Effect of cropping on a teleconverter

trolleytrolley Posts: 126Member
edited February 2015 in General Discussions
I have a cheap 2X teleconverter. What is it's effect on the focal length when you switch an FX camera to DX crop mode?
For instance, a 300mm lens with a 1.5X crop would be 450mm. With a 2x converter, do you get 900mm (2x450)?
It seems a bit like a free lunch. Or does degradation mean it's unusable anyway?

Comments

  • scoobysmakscoobysmak Posts: 214Member
    The file the camera would create is the equivalent field of view of 900mm but you lost a majority of your pixels due to switching to DX mode and usually a 2x TC does affect the image quality. You magnified the issue of the image quality by "zooming in" using the DX mode. There are a few exceptions that a 2x TC doesn't affect the image that bad but usually these are with Nikon Pro lenses like a 400mm f 2.8 or similar.

    I prefer to just crop the image how I see fit Vs using DX mode, gives me more flexibility to crop what I want in my photo than a split second decision that might have something "weird" I don't like later.
  • trolleytrolley Posts: 126Member
    Since I am that way inclined, when the camera & lens arrive I'm going to take the same picture with & without the converter on & with & without crop & see what I get.
    I'm thinking that at full frame, if you enlarge part of the area it may be better than DX mode.
    But I won't pre-empt the results ;;)
  • sevencrossingsevencrossing Posts: 2,800Member
    what camera are you using?
    As far as IQ is concerned, there is no difference between putting in Dx mode and cropping in post
    a cheap teleconverter on a modern DSLR is more likely to degrade rather than improve IQ
  • trolleytrolley Posts: 126Member
    It'll be on a D800
  • IronheartIronheart Posts: 3,017Moderator
    @trolly, the free lunch, or lack thereof, comes in the form of light. A 2x teleconverter chews up two stops of light, so an f/2 lens becomes an f/4, an f/2.8 becomes a f/5.6. An f/4 becomes an almost useless f/8 and an f/5.6 becomes a completely useless f/11. The reason it is useless is that a) the camera can't autofocus b) you can't either 'cause you can't see jack s#%t. Don't even bother with a variable zoom. A fixed prime, maybe. If it is a 3rd party TC, you will also need to worry about physical interference with the back element on the lens; if they whack into each other you could get scratches or worse.
  • sevencrossingsevencrossing Posts: 2,800Member
    edited February 2015
    It'll be on a D800
    You will almost certainly be better off cropping in post
    as Ironheart says you will also need to worry about physical interference with the back element on the lens
    Post edited by sevencrossing on
  • heartyfisherheartyfisher Posts: 3,172Member
    It'll be on a D800
    Whats the lense ?

    Moments of Light - D610 D7K S5pro 70-200f4 18-200 150f2.8 12-24 18-70 35-70f2.8 : C&C very welcome!
    Being a photographer is a lot like being a Christian: Some people look at you funny but do not see the amazing beauty all around them - heartyfisher.

  • PhotobugPhotobug Posts: 4,537Member
    When I cropped a few of the Bald Eagle pictures taken on the D750 the IQ was impressive. Agree with severncrossing on cropping in post.
    D750 & D7100 | 24-70 F2.8 G AF-S ED, 70-200 F2.8 AF VR, TC-14E III, TC-1.7EII, 35 F2 AF D, 50mm F1.8G, 105mm G AF-S VR | Backup & Wife's Gear: D5500 & Sony HX50V | 18-140 AF-S ED VR DX, 55-300 AF-S G VR DX |
    |SB-800, Amaran Halo LED Ring light | MB-D16 grip| Gitzo GT3541 + RRS BH-55LR, Gitzo GM2942 + Sirui L-10 | RRS gear | Lowepro, ThinkTank, & Hoodman gear | BosStrap | Vello Freewave Plus wireless Remote, Leica Lens Cleaning Cloth |
  • trolleytrolley Posts: 126Member
    Lens will be a Nikkor 300 f4. I currently use a Sigma 150-500mm on a D200
  • sevencrossingsevencrossing Posts: 2,800Member
    edited February 2015
    I believe there are 3 versions of the lens

    The 300mm f/4 IF-ED (1987 to 2000)
    The 300mm f/4D ED IF AF-S ( 2000 to 2014)
    and the latest AF-S NIKKOR 300mm f/4E PF ED VR


    I have not used any of them but all get good reviews and should give excellent results with a D800 ( which I do have )

    They seem to get good reviews with a Nikon 1.4 converter

    I feel adding a third party 2x converter will not give you good results

    Post edited by sevencrossing on
  • MsmotoMsmoto Posts: 5,396Moderator
    The operative word is "cheap". A question regarding unknowns is only answered by reviewing the results of its use. My suggestion would be to take a few images, make certain no other confounding factors are present, i.e., shoot in adequate light so as to be able to stop down a few stops, have a high shutter speed or on sticks, and make certain the exposure is correct, then post a full size image on Flickr and give us a link.

    Then, and only then can one properly evaluate the image quality.
    Msmoto, mod
  • PhotobugPhotobug Posts: 4,537Member
    I believe there are 3 versions of the lens

    The 300mm f/4 IF-ED (1987 to 2000)
    The 300mm f/4D ED IF AF-S ( 2000 to 2014)
    and the latest AF-S NIKKOR 300mm f/4E PF ED VR
    Yes you are correct Nikon made three 300 F4 lens. For the record, Nikon has made SIX 300mm lens; the other there at F4.5. Here is the link to a comparison table for all six lens.
    http://www.kenrockwell.com/nikon/comparisons/300mm-f4.htm

    This is an example where KR's web site is good. He loves to put these comparison tables together.


    D750 & D7100 | 24-70 F2.8 G AF-S ED, 70-200 F2.8 AF VR, TC-14E III, TC-1.7EII, 35 F2 AF D, 50mm F1.8G, 105mm G AF-S VR | Backup & Wife's Gear: D5500 & Sony HX50V | 18-140 AF-S ED VR DX, 55-300 AF-S G VR DX |
    |SB-800, Amaran Halo LED Ring light | MB-D16 grip| Gitzo GT3541 + RRS BH-55LR, Gitzo GM2942 + Sirui L-10 | RRS gear | Lowepro, ThinkTank, & Hoodman gear | BosStrap | Vello Freewave Plus wireless Remote, Leica Lens Cleaning Cloth |
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