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I'm looking for a normal prime lens, desirably fast and not too expensive, for my 450D. 50mm seems to be the normal focal length on FF, thus for APS-C, I need about 30mm.

I want it to be fast as I'm going to use it at night for available light photography. The most interesting candidates so far are:

  • Canon 28mm f/1.8
  • Sigma 30mm f/1.4

I've read a lot of stuff about both lenses and ended up confused. From my current understanding, the Canon's AF is faster than the Sigma's (the AF should be fast and reliable for street photography - however, I can't tell how big this difference is in practice. Maybe you can help me?) Also, I will be able to keep the Canon when I switch to full-frame. The only thing about the Sigma that keeps teasing me is the f/1.4. How much of a difference is there really between f/1.4 and f/1.8 (what exactly will the difference in shutter speed be)?

Today I got to try out the Canon in a photography store. I'm not experienced with testing and judging lenses though, so my judgement is mostly subjective. The unsharpness in the corners that everybody seems to mention was noticeable, but did not disturb me much (might also be because of the APS-C sensor). What bothered me far more were the purple fringes around bright objects (I tested it at f/1.8). Wikipedia says you can avoid those with a strong UV filter - is that true and does the usage of such a filter have any disadvantages?

Last but not least, if there are any other lenses you'd suggest or factors I missed out, please tell me!

Thanks in advance for your advice :)

PS: I already have the Canon 60mm f/2.8 Macro and am very content with it for portraits. It is, however, way too long for an always-on lens and the 2.8 is clearly too slow for shooting at night.

PPS: Thanks for your answers! Obviously, f/1.4 does indeed make a significant difference. What bothers me the most about the Sigma is that I can't use it on an full-frame camera, which I will definitely buy sooner or later. It is said that you can sell lenses very close to the new price. However, I've read that the Sigma wears out very quickly. Someone else in the same thread replied this was because of the use of suncream. This happens when you read to much. Aargh!

PPPS: I bought the Sigma yesterday. From what I can tell after one and a half day of usage, it works pretty good. The AF needs a little adjustment, but that turned out to be no problem as I currently stay in Singapore where I can just visit the Sigma office personally and wait while they adjust the lens. I'll do that tomorrow and tell you if it made a big difference.

PPPPS: The lens was adjusted a couple of weeks ago so I've had some time to work with it. I have to say, the AF weaknesses are noticeable. However, one has to admit, the focus is required to be much more accurate on a 1.4 aperture. Also, it is an entirely new experience for me to work with such a fast lens so I also had to get used to it.

When I used the lens as an always-on for a few days and then switched to my Canon 60mm/2.8, the focus speed seemed incredibly fast. Hence, my conclusion: The lens can be great, if you know how to work with it.

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my 2 cents: In getting my first prime I first tried out a friends 35mm and found it to be too wide for my taste. I went to a 50mm when making my purchase. –  kacalapy Jan 25 '11 at 15:49
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Don't assume that you will "upgrade" to full frame - see several questions about the pros and cons on this site, including photo.stackexchange.com/questions/840/dx-or-fx-lenses –  Reid Jan 25 '11 at 23:38
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Just don't get fooled into thinking that wider aperture means you will be able to shoot in low light. If you open the aperture more, you will get a shallower DOF. It only works if you want such a shallow DOF in low light... If you don't want a shallow DOF, you need to rely on your camera's ISO setting or use a flash. –  Tom Jan 26 '11 at 13:55
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Thanks to everybody for your answers! Check out the latest edit to my question for my conclusion.. –  eWolf Mar 30 '11 at 7:29
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@eWolf: Agree with your "Aargh!" on reading too much! –  khedron Dec 14 '11 at 16:31

9 Answers 9

up vote 9 down vote accepted

A few thoughts and links for your perusal:

  • Any reviews you're going to read will be subjective but they can be good data points. Here's a thread on DPreview comparing those two lenses as well as the FredMiranda review page for the Canon.
  • You did the right thing by trying out the lens for yourself.
  • It seems that the verdict is undecided on whether a UV filter can reduce chromatic aberrations. There is another question on this site about the downsides to using a UV filter.
  • The difference between f/1.4 and f/1.8 is 2/3 of a stop. You asked about how this would affect the shutter speed and this means that assuming all other conditions are the same, the faster glass (f/1.4) would allow for a shutter speed that's 66% faster than the slower glass (f/1.8).
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Haha this (forums.dpreview.com/forums/…) gives the FF thing an entirely new aspect :D Thanks for the two links, I tend towards the Sigma again now.. I'll try to find a shop where I can try it out, too. Hopefully that'll make the decision easier for me! –  eWolf Jan 25 '11 at 16:46
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@eWolf That post misses a huge thing about full frame, which is the shallower depth of field it offers, a crop body & 30 f/1.4 will not replicate the look of a 50 f/1.4 on full frame. See photo.stackexchange.com/questions/3986/… –  Matt Grum Jan 25 '11 at 17:26
    
@Matt I know about that. I'm not really after the bokeh too much though, I'm more interested in being able to shoot at night. –  eWolf Jan 25 '11 at 22:12

Throwing my hat in to the debate I'd say get the Sigma. By all accounts it's a great lens for the price. In fact I'm planning to get one myself!

The Sigma is a more modern lens designed for your sensor size. You can therefore expect it to be a bit sharper - crop sensors usually have higher pixel densities whereas the Canon 28 f/1.8 was also released in 1995, before manufacturers started optimising lenses for digital. It also means the hood is optimized and is just the right diameter (the Canon hood (which costs extra) is designed for FF so will let in stray light which is very bad for street photography as you're frequently shooting into streetlights etc.)

If and when you go FF you can sell it (it's a popular lens so you'll have no problems shifting it). You can reduce the loss by buying used now, treat the lens well and you may be able to sell it for what you paid.

You can also use the Sigma on FF!. Yes that's right it's an EF mount (unlike your EF-s 60mm macro) so it will go on a FF camera. You will just have dark corners, which you can either use for effect (might not be all that noticeable if your shots are dark anyway) or crop out!

You never know by the time you upgrade you light have got a promotion, won the lottery or become a pro street photographer. In the meantime it pays to be using the right lens right now.

Oh and definitely try one out.... you'll things that are never in the reviews, for example I find I don't really like the plastic finish Sigma use on their lenses!

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Sigma on FF: i.imgur.com/6AJC1.jpg = instant art :-D –  che Jan 25 '11 at 21:08
    
I actually quite like the effect of an undersized image circle. It would get repetitive if you did it for every shot though. But if your FF camera has enough megapixels you can crop out the middle and get similar shots to what you would with the 450D –  Matt Grum Jan 25 '11 at 23:28
    
I think the "APS-C lens => sharper on APS-C" is a bit of an overgeneralization. Certainly the Sigma in question could be very sharp, but there are plenty of APS-C specific lenses that aren't sharper than their FF equivalents. –  Reid Jan 25 '11 at 23:41
    
@Reid There are exceptions yes, but the Canon lens was released in 1995 before manufacturers started optimising lenses for digital, whereas the Sigma was designed a year or so ago specifically for smaller, more pixel dense APS-C sensors so I'd back it to be sharper. –  Matt Grum Jan 25 '11 at 23:51
    
sure, and given your edit I think it's a better answer. But, why generalize about sharpness using a rule of thumb when one can simply look up the numbers for this specific lens? (with caveats about sample variance, of course) –  Reid Jan 26 '11 at 3:50

I haven't used either of the two lenses you mentioned, so I won't comment on those

However you also asked about alternatives: Lens Hero has comprehensive a list of fast wide primes for canon ef/ef-s.

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+1 - Lens Hero is a great place to read and compare lenses. –  Hondalex Jan 25 '11 at 16:55

I'd go for the Canon 28mm f/1.8 unless you're willing/able to pay for the Canon 35mm f/1.4 L. Either of the two you mentioned will probably have a bit of chromatic abberation, which is annoying, but fixable in post (with a slight loss of sharpness). If you're able to step up to the 35 L the fringing will largely go away.

The difference between the 1.8 and 1.4 is 2/3rd's stop, which means that you can cut the shutter speed nearly in half (a full stop mean's double the light), this is a significant difference, but you also have to keep in mind that all lenses tend to be a bit soft wide open, so you might end up at f/2 or so a lot of the time either way.

Edit:

If you are planning to switch to a full-frame in the near future, go ahead and get the 50mm f/1.4 USM. Optically, it's a great lens, it's "normal" on a FF, and it's comparatively cheap.

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I'm not willing to pay the price of the Canon 35mm f/1.4 - I'll rather save that money to buy an FF camera. –  eWolf Jan 25 '11 at 16:21
    
Have a look at my second edit - f/1.4 would be very nice to have, but it's the FF compatibility that currently keeps me away from it. Do you think I'll be able to sell the Sigma easily? –  eWolf Jan 25 '11 at 16:31
    
You could probably sell it, but if you're planning to make the switch to FF then only buy EF lenses. Besides the loss you take when you buy/sell a lens, there is also the learning curve when you buy a lens... there's no reason to learn the quirks of one lens, then sell it and go through the process on a new one. –  chills42 Jan 25 '11 at 16:56
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normally I'd agree and say get the EF lens, but the questioner has no definite plans to go FF, it could be a year away which is plenty of time to learn a lens, and benefit from it offsetting the cost of selling it. –  Matt Grum Jan 25 '11 at 17:31

There's quite a bit packed in here, so let me break it out a bit.

  1. The 50mm would be a perfectly fine lens to have. "Normal" is somewhat of a relative term, it just depends on what you are wanting to use the lens for really. 50mm is a great portrait lens on a crop sensor.
  2. The purple fringes you noticed are called Chromatic Aberrations. There is no cure for them at all, except for paying more for a better lens. The UV filter might do something for film camera, but it's doubtful it would do much if anything for a digital sensor (Digital sensors aren't sensitive in the UV typically, so they won't make much of a difference).
  3. There are some negative things associated with a UV filter, typically it will make your images have less contrast, might introduce some unwanted artificts, etc.
  4. The difference between a 1.4 and 1.8 is noticable, but I wouldn't make it the focal point of your decision.
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Check out my two edits - 50mm is too long for me and already covered by my 60mm lens. Do you think that 1.4 could make an important difference when shooting at night? –  eWolf Jan 25 '11 at 16:47
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#2, The purple fringing is probably caused by chromatic aberration. –  chills42 Jan 25 '11 at 17:07
    
@chills42 purple fringing is different to (lateral) chromatic aberration, CA turns up in the corners whilst purple fringing happens around highlights anywhere in the frame. –  Matt Grum Jan 25 '11 at 17:23

Many image processing programs can deal with chromatic aberrations (of which purple fringing is an example) pretty well. Photoshop, Lightroom, Bibble, to my knowledge - maybe others too.

I used to own the Sigma 30/1.4 and loved it. I'm not going to tell you which to buy but remember that when the lens is wide open, central sharpness is far, far more important than corner sharpness, which is mostly irrelevant as those regions will be completely out of the depth of field.

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From my understanding, purple fringing is a kind of CA that can not be removed by simply flipping a switch. You can certainly do some PS work to get rid of it, but that takes a lot of time and work and thus is not really a solution. –  eWolf Jan 26 '11 at 7:51
    
Also, I can't quite follow your assumption that corner sharpness is less important on an f/1.4 lens. Why do you assume the focused subject is always in the center of the image? –  eWolf Jan 26 '11 at 7:53
    
Just look at the photo pool in any of Flickr's fast prime groups. 99% of them don't need sharp corners, but being soft in the central portion would be a big issue. It's not an assumption - there are a few people out there who really need that corner sharpness in a small fraction of their photos, but statistically, most people never need it. And if that can save you thousands, it's worth knowing. –  Max Sang Feb 21 '11 at 9:03

The Sigma is a great lens. But, I have found that on my 40D, autofocus is hit or miss in low light. At f/1.4 there's not much room for error, so there are a lot of missed shots.

I have had much better luck manually specifying a focus point. With the extra control dials on the 40D, this is not an issue. But on a 450D, this may be more difficult to do quickly.

I am not sure if the Canon lens wouldn't have the same issues. Maybe it's worth renting each and trying it out yourself.

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Thanks for your answer! I'll probably take the Canon then. From what I've heard its AF is really good. In all the confusion, this seems to be a clear fact :-) –  eWolf Jan 28 '11 at 10:03

Although you'll be able to see the Depth of Field difference in your pictures, you won't be able to see it through your viewfinder. See Depth-of-field preview, optical viewfinder, Canon 500D, large aperture . I have the Sigma 30/1.4 on a 30D, and wider than f/2.2 I see no difference through the viewfinder when I press the DOF Preview button. Even at f/2.2 and f/2.5 the difference is barely noticeable. AF still seems pretty accurate at f/1.4, but at that aperture, if you're at all close to your subject, you will probably want to be using manual focus (I can vouch for the Sigma's easy-to-grasp, responsive, smooth focus ring!) to ensure that the part of the subject that you care about (e.g. their eyes) is in focus... and since the viewfinder is showing you essentially an f/2.2 or f/2.5 DOF, that is pretty difficult. So while an f/1.4 lens will give you a low light advantage, neither lens will be especially easy to focus wide open (I tend to take a few pictures, slightly bracketing my focus, to ensure I end up with good results).

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I noticed this, too, when trying out the Sigma today. However, I always found manual focus pretty hard to get right with my viewfinder. I guess to solve this problem I need a different body. –  eWolf Jan 29 '11 at 12:54

Here's a list of the options I've found, with some links to reviews and benchmarks.

The question is pretty specific, but I'm going for a more generic answer here (which I hope myself/others will update as new lenses come out), as I think this is a really common question without a really obvious answer (many options, with lots of trade-offs, I think it's a lot less simple than the 50mm line-up).

Canon

Other (Auto Focus)

  • Sigma 28mm f/1.8 EX DG Asph Macro (2005) — slrgear | DxO | FM | TDP
  • Sigma 30mm f/1.4 EX DC HSM (2005) — slrgear | DxO | FM | TDP
  • Sigma 30mm f/1.4 DC HSM "A" (2013) — slrgear | DxO | FM | TDP
  • Sigma 35mm f/1.4 DG HSM "A" (2013) — slrgear | DxO | FM | TDP
  • Tokina 35mm f/2.8 AT-X M35 PRO DX (2007) — slrgear | DxO | FM | TDP

Sigma's 30mm 'DC' lenses listed above are designed for APS-C, not full-frame.

Other (Manual Focus)

I'm not sure the best way to present all this just yet. It may be useful to briefly mention primary features & failings of each, to differentiate FF-compatible vs APS-C-only, so will consider some edits to add some high level info.

Also note a few are discontinued, which should probably be marked too (2nd hand only now).

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