My Nikon AF-S 35mm 1.8G lens is not up to the mark - why???

CtrlU

Dear Friends,

I own a Nikon D5100, and have been using the 18-55 kit lens along with it, as you all know that this kit lens is superb for macros and closeups but not so great for landscape photography since the lens lacks the sharpness and also is crappy for low light shots, .

I heard lots of users praising the capabilities of the 35mm 1.8g prime lens, regarding its sharpness and its ninja ability to capture low light shots without sacrificing on shutter speed and iso .

So i decided to get my self this prime lens. but to my horror it all turned out to be wrong.

so i did a comparison test to find whats wrong.. pls note that all shots were made in aperture priorty mode and both at 35mm focal lenghts and all at the same lighting conditions and at ISO 100.

1. the first was a shot of some oranges on a table with the morning sun rays gleaming onto them.

first the 18-55 kit lens fixed at 35mm, the aperture was fixed at 5 the highest aperture the lens was capable of when zoomed to 35mm. when metered the shutter speed was fixed at 1/80th of a second. OK went ahead and took the shot

Now with the 35mm lens , again i fixed the aperture at 5, since i wanted to compare both the shots, But heres were the problem starts, When i metered the shutter speed was fixed at "1/60th of second" NOW HOW ON EARTH IS THAT POSSIBLE. why did the shutter speed become lower than the kit lens. i thought this prime lens was a fast one, and took superb shots in low light conditions. I really thought that the shutter would be meterd at somewhere in 1/100 and 1/200 range.

Why is this happening.

2. So i decided to take an out door landscape shot to check if this was the case again.

the shot was a rice paddy filed at 8:00 in the morning, sunrays shining brightly over the green rice field.

First with the kit lens, at 35mm, the aperture was fixed again at 5, when metered shutter speed was fixed at 1/3200 of a second. fast isn't it....OK

now with the prime lens and to my horror the shutter speed was fixed at 1/1600 of a sec.... WHAAAT lower than the KIT lens again.... WHATS GOING ON... why this lens is capable of capturing more light in right... then what wrong with the lens.

MY question to all is ....

is there something wrong with my lens, if yes how to find whats wrong and...

Please guys i need your expert advice... I EXPECTED more from this lens and now i am sad.

PB_PM

If you use the 18-55mm F3.5-5.6G VR at 35mm F5 and then set the 35mm F1.8G at F5, you should see the same shutter speed. Not sure what the confusion is, that's how it works. You only see faster shutter speeds when you use wider apertures, aka F1.8-2.8. There will be some variance between the two lenses, due to the difference in optical design.

Question, when you saw different shutter speeds were you targeting a subject under controlled lighting (aka indoor lighting) or natural outdoor light? If the answer is natural light, that will very, even a few minutes can make a big difference.

Golf007sd

+1 @ PB_PM

What was the result of the images taken...that is what counts. I would not worry about the shutter speed at all @ f/5.0.

CtrlU

If you use the 18-55mm F3.5-5.6G VR at 35mm F5 and then set the 35mm F1.8G at F5, you should see the same shutter speed. Not sure what the confusion is, that's how it works. You only see faster shutter speeds when you use wider apertures, aka F1.8-2.8. There will be some variance between the two lenses, due to the difference in optical design.

Question, when you saw different shutter speeds were you targeting a subject under controlled lighting (aka indoor lighting) or natural outdoor light? If the answer is natural light, that will very, even a few minutes can make a big difference.

But the problem here is even with the same exposure settings and frame composition the shutter speed of the 35mm lens is always lower than the kit lens. even under controlled lighting conditions... i always though that prime lens were superior to than telephoto lens and captured more light, any ways photos are exposed properly on the prime..

CtrlU

+1 @ PB_PM

What was the result of the images taken...that is what counts. I would not worry at the shutter speed at all @ f/5.0.

the images on the 35mm looks better btw, more color, and bright... have to check on the sharpness though.... can anyone suggest how to test the sharpness of a lens..

FlowtographyBerlin

@CtrlU: To get that one misconception of yours out of the way: If a lens "captures more light", this means it will have a larger aperture to do so, i.e. if someone tells you to get the 35mm DX lens for low-light ability, he or she is NOT referring to the lens "capturing more light" at a given aperture, say, f/5.6, but he's referring to the fact that you can OPEN the aperture more and go to f/1.8 (vs., as you noted f/5 as the fastest possible value with your zoom).

So: Your concept of a lens getting faster shutter speeds at the same aperture in the same lighting conditions is wrong. I hope the logic is comprehensible from my explanation above and from @PB_PM.

That said, there can be minor differences in the transmission that a lens has. This COULD explain minor differences in measured shutter speeds. But not large ones.

FlowtographyBerlin

have to check on the sharpness though.... can anyone suggest how to test the sharpness of a lens..

Are you kidding? If not: Take a picture of something contrasty and look at the image at 100% magnification on your screen.

To avoid bias from misfocusing, make sure your subject has some depth, i.e. is not flat and parallel to your image plane.

To avoid bias from camera shake, using a tripod and turning on shutter delay is a good idea.

CtrlU

@CtrlU: To get that one misconception of yours out of the way: If a lens "captures more light", this means it will have a larger aperture to do so, i.e. if someone tells you to get the 35mm DX lens for low-light ability, he or she is NOT referring to the lens "capturing more light" at a given aperture, say, f/5.6, but he's referring to the fact that you can OPEN the aperture more and go to f/1.8 (vs., as you noted f/5 as the fastest possible value with your zoom).

So: Your concept of a lens getting faster shutter speeds at the same aperture in the same lighting conditions is wrong. I hope the logic is comprehensible from my explanation above and from @PB_PM.

That said, there can be minor differences in the transmission that a lens has. This COULD explain minor differences in measured shutter speeds. But not large ones.

ok... i seemed to have got it wrong with what low light ability meant... its understood now, but don't you think its odd to find that the prime lens is slower than the telephoto kit lens... i am pretty sure the optics of the 35mm are better and atleast should have had equal shutter speed that to the kit lens not lower... any ways i;ll post some comparison shots here later... so you guys can check for yourselves...

CtrlU

have to check on the sharpness though.... can anyone suggest how to test the sharpness of a lens..

Are you kidding? If not: Take a picture of something contrasty and look at the image at 100% magnification on your screen.

To avoid bias from misfocusing, make sure your subject has some depth, i.e. is not flat and parallel to your image plane.

To avoid bias from camera shake, using a tripod and turning on shutter delay is a good idea.

i'll try that and post the results here thanks...

FlowtographyBerlin

You can also use a Focus Test Chart by Tim Jackson (get the pdf on the net and print it out) to experiment a little and see how your focus is aligned.

tcole1983

I think there is something wrong in your testing. What mode are you using? A, M, auto? You haven't provided any information for us to make a logical suggestion of what the problem might be. However there is an obvious disconnect on how you think or understand your lenses are working. I think it was fairly well explained above. A fast prime indicates a small f stop ie f1.4-f2.8 which means the aperture opens up more and allows more light in. So shooting at f5 isn't going to benefit you with more light and faster shutter speeds. Shoot at f1.8 and it will. However it changes the lenses depth of field and at f1.8 it can be pretty narrow. Sometimes leaving parts out of focus that you wanted in focus.

Not trying to be snarky but there is more to just getting a prime lens and automatically getting amazing pictures. I do see you are trying to understand the difference. My guess is unless you are using a tripod, using the exposure lock and having a continuous source of light then it is user error that is making the difference in your shutter speeds. You don't have to move far on a bright day to get large changes in you shutter speed and once you hit your shutter release button and recompose your image you just changed the focus and exposure unless you set your camera up correctly.

CtrlU

I think there is something wrong in your testing. What mode are you using? A, M, auto? You haven't provided any information for us to make a logical suggestion of what the problem might be. However there is an obvious disconnect on how you think or understand your lenses are working. I think it was fairly well explained above. A fast prime indicates a small f stop ie f1.4-f2.8 which means the aperture opens up more and allows more light in. So shooting at f5 isn't going to benefit you with more light and faster shutter speeds. Shoot at f1.8 and it will. However it changes the lenses depth of field and at f1.8 it can be pretty narrow. Sometimes leaving parts out of focus that you wanted in focus.

Not trying to be snarky but there is more to just getting a prime lens and automatically getting amazing pictures. I do see you are trying to understand the difference. My guess is unless you are using a tripod, using the exposure lock and having a continuous source of light then it is user error that is making the difference in your shutter speeds. You don't have to move far on a bright day to get large changes in you shutter speed and once you hit your shutter release button and recompose your image you just changed the focus and exposure unless you set your camera up correctly.

please read again, i have already mentioned in my original post that the tests were shot at aperture priority mode at f5, iso at 100 and at 35mm focal length on both lens to make a comparison. all of the shots where composed at the same lighting conditions on a tripod and no matter how hard i tried i could not get the shutter speeds on both the lens to be the same. the shutter speed was always a step lower on the prime lens. as for exposure lock, how can i if i am not able to get the same shutter speed as my kit lens. any ways today night i am going to do some test on a subject that has some high contrast on artificial controlled light, and of course on a tripod... with the exact same settings... i'll post the results here thx

Emcee

@CtrlU You really should heed Flow's advice

@CtrlU: To get that one misconception of yours out of the way: If a lens "captures more light", this means it will have a larger aperture to do so, i.e. if someone tells you to get the 35mm DX lens for low-light ability, he or she is NOT referring to the lens "capturing more light" at a given aperture, say, f/5.6, but he's referring to the fact that you can OPEN the aperture more and go to f/1.8 (vs., as you noted f/5 as the fastest possible value with your zoom).

Also you cannot expect the camera to meter exactly the same with different lenses at the same aperture, might want to look into lens transmissions (T-stops). You also have to think about that when the camera is metering it is looking at the subject through different apertures. The 35 1.8 is looking at the subject through a 1.8 aperture and the 18-55 is looking with a 3.5 aperture while metering.

Now Nikon has probably worked really hard to make sure you get an even exposure for the scene selected, and honestly I'd tell you to stop comparing EXIF data and comparing the look of the images produced by each of the lenses. Focus on the images not the numbers, cause that's what it's truly about.

Now if you want to learn more about how the lenses work and why things like what you describe happen, we'd be more than happy to help you figure it out.

FlowtographyBerlin

@CtrlU: Don't feel dissed by any of our comments, even if they sound harsh to you. It's just that the impression one gets or got from your first posts was that you mixed up some things or hadn't understood the principles of how the variables are connected.

With your sharpness comparisons: Keep in mind the practical use of this, or put differently: What is your "research interest"? Is it really comparing the two lenses at the same (closed) aperture? This would mean that the problem you're trying to solve with your test is: "I'm in a situation with a tripod and good light. I want maximum sharpness, which lens is better?"

The thing is, it's not gonna be that much of a difference: If you shoot at f/5, you're in a situation where you can afford to go to the full f/5.6, which is an aperture that's the "sweet spot" with many lenses, and where the differences are very small. That's not the advantage of the prime lens you got yourself.

The advantage of that prime is exactly what you wanted, which is that you can "get more light in". This, as we pointed out, means opening up the aperture.

Now, as I understand it, your research question is more: "I'm in a low light situation and my zoom is giving me too low shutter speeds. If I take a prime to get those speeds up by opening the aperture, will my image still be sharp enough?"

This means that what you actually want to do is not an A/B lens comparison, but you want to check if your prime will give you sufficiently sharp results when you open the aperture. So, check how sharp it can do at f/2.8 and lower and if you're content with the results. Just for the heck of it, you can also try your zoom at its widest possible aperture, but it wouldn't be a fair comparison.

Keep in mind that opening the aperture also means reducing the depth-of-field. (Which is something that looks good, but of course means there are more things out of focus.) So your test (i.e. if the question as I put it is correct) would actually make more sense to be "hands on", taking some images and checking the practicability of the wide-aperture use of your prime. Then, you can also take your zoom and see what results that gives you in the same situation.

FlowtographyBerlin

You also have to think about that when the camera is metering it is looking at the subject through different apertures. The 35 1.8 is looking at the subject through a 1.8 aperture and the 18-55 is looking with a 3.5 aperture while metering.

Even worse, if @CtrlU said f/5 is the widest aperture at 35mm, the metering happens at that, f/5.

Emcee

@FlowtographyBerlin you are correct, good catch.

Ironheart

@CtrlU, I'd like to point out that f/5 1/60th vs f/5 1/80th is only 1/3 of a stop difference, which is "not much" <- scientific term

What is happening is that the Aperture program on the camera was right on the edge between 1/60 and 1/80, but it has to choose one or the other since 1/70 isn't an option. A slight movement of the sun at that hour (8am) and the fact that the 35mm is metering at f/1.8 and having to translate that to f/5 vs the 18-55mm metering at f/5 (as @Flow points out) with no translation could account for the difference.

I would use M mode and lock your exposure to a specific f-stop, shutter speed and ISO. Take both shots and look at the histograms, they will likely be very close.

http://www.dxomark.com/Lenses/Compare/Side-by-side/AF-S-DX-NIKKOR-35-mm-f-1.8G-on-Nikon-D5200-versus-AF-S-DX-Nikkor-18-55mm-f-3.5-5.6G-VR-on-Nikon-D5200___313_850_159_850

Also it would be good to know which 18-55mm and 35mm lenses you are talking about. There are several of each to choose from.

One last thought, metering (esp. matrix) is not an exact science, there is a bit of "slop" in every camera, which is why there is no need to go to less than 1/3 or 1/4 stop. My old FT-n can only increment at full stops (unless you cheat and go between the "clicks") and I never had any problems. Also at the higher shutter speeds, 1/1000th isn't really 1/1000th, it can vary as much as 10% from click to click (the shutter is, after all, mechanical).

FlowtographyBerlin

Also at the higher shutter speeds, 1/1000th isn't really 1/1000th, it can vary as much as 10% from click to click (the shutter is, after all, mechanical).

Wow, I didn't know that. Interesting fact! I'd never have thought that, especially with today's values like 1/8000th. Thanks!

tc88

Here is my 2 cents. Shutter variation probably matters for very fast speed, but I would imagine it's more in absolute variation instead of percentage.

I think it's the effect of vigetting on the non exact science of metering. Fast lens with large aperture tends to have more vigetting when fully opened. So at f3.6, it's going to take in more than 1/4 of the light of f1.8.

Since the metering is done at full aperture (f1.8 in this case), it may underestimate the light gathering capability at f5 and consequently overestimate the shutter time needed. On the other hand, since the real aperture used for capturing is f5, you end up with slight over exposure. That explains why you shutter is longer, but the picture is also brighter.

PB_PM

The question is, does the camera meter based on the F stop or the T stop of the lens? For accurate metering you'd think it would have to use the T stop. Maybe I'm way off base though.

KnockKnock

the images on the 35mm looks better btw, more color, and bright...

This tells me that your lens is fine. Sounds like you're learning about photography's technical side now. A "fast" lens loosely means it is able to shoot at wider apertures. So if you choose to shoot at f/5 (not very wide) then you are not taking advantage of its abilities. There is no other magic variable associated with a lens' ability to collect light. Just aperture. If you shoot at f/1.8 you will find your shutter speeds go up 3-4x faster and that's what is meant by "fast."

The slight variation in shutter speed at the same f/5 is partly mechanical variance, partly your shifting scene, and most likely Nikon programming. Case in point is that you say the 35mm looks more bright. Its shutter was open longer, so that's probably why. If you shoot in Manual exposure to take that variance away, your exposure will be much closer.

Welcome to the wonderful world of photography!

Correlli

The camera measures the light that passes through the lens. It knows the max aperture that the lens has got at a given focal length (in case the max aperture changes when zooming) so it can calculate what exposure you will need if you step down to the aperture that is set by the user or camera automatic. It does not need to know what T-stop the lens really has.

The t-stop only influences the final exposure value - so a lens with a higher transmission will show a shorter exposure time at a given aperture than a lens with less transmission.

To really test the difference between your lenses use a grey card (or something similar) and spot metering on that card to determine the exposure. With matrix metering there are too many variables in the game. If the 35 mm setting of the zoom has got a slightly smaller or larger field of view the matrix metering might change the exposure quite a bit - or not at all. Using a grey card and spot metering you at least know that with both lenses you are measuring the same thing.