EF lens on crop body. Am I thinking odd?

After I purchaised 28-75, I stopped using 50 1.8 on my Rebel.

Sirrith wrote in post #14549330
Why do you need to know what picture you'll capture on FF? Do you use both FF and crop? If not, then forget about crop factor, just know what FOV your lens will give you on your camera, no need to confuse yourself with the FOV it will give on another camera which you aren't using because that is just irrelevant.

Because based on what people say, one is supposed to havethe mentality that if they get whatever lens, it should match some magical number based on what a FF camera would see or shoot with that lens. At least that's what I've gotten in my short stint here so far. For me, I've planned my purchases so that they will work with what I have as well as work with a FF if I ever get one. I don't mind taking an extra 3 steps back to get a shot. The lens is quality and will deliver.

mikeinctown wrote in post #14549613
Because based on what people say, one is supposed to havethe mentality that if they get whatever lens, it should match some magical number based on what a FF camera would see or shoot with that lens.

Soon you'll learn to ignore those people

Sirrith wrote in post #14549183
You're going wrong. The 17-50 is 17-50 and the 28-75 is 28-75. There's a 25mm difference only. Focal length doesn't change with sensor size, only effective FOV.

You say this is your first lens, but you rarely shoot wide? What are you basing your usage on? What subjects do you normally shoot?

1) May be my wording is incorrect. Let me put it other way. With 50mm I will reach X in a FF, whereas with 75mm I will reach X+y but because I'm using a crop body I will get even more closer (read reach) by 1.6 times. May be thats what is termed as FOV? In essense doesn't my reach increase by 1.6 times because of crop body. I can't find a suitable word to explain this further.


2) I used to own a P&S (Canon SX10IS) where the actual lens measurements were 5-100mm but the FF equivalent (reach) was mentioned as 28-560mm. I rarely shot @ 28mm FF equivalent (or 5mm +-10mm on my camera) of the 9.5K pics I clicked till last week, before I sold it.
Subjects I shoot: Can't I shoot a bird with wide lens and also with 200mm lens. I thought its the distance from the subject which determines lens and not the subject, only. Please correct me. Unless a bird clicked with 50mm (prime) looks better than a 17mm wide lens. I thought it all boils down to reach (intentionally ignored the word focal length to not confuse any further). Please correct me where I'm missing!

kf095 wrote in post #14549436
After I purchaised 28-75, I stopped using 50 1.8 on my Rebel.

Dont you feel the need of one extra stop in 'extremely' low light situation?

I would say if you can afford it - EF is the way to go. With the exception of a few lens that canon makes to fill the gap with the crop factor (10-22 and 17-55 2.8 come to mind), buying EF will allow you to more easily upgrade to FF when it becomes the norm in a few years.

I am not sure what the "norm" will be in a few years, but there are good crop lenses, and of course, good EF lenses. All of them work fine on crop bodies. The EF lenses show less vignetting on crop bodies, and they lose the blurry corners that some may show on full-frame bodies.
Some full frame lenses are fine on both formats, some are less so on one or the other.
Some efs lenses are sharp corner to corner without much in the way of optical defects (this is relative, or course and depends on f stop) - e.g., the Tokina 35f2.8 macro lens.
I have more EF than EFS lenses, but I use both when they suit me.

Pupu wrote in post #14549844
1) May be my wording is incorrect. Let me put it other way. With 50mm I will reach X in a FF, whereas with 75mm I will reach X+y but because I'm using a crop body I will get even more closer (read reach) by 1.6 times. May be thats what is termed as FOV? In essense doesn't my reach increase by 1.6 times because of crop body. I can't find a suitable word to explain this further.

First off, just forget completely about FF. Don't even think about it. You aren't using FF, so there's no point factoring it into your thought process.

Ok, so now I know you have some idea what you need thats good. Since you've shot with a camera before, and you know you don't use the wide end, then thats fine, the 28-75 may work for you. Especially if you're building a 3 lens package which will include an UWA and telephoto.

You can definitely shoot most subjects with any lens (again, in theory, and good luck getting close enough to birds with 17mm!). But you have to consider perspective. An image shot with a 17mm lens and then one shot with a 200mm lens, even if framed the same, will look completely different because you'll have to position yourself very differently for each shot. What you need to do when taking a photograph is decide what you want the final image to look like, and then choose the right lens to get it to look the way you want. If you want to take a portrait of someone and have a very shallow DOF, there's no point trying to do that with a wide angle lens, it won't work; you'd be better off with a short telephoto.

I'm happy to try and help you, just ask if I'm not making things clear enough

Sirrith wrote in post #14550119
First off, just forget completely about FF. Don't even think about it. You aren't using FF, so there's no point factoring it into your thought process.

How am I supposed to know the relative reach I will get with a lens, if I'm not quoting it @ FF equivalent. A 5-100mm lens (that I had on my P&S) will not give the same reach as 5-100mm on a crop (because of different sensors leading to different FOV). Isn't it?

Sirrith wrote in post #14550119
You can definitely shoot most subjects with any lens (again, in theory, and good luck getting close enough to birds with 17mm!).

Again it boiled down to how close you go to the subject (reach). Isn't it.

Sirrith wrote in post #14550119
But you have to consider perspective. An image shot with a 17mm lens and then one shot with a 200mm lens, even if framed the same, will look completely different because you'll have to position yourself very differently for each shot. What you need to do when taking a photograph is decide what you want the final image to look like, and then choose the right lens to get it to look the way you want. If you want to take a portrait of someone and have a very shallow DOF, there's no point trying to do that with a wide angle lens, it won't work; you'd be better off with a short telephoto.

ok I think I got your point. But can you elaborate (or direct me to a website), which will explain why the bold underlined portion (above) is not gonna work. Thanks for your answers!

Pupu wrote in post #14550243
How am I supposed to know the relative reach I will get with a lens, if I'm not quoting it @ FF equivalent. A 5-100mm lens (that I had on my P&S) will not give the same reach as 5-100mm on a crop (because of different sensors leading to different FOV). Isn't it?

You find out by experience and looking at photos from others. You don't really know what lenses perform like on FF anyway because you've never used an FF camera (or have you?).

Not really. If you decide to buy only one lens and shoot everything with it, your results will likely not be very good. Why? Because instead of creating a good photograph, everything you do will be dictated by that one focal length and its limitations. You will deprive yourself of options in terms of framing, composition, perspective, DOF, etc...

ok I think I got your point. But can you elaborate (or direct me to a website), which will explain why the bold underlined portion (above) is not gonna work. Thanks for your answers!

Because wide angle lenses have very large DOF, so everything will be in focus even with the lens wide open.

Sirrith wrote in post #14550119
First off, just forget completely about FF. Don't even think about it. You aren't using FF, so there's no point factoring it into your thought process.

Pupu wrote in post #14550243
How am I supposed to know the relative reach I will get with a lens, if I'm not quoting it @ FF equivalent. A 5-100mm lens (that I had on my P&S) will not give the same reach as 5-100mm on a crop (because of different sensors leading to different FOV). Isn't it?

As Sirrith suggested, you very likely don't have enough hands-on experience with a camera having the 35mm film format (the so-called "full frame" format) to have a feeling for what focal lengths you'd use in a variety of situations. Thus, using the 1.6 multiplier will mean nothing to you.

What MAY possibly help you, assuming you know what actual focal lengths you've used with your P&S camera, is to use a 3.5 "crop factor". For example, if you were using the 5mm (shortest focal length) with the P&S, multiply that by 3.5 and you'll get 17.5mm. That's the APS-C equivalent of the widest focal length on your P&S. Likewise, 100mm X 3.5 or 350mm is the APS-C equivalent of the 100mm setting on your P&S.

Honestly, if you're putting the P&S camera away, you can do a one-time set of calculations to determine what lenses to buy for your new camera. Then, simply start getting a feel for what focal lengths to use in different situations (camera-subject distances and sizes of the subjects).

I suggest that you learn about controlling perspective and other composition issues before being too worried about focal lengths. Please read our "sticky" (found in the General Photography Talk forum) tutorial titled Perspective Control in Images - Focal Length or Distance?. That will give you some good insight to what I'm referring to here.

For starter lenses, I'd recommend the Canon EF-S 18-55 and EF-S 50-250. These lenses are fairly inexpensive and would give you a fairly wide choice of focal lengths to work with. Once you've mastered these than you can go forward to better lenses.

There is some truth to the idea that using a lens designed for full frame on a crop camera, you'll be using only the sharpest, center portion of that lens.

However, there are other factors to consider...

EF lenses that were designed for full frame might not be updated for digital, might date to the days of film. Optics designed specifically for digital work harder to "align" rays of light and make them more fully perpendicular to the sensor plane, because the pixel sites on a sensor sit down inside tiny wells. A lens that's not designed this way can have some light falloff at the edges and in the corners, particularly wider angle lenses. Also, image sensors have more reflectance than most film, so additional anti-reflective coatings have been added to the rear elements of lenses.

Also, a film lens designed for full frame might have seen less attention to chromatic aberrations or other image flaw correction, or in the case of wide lenses less effort to to correct for barrel or pincushion distortion. Using these on a crop sensor camera will magnify any lens faults (by the lens factor or 1.6X in the case of Canon).

All this adds up that a lens optimized for crop sensor, digital cameras might give superior performance to an older lens that was originally designed for film and full frame. They also can be smaller, lighter, and offer angles of view that full frame lenses don't reach, much more affordably.

All you really need to know are the generalities of how a lens focal length performs on your new camera.... forget about all the math and conversion factors....

A lens that's 8mm to 11mm can be called an ultrawide.

A lens that's 12mm to 15mm is very wide.

16mm to 22mm is moderately wide and 24mm to 28mm are slightly wide normal.

30mm to 35mm are standard or normal lenses.

40mm to 60mm act as short telephoto.

70mm to 100mm are moderate telephoto.

120mm to 200mm might be considered fairly strong telephoto.

Anything longer than 200mm gets into super telephoto range.

There are many other factors to consider.... Lenses with USM focus (or equivalent) are quieter, faster and more accurate focusing. Sigma offers some HSM lense and Tamron is just starting to offer USD lenses, both of which are similar to USM in design and performance. There are some new focus drive mechanisms that come close to the same performanced, though (such as Canon STM). This is less important with wide lenses, that don't need to move their focus group very much to achieve focus. It's more important with normal to telephoto lenses.

IS is Image Stabilization, nice to have to help keep shots steady and avoid blur from camera shake, allow using slower shutter speeds. Sigma offers some lenses with OS (which some people feel it's as good or even better than Canon IS in some cases). Tamron also is now offering similar VC on some lenses. Keep in mind that no form of stabilization can stop subject movement.... use too slow a shutter speed with a fast moving subject and it will still end up blurred. Also, IS tends to be most useful on longer focal lengths, which are harder to hold steady. There are rules of thumb or general guidelines about how slow a shutter speed one can hand hold without any stabilizatioin, but we all are different and usually get better with practice. Also, stabilization adds optical complexity to lenses... in some cases they give up a little bit of image quality as a trade-off. Plus, more glass and mechnisms mean more cost, a little more weight, and will have more moving bits and gear to possibly break down and require a trip in for repair.

One of the really nice things about crop sensor cameras is that you can use both EF-S and EF lenses on them. So you have more lenses to choose from. Just pick lenses carefully, they are ultimately more important than the camera they're used on, will have more effect on your images. Carefully chosen lenses might give you many, many years of service. I switched to Canon in 2001 and many of the lenses I use today were bought then or shortly after, and still serrve well. Meanwhile, cameras have come and gone. I've used film and at least four different generations of DSLRs, crop and FF, with the same lenses, only added a few as needed or made minor changes. Good lenses also hold their value much better than DSLRs do!

It was pretty easy for me to choose, since I had 20+ years experience with a wide variety of lenses and cameras. Since you are really new to using SLRs, I'd recommend just get a couple starter lenses, to learn more what you want to shoot and what focal lengths appeal to you, then consider an upgrade. I agree that the 18-55 IS and 55-250 IS are hard to beat for this purpose. Maybe you'll find you want wider and don't need such a long telephoto... or maybe you'll want even longer. But you won't be out much, can likely resell the lenses at little loss, once you know better what you want.

A lens' maximum aperture, aperture design (number of blades and the shape of the blades), type of glass elements, overall construction, even filter size, effectiveness of matched lens hood and overall construction quality can be other considerations.

ok from the above two posts (Sirrith, SkipD) what I can conclude is its not the FOV that matters for a good composition but the 'actual focal lengths' (whichever format it be) that matters. Cool!

Pupu wrote in post #14550812
ok from the above two posts (Sirrith, SkipD) what I can conclude is its not the FOV that matters for a good composition but the 'actual focal lengths' (whichever format it be) that matters. Cool!

Getting closer

Basically you form the image you want in your mind, then choose the lens which will let you produce that image and there you have it; no crop factor, no calculations, none of that confusing rubbish.

amfoto1: I was talking about EF & EFs digital lenses only. Is there any categorisation of recent date EF lenses into made for digital / film cameras?

Sirrith: All this while I was looking @ focal lengths only from 'reach' perspective. I didn't bother to look at it from 'actual focal lengths' perspective and what impact they had on different pictures I clicked.

Now I think I have a hurculean task to go back to all those pictures which I clicked and I like, recalculate the focal lenghts and see which ones I prefer the most. Thank you all for all the knowledge sharing and suggestions!

GOD save me