Does Lens quality effect ISO noise?

[onlybill]

I don't know if its just my imagination but I swear I have virtually no noise in images shot with a A-700/ 70-400mm G lens at ISO 400 (RAW), whereas I always had it with the Tamron 200-500mm at ISO 400 (not always a whole lot, but enough that noise reduction software was often needed). I was under the impression that noise was strictly due to the sensor. I now think that lens resolution or something else is involved. Is this true? regards~onlybill

 

[WaltKnapp]

I don't know if its just my imagination but I swear I have virtually
no noise in images shot with a A-700/ 70-400mm G lens at ISO 400
(RAW), whereas I always had it with the Tamron 200-500mm at ISO 400
(not always a whole lot, but enough that noise reduction software
was often needed). I was under the impression that noise was strictly
due to the sensor. I now think that lens resolution or something else
is involved. Is this true? regards~onlybill

What you are calling noise here is not noise. Not all image quality differences are noise.

Walt

 

[KEITH-C]

I think that you may have a point however it may have more to do with our global appreciation of image quality rather than measurable noise although more noise may come into the equation....

When viewing images at high magnifications , which tends to happen on computer monitors, we are more aware of poor focus & ragged edges which is readily noticed by the brain. Sharp , well defined images put less stress on our perceptions & we relax when viewing them.

However it is possible that poorly defined edges which have graduated brightness gradients cause signal processing difficulties at the pixel level which is seen as noise.

Keith-C

 

[onlybill]

However it is possible that poorly defined edges which have graduated
brightness gradients cause signal processing difficulties at the
pixel level which is seen as noise.

Keith-C

--

I think you aredefinitely on to something there Keith. There is no doubt that higher quality lenses produce sharper more defined edges. I am referring to noise visible in the image, and I can't see how that wouldn't be considered noise, whether it was a direct result of the sensor, or how the sensor reacted to the optics. regards~onlybill

 

[onlybill]

What you are calling noise here is not noise. Not all image quality
differences are noise.

Walt

I may be incorrect here, but I consider noise to be a grainy texture that appears in digital images, and its appearance correlates with the ISO that the image was shoot at.(HigherISO, more noise) Noise also results from image sharpening, such as unsharp mask, and other filtering techniques such as Topaz Adjust. Am I missing something? regards~onlybill

 

[nygus]

some lenses has little yellow tint - maybe this can lead to different RGB levels from sensor, white balance can fix that, so both photos will appear the same, but at expense of higher noise levels... but I think this difference should be neglible, but maybe it is not...

 

[WaltKnapp]

What you are calling noise here is not noise. Not all image quality
differences are noise.

Walt

I may be incorrect here, but I consider noise to be a grainy texture
that appears in digital images, and its appearance correlates with
the ISO that the image was shoot at.(HigherISO, more noise)

Not all noise correlates with Higher ISO.

Noise is artifacts produced by the sensor. Produced by anything else they have other names.

Noise

also results from image sharpening, such as unsharp mask, and other
filtering techniques such as Topaz Adjust. Am I missing something?

These are called processing artifacts, not noise.

One of the most common image quality damaging things I see on images here is motion blur. That, for instance, is not noise.

Walt

 

[lock]

But maybe we should not talk about sharpness but about information. The quality of the lens allows a certain amount of detail or information. The noise you are referring to is simply related to the inherent noise associated to iso 400 and is not associate to information at all. If you blow up a picture (or crop a picture) you will blow up noise and reduce the amount of existing information. Hence the information, that defines the picture you intended to take, to noise ratio drops (like with sounds and signal to noise). With a better lens, or a superior lens, you will see a sudden increas of the Information (or if you wish:signal) to noise ratio. The effect is that you interpret this as is if there is no (or less) noise. But what you are actually is seeing is 'more picture' (information/signal).

What you are experiencing isalmot similarto the effect of the high MP sensor in the A900. The amount of information is so staggering, it ' even overrules the increase in noise ( up to a certain iso level, of course).

lock

 

[Tarcat]

--

"When viewing images at high magnifications , which tends to happen on computer monitors, we are more aware of poor focus & ragged edges which is readily noticed by the brain. Sharp , well defined images put less stress on our perceptions & we relax when viewing them."

Thats what I hate about 100% crops. I think they give us a very misleading sense of image quality and don't represent what an image will look like when it is actually printed. A lot of people put WAAAAAAAAAAAAAY too much stock in them.

 

[PortraitShooter]

I had the same impression using my Sony A700 V2 with Minolta 100mm f2. A year ago I got very noisy, disappointing results with a very old Minolta 50mm f1.4 @ISO 3200. Then I did candids in Japan in very bad light conditions with the Minolta 100mm f2 @f2, ISO 3200. The results were night and day.



Post-processed

 

[GaryW]

WaltKnapp wrote:
....

also results from image sharpening, such as unsharp mask, and other
filtering techniques such as Topaz Adjust. Am I missing something?

These are called processing artifacts, not noise.

One of the most common image quality damaging things I see on images
here is motion blur. That, for instance, is not noise.

Another common thing is oversharpening which not only exaggerates any noise, but will also harm the low-level detail. But a lot of people like the effect.

Walt

--
Gary W.

 

[onlybill]

Appreciate the input. I feel confident that I am not just "seeing things", and there is an effect of image quality on what can be perceived as "noise". Image information delivered by the lens must be the key, as lock pointed out. What is noise but the on board sensor/chip trying to fill in missing information? As light decreases, and consequently the information that the light contains, less information is hitting the sensor. Less information=noise. Consequently(obviously) more information, less noise. regards. onlybill

 

[Mark VB]

Appreciate the input. I feel confident that I am not just "seeing
things", and there is an effect of image quality on what can be
perceived as "noise". Image information delivered by the lens must
be the key, as lock pointed out. What is noise but the on board
sensor/chip trying to fill in missing information? As light
decreases, and consequently the information that the light contains,
less information is hitting the sensor. Less information=noise.
Consequently(obviously) more information, less noise. regards.
onlybill

You don't provide an example of what you are seeing, nor is there a description of where you are seeing the differences. For example, is it across the entire image, in out of focus areas, or in the primary focus points of an image. Are you comparing the same subject shot with the two lenses, or different subjects? How about the tonality of the subjects, light levels and exposure? Were they the same?

The appearance of noise is due to many factors, but generally it is more noticeable in out of focus areas, and darker tones, including shadow areas. Underexposure will exaggerate noise (while overexposure that is compensated for in post-processing can help reduce noise - this is also known as "exposing to the right," a method more appropriate for RAW files than jpegs).

If the greater noise you are perceiving is in the primary subject of the photograph (i.e., the area you focused on), take a look at the tonality of the subjects (is one darker than the other?) and also the relative levels of apparent sharpness. If one lens (e.g., the Tamron) is not delivering quite as sharp an image as the 70-400, that also might be contributing to an apparent increase in noise.

In reality, noise is a fixed characteristic of the sensor and the camera's processing engine that creates the jpeg or RAW files you are viewing. Noise generally increases as ISO increases (putting aside in-camera noise reduction processing which may alter how the noise appears). However, our perception of noise in a particular image is dependent on many different factors, some of which I've noted above. So, while lens quality will not affect ISO noise in the camera, it can affect our perception of noise in a particular image, and a less sharp lens may appear to result in noisier images than a sharper lens.

--
Mark Van Bergh

 

[Iliah Borg]

Have you checked how the camera meters with that Tamron lens? Are shots resulting from the Tamron look underexposed compared to the other lens?

--
http://www.libraw.org/

 

[qtfsniper]

Appreciate the input. I feel confident that I am not just "seeing
things", and there is an effect of image quality on what can be
perceived as "noise". Image information delivered by the lens must
be the key, as lock pointed out. What is noise but the on board
sensor/chip trying to fill in missing information? As light
decreases, and consequently the information that the light contains,
less information is hitting the sensor. Less information=noise.
Consequently(obviously) more information, less noise. regards.
onlybill

I'm sure you have not come across a revelation in lens technology and the way it interacts with the sensor. The lens is not related to noise. Camera noise comes from when the heat from the sensor contaminates the signal , along with the camera amplifying the signal to increase sensitivity (increasing ISO). Any difference in lens design will be miniscule as they all will be focusing on the sensor plain, and same area so any light hitting the photosite will still be in the same area. It wouldn't really be altering that signal. Everything you have been seeing is just perceived with no real factual basis. Given the same exposure settings and ISO I can gaurentee that amount of noise in the scene will be the same (given every variable is the same).

 

[lock]

..iIf I understand him correctly. We perceive the picture as cleaner, and falsely interpet this as 'because there is less noise'. The only thing the pro lens does is provide more detail.

lock

 

[ph0t0man]

A little bit of it is just perception - when everything else in a shot is right, noise matters less, and can even slightly help the overall feel of a shot.

However, I'd totally agree with you that it's not 100% your imagination...here are my thoughts. Lenses like the 200-500 tend to slightly underexpose, have poor bokeh, and let in very little light overall (unless it's mid-day). These 3 things can increase the feel of noise, especially when combined. I'm not saying that it's a bad lens, it just has to be used for the right type of photography in order to provide great results. I haven't got my 70-400 yet, but I suspect that the only one of these things it shares with the 200-500 is the fact that it's relatively slow when compared with other top-tier glass (f/2.8). For it's range, it's quite decent. I look forward to getting my paws on one soon.
--
-Matt
Rent Alpha Mount Lenses! - http://www.alphalensrental.com
http://www.ouatphotography.com

 

[onlybill]

I agree, I am no expert (at all) on sensors and I haven't come up with a revelation! What I do know is that having shot 80,000+ images with the Tamron 200-500mm with both the A-100 and A-700 and what I perceive as significant noise (whatever it is Noise Ninja takes care of it) occurs when shot at ISO 400 and above. I am talking about properly exposed images, and not images that were under exposed, which absolutely induces noise when corrected regardless of the lens. I am a bird photographer and I'd say 85% are ISO 200. I must also note that I have photographed birds usually under good lighting conditions thinking that are certain limitations of this lens, which I have observed . On cloudy or overcast days I don't head on out. I have been happy with the lens overall, albeit there is a noticeable decrease in sharpness above 400mm (nothing a little smarts harpen or high pass sharpening can't deal with), and noise issues at ISO 400 and above (yes even with firmware V4). I think the bokeh is excellent IMO, and chromic aberation is minimal, and very rarely an issue (much to my delight).

The bottom line is the Sony 70-400mm, though admittedly not really that much faster than the Tamron, does create images with an noticeable increase in detail. It also creates images at ISO 400 that I percieve to have much less "noise" than those shot at ISO 400 with exactly the same aperture and shutter speed on the Tamron. I've shot 3000+ images with the 70-400mm, some with a Sony 1.4 teleconvertor , and I since I perceive no degredation in image quality at ISO 400, you have a happy camper that can now take advantage of smaller apertures and faster shutter speeds that higher ISOs deliver and achieve higher quality images to boot! Of course it could all be in my head.
I appreciate the input! regards~onlybill

 

[KEITH-C]

While there has been a growing consensus in this thread that there is a difference between sensor induced noise & perception of image quality I think nevertheless that we should not be too quick to dismiss lens quality & its contribution to increased noise.

As was pointed out good lenses increase information ie small detail & colour gradients are more faithfully reproduced but also the sensor/processing engine has to handle this information. When ,in a poorer lens , information is lacking the processor can be confused in what it is dealing with.

It is known that some de-mosaicking algorithms handle certain types of image better than others. These magic formulae have to take single pixel information & relate this data to that of surrounding pixels (detector sites). When a low quality lens passes light info onto the sensor there are small local distortions to edge information which the image engine has to take decisions on & I believe that incorrect interpretation of these 'distorted' signals can result in incorrect reproduction of information which results in increased noise.

The confusion of signal info is worse in low light so that using high ISOs in good light is more forgiving than when the same ISO is employed in low light. Poor quality lenses cannot 'see' the subtle differences in info & this results in mush & although this could just be dismissed as blurring due to poorer focus this mush tends to be resolved by the processor into varying clumps differing in light intensity & colour ie. NOISE.

This confusion can take place in in-camera Jpeg processing or in computer RAW conversions. The more sophisticated computer RAW programs have a better chance of performing these task but even they can vary in ability & quality of reproduction.

Keith-C

 

[Chris G B]

Strange observation in theory, but there may be an explanation. Noise is not merely a function of sensor sensitivity, it is also in theory related to exposure time. A longer exposure will leave the sensor powered for longer, and will have time to "absorb" more signal noise. Of course, the longer exposure will potentially strengthen the signal too, but if the balance is to increased noise with longer exposures then we have a possible cause with a couple of ways for it to be the case.

Firstly, if the G is sharper with a wider aperture and can be used with shorter shutter speeds, then you will have helped reduce noise if the scenario above is valid.

Secondly, lenses are complex optical systems. In theory, any lens working at the same aperture will let the same light through. In reality, the amount and quality of the glass in the system will have a significant effect on the transmission of light as well. I am experienced with rifle scopes, and here, two scopes that share the same magnification and objective diameter can have a very big difference in perceived image brightness. If the same applies to camera lenses (and I see no reason why it should not), then it is entirely possible that one lens needs a longer exposure than another given the same aperture.

Not 100% sure on how the noise is affected by exposure, but if increased exposure = increased noise, then it is a good basis for what you are observing.

Chris