Results 1 to 19 of 19

Thread: Teleconverter turns cropped lens into FF lens?

  1. #1

    Default Teleconverter turns cropped lens into FF lens?

    Hey dudes and gals,

    I got a question. Let's say I was a Nikon user, and I put a 1.5X tele-converter between an old DX lens and a Full Frame sensor, would it project the image into a larger circle, effectively covering the entire full frame sensor?

    Anybody ever tried this? And if it doesn't work, shouldn't they have come out with something like this by now? A retro-active backward-forward upscale-downscale DX-FF tele-nonverter thingy... I mean, the image is there, it just needs to be magnified right?

    If someone already posed this question, share a link pls...

    Thanks, cheers

  2. #2
    Senior Member G-man's Avatar
    Join Date
    Mar 2006
    Location
    My House
    Posts
    2,219

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by ShutterbugPat View Post
    Hey dudes and gals,

    I got a question. Let's say I was a Nikon user, and I put a 1.5X tele-converter between an old DX lens and a Full Frame sensor, would it project the image into a larger circle, effectively covering the entire full frame sensor?

    Anybody ever tried this? And if it doesn't work, shouldn't they have come out with something like this by now? A retro-active backward-forward upscale-downscale DX-FF tele-nonverter thingy... I mean, the image is there, it just needs to be magnified right?

    If someone already posed this question, share a link pls...

    Thanks, cheers
    No it does not. A teleconverter extends the focal length of your lens, it does not make your sensor from DX to FX.

    Your image sensor's size is fixed, the lens focal length is fixed (assuming a prime lens), and what the teleconverter does is make that lens 1.5 times its effective focal length. That's all.

    Do you even know the difference between FX & DX?

  3. #3
    Senior Member sinned79's Avatar
    Join Date
    Jun 2009
    Location
    Singapore
    Posts
    10,850

    Default Re: Teleconverter turns cropped lens into FF lens?

    *piaks* forehead.

    do u think camera makers so stupid to make teleconverter to make a run for their revenue?

  4. #4

    Default

    Short answer - no, it doesn't work.

    Slightly longer answer - why don't you try it yourself to understand why it doesn't work the way you think it'd work?
    KF Photography
    Thanks for viewing!

  5. #5

    Default

    Dear G-man,

    No need to be rude, it was a simple question. I know the difference very well between DX and FX.

    Sinned79,

    Although camera makers may not want to ruin their revenue, I'm sure there are other companies out there who could see some profit returns from making such a "lens magnifier". There are more than likely a lot of people who would like to invest in an FX camera body, and who would not object to a slight dip in quality by using their DX lenses on an FX body, but without that cropped circle image.

    Flippen rude know-it-all people in this country! Forgive me for thinking "outside the box"! But it seems to be the norm here that anything different from the ordinary gets frowned upon. Open your minds!!

  6. #6
    Senior Member G-man's Avatar
    Join Date
    Mar 2006
    Location
    My House
    Posts
    2,219

    Default

    This is not even rude. Your question suggests you don't understand the difference between sensor sizes.

    If you can't take the way answers are given then pardon me for "being rude" as you put it! Go live in your strawberry world then when everything is soft and mushy!

    All I will say is this, "1 type of rice will feed 1000 types of people."

    Have a good day!

  7. #7

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by G-man View Post
    No it does not. A teleconverter extends the focal length of your lens, it does not make your sensor from DX to FX.

    Your image sensor's size is fixed, the lens focal length is fixed (assuming a prime lens), and what the teleconverter does is make that lens 1.5 times its effective focal length. That's all.

    Do you even know the difference between FX & DX?
    I believe the TS knows the difference... after all, the TS is asking about mounting a DX lens onto a teleconverter, and then mounting the combination onto a camera with an FX sensor... maybe reread the TS's post?

    Quote Originally Posted by ShutterbugPat View Post
    I got a question. Let's say I was a Nikon user, and I put a 1.5X tele-converter between an old DX lens and a Full Frame sensor, would it project the image into a larger circle, effectively covering the entire full frame sensor?
    well, it could work, if we can find (1) a 1.5x teleconverter that can (2) accept DX lenses... in all honesty, I have thought of this, but never got round to testing it cause don't have an FX body with me as of now...

    on part (1), the common ones at the moment are 1.4x, 1.7x, 2x, and 3x teleconverters... if we go for 1.4x, it may or may not be enough of an expansion, depending on the DX lens' coverage in the first place, something that can only be tested with each particular lens... we could go for >1.5x, but the greater the value of the conversion, the greater the negative effect on the image quality, all else being equal...

    regarding part (2), in the case of Nikon, please DO NOT use Nikon teleconverters on DX lenses, because most if not all DX lenses do not have the clearance in the back of the lens to accept Nikon teleconverters... if we look at Nikon teleconverters (or for that matter Canon, Sony or Sigma ones), we can see on the lens mounting side of the teleconverter there are lens elements that stick outwards, out of the teleconverter body... this sticking out portion will prevent most if not all DX lenses (and I believe even some FX lenses) from mounting onto the teleconverter... cunning, huh... please, anyone feel free to suggest DX lenses which are exceptions, cause I admittedly have not seen all DX lenses...

    so for part (2), we would need a teleconverter that does not have lens elements that stick forwards... like, say, a Kenko one, where the first lens element in the "forwards" direction is recessed into the teleconverter body... that does not guarantee that the first element of the teleconverter would not hit the last portion of the lens that one would mount onto it, and I would not guarantee the safety lens-wise and/or teleconverter-wise and/or pocket-wise of any attempt to mount any lens onto such a teleconverter, so trying such a combination is strictly at your own risk... but if it does fit, it just might work... they have 1.4x, 2x, and 3x teleconverters I believe... so the most likely candidate would probably be the Kenko 1.4x...

    why are there no 1.5x teleconverters specially designed to convert DX lens coverage to FX sensor coverage requirement?... so that they can sell us more lenses

    but do note that by adding a teleconverter, the image quality would deteriorate to some extent... obviously some lenses may work better than others, possibly the faster and better quality DX lenses, maybe say the 17-55 2.8... others lenses known for their vignetting and/or small image circles would probably struggle, like possibly the Sigma 10-20... but overall, vignetting could be quite significant still...

    and also, the relative aperture value would decrease, which may mean that the camera could have a harder time autofocusing if it could actually still autofocus... and also that the exposure time would be longer, all else being equal, due to the reduction in the relative aperture value... also, the "DX lens"-"teleconverter"-"FX camera" combination would typically be longer and heavier than an equivalent "FX lens"-"FX camera" combination because of the adding the teleconverter to the setup... YMMV, and again, try at your own risk.

  8. #8

    Default Re: Teleconverter turns cropped lens into FF lens?

    I actually tried my dx lens with a kenko in my 5d and it won't work.there's not enough clearance in the lens to fit the tc.the lens will touch the tc rear.can force in la but i won't do that.

  9. #9

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by spinworkxroy View Post
    I actually tried my dx lens with a kenko in my 5d and it won't work.there's not enough clearance in the lens to fit the tc.the lens will touch the tc rear.can force in la but i won't do that.
    thank you for sharing


    anybody has experience with Sony or Nikon DX lenses? I personally know that some Nikon DX lenses at least will actually fit onto the Kenko 1.4x... maybe for Canon, according to their own recommendation on their DX-lenses, their DX lenses may have rear-most elements that extend rearwards more than their non-DX lenses, and these "sticking-out" rear-most elements may get hit by the larger reflex mirror of a "full frame" camera body... which according to Canon is why they have made it so that their DX lenses cannot mount onto their "full frame" bodies... so it seems possible that these "sticking-out" rear elements could also be preventing Canon DX lenses from mounting onto Kenko teleconverters


    again, I stress, anyone trying this is doing it at his or her own risk...

  10. #10
    Senior Member G-man's Avatar
    Join Date
    Mar 2006
    Location
    My House
    Posts
    2,219

    Default

    Quote Originally Posted by theRBK
    I believe the TS knows the difference... after all, the TS is asking about mounting a DX lens onto a teleconverter, and then mounting the combination onto a camera with an FX sensor... maybe reread the TS's post?
    From the way the post was structured it seems to suggest using a DX lens on an FX body, projecting the DX's image circle onto FX body thereby negating the dark circle.

    However, I make no apologies for asking if TS knew the difference between FX & DX. I do not see it as rude at all but of course different strokes for different folks.

  11. #11
    Moderator Octarine's Avatar
    Join Date
    Jan 2008
    Location
    Pasir Ris
    Posts
    12,394

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by ShutterbugPat View Post
    I got a question. Let's say I was a Nikon user, and I put a 1.5X tele-converter between an old DX lens and a Full Frame sensor, would it project the image into a larger circle, effectively covering the entire full frame sensor?
    Anybody ever tried this? And if it doesn't work, shouldn't they have come out with something like this by now? A retro-active backward-forward upscale-downscale DX-FF tele-nonverter thingy... I mean, the image is there, it just needs to be magnified right?
    I'm on Canon and I have zero detailed knowledge about Nikon. (But I expect similarities, finally everyone puts their pants on one leg at a time since nobody can get around the laws of Physic.) Canon EF-S lenses (the DX types) cannot be used because of their optical and physical construction. First of all, the lens design is adapted for smaller sensors and secondly, there is a plastic ring at the back of the lens blocking the mounting on any FF camera. The teleconverter resembles an FF camera mount on the front end. But then again, there are people 'shaving off' the plastic part of the lens and it works. So it might not work 'out of the box' but rather with 3rd party stuffs and DIY.
    Curiously, I just searched around with Google and came across some links. Seems your idea is not wrong, but you have to factor in the side effects of any teleconverter on aperture. Also, you should not use the cheapest DX lens since the teleconverter enlarges and magnifies everything: the picture, the distortions, CA .. Some links:
    The official "Cannot 'lah!" explanation: https://nikoneurope-en.custhelp.com/...h-dx-lenses%3F
    But there are 3rd party solutions: DX lens on FX & Kenko teleconverter: Nikon SLR Lens Talk Forum: Digital Photography Review
    Try to rent the Kenko converter and see whether it works for you.
    EOS

  12. #12

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by Octarine View Post
    there is a plastic ring at the back of the lens blocking the mounting on any FF camera. The teleconverter resembles an FF camera mount on the front end. But then again, there are people 'shaving off' the plastic part of the lens and it works. So it might not work 'out of the box' but rather with 3rd party stuffs and DIY.
    this is not the case for Nikon, and I believe also Sony, lenses, where the mount itself is not differentiated between DX and non-DX...

    Quote Originally Posted by G-man View Post
    From the way the post was structured it seems to suggest using a DX lens on an FX body, projecting the DX's image circle onto FX body thereby negating the dark circle.

    However, I make no apologies for asking if TS knew the difference between FX & DX. I do not see it as rude at all but of course different strokes for different folks.
    that is what the TS is asking... maybe I misread your post but you were saying that a teleconverter would not make a DX sensor into an FX sensor, and that a sensor's size is fixed, which is not what the TS was asking... maybe, it's just all abit of misunderstanding on everyone's part

  13. #13
    Senior Member sinned79's Avatar
    Join Date
    Jun 2009
    Location
    Singapore
    Posts
    10,850

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by ShutterbugPat View Post
    Flippen rude know-it-all people in this country! Forgive me for thinking "outside the box"! But it seems to be the norm here that anything different from the ordinary gets frowned upon. Open your minds!!
    there is nothing to "think outside the box". First of all, what you think of... those camera makers already can think of. and nah, the profits from a true blue FF is way better then a "lens magnifer". they are not that silly to make small profits when they can make big profits (look at the price of 5DMKIII and 1Dx and compared to the price of teleconverters?)!

    for canon lens, there is big differences in EF and EF-S lens to the rear elements construction, I am not sure about Nikon DX and FX but for sure, Canon is definitely not so stupid to make a run for their money by creating teleconverters, it was created rather for a specific group who is into birding, animals etc when they need an extension to their lens.

  14. #14

    Default Re: Teleconverter turns cropped lens into FF lens?

    I think theRBK has covered the salient points.

    Optically, it seems like a sound argument. After all, that's what a teleconverter does -- magnify the central portion of a lenses image circle.

    The mechanical issues? Most of the TCs I've seen have front elements sticking out beyond the mounting flange, okay for long teles, not okay for most mid-range zooms. Mechanical/electronic coupling may not be complete or reliable, so metering, exposure and AF may be crippled.
    Optically, you'd lose image quality (sometimes a digitally resampled enlargement works better, see Teleconverters (Multipliers) - how well do they work?). The resulting loss of image brightness (effective aperture) may or may not be acceptable, bearing in mind that it would also affect AF performance (if the mechanical/electronic linkages allow it in the first place).

    It would be interesting to see the results of anyone who's tried this. Spinworkxroy seems to have eliminated one combination, but there may be others that work.

  15. #15
    Moderator Octarine's Avatar
    Join Date
    Jan 2008
    Location
    Pasir Ris
    Posts
    12,394

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by sinned79 View Post
    there is nothing to "think outside the box". First of all, what you think of... those camera makers already can think of. and nah, the profits from a true blue FF is way better then a "lens magnifer". they are not that silly to make small profits when they can make big profits (look at the price of 5DMKIII and 1Dx and compared to the price of teleconverters?)!
    That's the reason why third party lens makers come in and bridge the gaps that the big guys have left to make more money. Just think about IR modifications - what would be the 'official' approach using only stock equipment from Canon & Co and how far could you get with that? Or Macro photography: does Canon officially supports idea like reverse mounting of 50mm? I would not dismiss an idea too quickly just because the official answer of the C/N/S... is 'No.' I understand why they respond this way, but that does not mean we should accept this as the only answer. It's just their answer, nothing more
    EOS

  16. #16

    Default Re: Teleconverter turns cropped lens into FF lens?

    On a side note....what dx lenses are there that you would want to put on fx? The focal range of dx lenses usually aren't ideal for fx anyways.the 2dx lens i have definitely won't fit on my kenko tc...i can't think of any dx lens i would want on an fx

  17. #17

    Default Re: Teleconverter turns cropped lens into FF lens?

    Thanks for the responses everyone, as a Pentax user, I have no experience with Nikon or Canon lenses, so I wasn't aware of the protrusions preventing the TC being connected to DX lenses. My Pentax TC's have quite deep tubes with only one piece of glass inside, pretty much no chance for anything to touch anything, and I can mount any lens I wish on there. As a sad Pentaxian, no full frame sensor option at the moment, or on the horizon Hence my question.

    My main theory is that, there must be a way to optically magnify the projected circle by 150%, which would then cover the entire sensor. There is no reason why this shouldn't work. Yes it will result in less light hitting the sensor (1 to 1.5 stops I suppose) and a little loss of pixel density. But all in all, not a bad way to bridge the gap if you wanted to buy an FX body and a couple of DX lenses now, while saving up for those more expensive full frame lenses.

    spinworkxroy, I think the focal length would be calculated the same as if it were on a DX body. So a DX-sized 18mm image (which is actually a 27mm equivalent field of view) magnified onto an FX sensor, would come out as a 27mm field of view on the FX sensor. So, in essence the picture would be the same field of view as it would have been on DX format.

    octarine - thanks for the dpreview forum link! Seems the combination of Kenko and 17-55 lens works fine, no vignetting (as there would have been without the TC), but losing one stop of light. 18-70 also working. And when combined with 70-200 VR, edge results were actually sharper than before.

    * So the result is, using a Kenko TC, you can overcome the Manufacturer's purposefully placed sticking-out bits, and the image can be magnified into a FX sized circle. So for now I can go out and buy an FX body, some DX lenses, and a Kenko 1.4 TC, and be pretty much ok to wait a while and save up for the lenses that I actually want. *

    Thank you everyone, thread closed.

  18. #18

    Default Re: Teleconverter turns cropped lens into FF lens?

    The Nikon 17-55 plus teleconverter works on FX, but the problem is the 24-120 f4 is cheaper. You'd rather sell off your 17-55, and get a 2nd hand 24-120 f4 for that FX body.

  19. #19

    Default Re: Teleconverter turns cropped lens into FF lens?

    Quote Originally Posted by ShutterbugPat View Post
    Thank you everyone, thread closed.
    Good luck! To close the thread you have to click the "Administrative" on the grey bar and select "Close Thread."
    It is a pity that this thread has not been a more pleasant experience for you, but don't give up, there are many nice people here too.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •