Your last statement is correct, but I still have the feeling that you are thinking the larger aperture on a FF lens is going to net you better performance on an aps-c camera and that is not typically the case because the FF lens is going to illuminate an area beyond the aps-c sensor and that light will be wasted. OTOH, using a FF lens on an aps-c camera does have the benefit that you are using the middle of the image circle and that results in less vignetting, so to that degree, you will typically get a bit more light on the aps-c sensor with a ff lens than with an aps-c lens with the same f number.Thanks. I am actually comparing two lenses and assume that the one that collects more light and direct it to the image circle would then require a lower ISO setting, hence 'better' in ISO performance. This all assumes the same aperture, and f-stop can certainly change depending on focal length (ie 50mm at f5 for apsc would have the same aperture diameter as 80mm at f8 for FF).
Yes. In terms of fstop equivalence, the iphone 16 is f/1.8. This equates to f/4 for APSC and to f/6.3 for full-frame. So the iphone's 6.9 mm f/1.8 lens can be thought of as 24 mm f/6.3, in full-frame terms.For example, the main camera in the iPhone 16 has a focal length of 6.9mm, meaning its f/1.78 lens requires a maximum physical aperture diameter of 3.9 mm. The reason the focal length can be short and the aperture can be small is because the sensor is small.
the 6.9mm lens of the iPhone 16 (~3.5x crop sensor), a 15mm lens on a Canon APS-C camera (1.6x crop sensor) and a 24mm lens on a FF camera all give the same field of view. That's equivalence in terms of field of view, or if you prefer equivalence in terms of focal length.
I stated, “The FFeq [full frame equivalent] of 17-40/1.8 is 27-64/2.9,” which is accurate. If I’d meant only focal length, I’d have stated that 17mm on APS-C delivers an equivalent field of view to 27mm on FF.You didn’t mention depth of field equivalent in the post I replied to. You simply refered to f-stop. Everyone knows that depth of field increases as the lens objective diameter decreases. As I said you didnt mention depth of field.
Thanks again. It is probably the way I express the idea that was not clear. No, I was not thinking that a larger aperture on a FF will have better performance. I was simply trying to figure out if a FF lens with larger lens (front) elements would provide more light when compared to an (equivalent) APSC lens with smaller (front) lens element when the aperture (not f-stop) is kept the same. I realise that it is not easy to compare in reality, but as you said, it is probably valid at least for the central region of the image.Your last statement is correct, but I still have the feeling that you are thinking the larger aperture on a FF lens is going to net you better performance on an aps-c camera and that is not typically the case because the FF lens is going to illuminate an area beyond the aps-c sensor and that light will be wasted. OTOH, using a FF lens on an aps-c camera does have the benefit that you are using the middle of the image circle and that results in less vignetting, so to that degree, you will typically get a bit more light on the aps-c sensor with a ff lens than with an aps-c lens with the same f number.
For telephoto designs, the size of the front element is typically a reasonable rule-of-thumb measure of how much light the lens can capture, but for shorter designs, that is not necessarily the case. Retrofocus designs that were typical of short lenses used on DSLR cameras that required a long back throw to clear the mirror usually had large front elements, whereas designs for mirrorless cameras with a short flange distance can avoid a retrofocus design and thus will typically have a smaller front element and a larger rear element. Here is a comparison to make the point. https://www.the-digital-picture.com/Reviews/Lens-Specifications.aspx?Lens=824&LensComp=1224 . The RF lens is actually a slightly faster lens with a much smaller front element. Otherwise, the two lenses are very similar at f/4 and f.5.6 with the RF version being a bit sharper and wide apertures. https://www.the-digital-picture.com...LensComp=824&CameraComp=0&FLIComp=0&APIComp=0Thanks again. It is probably the way I express the idea that was not clear. No, I was not thinking that a larger aperture on a FF will have better performance. I was simply trying to figure out if a FF lens with larger lens (front) elements would provide more light when compared to an (equivalent) APSC lens with smaller (front) lens element when the aperture (not f-stop) is kept the same. I realise that it is not easy to compare in reality, but as you said, it is probably valid at least for the central region of the image.
There is no aperture ring for the RF version.So this new zooms will be an 535g internal zoom, declickable apertur ring, wheater sealed, optically very good and with low focus breathing? Nice work, Sigma!
I think you would be better off with the RF 28-70 f/2.8 IS on your R6.I'm starting thinking about going R5 with the 17-40, that could be an interesting solution, 17mpx crop is not far from the 20mpx of my R6, and I get a stop (and a third) better then the 28-70 STM; if the performance is good on R7, then it's probably killing on the R5, let's see when test will show online, and which price they'll ask for it
This lens is within the focal range where lens stabilization does not provide much benefit over IBIS.One further thing to keep in mind is that the 28-70 has IS while the Sigma supposedly does not. This allows one to shoot with higher fstops.
I do not think it will sell as well.The DSLR era 18-35 f/1.8 that this lens would be replacing is an APS-C Art lens, and a popular one at that. No surprise that they would eventually create a mirrorless successor.
There are a lot of factors that go into ISO performance.ISO performance is a function of the sensor and subsequent circuitry, not the lens.
The effect of pixel size on ISO performance is most obvious to and gets talked about the most by people who don't have a clue about the underlying principles. Those of us who do understand those principles know that pixel size has a minimal impact on the ISO performance of a sensor.There are a lot of factors that go into ISO performance.
The pixel size the most obvious and gets talked about the most.
I think the 24 MP R6 II aoutperforms the 20 MP R6 in low light, so it is not always so simple.
Then do it. Every person should choose the brand that gives them products that best suit their needs. This seems obvious to most people when it comes to buying a washer or drier or vacuum cleaner, but for whatever reason, people on photography forums think that brand loyalty is somehow important. What is even stranger is the threats of switching (why would anyone else care?) or the announcement of switching (again, why would anyone else care?).I don’t care about APS-C lenses. I want third party full frame lenses. I kid you not, I’m closer now than ever to switching!
Maybe he thinks posting a threat on a forum will alter Canon's business planThen do it. Every person should choose the brand that gives them products that best suit their needs. This seems obvious to most people when it comes to buying a washer or drier or vacuum cleaner, but for whatever reason, people on photography forums think that brand loyalty is somehow important. What is even stranger is the threats of switching (why would anyone else care?) or the announcement of switching (again, why would anyone else care?).
Sorry my ignorance, but I am still not quite sure about the equivalence.The lenses look very interesting, but not sufficiently so to tempt me to buy an APS-C R body to use them.
To those who understand equivalence, the advantages of APS-C remain lower cost and size/weight. The FFeq of 17-40/1.8 is 27-64/2.9, so my RF 24-105/2.8 is ‘better’. Likewise, 12/1.4 is equivalent to 19/2.2 and the extra 1-1/3 stops of my 20/1.4 is worth more than the 0.5 mm difference (to me, based on DxO correction of barrel distortion).
Equivalence applies to most of those, but not sharpness (at least, not directly though of course image noise affects resolution).Sorry my ignorance, but I am still not quite sure about the equivalence.
Are we talking amount of light, amount of noise, depth of field, dynamic range, sharpness or what else?
I remember when I used the crop mode on my R5 video, I didn't change the exposure, I switched to crop mode to get more reach and I continued shootng. The crop yes, the noise in the raw files yes, but I would like to know more about it.
Thanks for additional explanation.
I need to know where I am wrong in my reasoning below.
I have a 12mm F1.4, I don't put my camera on a crop mode, I have very strong vignette, but in video mode I put IS on, and digital IS enhanced, vignette is gone, or reduced to minimum. My VCM doesn't have IS either so regardless I need to put on the same settings. In one word, whether it is the rumored Sigma or my own VCM, I have to put both on full frame and activate same IBIS.
There is no 20mm IS at F1.4 that allows me to rely only on lens IS so I am stuck.
Currently, I am using a Laowa 15mm F2, but for what I am shooting, F2 is still too dark and no auto-focus, I need F1.4. What am I loosing here?
Obviously, on a photography side of things, I loose 100% going 17MP on a crop mode.
I do not intend to buy any Sigma lens at least for now, I hated what happened when moving from DSLR to mirrorless, I don't want that any longer.
I just want to know how it works.
Thanks.
What happened?I do not intend to buy any Sigma lens at least for now, I hated what happened when moving from DSLR to mirrorless, I don't want that any