EOSHD

Welcome to the EOSHD forum. The knowledge-base for all mirrorless, DSLR and pro video cameras.

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  1. ANAMORPHIC

    The largest online community devoted to anamorphic filmmaking.
    Discuss lenses, adapters, workflows and post lenses for sale

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  2. BLACKMAGIC CINEMA CAMERAS

    Raw shooting cameras - URSA Mini 4.6K, BMCC, BMPCC and more

    2,227
    posts
  3. SHOOTING

    Screening room and the creative side of filmmaking - share your ideas / stories

    2,444
    posts
  4. SAMSUNG NX1 / NX500 HACK

    Discuss the NX1 hack and more. Share your mods. Share your tests.

    2,016
    posts
  5. GEAR FOR SALE

    Post classified ads for your camera gear and filmmaking related kit!

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The EOSHD Panasonic GH4 Shooter's Guide
The EOSHD Samsung NX1 Setup Guide
The EOSHD Sony A7R II Setup Guide and LUT Pack
The EOSHD Anamorphic Shooter's Guide - Second Edition
The EOSHD 5D Mark III Raw Shooter's Guide
The EOSHD Sony A7 Series Guide to Full Frame Lenses

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  • Posts

    • Elliptical/Oval Bokeh Explained
      Apologies in advance if this is widely known.  Personally, I've never found a really good explanation of why front anamorphs produce oval bokeh and rear anamorphs don't, despite reading my fair share of patents, technical papers, internet gossip and the like.  Feeling that my own understanding needed some firming up I finally set up some paraxial models and went through the math in gory detail.  It all boils down to how front and rear converters alter (or don't alter) the f/#, and basic DOF type circle of confusion calculations.  It has nothing to do with higher order aberrations, or the shape of the front lens, or various mechanical aspects of the lens. Briefly: 1) A front anamorph is just a special case of a front afocal attachment, and as a result it preserves the f/# of the lens its attached to.  With an anamorphic front lens the focal length is shorter in the powered axis than in the non-powered axis.  For example, consider a 2:1 anamorph attached to a 100mm f/2 spherical lens.  In this case the net focal length is 50mm in the powered axis and 100mm in the non-powered axis, but in both cases the aperture remains f/2.  If you venture into the weeds to do circle of confusion calculations for a given object-space defocus you discover that a de-focused point source evaluated at the image plane is an ellipse with an aspect ratio of 4:1.  However, you only need to de-squeeze the image by 2x to correct the in-focus geometry, so you are left with de-focused ellipses with an aspect ratio of 2:1. 2) A rear anamorph is just a special case of a rear-mounted teleconverter, and as a result it *does not* preserve the f/# of the lens its attached to.  In particular, in the powered axis the aperture becomes slower.  For example, consider an 50mm f/2 spherical lens with a 2x rear anamorph.  Here the net focal length is 100mm in the powered axis, but the aperture has dropped to f/4, and is still 50mm f/2 in the non-powered axis.  When you do the circle of confusion calculations with object-space defocus you find the on-sensor defocused image to be an ellipse with a 2:1 aspect ratio.  When you desqueeze by 2x this defocus ellipse becomes a perfect circle. Bottom Line:  Rear anamorphs have circular bokeh because they *don't* preserve the f/# of the spherical lens in both axes, while front anamorphs have elliptical bokeh because they *do* preserve the f/# of the spherical lens in both axes.
    • Anybody compared an NX1 w/ 18-200 to XC10, RX10, FZ1000?
      @tugela have you tried the 16-50s ? Really curious about that lens
    • Aputure: the Blackmagic of lighting
      I'm not sure it is more powerful than the 60w Chinese fresnel. Sure it draws more power, but there's other factors besides power draw that contribute to illuminance. We'll know for sure as soon as it arrives. There's a 100w version of that Chinese fresnel with a 24v input; if the 60w is close to the brightness of the Pixapro, I'm thinking of getting one and powering it with a 24v LiPo ebike battery. Works out a lot cheaper than v-mounts and should power the light for a few hours. Sending it back is a hassle but it's just not that great as a hard light (which is what I really need it for), with a fresnel lens it's hard but the beam is very narrow. With the reflector it casts wonky shadows. I think that might be due to change from a rough to a smooth reflector surface on the rim of the reflector.
    • Aputure: the Blackmagic of lighting
      1 hour @ full power, 2,5 hours @ 50%. Not bad, given that 30 to 40% (with softbox, grid and double diffusion on) is the sweet spot when I shoot 800 iso with the BMMCC + Speedbooster. And if I need extra power, for exteriors mainly,  I can get up to  3 hours... I was tempted to do the same thing, but I do think the extra power can be handy. And I must say that I'm pleased to avoid customs (in Spain it's a nightmare) and all the hassle/cost of sending it back to UK.
    • Sony A6300 review (rolling) - Striking image but nagging issues
      Erik Naso found that when he switched to faster memory cards, many of the heating issues were improved.    
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