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Sigma 30mm f2.8 on the A7

Discussion in 'Sony Alpha E-Mount Lenses' started by ggibson, Oct 31, 2014.

  1. ggibson

    ggibson TalkEmount Regular

    154
    Sep 1, 2011
    I thought I would share some pictures of this combo for anyone looking into budget lens options for the A7.

    Although the 30mm is an APS-C lens, it has 85-90% full-frame coverage. By taking out the rear baffle on the lens (removing 3 screws), it can be used on the A7 quite well, with only minimum vignette. For JPG shooters, cropping down using the camera's "Clear Image Zoom" at 1.2x makes this a 36mm lens, with very similar framing to the Zeiss FE35. Alternatively, shooting RAW and cropping my photos manually usually results in around a 20MP image on the A7. MUCH better than APS-C mode, which would crop it down to 10MP!

    I'm using the older version of the lens, but the new Art version is only a cosmetic change as far as I know. I think this is a great option for FE camera owners who want a small lens, but don't want to spend the money for the Zeiss 35mm (the two are almost exactly the same size).

    Anyways, here are a few shots--first the camera+lens, then a few shots showing what the combo can do. All images were post processed to some extent, except the Thunderbird taillight image. Enjoy!
    15403363370_d35954ed26_c.

    First, a non-cropped JPG straight out-of-camera (corners vignette the least at minimum focal distance, which you can see a close example of here):
    15477373239_d1409251f8_c.

    And some other various images, all processed and cropped slightly:
    15435402660_5cd1854184_c.

    15419742188_e1a5e15162_c.

    15412738090_e811e99bc6_c.
     
    • Like Like x 13
  2. Hawkman

    Hawkman TalkEmount Top Veteran

    939
    Sep 10, 2013
    Virginia, USA
    Steve
    Man, I almost pulled the trigger on one of these earlier today thanks to a sale going on at B&HPhoto (courtesy of SonyAlphaRumors) (consider using the link from this TalkEmount thread if you do decide to buy), but talked myself out of it at the last moment.

    Now, with these excellent shots - and thus proof that this lens is, in fact, FF future proof, so to speak - I've got an itchy finger again. ;)
    Seriously though, great shots.
     
  3. davect01

    davect01 Super Moderator

    Aug 20, 2011
    Fountain Hills, AZ
    Dave
    As long as you are aware not to fill in all the corners, a very livable image.
     
  4. southy

    southy TalkEmount Veteran

    370
    Feb 5, 2014
    Australia
    Nice inexpensive alternate to the FE35. I've not used the Sigma but it has an excellent reputation on apsc and looks the goods on the A7. Do you know if this mod will also work with the 19mm? Maybe end up somewhere in the 24mm range.
     
  5. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Interesting option, thanks for posting that up. :)
     
  6. ggibson

    ggibson TalkEmount Regular

    154
    Sep 1, 2011
    Yes, all of the Sigma lenses work pretty well. The 30mm has the largest coverage, but the other two are close. I tried my coworker's 19mm (with the baffle still in), and even then it seemed to be able to be cropped to 24mm. The 1.2x zoom eliminated most of the dark corners.

    I have the 60mm also, which is usable as more like a ~72mm lens. It is kind of an awkward focal length though, so I don't use it as much!
     
  7. ggibson

    ggibson TalkEmount Regular

    154
    Sep 1, 2011
    Another image with the 30mm:
    15704992031_45271c2c52_b.
     
    • Like Like x 4
  8. christilou

    christilou TalkEmount Veteran

    415
    Nov 26, 2012
    Surrey, UK
    Christina
    I'm a bit confused about the fitting. If it's at E fit why would you have remove some screws?
     
  9. José De Bardi

    José De Bardi Assistant in Virtue

    Aug 31, 2013
    Dorset, UK
    José
    The lens is APS-C, the camera is FF. Removing the baffle allows a slightly bigger image circle through the lens onto the larger sensor.
     
    • Like Like x 1
  10. christilou

    christilou TalkEmount Veteran

    415
    Nov 26, 2012
    Surrey, UK
    Christina
    Okay, thanks. I assumed you would just set the A7R to APSC lens in the menu and use it that way.
     
  11. José De Bardi

    José De Bardi Assistant in Virtue

    Aug 31, 2013
    Dorset, UK
    José
    As the OP says, using it FF and manually cropping only what you have to yields ~20MP, whereas the APS-C mode in the menu would give you only ~10MP (and a narrower field of view).
     
    • Like Like x 2
  12. ggibson

    ggibson TalkEmount Regular

    154
    Sep 1, 2011
    Yeah, the modification is removing the plastic baffle on the back of the lens. On APS-C cameras, this part can help block excess light that wouldn't hit the sensor directly, but might reflect internally and reduce contrast. It also of course serves to protect the internal electronic components in the lens. Removing the baffle is easy, since it's just 3 tiny screws. =)
     
    • Like Like x 1
  13. bartjeej

    bartjeej TalkEmount Rookie

    23
    Oct 8, 2014
    This same trick works on the Sony E-mount 16/2.8 and 20/2.8. The 20 has a clearly noticeable fully black vignette, the 16 does cover the entire frame but the corners are severely blurred / smeary. Cropping the 16 down to about 18mm seems to work fine at f/8; at wider apertures, you're probably looking at cropping down to ~20mm in order to get usable corners.

    I have a question for anyone who can test this; does the lens correction profile for APSC lenses also work if you don't use APSC crop mode?