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Thread: How come till now still no long lenses for cropped sensors

  1. #21
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    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    You are still stuck in history and FF mentality. To have meaningful discussion on this the FOV must be taken into account. For example, in medium format land we have 75mm/f2.8 as the standard lens, while 35mm we have 50mm/f1.4, with roughly the same FOV. Kinda like a cropped sensor when compared to medium format. We have the same FOV, and have f1.4 instead of f2.8, and significantly smaller size.

    So your 200mm f2.8 is really the DX or DC 135mm f2.8, and look around, they are with filter size 52mm. Only when you are either stuck with FF (or FF mentality) that 200mm f2.8 must have 77mm, I can have my 135mm f2.8 with roughly the same FOV as your 200mm f2.8 and have a significantly smaller, lighter lens. May be sharper and more contrasy also. Light falloff will also be better as I now use the centre of the image circle. If the lens is made to DX format, ok the light falloff will increase but the lens size will drop. See the 55-200 DX, equivalent of roughly 80-300 FOV, but see the size!

    And you can lug your monstrous 80-200/2.8 and I can carry a 50-135/2.8 (if such a lens exists) and have the same FOV. Herein lies the benefit of DX format. Now if you say your 80-200/2.8 in DX format would be 120-300/2.8 then the discussion is not on the same footing anymore, and you are right I will be stuck with the 77mm filter size. But let's compare apple to apple, and FOV is a must in such comparison, i.e. 50-135 DX vs 80-200 FF, they are roughly the same animal.

    But such a lens (50-135/2.8 DX, mickey mouse size, $500) is unlikely to ever exist in the camera makers race to make the 1000x zoom lens. There is no glamour in making small zoom ratio lens. But I for one would love this 50-135/2.8DX if I am to restrict myself to the 80-200 FOV.
    50-135 f2.8 dx range do exist but not by Nikon. Tokina have the 50-135 while Sigma have the 50-150 (both f2.8) they are all below 1kg.

  2. #22

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by ExplorerZ View Post
    50-135 f2.8 dx range do exist but not by Nikon. Tokina have the 50-135 while Sigma have the 50-150 (both f2.8) they are all below 1kg.
    I stand corrected.

    The Tokina 50-135/2.8DX is 845g light, available November 2006 (can't blame me for not knowing it exists, can you?). What's the price, any idea? Sigma as well...

    Oh and there was a Nikkor 50-135/3.5 AIS as well. Hmm... time to buy D200 and hunt one down...

  3. #23

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by lsisaxon View Post
    Not likely will happen. For long lenses the aperture is pretty much determined by the first element, eg 200 f/2.8 diameter is at least 200/2.8=72mm ==> 77mm filter, so there won't be a significant size and price reduction even if you reduce the image circle.
    Dratz.. now I know photography f-stops uses relative apertures. There goes the imaginary Canon 10-1000mm F1.0 L IS

    That being said, I believe that having a smaller image circle means the rest of the lens can be smaller as the rear elements groups need not be that big.
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  4. #24
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    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    I stand corrected.

    The Tokina 50-135/2.8DX is 845g light, available November 2006 (can't blame me for not knowing it exists, can you?). What's the price, any idea? Sigma as well...

    Oh and there was a Nikkor 50-135/3.5 AIS as well. Hmm... time to buy D200 and hunt one down...
    iirc sigma 50-150 f2.8 is around 1000-1100+.

  5. #25

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    You are still stuck in history and FF mentality. To have meaningful discussion on this the FOV must be taken into account. For example, in medium format land we have 75mm/f2.8 as the standard lens, while 35mm we have 50mm/f1.4, with roughly the same FOV. Kinda like a cropped sensor when compared to medium format. We have the same FOV, and have f1.4 instead of f2.8, and significantly smaller size.

    So your 200mm f2.8 is really the DX or DC 135mm f2.8, and look around, they are with filter size 52mm. Only when you are either stuck with FF (or FF mentality) that 200mm f2.8 must have 77mm, I can have my 135mm f2.8 with roughly the same FOV as your 200mm f2.8 and have a significantly smaller, lighter lens. May be sharper and more contrasy also. Light falloff will also be better as I now use the centre of the image circle. If the lens is made to DX format, ok the light falloff will increase but the lens size will drop. See the 55-200 DX, equivalent of roughly 80-300 FOV, but see the size!

    And you can lug your monstrous 80-200/2.8 and I can carry a 50-135/2.8 (if such a lens exists) and have the same FOV. Herein lies the benefit of DX format. Now if you say your 80-200/2.8 in DX format would be 120-300/2.8 then the discussion is not on the same footing anymore, and you are right I will be stuck with the 77mm filter size. But let's compare apple to apple, and FOV is a must in such comparison, i.e. 50-135 DX vs 80-200 FF, they are roughly the same animal.

    But such a lens (50-135/2.8 DX, mickey mouse size, $500) is unlikely to ever exist in the camera makers race to make the 1000x zoom lens. There is no glamour in making small zoom ratio lens. But I for one would love this 50-135/2.8DX if I am to restrict myself to the 80-200 FOV.
    No. If you talk about focal length, it is the real focal length. A 135/2.8 would require at least a 49mm diameter opening. It is irregardless of the image circle you're trying to form.

    By the way, this kind of confusion does not exist until some idiots coined the term "equivalent focal length". An 85mm is an 85mm, whether you use it on a large format, medium format or a 135 format or a DX sensor. Just the field of view is different.. and for sooooo many donkey years, there never was any confusion. An 85mm is wide angle for 4"x5" large format, normal lens for 6x6 medium format, medium tele for 135 and a longer medium tele for DX. BUT it is STILL 85mm!! It's your mentality that need to change. There is no such thing as equivalent focal length. Only equivalent field of view.

    On a DX body, this is equivalent to a 202mm FOV, BUT it is NOT a 200mm lens. Yes, you get a 200mm/2.8 EQUIVALENT FOV at a smaller diameter.

    By your argument, can I jolly well sell you a 135/2.8 when you ask for a 200/2.8 to be used on a DX? No! Because you might be intending to use it as a 300mm FOV. Is it a 300mm lens? No! Physically it's still a 200mm lens.

    That is why I refrain from using the term "equivalent focal length" because it does not make sense. I prefer to call it equivalent field of view.

    So if you ask me if I could make a lens with a smaller diameter to give you an equivalent FOV, yes. Absolute focal length, no, laws of physics dictates that the opening area has to be big enough to collect the light.

    If you could do that, let me know, because there will be many astronomers who are interested to have a smaller telescope with larger light collecting power.
    Last edited by lsisaxon; 19th December 2006 at 06:22 PM.

  6. #26

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by CYRN View Post
    Dratz.. now I know photography f-stops uses relative apertures. There goes the imaginary Canon 10-1000mm F1.0 L IS

    That being said, I believe that having a smaller image circle means the rest of the lens can be smaller as the rear elements groups need not be that big.
    Yes, you can put it that way but in all compound lenses it really depends on which is the element/group which is limiting the aperture.

    BTW, the f in the aperture designation, eg f/2.8, stands for the focal length. So it just means an opening relative to the focal length of the lens.

  7. #27

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by lsisaxon View Post
    (snipped)

    There is no such thing as equivalent focal length. Only equivalent field of view.

    On a DX body, this is equivalent to a 202mm FOV, BUT it is NOT a 200mm lens. Yes, you get a 200mm/2.8 EQUIVALENT FOV at a smaller diameter.

    ...(snipped)

    That is why I refrain from using the term "equivalent focal length" because it does not make sense. I prefer to call it equivalent field of view.

    So if you ask me if I could make a lens with a smaller diameter to give you an equivalent FOV, yes. Absolute focal length, no, laws of physics dictates that the opening area has to be big enough to collect the light.

    ...(snipped)
    That's what I said, right? FOV all the while. Not one moment did I mention Equivalent Focal Length. Is it a 200mm or 300mm? No I talked about 80-200 FOV all the while.

    So we are argeeing with each other, yet you appeared to be disagreeing.

    I only want a 80-200/2.8 FOV on DX sensor so I get a 50-135/2.8 lens, actual focal length. What's the confusion?

    Why deny the benefit of DX sensors? It is like the old days where medium format guys deny the 35mm format. Now FF guys are denying the benefits of DX sensors.

    I hated DX when my 20mm became 30mm. Had to be. So I ended up buying the Sigma 10-20 DX lens to get the stuff I need. But I moved on...

  8. #28

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    That's what I said, right? FOV all the while. Not one moment did I mention Equivalent Focal Length. Is it a 200mm or 300mm? No I talked about 80-200 FOV all the while.

    So we are argeeing with each other, yet you appeared to be disagreeing.

    I only want a 80-200/2.8 FOV on DX sensor so I get a 50-135/2.8 lens, actual focal length. What's the confusion?

    Why deny the benefit of DX sensors? It is like the old days where medium format guys deny the 35mm format. Now FF guys are denying the benefits of DX sensors.

    I hated DX when my 20mm became 30mm. Had to be. So I ended up buying the Sigma 10-20 DX lens to get the stuff I need. But I moved on...
    Yeah, maybe I got you wrong, apologies for that.

    I thought you were disagreeing because the TS talked about long focal length for DX and I made the remark that for the same focal length, there would not be any size advantage if it's made to cover only a DX image circle.

    But if you talk about FOV (that was what I misssed out, but I'm not sure if it's the TS' intention), then that's different. Still, it need not be made for DX, I could pay less for a 135/2 and get an equivalent FOV of a 200/2 on 135 film and at a smaller size.

    In fact, cropped frame is bonus for tele shooters but of course, the demands on the resolution of the lens is higher.
    Last edited by lsisaxon; 20th December 2006 at 10:53 AM.

  9. #29

    Default Re: How come till now still no long lenses for cropped sensors

    Guys, you need some alcohol to think clearly.

  10. #30

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by lsisaxon View Post
    Yeah, maybe I got you wrong, apologies for that.
    No need to apologize, it's good to be in agreement, isn't it?

  11. #31

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by CYRN View Post
    Dratz.. now I know photography f-stops uses relative apertures. There goes the imaginary Canon 10-1000mm F1.0 L IS.

    That being said, I believe that having a smaller image circle means the rest of the lens can be smaller as the rear elements groups need not be that big.
    Let's take this discussion a bit further, taking into account FOV and sensor sizes.

    As lsisaxon puts it "An 85mm is wide angle for 4"x5" large format, normal lens for 6x6 medium format, medium tele for 135 and a longer medium tele for DX. BUT it is STILL 85mm!!"

    So actual focal length does not mean anything until the application is specified. In my case on 135 I use my 85mm as a medium tele (actually I would call it short tele/portrait).

    So a Canon 1000mm f1 lens I'll have to assume it to be intended for 135 or FF sensor. That said, in FF land for 1000mm FOV you'll have 1000mm actual focal length and a minimum element size of 1m. In (Nikon) DX land, 1000mm FOV would be 667mm actual focal length and my element size has shrunk to 0.67m.

    For a moment now think if I choose to use an even smaller sensor, like the prosumer cameras, say Canon S70 or S80. These sensors have a crop factor of approximately 5. So in prosumer land the 1000mm FOV becomes 200mm actual focal length. Suddenly your f1 lens may be possible with a 0.2m element, still montrous, but you are starting to look at possible actual lenses. And for a moment drop your need for f1 and say I can live with f2.8, then lsisaxon's calculation for a 200mm lens comes in handy - you now have a min filter size of 72mm or actual filter size of 77mm!

    Indeed if you can manufacture a prosumer camera to take interchangeable lens on a Canon or Nikon or any DSLR mount, or take a Nikon D70 and graft a prosumer sensor to it, you can have your 1000mm FOV f2.8 by mounting a physical 200mm f2.8 lens! And you have your application satisfied, shooting birds from a comfortable distance, resolution not too bad, 7-8 megapixels, and a manageable-affordable solution that doesn't cost an arm or a leg.

    Let me go talk to my electronics designers and see if he can do the grafting...

    That said, you need to look at the sensor size issues, pixel pitch, noise, lens resolution when you crop so much, etc. All OT. Can't have your cake and eat it too, huh?
    Last edited by diediealsomustdive; 20th December 2006 at 12:55 PM.

  12. #32

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    Let's take this discussion a bit further, taking into account FOV and sensor sizes.

    As lsisaxon puts it "An 85mm is wide angle for 4"x5" large format, normal lens for 6x6 medium format, medium tele for 135 and a longer medium tele for DX. BUT it is STILL 85mm!!"

    So actual focal length does not mean anything until the application is specified. In my case on 135 I use my 85mm as a medium tele (actually I would call it short tele/portrait).

    So a Canon 1000mm f1 lens I'll have to assume it to be intended for 135 or FF sensor. That said, in FF land for 1000mm FOV you'll have 1000mm actual focal length and a minimum element size of 1m. In (Nikon) DX land, 1000mm FOV would be 667mm actual focal length and my element size has shrunk to 0.67m.

    For a moment now think if I choose to use an even smaller sensor, like the prosumer cameras, say Canon S70 or S80. These sensors have a crop factor of approximately 5. So in prosumer land the 1000mm FOV becomes 200mm actual focal length. Suddenly your f1 lens may be possible with a 0.2m element, still montrous, but you are starting to look at possible actual lenses. And for a moment drop your need for f1 and say I can live with f2.8, then lsisaxon's calculation for a 200mm lens comes in handy - you now have a min filter size of 72mm or actual filter size of 77mm!

    Indeed if you can manufacture a prosumer camera to take interchangeable lens on a Canon or Nikon or any DSLR mount, or take a Nikon D70 and graft a prosumer sensor to it, you can have your 1000mm FOV f2.8 by mounting a physical 200mm f2.8 lens! And you have your application satisfied, shooting birds from a comfortable distance, resolution not too bad, 7-8 megapixels, and a manageable-affordable solution that doesn't cost an arm or a leg.

    Let me go talk to my electronics designers and see if he can do the grafting...

    That said, you need to look at the sensor size issues, pixel pitch, noise, lens resolution when you crop so much, etc. All OT. Can't have your cake and eat it too, huh?
    Erm.. what you can do is to take a webcam with a thread, then go to a machine shop to make an adapter to mount to an SLR lens. Note, I said mount to the lens because the lens is much bigger than the webcam.

    Actually people are already doing this for astronomy, using high resolution webcams instead of using DSLRs for high magnification astro shots.

    Alternatively, it may be cheaper to implement a DSLR mount on a digital compact than to graft a smaller CCD onto a DSLR. However, don't forget that the resolution demands will become 5 times as much and focusing becomes 5 times more sensitive also.
    Last edited by lsisaxon; 20th December 2006 at 01:47 PM.

  13. #33

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    No need to apologize, it's good to be in agreement, isn't it?
    Yeah.. Still need to apologize because I got you wrong at first.

  14. #34

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by lsisaxon View Post
    Yeah.. Still need to apologize because I got you wrong at first.
    You're a gentleman (I assume you are a male, otherwise should be lady).

    From the last post, we are certainly in agreement. I would do the grafting one way or the other if it doesn't cost too much, but putting it off as it may be more affordable to try to get one of those birding scope and adapter for my prosumer instead of using my D70.

    Anyway $1100 for Sigma 50-150/2.8 is a bit too much for me. Probably going to get my D200 first and then hunt for a secondhand AIS 50-135/3.5.

  15. #35

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    Let's take this discussion a bit further, taking into account FOV and sensor sizes.

    As lsisaxon puts it "An 85mm is wide angle for 4"x5" large format, normal lens for 6x6 medium format, medium tele for 135 and a longer medium tele for DX. BUT it is STILL 85mm!!"

    So actual focal length does not mean anything until the application is specified. In my case on 135 I use my 85mm as a medium tele (actually I would call it short tele/portrait).
    Actually, I tot everyone would understand that 50-500 or 300-800mm (even in DC format) would refer to 135 format. Isn't that the common reference for DSLRs lens?
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  16. #36

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    You're a gentleman (I assume you are a male, otherwise should be lady).

    From the last post, we are certainly in agreement. I would do the grafting one way or the other if it doesn't cost too much, but putting it off as it may be more affordable to try to get one of those birding scope and adapter for my prosumer instead of using my D70.

    Anyway $1100 for Sigma 50-150/2.8 is a bit too much for me. Probably going to get my D200 first and then hunt for a secondhand AIS 50-135/3.5.
    Thanks for your compliments! I think the birding scope and adapter would not be cheap also plus I believe that the quality will be somewhat compromised because of the smaller CCD.

    If you are into birding, then get a DSLR with a good high ISO because most of the time, you will need the shutter speed with that kind of magnification also. D200 is not too bad. Lens wise, I'm sure you will benefit from f/2.8 but if you need the reach, I think the 70-300/3.5-5.6VR is quite good and affordable. Only downside is the f/5.6 but sometimes it's ok because for that kind of focal length, most of the time you might want to close down to f/8 to get a better depth of field. So at the end of the day, good and clean high ISO is still better.

  17. #37

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by CYRN View Post
    Actually, I tot everyone would understand that 50-500 or 300-800mm (even in DC format) would refer to 135 format. Isn't that the common reference for DSLRs lens?
    Well, if you state the actual focal length, I would take it to mean the actual focal length. It's the same for all formats just that the angle of view is different, that's all. 1mm is 1mm, it's an ISO standard and it will not magically become 1.5mm nor 0.66mm.

    Focal length is format independent. Angle of view or field of view is dependent of the format for a particular focal length. Diediealsomustdive puts it correctly that without knowing the format, you can't tell whether a particular focal length is regarded as tele or wide.

    So in your title "how come till now still no long lenses for cropped sensors", I explained in an earlier post that there would be not much difference in size if you reduce the image circle. On hindsight, diediealsomustdive is also right to say that a shorter focal length would have given you the same angle of view at a smaller size/price, so in a sense, that is already a bonus.

    But my understanding is that you are asking for the actual focal length and not the equivalent field of view.
    Last edited by lsisaxon; 20th December 2006 at 06:03 PM.

  18. #38

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by lsisaxon View Post
    I think the 70-300/3.5-5.6VR is quite good and affordable.
    I wish it were that simple, birding needs 600mm onwards, and many use 600mm plus a 1.4x or 1.7x, and that's on DX format.

    I am currently using the 70-300ED and I have lots of chicken littles, no decent bird shots.

    But then I may be dividing my resources too thinly, still have scuba shots as well, along with wide angle landscape, portraits...

    Just can't commit enough $ for the long lens, and hence why I won't pay $1100 for a 50-150/2.8 Sigma, need that money for an underwater strobe. Sigh...

  19. #39

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by lsisaxon View Post
    I explained in an earlier post that there would be not much difference in size if you reduce the image circle.
    My understanding is that by reducing the image circle you will reduce the need for optical corrections that generally fare much worse at the edges than at the centre. That would make the lens much smaller than if it were to be built for FF. Witness the Nikkor 12-24/4, in Nikon's literature much was made on the reduce image circle and how it made the lens smaller, even for the same aperture. But you are still correct on the calculation on the min element size to collect the light, but not needing to do the extra correction the designer can make the actual physical lens closer to the theoritical lens, or the 200/2.8 could be that much closer in size to the 72mm diameter rather than having to go to 77mm. And not needing to do the complex correction also allows for the reduction of the number of elements and the complex cam system to move the lens elements (I am sure you know this, in some zoom lens system the element groups may move in opposite directions!).

    That's why a 135/2.8 can be so compact while a 50-135/2.8 is that much larger and heavier - due to the need to do more correction to compensate for zooming, and a DX lens would be smaller than a FF lens in that now the designer have less to correct for the same focal length range.

    Look at the 12-24 Sigma versus 12-24 Tokina and you will see the benefit of reduced image circle. The Sigma FF lens is so montrous, while the Tokina DX lens is actually quite petite. So reducing the image circle do result in smaller lenses, but they can never be smaller than what lsisaxon had calculated. Oh generally the Tokina DX lens is reported to have much better optical performance than the Sigma FF lens, another benefit of reducing image circle, less to correct, smaller lens size, easier to correct and hence better optical performance. All benefits so long as you can live with the reduce sensor size.

    If you need further convincing go see the Olympus 4/3 catalogue and you will see lenses that are much more compact than 135 lenses.

    It puzzles me too why smaller telephoto lenses for the DX format had never made the scene. Maybe FF sensors are really on the horizon for Nikon-land too.
    Last edited by diediealsomustdive; 20th December 2006 at 08:16 PM.

  20. #40

    Default Re: How come till now still no long lenses for cropped sensors

    Quote Originally Posted by diediealsomustdive View Post
    If you need further convincing go see the Olympus 4/3 catalogue and you will see lenses that are much more compact than 135 lenses.

    It puzzles me too why smaller telephoto lenses for the DX format had never made the scene. Maybe FF sensors are really on the horizon for Nikon-land too.
    The reason for 4/3 system to be able to make smaller lenses is because they have a reduced flange to sensor distance. Most wide angle lenses would require a retro focus (I'm not sure if it's the correct term) design to be able to project the image from the lens mounting flange. Otherwise, the rear elements would protrude into the mirror box. The 20/2.8 is one classical example of pushing the rear elements to the limits, so are the extinct fisheye 6mm and 8mm where you need to lock up the mirror before mounting these lenses.

    You are right on the aberration correction though. But if you notice, it is the wide angle lenses which are more difficult to correct. So for a zoom range which extends from wide angle to tele, you do get DX lenses because it would be cheaper. But for a mid-tele to long-tele zoom, if I'm not wrong, the correction should be quite straightforward and the more critical elements are probably the front elements and the ED elements.

    In fact, I'm quite sure some of these longer lenses are capable of a larger image circle than just for 135 FF if the rear elements are not recessed into the lens like most of the longer teles. The image circle would then only be limited by the blockage by rear opening.

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