apeture changes that were freaking me out) so I just set it high and left it there.

Thanks again to everyone, I'm sure I'll be back with more stupid questions later!!

 

[mom2rtk]

Thanks to everyone who replied (and those who may still do so). This all makes sense now. I guess I was thinking I could adjust only between 3.5 and 4.5 at any length, not that those were settings for the longest and shortest lengths. Now if I just work with the lens and figure out which settings work best to not blow out the shot with too much light, I'll be all set.

Note to ssanders79, I cranked up the ISO because I was shooting in a dim room and just wanted to capture as much light as I thought I would need with each shot. I didn't want to change anything between captures myself (to observe the automatic apeture changes that were freaking me out) so I just set it high and left it there.

Thanks again to everyone, I'm sure I'll be back with more stupid questions later!!

The only reason to crank up the ISO is to allow the camera to gather all that light at a fast enough shutter speed to allow you to hand hold it with out shake.

Once you put it on a tripod, you take shake out of the equation, so use the lowest possible ISO, which will give you the best image quality (the least noise). Since it's on a tripod, the camera can use a longer shutter speed to let all the light in.

Have fun with the lens!

 

[DoleWhipDVC]

The only reason to crank up the ISO is to allow the camera to gather all that light at a fast enough shutter speed to allow you to hand hold it with out shake.

Once you put it on a tripod, you take shake out of the equation, so use the lowest possible ISO, which will give you the best image quality (the least noise). Since it's on a tripod, the camera can use a longer shutter speed to let all the light in.

Have fun with the lens!

Ah ha! That explains the earlier question about why I upped the ISO while using a tripod. I was under the impression that you always increased ISO in dark settings to allow for more light. Thanks for pointing out that once on a tripod, I can let the apeture stay open since the camera shouldn't move, and that way I can get a nice shot with less noise. That will cut down on my need for noise reduction in post processing. I guess sometimes the obvious stuff just escapes us newbies! Oh wait, but what if I'm trying to shoot on a dark ride? Now I'm moving, so I would need a higher ISO, and a larger apeture, yes? Hmmm....but wouldn't I get a ton of blur as well??

 

[mom2rtk]

Ah ha! That explains the earlier question about why I upped the ISO while using a tripod. I was under the impression that you always increased ISO in dark settings to allow for more light. Thanks for pointing out that once on a tripod, I can let the apeture stay open since the camera shouldn't move, and that way I can get a nice shot with less noise. That will cut down on my need for noise reduction in post processing. I guess sometimes the obvious stuff just escapes us newbies! Oh wait, but what if I'm trying to shoot on a dark ride? Now I'm moving, so I would need a higher ISO, and a larger apeture, yes? Hmmm....but wouldn't I get a ton of blur as well??

On a dark ride, you're 1) not going to be able to set up a tripod and 2) not going to benefit from a tripod since there's movement involved. This is where a high ISO is your friend. You need to figure out what shutter speed will accomplish that for you and adjust your aperture and ISO to balance that out. I usually go with the slowest shutter speed I can hand hold without shake, then up the ISO until I get a stop or two down from wide open (if possible. Wide open might be the only way to do it). But I'm typically using a fast lens, offering my f-stops up to 1.4 or at the very least 2.8.

 

[disneyboy2003]

Ah ha! That explains the earlier question about why I upped the ISO while using a tripod. I was under the impression that you always increased ISO in dark settings to allow for more light. Thanks for pointing out that once on a tripod, I can let the apeture stay open since the camera shouldn't move, and that way I can get a nice shot with less noise. That will cut down on my need for noise reduction in post processing. I guess sometimes the obvious stuff just escapes us newbies! Oh wait, but what if I'm trying to shoot on a dark ride? Now I'm moving, so I would need a higher ISO, and a larger apeture, yes? Hmmm....but wouldn't I get a ton of blur as well??

mom2rtk is correct. If you're using a high ISO and a large aperture, you will be able to use faster shutter speeds, which will decrease any motion blur. The downside to this, however, is that higher ISOs will give you more noise / grain in your photos, and larger apertures will limit your depth of field. Photography is all about compromises, so you always have to figure out which setting is most important to you.

In the case of dark rides, my biggest goal is to get sharp photos because of all the movement on those rides. That's why I would choose faster shutter speeds, and I am willing to sacrifice noise / grain (with high ISOs) and depth of field (with large apertures) in order to get sharp, low-light photos.


As you've already noticed, there are 3 components to the exposure triangle. In other words, there are 3 things that let more light into your camera: shutter speed, aperture, and ISO. When you make changes to 1 of these, you can compensate by making changes to the either of the other 2.

How do each of these 3 components let more light into your camera?

• shutter speed - a slower shutter speed will let more light into your camera. However, a slow shutter speed will introduce motion blur if you can't hold the camera steady.
  
  Conversely, a faster shutter speed will "freeze" any motion, such as for sports photography. However, a fast shutter speed will let less light into your camera.
  
  
• aperture - a large aperture (small f-number) lets more light into your camera. A large aperture, however, can make your depth of field smaller, which might sometimes be a good thing, especially for portraits.
  
  A small aperture gives you a lot of depth of field, which is great for landscape photography. However, a small aperture lets less light into the camera.
  
  
• ISO - ISO itself doesn't have anything to do with letting light into the camera. ISO is a measure of the sensitivity of the camera's sensor to light. A high ISO makes the sensor more sensitive to light (similar to letting more light into your camera), which is good for handheld low-light photography. However, high ISOs introduce noise / grain into your photos.
  
  Low ISOs will give you nice, clean, noise-free photos. However, low ISOs make your camera's sensor less sensitive to light (similar to letting less light into your camera).

That's what exposure is all about...letting more or less light into your camera. That's how you get a photo.

So these are the compromises you must decide for each photo you take. Which of these features is most important for your photo. And then adjust the other settings to compensate for letting more or less light into your camera.


Let's take the "low-light tripod" example. Because your camera is on a stable tripod, you don't have to worry about blurring from an unsteady hand. You can afford to use super-slow shutter speeds to let more light into your camera.

How about aperture? If you're not doing a portrait, you can use smaller apertures to increase the depth of field. Smaller apertures let less light into the camera.

How about ISO? You can afford to use a low ISO to get a nice, clean, noise-free photo. Low ISOs let "less light into your camera."

In this case, your small aperture lets less light into the camera. Your low ISO lets less light into the camera. How do you compensate for this? By using a super-slow shutter speed to let more light into the camera.


On the other hand, the "low-light handheld" example at the beginning of my post uses different settings. Because you're not on a tripod, you want to prevent blurring from an unsteady hand. You are, thus, forced to use faster shutter speeds, which lets less light into your camera. To compensate, you end up using large aperture and high ISO to let more light into your camera.


Anyway, that's the general thought process behind how to choose shutter speed, aperture, and ISO for each photo you take. Hope that helps.

 

[DoleWhipDVC]

On a dark ride, you're 1) not going to be able to set up a tripod and 2) not going to benefit from a tripod since there's movement involved...

Well there goes my plan for interior shots on Aerosmith! Seriously, I'll work on your suggestions in August. I'm curious though, what would you recommend for initial settings with the wide angle lens on, say, haunted mansion?

 

[DoleWhipDVC]

mom2rtk is correct. If you're using a high ISO and a large aperture, you will be able to use faster shutter speeds, which will decrease any motion blur. The downside to this, however, is that higher ISOs will give you more noise / grain in your photos, and larger apertures will limit your depth of field. Photography is all about compromises, so you always have to figure out which setting is most important to you...

Anyway, that's the general thought process behind how to choose shutter speed, aperture, and ISO for each photo you take. Hope that helps.

Great advice Disneyboy, and thank you. I edited you quote for space saving, but please rest assured, I read (and will re-read) every word. If I may, can I pose the same question to you that I asked of Mom2rtk? What would you recommend for starting settings on a ride like mansion with the wide angle lens?

 

[mom2rtk]

Well there goes my plan for interior shots on Aerosmith! Seriously, I'll work on your suggestions in August. I'm curious though, what would you recommend for initial settings with the wide angle lens on, say, haunted mansion?

LOL! I'm still waiting for someone to post some pictures from Rock 'n Rollercoaster! Maybe you'll start a trend?

I set my camera to burst mode. If I'm on a dark ride like Haunted Mansion, I'd probably go with spot or center weighted metering (or whatever you have on yours like that). Then I'd probably set my ISO high, maybe 3200 or even 6400 if I had to. (remember, the higher the ISO, the more noise, but the more light sensitive the sensor will be). Then I would probably go shutter priority with 1/40, because that's about where I'd expect to get a shot or 2 that wasn't blurry. Others here will say go aperture priority with it set to the largest aperture (smallest number) your lens will do. Still others will go full manual and set both.

Another trick if you can't get your shutter speed fast enough is to dial down the exposure compensation a bit. That will allow your camera to use a little faster shutter speed (to avoid the blur). You can then lighten the exposure in post processing if needed.

Have fun, and be sure to post your pictures back here when you get back!

 

[ukcatfan]

I personally would not use your new lens in HM. The wide end is probably a bit too wide and at 24mm it is f/4.5, which is not fast enough for that ride even at 6400. I personally feel that 30-35mm is the perfect focal length. You can always try, but you will probably end up doing a lot of cropping since the displays are not all that large and will likely look really small at 10mm. All the more reason to ride more than once! Wide angle would probably be fun on POTC though.

 

[zackiedawg]

Congrats on the lens purchase, and glad to see you've already gotten clear advice on how the aperture works and what those maximum aperture settings on the lens mean. I've just arrived back from 5 days at Disney World, so I'm just catching up on threads in here...still have much sorting through photos to do and get them posted! Of course, my 10-24mm got some exercise while up there.

I'd agree with UKCatfan - the ultrawide angle lenses aren't really a great choice for most dark rides - the focal length is actually TOO wide for many shots, and even the fastest UWAs are generally too slow for very dark rides like HM. Most of us who shoot in Haunted Mansion are using F1.4 to F1.7 lenses...and even with those we often need ISO3200-12800! POTC is also dark, but you could probably get enough light in a few of the scenes to shoot at ISO6400 or so and get a few fun shots. I've used my 10-24 on Spaceship Earth before and gotten a few good ones.

In general, a good way to think of an ultrawide lens is to always try to use the lowest ISO possible, and always try to use the smallest aperture you can up to about F14 (the BIGGER F numbers). That doesn't mean to shy away from the big apertures like F3.5 - use them happily...but because UWA lenses are all about massive depth of field and huge perspective, the smaller apertures tend to help with keeping good sharp focus throughout a big, deep scene, from close to the lens all the way to the horizon. I often use my lens at F3.5, so by no means should you shy away from it - but when I have enough light, I will always stop down the aperture to F8 - F14 or so and really open up that massive depth of field that these lenses do so well.

 

[DoleWhipDVC]

I personally would not use your new lens in HM. The wide end is probably a bit too wide and at 24mm it is f/4.5, which is not fast enough for that ride even at 6400. I personally feel that 30-35mm is the perfect focal length. You can always try, but you will probably end up doing a lot of cropping since the displays are not all that large and will likely look really small at 10mm. All the more reason to ride more than once! Wide angle would probably be fun on POTC though.

I just read Todd Hurley's essay on dark ride captures. Do you think it would be worth my while to just purchase the Canon 50mm f/1.8 to go after the dark ride shots? I am really looking forward to using the wide angle in the parks, plus have my other lenses for zooming or standard work, but at roughly 100 bucks, I can see the value in grabbing the 50mm and dropping it into my bag. Or am I just getting lens crazy at this point?

 

[DoleWhipDVC]

I'd agree with UKCatfan - the ultrawide angle lenses aren't really a great choice for most dark rides - the focal length is actually TOO wide for many shots, and even the fastest UWAs are generally too slow for very dark rides like HM. Most of us who shoot in Haunted Mansion are using F1.4 to F1.7 lenses...and even with those we often need ISO3200-12800! POTC is also dark, but you could probably get enough light in a few of the scenes to shoot at ISO6400 or so and get a few fun shots. I've used my 10-24 on Spaceship Earth before and gotten a few good ones.

Thanks for letting me know your thoughts, like most people on the boards, your work inspires me to go out and try cool stuff. I asked UKCatfan and since I value your opinion, I'd like to ask you too: is the Canon 50mm f/1.8 a good purchase for going after the dark ride captures? Todd Hurley wrote a great essay on the subject, and it seems he was shooting everything with that lens. For around 100 dollars, it will definetly be the cheapest lens in my arsenal (plus it should serve well for family shots like portraits too, correct?).
Or am I just getting bit by the "more equipment is better" bug? I know having the lens won't ensure good shots, but I at least want the equipment that gives me a fighting chance to get the pictures I desire. Any advice would be very much appreciated.

 

[zackiedawg]

I would always endorse the idea of having at least one fast prime like that...if you can find one that gets you in the door for under $100 or so, that would be exactly what I'd recommend to start with. If you find you use it a lot, and really come to love low light shooting with it, but find it a bit too long, you can always look to invest in a good 28mm, 30mm, or 35mm version down the road. But a cheap 50mm is always a great place to start. I myself got a Minolta 50mm F1.7 as my first low light lens, picked up used for $60. I'd suggest the same - you might even find that lens used for even less...check out KEH.com to see if they've got any.