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18-35mm F1.8 Sigma DC zoom lens
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  • brianc1959brianc1959

    @ala_img: f/# or T/#? What measurement technique did you use?

  • ala_imgala_img

    @brianc1959 It is not scientific test) I just compared it with wide open samyang 85mm f1.4 and Panaleica and saw difference on my monitor

  • vicharrisvicharris

    @ala_img What do you mean by "slightly lighter"?

  • itimjimitimjim

    @vicharris I'm reading that as brighter, not less heavy. I've seen lighter canon balls than the Sigma 18-35 :)

  • ala_imgala_img

    @vicharris I mean - slightly brighter, but almost no difference.

  • itimjimitimjim

    About the difference between 1.4 and 1.2? :)

  • ala_imgala_img

    @itimjim I made some more tests and i can say that Panaleica at 1.4 is even slightly brighter than sigma + speedbooster. Tomorrow i will try to upload some frames.

  • dracoredracore

    Any sample video clips for GH2+SB at the wide end? I'm curious to see how noticeably vignetting affects video?

  • ala_imgala_img

    Some more GH3+Sigma 18-35+Speedbooster frames

  • kholikholi

    I watched the video before it started re-converting.

    Although I can't stand what the SB does to Bokeh wide open, and I can see it in this example, this looks good to me. Was already likely going to pick up an SB just because I no longer want to mix lenses on my cameras, but it's good to see more encouraging examples.

    Thanks for posting.

  • itimjimitimjim

    @kholi What is it that you don't like about the bokeh wide open. Seems OK to me, better than some lenses even. I find busy bokeh quite distracting. I suppose it renders bokeh quite soft. I'd really like to see some A/B comparisons with and without the SB. Hell, I might just buy one (Sigma 18-35) and do my own testing :)

  • kholikholi

    You nailed it, it's super soft and mushy wide open. My frame of reference for something as fast as a 1.2's Zeiss Superspeeds, and the bokeh isn't busy, it's smooth, but it is not soft/blurry.

    SB wide open looks like a 35mm Adapter wide open.

    But, from what I've seen in my own passive testing. Sigma 18-35/1.8 + SB set to around 2 looks fine, and that's beneficial enough.

  • _OZ_OZ

    Yeah, bokeh definitely looks more nervous than creamy with the SB.

  • ala_imgala_img

    Almost all this frames were made at 18mm, because it is most interesting distance for me now. I think that bokeh is good enough for so wide focusing distance.

  • oscillianoscillian

    @ala_img So most shots are at 13mm f1.4 then? Looks very nice to me :)

  • ala_imgala_img

    @oscillian Yes, i am testing it mostly at max wide angle and wide open, because i bought it for indoor and low light shooting project. It is 13mm f1.2 (but for real it is about f1.4)

  • brianc1959brianc1959

    @ala_img f/1.2; T/1.4 I presume.

  • kholikholi

    Yeah I agree it still looks fine, more so than a Lot of tests so far.

  • ala_imgala_img

    @brianc1959 No, its real brightness near f1.4 compared to another lenses.

  • brianc1959brianc1959

    @kholi I would love to see a comparison between, say a 12mm f/1.2 Superspeed and the Sigma/SB at 12.8mm f/1.2 so that I could fully understand what you are talking about. Do you have the former lens? I assume the Zeiss SS wouldn't cover 4/3 format, but a careful crop would suffice.

    At f/1.2 the Speed Booster contributes less than 1/4 wave of spherical aberration, so I really do believe that its having little or no effect on the lens bokeh.

  • brianc1959brianc1959

    @ala_img Since you are comparing exposure you are effectively comparing T/#, not f/#. To measure f/# you would need to measure the entrance pupil diameter and the paraxial focal length, and then divide the latter by the former. Alternatively, you could measure the cone angle in image space by determining the blur circle diameter at a certain distance from focus.

    Bear in mind that the Sigma 18-35/1.8 has 17 lens elements, so its going to lose significantly more light due to internal reflections and absorption than a typical prime lens like the 25/1.4.

  • kholikholi

    The Zeiss SS MKIIs are S35, so they would cover M4/3 down to Pocket Camera for sure, but I don't have them in my possession right now. I meant T1.3 by the way, sorry about that.

    You could compare them to the 16, 18, and 24 as the 12's a lot more rare in a set. I'm pretty positive the differences in bokeh would be startling.

    I actually think I have some S16 Zeiss Superspeed footage on Vimeo, shot wide open... I have to check.

    On the subject of T-Stop, I've heard recently that the Sigma's rated more like a T2.4!? That sounds crazy to me...

  • brianc1959brianc1959

    @kholi You're right about the S35. I was thinking S16. I just checked the price of a few samples on eBay, and unfortunately this will not be an inexpensive experiment! May have to wait a few months. In the meantime, my 18-35 appears to finally be shipping, so I should be able to do some test shots with and without a Speed Booster in the near future.

  • brianc1959brianc1959

    Just occurred to me that the Zeiss Superspeeds for S35 would make a very interesting pairing with the Speed Booster to create a wide-ranging set of high performance f/0.90 lenses for m4/3 and Blackmagic cameras.

  • kholikholi

    Sorry I take that back, I just went through my email chain and I DID get a response about the PL adapter Speedbooster.

    Just not a date.

    Apologies.

    I agree, a SB+PL Combo would make for some incredibly interesting options when it comes to the S35 Superspeeds, but also slower and older PL primes like the Super Baltars (I have a set that I borrow), go-to-favorites like Cooke S4s, and even better, using Cinema Anamorphics on the Pocket and 2.5K to get the FOV back.

    Kowa 2.4s + SB + Pocket Camera... dreamy.

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