I recenty went out on vacation and bought two new lenses to the travel.
A Sigma 18-200 mm (which has replaced my 18-55mm kit lens) with a farther range, although it is a dark lens (f6.3 at the end - ugh). But my thought was: if with my kit lens i get f5.6 at 55mm, what the matter with having f6.3 at 200mm? I guess at the zoom of 55mm the sigma will have f5.6 as well.
And a fixed Canon 50 mm f1.8 (you all know this one too well).
I found out a few stuff about this two lenses after my trip.
1)
First thing: it took me a few days to realize my long exposure shots were ruined by the Image Stabilization on the Sigma lens. The crazy thing is i wasn't used to that, because that does not happen with the 18-55mm IS kit lens. I was thinking my tripod was not properly set up at first. Then i shot this with the camera steady in a window edge, it was impossible to have camera shake here.
If possible, click to view it big.
The fixed 50mm is much more sharper than the Sigma.
And this is a great example of why you should use IS with long exposures.
2)
Turns out the 18-200mm zoom coverage is GREAT. Excellent for everyday use. One lens to carry along everytime. But i wasn't happy with it's sharpness. I recently tested a 50-250mm Canon from a friend and also got the same unsatisfying sharpness at the zoom end. Wasn't due to shakeness. It's the image result.
But there's a huge difference of range when capturing landscapes. You just want to use 18mm:
If possible, click to view it big.
50 mm is a much sharper lens (see the two lenses comparison below), but i got A LOT of flare. Can anyone point me out why? See the flare above:
If possible, click to view it big.
Also i noticed that even with the same configuration, at f22 and same exposure and ISO for both lens, the 50mm image came out a little brighter. Why is that?
3)
Can anyone point me out which is the BEST and sharpest 18-200 or equivalent lens you have ever used? I may think in replacing this Sigma.
I unfortunately don't have answers, but I appreciate you posting this with sample pictures because it really helps me to learn and better understand. Cheers,
I can't help either, but wow, there's a difference alright. So interesting to see shots side by side making for a great comparison. Thanks for sharing and asking. I will be keeping an eye on this as I'd like to get another lens also.
The way it was explained to me is that the optics required to produce a wide angle image is quite a bit different than what's required to make a telephoto. And the greater the difference between the two extremes, the more compromises the manufacturer has to make. On the other hand, a prime lens, like your 50 mm, is relatively simple. With a few exceptions a prime will be much sharper than a zoom, especially an all-in-one type, where the compromises are huge. That's just the nature of it.
If you want maximize quality, then get a lens with less range. If that's not an option for you, spend some time shooting a fence post. Or similar subject using the full range of apertures and focal lengths, at various distances so you can figure out where your lens will give. You the best performance, and what to stay away from.
IS and tripods don't mix. Always turn it off when you use some type of stabilization, otherwise the system will try to compensate for something that's not there and you'll get blur.
Different lenses have different coatings and different elements. I know my lenses that were designed for film are more prone to flare than those designed for digital. Also, if you use UV filters you are more likely to have flare at night - there's another layer of glass that might cause light to bounce around in odd ways. My personal experience is that if you use a little larger aperture you'll get less obvious flare, don't ask me why though.
@mtngal great answer! thanks a lot. I will try different apertures then.
Also, i have the UV filter on at all times, so maybe that is the issue. The quality of the UV filter has something to do with it or no? Because i bought the cheapest the store had. Never heard of that as a big issue, so...
Unless it's the same with sunglasses, the more expensive the lens, better the image you view.
@gabrielklee Cheap filters are a lousy idea. Think of looking through an old window with lots of differences in thickness. Cheap filters are made to less strict tolerances and are likely to be a bit like looking through the old window. Also, I understand that the thinner filters are better - by having the filter surface as close to the front element as practical there's less opportunity for the light to be bent inappropriately. You can make a perfectly good lens look lousy with a bad one. Personally, I only use filters in some specific conditions - like shooting outdoors in blowing dust or when I want to use a polarizer. Otherwise I don't use them, preferring to protect the front element with the lens hood. But it's a personal preference, and if I were constantly shooting small kids I'd always use one. It's such a pain to clean jelly fingerprints off of a lens!
@mtngal I read "shooting small kids" while skimming this and got scared. Great responses, though :)
Like Harriet said, the glass used in the construction of lenses (and filters) makes all the difference. This is why there are plastic lenses, glass lenses, and high end lenses made of crystalized human bone and the flesh of gods -- and cost as much as you think they would.
Now, I'm no pro on the below information, but practically speaking, it makes sense. I'm sure a few others will have something to say as well, so I'll go ahead and tag @agima at least, because he's the boss.
The Sigma has 15 lens elements, meaning the light has to pass through fifteen layers of glass before hitting the center. Usually zoom lenses have a much higher number of elements, as the shifting of these elements is how the zoom is created.
The Canon has 6 elements. Primes usually use less (at least as far as I can remember). (Also, the Canon 50mm 1.2L has 8 elements. How does this work out as far as quality goes? I have no clue, but I'm guessing that glass is made out of unicorn eyes, and the red stripe on the lens is painted with the blood of virgin dinosaurs. Otherwise, what else would make it $1500 more than the nifty-fifty? That was rhetorical, don't answer it.)
Because the light is passing through so many additional layers of glass, you can get anything from contrast issues, to flares, to distortion, to softness -- just about any kind of problem can be introduced by a bad layer of glass, so the fewer the better, I suppose, but I have no idea how to isolate such an issue.
@gurry hahaha!
Yup, i guess you helped. Now i am browsing through dpreview's articles. Turns out my sigma lens are well rated among its competitors (for the cheap range zoom, at least.)
@gabrielklee I have a Sigma 10-20 and I love it. I do, however, get a fair amount of distortion and occasionally some weird glares. But... what can you do? :)
What @mtngal said.
Larger aperture(LA) lenses generally give better results for tow reasons. More light and better design. Lens design is a compromise between quality and function. The more function, the lower the quality. Theoretically, the best quality lens would be one of fixed focal length and fixed focus designed to shoot at a specific distance. Not very practical.
The number of elements is not always directly proportional to the image quality. Multiple element lenses are designed to correct the problems that occur when the glass is moved and rotated to zoom and focus.
The more a lens is intended to do, the more difficult the design. In other words, shorter zoom=better IQ. Mostly.
Unfortunately, this usually means purchasing (or leasing) greater quality lenses in greater numbers. 18-200 represents a lot of compromise. For that range, I have a 17-40, 24-70 and a 70-200. The side effects are a lessening of portability and a lightening of the wallet.
I am not sure that I can all too much more to all the excellent answer already however I can give you some real world advice.
I have both L lens and the el-cheapo lens. 99% of the time I am using the L lens and there is a reason for this.
1) the do cost a heap so I get my moneies worth
2) the construction is far superiour
3) the coating on the glass reduces these problems
4) the glass quality it self is far superioer where I get a constant focus all the way out to the edge
5) I dont get distortion at the edges of the image
For example. I just popped out side as it is 5am here and still dark to replicate your photo with my L lens..... Sorry to say I couldnt do it. See my example.
If I actually wanted to do this I would switch over and put on my el-cheapo lens. Now having said that I would have to try it and I will over the next week and post my examples.
I went back through some of my photo and I extracted a 100% view of a night/sun set 30 second exposure I took a few weeks ago.
The flare is also affected by the amount of blades your lens has the less blades the sharper the spikes off the light.
The el-cheapo can only have around 4 blades where the L have 8.
Each lens has its sweet spot where it is tack sharp - or the sharpest it will be. For example my 100-400mm lens is soft after 350mm but very sharp at 150-200. So I know when taking portrait shots at 400mm I dont do close ups. The tend to be full body shots.
Before I start getting off the subject here are direct answers to your questions;
1) Turn off IS when on a tripod. IS works as it tries to detect shake but to do that there has to be some. When it is searching for this shake it can cause shake. For example the IS in my 100-400 is so strong you can feel and hear it when you half depress the shutter but boy it works really really really well. I hand hold out to 400mm all the time and the images are sharp.
You should also use mirror lock up, cable release or the timer... Go google for more details.
2) As mentioned its due to the glass, the coating on the glass, the gas in the glass, the construction, the fittings, lots of things. As you mentioned you are seeing this between models, but this comes back to the same ideas. I will over the next week perform the same test of switching between my 70mm and my 100mm and see if the exposure changes.
@agima I disagree about the UV filter. Know too many people with broken UV filters that might have been broken front elements. Or at least scratched. And they had a rigid lens hood on at the time
@lilbudhha@agima wow. almost a lens school. Thank you a lot Brendan and Lil Buddha.
So it seems all that is left to me is to save money for my L lens. Haha. I mean, once i finish paying for those i already bought.
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If you want maximize quality, then get a lens with less range. If that's not an option for you, spend some time shooting a fence post. Or similar subject using the full range of apertures and focal lengths, at various distances so you can figure out where your lens will give. You the best performance, and what to stay away from.
IS and tripods don't mix. Always turn it off when you use some type of stabilization, otherwise the system will try to compensate for something that's not there and you'll get blur.
Different lenses have different coatings and different elements. I know my lenses that were designed for film are more prone to flare than those designed for digital. Also, if you use UV filters you are more likely to have flare at night - there's another layer of glass that might cause light to bounce around in odd ways. My personal experience is that if you use a little larger aperture you'll get less obvious flare, don't ask me why though.
Also, i have the UV filter on at all times, so maybe that is the issue. The quality of the UV filter has something to do with it or no? Because i bought the cheapest the store had. Never heard of that as a big issue, so...
Unless it's the same with sunglasses, the more expensive the lens, better the image you view.
Like Harriet said, the glass used in the construction of lenses (and filters) makes all the difference. This is why there are plastic lenses, glass lenses, and high end lenses made of crystalized human bone and the flesh of gods -- and cost as much as you think they would.
Now, I'm no pro on the below information, but practically speaking, it makes sense. I'm sure a few others will have something to say as well, so I'll go ahead and tag @agima at least, because he's the boss.
The Sigma has 15 lens elements, meaning the light has to pass through fifteen layers of glass before hitting the center. Usually zoom lenses have a much higher number of elements, as the shifting of these elements is how the zoom is created.
The Canon has 6 elements. Primes usually use less (at least as far as I can remember). (Also, the Canon 50mm 1.2L has 8 elements. How does this work out as far as quality goes? I have no clue, but I'm guessing that glass is made out of unicorn eyes, and the red stripe on the lens is painted with the blood of virgin dinosaurs. Otherwise, what else would make it $1500 more than the nifty-fifty? That was rhetorical, don't answer it.)
Because the light is passing through so many additional layers of glass, you can get anything from contrast issues, to flares, to distortion, to softness -- just about any kind of problem can be introduced by a bad layer of glass, so the fewer the better, I suppose, but I have no idea how to isolate such an issue.
That's about all I got. Hope it helped a bit.
Yup, i guess you helped. Now i am browsing through dpreview's articles. Turns out my sigma lens are well rated among its competitors (for the cheap range zoom, at least.)
Larger aperture(LA) lenses generally give better results for tow reasons. More light and better design. Lens design is a compromise between quality and function. The more function, the lower the quality. Theoretically, the best quality lens would be one of fixed focal length and fixed focus designed to shoot at a specific distance. Not very practical.
The number of elements is not always directly proportional to the image quality. Multiple element lenses are designed to correct the problems that occur when the glass is moved and rotated to zoom and focus.
The more a lens is intended to do, the more difficult the design. In other words, shorter zoom=better IQ. Mostly.
Unfortunately, this usually means purchasing (or leasing) greater quality lenses in greater numbers. 18-200 represents a lot of compromise. For that range, I have a 17-40, 24-70 and a 70-200. The side effects are a lessening of portability and a lightening of the wallet.
Here is a better explanation.
I have both L lens and the el-cheapo lens. 99% of the time I am using the L lens and there is a reason for this.
1) the do cost a heap so I get my moneies worth
2) the construction is far superiour
3) the coating on the glass reduces these problems
4) the glass quality it self is far superioer where I get a constant focus all the way out to the edge
5) I dont get distortion at the edges of the image
For example. I just popped out side as it is 5am here and still dark to replicate your photo with my L lens..... Sorry to say I couldnt do it. See my example.
If I actually wanted to do this I would switch over and put on my el-cheapo lens. Now having said that I would have to try it and I will over the next week and post my examples.
I went back through some of my photo and I extracted a 100% view of a night/sun set 30 second exposure I took a few weeks ago.
Example image:
The el-cheapo can only have around 4 blades where the L have 8.
Each lens has its sweet spot where it is tack sharp - or the sharpest it will be. For example my 100-400mm lens is soft after 350mm but very sharp at 150-200. So I know when taking portrait shots at 400mm I dont do close ups. The tend to be full body shots.
Before I start getting off the subject here are direct answers to your questions;
1) Turn off IS when on a tripod. IS works as it tries to detect shake but to do that there has to be some. When it is searching for this shake it can cause shake. For example the IS in my 100-400 is so strong you can feel and hear it when you half depress the shutter but boy it works really really really well. I hand hold out to 400mm all the time and the images are sharp.
You should also use mirror lock up, cable release or the timer... Go google for more details.
2) As mentioned its due to the glass, the coating on the glass, the gas in the glass, the construction, the fittings, lots of things. As you mentioned you are seeing this between models, but this comes back to the same ideas. I will over the next week perform the same test of switching between my 70mm and my 100mm and see if the exposure changes.
3) With out a doubt this has been marked as the best lens ever built. http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_70_200mm_f_2_8l_is_ii_usm
I hear of people spending big bucks on a lens and so they dont want it damaged they put a crappy UV filter on... Fair dinkum....
You pay for the glass dont hide it behind another filter unless you have too. i.e. ND, etc
So it seems all that is left to me is to save money for my L lens. Haha. I mean, once i finish paying for those i already bought.