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  1. 📚 Buy Our Books on Amazon! 📚
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  2. Excellent video! I'm waitng for the next sony aps-c camera (hopefully a kinda mini a9) to match with my 100-400gm for wildlife

  3. Very well explained! I was, in fact, wondering what was going on with my 70-200 f2.8 mark I on my Canon SL2. Wide open the picture is quite soft and for astrophotography it shows coma unless I stop it down to f4. However, for astrophotography I'd better stick to my APS-C instead of my 5D II, since I also need to do some cropping.

  4. I'd like to repost a previous comment of mine, it might help to understand the point of this video. The theory seems to me quite straight forward. I do astrophotography, so take refractor telescopes, for example. They basically are prime lenses with fixed aperture. Eyepieces are used to look at deep sky objects. These eyepieces are like the camera sensors, the smaller they are the more magnification they give. But at a price. You just can't infinitely magnify an object. The image quality degrades as the magnification goes higher. It's as simple as that.

  5. Thanks, again. Seeing this video via my e-reader version of your book. I will not buy that $1300 Canon 70-200 f/4L is mark 2, with 5 stops of image stabilization, for my canon 80d. Instead, I could buy a better bandsaw and document my woodworking with my android phone camera.

  6. Combination of your books, stunning digital photography and the one on equipment plus your videos in the book and here on utube, I am convinced that my idea to buy the ef 70-200 f4 is2 usm lens for my 80d would be a waste of money. I'd get better use of that money, buying a new power tool for my woodworking hobby and document that work with my smartphone. Then sell or dispose of all the crappy efs lenses and my two canon apsc cameras. I reviewed a 20×30 poster I had made from kodachrome 64 film, done with a minolta 202 and a sears 24mm f/2.8 lens. The quality of that poster is much better than any of the 11×14 prints done with efs lenses on 80d.

  7. I have a question because I'm a confused beginner. I'm getting into food photography and looking at the Canon T7i. Let's say I buy a prime lens, the Canon EF-S 24mm f/2.8, made for APS-C bodies. Since it's a crop lens on a crop body, will it act as a TRUE 24mm, or does the 1.6x calculation still apply meaning it would behave like a 38mm f/4.5? I'm not overly concerned about the close-up shots with a crop body, but for overhead flat lays I'll need a lens with a wide field of view that won't show bowing or distortion. A most sincere thank you to anyone who replies – and I must say the Northrups are some of the best teachers I've ever seen – thanks so much for all the knowledge you share on here!

  8. Saying that because the sensor is smaller does not make the aperature different. There is no perceptual megapixel. Whatever the camera mp is will be what that picture is. This is like saying i cant burn a small ant with magnifying glass but i could if it was bigger. You're confusing pixel density with some crazy equation or explaining it wrong. If anything a ff lens will have more light than needed because it will be hitting all kinds of areas it shouldn't be on an aps-c.

  9. Thank you so much Tony for concluding this topic for me. You are the best photography teacher out here on YouTube! I love your content with all my heart. Thank you so much for your time and vast knowledge. You are my photography hero, God bless you!

  10. Great info. I never thought to multiple the aperture as well. One of the things that makes sense once realized…

  11. What about a cropped sensor + full frame lens + metabones speedbooster? Isn't that the best you can do? Like a 7D II + metabones + 85mm 1.2? 🙂

  12. A f2.8 aperture lens on a full frame sensor is the same f2.8 on a crop sensor it doesn't get darker and doesn't change the depth of field. Your correct in saying that it changes the area of view.

  13. Pls. help me out now… I was so sure to buy canon L series lens (24-70mm or 85mm f/1.4) to be used with my canon 80D before watching this video, now am more confused than ever what to buy with my next lens. I own Canon 18-135mm and 50mm f/1.8 lens, and I shoot mostly portraits. Should I go ahead buy an L series or the sigma art 18-35 f/1.8? Which gives sharper images with Canon 80D? Thanks in advance for those who are helping me out…

  14. Hi Tony, i had seen this video of yours and had moved away from investing in a full frame lense. I have a Nikon D7100. However recently for an musical concert assignment i had rented an 80-200 f2.8 full frame old Nikkor lense and before returning thought of experimenting and compared similar shots with my 55-300 crop sensor Nikkor lense. At 200mm f5.6 i tested both with the same far away tree and a relatively closer tree leaf. The 80-200 although reading f5.6 let in far more light and photo was significantly brighter than my 55-300. So my question is how do you read the f numbers and corelate with actual outcome. What I got does not apparently exactly correlate to your explanation here. Looking forward to your comments

  15. What about FF lenses used with speedboosters on crop bodies? Speedboosters shorten your focal length and focus all available light Inside the lens on the sensor. Do you get sharper images?

  16. I have been watching some of your videos. I am mostly interested in wildlife. I have a t3i with a 50 1.8 and a 55-250. Based on your videos I am considering a 400mm 5.6 as my next big purchase. You mention it is best on a 7d mk ii, but since the t3i is also crop would it be similar? I tried looking at dxomark but couldn't find anything on that lens. Thanks so much for you videos!

  17. Thank you Tony. I wish I watched this video before I bought my Canon M50 camera and then a 50mm f/1.8 with an adaptor ($325.00). I almost bought a 85mm f/1.8 If I had not seen this too. I should just save some money and go for full frame.

  18. Does using an
    FX lens with TC-14E III 1.4X AF-S Teleconverter on FX camera give the same
    image result if we use FX lens with DX camera? explain,

  19. First off, great video; I wish I had found it sooner! About 6 months ago I bought a Canon 17-40 f/4L for my 7D Mark ii, and after testing it I was disappointed that it was about as sharp as my 18-55mm kit lens. Shortly thereafter I found this video and returned the lens.

    Fast forward to the present day and I've been researching new lenses to buy. While researching on DxOMark for the 7Dii I found that the sharpest lenses available for the 7Dii are all full-frame lenses! I am ONLY looking at the sharpness ratings, but, for example, the sharpest lens they have tested for the 7Dii is actually the Canon EF 300mm f/2.8L IS USM. Out of the 10 sharpest lenses, only 1 is an EF-S mount, and it's ranked #9. It's worth noting that these are NOT cheap lenses, the cheapest in the top 10 is $750, but this seems to support the notion that if you invest in good glass, I mean REALLY good glass, you can more out of your investment.

    I didn't look at the release date of the lenses, but could this be because of improving lens technology, or maybe am I missing something here?

  20. Clear as mud…. Guess I have a lot to learn, because it's sounds like yes I should, but only if I want a lesser quality photo, unless I want a better quality, then I should also, but only if I understand that the shot will be lower MP, except when it isn't, then it's better, but only if it isn't…. Right?

  21. So if you want to shoot a crop body for sports. But, the manufacturer has no fast zooms for APS-C but do fo FF. Should you find another manufacturer?

  22. Also when printing say an A3 photo the image quality looks very similar when you are talking about the difference of about a few million pixels…its only when you print larger photographs that you notice the difference.

  23. I’m still stuck. I’m torn between D750 and D7500, don’t care about body cost – I do care about total lens cost to a point, assuming I buy 3 that nicely overlap / compliment each other.

    Before anyone says there’s no difference between DX and FX lenses, I’m coming from the viewpoint that I currently have a D3000 the kit lens and a 55-200 which I dislike for its constant hunting etc. Whereas I have tried a 70-200 f4/G and was impressed. I’ve no idea what 3 lens combo would be good in either format.

    Should there be a difference? What is x5 price getting me? (I’m not spending £2k per lens, draw the line at 1.5)

  24. Hi Tony,
    Thanks for all the valuable information,
    Just have a question about the speed booster.
    I use canon 77D and EF 24-105 f/4L. Just wondering do I need a speed booster to get sharper image? and if it’s not sharp enough why canon allowed ef lenses to be used on APS-C cameras?

  25. So going over the f-stop issue multiplying aperture with the crop factor, does the 24-70 f2.8 full frame lens acts like a normal APS-C standard kit lens 18-105mm with f4 aperture at 24mm on a Nikon DX body?

  26. OK, given that, should I buy the EF 100mm 2.8L macro, or the EF-S 35mm F2.8 macro. For info I have a Canon 77D. Will I be wasting money on the 2.8L?

  27. Well, at "only" £12,300 / $16,105 (approx) I don't think I'll be buying the Nikon 400mm f2.8 lens anytime soon 🙁

  28. All this math takes the fun out of photography. Just try a few settings, find a nice shot and take it. All depends on whether you want to be a photographer or earn a trigonometry major.

  29. Hi Tony. Love your videos and the technical information they provide! I would love for you to clarify something for me.. seeing as I will probably never find the answer anywhere else. In your opinion, will there be any image quality difference between using a 70-200mm f/2.8 on a Sony A7iii in crop mode(super 35), as opposed to the same lens on a Sony crop sensor body? Assuming the subject is a bird and the image is cropped down?

  30. You switched sides in the middle and kinda said exactly opposite things. First, you counted megapixels by the amount of light the Canon 7D APS-C sensor is capturing from a full-frame lense as fewer pixels. Then, you said because Canon 7DII APS-C sensor has more pixels than 5DIII in crop-body mode with the same lense. Sigh.

  31. The Sigma 18-35 is designed for APSC which means it's F1,8 remains F1,8 we don't multiply it like you used to

  32. Yes, one of the advantages is you can use.any lens with your Nikon crop camera.There are some good DX lenses, like the 17-55 f2.8 or Tokina 11-16, but for the most part an FX lens works wonderfully. Nikon , unlike Fujifilm, doesn’t have a huge selection of high end DX lenses. You can use FX on your crop camera. “But it render as good pictures”, “You buying high end equipment for your crop camera?” Yep, and the pictures look great. 😎

  33. Why isn't there any sort of speed booster for Sony FE to E? I know they physically fit, but would a speed booster allow an APS-C sensor to work better with FE lenses? I guess I'm missing something since something like that doesn't seem to exist.

  34. You only explain the mathematical figure. Show us actual image comparison with the varieties of lens and body combinations

  35. Does this apply to macro? No one seems to have an explanation as to why companies won't make better glass for macro and wildlife/sports for crop sensor cameras when the magnification of them makes them ideal.

  36. Lenses loose their value very slowly. Cameras? Not so. I'am glad I didn't fall for fancy camera bodies first.

  37. Fuji fanboys call the Fujinon f2 lenses Fujicron in reference to the Leica Summicron line of lenses. Based on your logic the Fuji lenses would be sharper than the Leica lenses on an x mount camera. I would have to see the pictures to believe that. Are there any comparisons with actual pictures?

  38. I understood that this way: Lens have certain ability to draw details :resolution (from the square area,that is big as possible to fit into that round area a lens produces).If you f.ex. crop that area to half , decreases also that lens resolution about to half(altrough corner resolution increaces).But in wild life fotographing with tele lens that resolution falling compensates by more pixels (on that croped area),when no need to crop after vs ff body…

  39. @9:34 fair enough that the 22mp 5d MK iii only has 8.6mp when cropped by a factor of 1.6. however, the 20mp 7d MK ii does have 20mp, but only if you're using an optically perfect lens. but if you are shooting wildlife you're using a lens made for a full frame camera which means you're getting at best 9p-mp.

  40. When you look at actual measurements of full frame/aspc lenses with full frames and aspc's the full frame lenses perform perfectly well in aspc bodies against aspc lenses. Obviously they get even sharper when put into full frame bodies.

  41. Yes, but this video argues fact, and other photographers who bought FF lenses for crop frame cameras argue with emotions.

  42. So it does seem like faster lenses get much higher DXO Mark P-Mpix scores. For example, compare the scores for the Canon 24-70 2.8L and 24-70 4.0L. This bias was everywhere I checked in the DXO Mark P-Mix scores. Either faster lenses are intrinsically much sharper (seems unlikely) or there is a bias problem in the DXO Mark calculations.

  43. Great video. I have a question: is it worth it to use the sigma 150-600mm contemporary on a Nikon DX body for wildlife? If yes What about the aperture drop to 7.2?

  44. I DIDN'T KNOW THE APERTURE HAD TO BE MULTIPLED TOO :O is it just for getting a feel for the bokeh or does it mean autofocus stops working too?

  45. I think the problem with a full frame lens vs a crop sensor that most people don't understand is that….. A LOT of light is lost on the sides of the sensor or even reflected past the sides of the sensor and camera body parts… AKA, A lot of reflected light jumps around in the camera body in areas the body was never intended to compassionate for …. Drive into fog with with a bunch of light and its harder to see the road because light it being reflected off the environment.

  46. Ok if I understand your demonstration the idea that I have to adapt all my big park of Nikkor ai-s manual focus optics to a Sony FS 700 camera in super 35 format (crap factor 1.6) is not recommended for professional use independent cinema project because I will lose in quality even coupled to a recorder atomos inferno

  47. yes i almost sell my sony a6000 and i bought the sigma 60mm 2.8 wowwwwww nigth and day diferent from the kit lens

  48. The explanation at 4:35 and following is just ridiculously wrong. It is just impossible to construct a lens that is sharper on a smaller sensor. That sounds like the lens would somehow "know" what sensor is behind it. And of course it does not. What lens does is that it focuses an image to a circle on a plane. That plane can be focusing screen or a sensor. But the resolution stays the same. It will drop to the outer edge of the image circle but that does not matter since we "focus" on the center-sharpness. This resolution cannot be measured acurately in pixels. Back in the days they used special magnifiers to measure how many ultra-fine lines the lens was able to depict on the screen. That is the resolution if the lens and of course is not able to change whether the the sensor is full format or crop.
    The point is that an 18 mp FF-sensor has larger pixels than an 18 mp crop sensor and it might be the case that a lens is not capable of resolving the picture so that the crop sensor pixels get a "sharp information".
    So if you say the EF-S 18-55 mm is sharper on the APS-C-sensor it has to be sharper on the FF-sensor too. In the center at least.

    Should I be wrong than give me a scientific explanation. And by that I mean real sience with real physical optics and so on.

  49. If you use and aspc lense on an aspc camera (specifically Sony or fugi) do you have to consider the "crop factor" or are you true focal length equivalents?

  50. Hi Tony. I have specifically bought Canons EF (FF) lenses for that exact reason. That when I switch to a full frame body, I only need to discard my EF-S kit lens. I think that also is a consideration.

  51. Sometimes in life you choose whether you want a sharp image with less background blur, or more detail in terms of pixels OR less sharp image with excellent background blur and good low light performance to freeze action.

  52. Do I have to multiply 1.6x to the aperture to lenses that are designed for crop bodies? such as 17-55 usm, so it would be f4.5 and not 2.8?

  53. I've always found DXOMark numbers "fishy" (first of all they don't describe how they come up with those numbers, secondly the P-MP units don't make sense to me) and this is the proof.

    I have a Canon 7D and a full frame L-series lens (70-20mm f4) and there is absolutely no comparison in terms of results compared to any other EF-S lens I have that according to DXOMark should give higher P-MPs

  54. Arg, forget about it.
    If Canon and Nikon want to stay in business, they should consider coming out with a really cost-effective full frame camera that accepts their traditional full frame lens line.
    I do not need something full of technology, I just need something to continue using the Canon system. If not, I likely will buy Sony.

  55. Well logically you are giving great information for the most part, but in some cases i guess there is confusion, especially pixel density changes with sensor size, when you are switching bodies with same full frame glass. That is main reason you get different pixel density on crop sensor, but the overall image quality is same, not affected actually, if keeps the focal length constant

  56. Tony; as a physical scientist (Ph.D. in Chemistry (Physical Biochemistry), a photographer and having done Digital Multimedia Forensics, I must say that I deeply appreciate your (and Chelsea's) videos. I especially like videos like this one when you go full Geek Mode and dive into the science. I get frustrated with arm-wavers who bloviate opinions that are wholly subjective (and often wrong). This is not to say that a significant fraction of Photography is not subjective itself, but you know what I mean. And, although I have come across this video some time after you posted it, I do appreciate your tackling a topic that few have even considered; however slightly. I have seen a number of your videos so far and find them useful, well constructed, enjoyably delivered and mostly timely and relevant. I also really liked some of your drone videos; especially the one for preparing for the FAA exam. So, Tony (and Chelsea), keep up the good work! And, although I don't ALWAYS agree with every opinion, you are solid in your research and thought processes and seem quite diligent. So, thanks again!

  57. What worked very well for me was buying fast full-frame primes (14mm, 28mm, 50mm) and native APS-C zooms for my old D50. When I moved up to the full-frame D750, and then the D850, the wide primes were still great to have and I concentrated on buying full-frame trinity zooms and longer primes like the 85mm and 105mm..

  58. Ok, I'm super confused and unsure how to proceed now. I have a Sony a6400, and I had been seriously considering investing in one of the full-frame Sony telephoto zoom lenses, as there just doesn't seem to be anything in their APS-C line of lenses that even comes close to the focal lengths of their FF lenses (I think the longest focal length in their APS-C line is the 55-210mm). Meanwhile they have 70-300, 100-400 and soon 200-600(!) in their FF lineup. So I was planning on saving up and shelling out the $2k for the 200-600. Then I found this video, and my heart sank. I want the focal length, but it's kind of disheartening to learn how much sharpness I'd be losing. The DXOMARK test for the 100-400 lens shows that using it on the a6000 results in only 10 P-Mpix (presumably the result would be similar on my a6400). I imagine the 200-600 would be somewhere in that ballpark as well (though it obviously hasn't been tested yet by DXOMARK). "Damn", I thought, "that's disappointing".

    But THEN, for the sake or comparison, I decided to look up their tests on some native APS-C lenses…and discovered something that now has me not knowing WHAT to think. I looked up the 18-105 F4 lens, and when paired with the a6000, their tests is showing that it only results in 9 P-Mpix! And that's a native APS-C lens! None of the Sony APS-C lenses I could find results for on their site seemed to produce much better results. So based on that, it doesn't really seem like I'm gaining much (if any) effective P-Mpix by sticking with the APS-C lenses vs the FF. Thoughts on this?

  59. Hai Tony. Canon 200D and efs55-250mm IS STM a right combination for taking videos? Please answer. I m a beginner in this area?

  60. Ohk i just have one doubt.. suppose i have two lenses.. a FF 1.8 and a Crop 1.8…
    if i put the Full frame f1.8 on a Crop sensor (1.5x) camera without changing shutter speed and iso and from the same spot with constant lighting.. will the aperture be different from that of the DX lens.. i mean will i get less light coming in or the 1.8 fx will act as 2.8 on the camera.. !!!

  61. I'd say if you can afford it to try to get a full frame. Even a relatively cheap lens will work a lot better on a better camera than an expensive lens of a cheap body.

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