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Importance of aperture in the taking lens


stefanmedia
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I'm trying to decide how important the widest aperture is of the taking lens for my Kowa (2:1) anamorphic lens. From the EOSHD guide, 35mm is the widest I should go for a MFT camera body. I see many 35mm lenses with f/3.5 for sale on eBay. Is that adequate for most outdoor shoots? How much light is lost by the anamorphic? I was considering a (possibly rarer) 35mm lens with f/2. How important is the widest f-stop in the taking lens for an anamorphic lens?

 

Thanks!

Stefan

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On a MFT body you can actually push it to 30mm, but if you ever want to use Diopters you'll need to get bigger ones to avoid vignetting. As far as F stop is concerned it really is up to the quality of your taking lens, as the Kowa can easily cope with fast lenses.

[This is assuming you're speaking about the Kowa for Bell&Howell]

I've used a Super-Takumar 35mm f3.5 wide open & it is nice'n'sharp and i've had no problems with f2 lenses, such as the Mir-24m or even the Helios 44-2 - again it all depends on the condition of your taking lens & if you use good quality diopters, they can also sharpen things up.

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**The below comments assume we are all aware that use of anamorphics is no longer something we do in order to maintain resolution since most anamorphic lenses degrade the resolving power more than the act losing pixels through cropping**

 

IMO use of anamorphic for the majority of our purposes should be undertaken with the fastest and sharpest taking lens available - particularly on smaller sensors.  

 

Since our use of anamorphics is an aesthetic choice rather than an attempt to maintain resolution, there is not much point in shooting anamorphic if the dof is so deep, and with no separation between in/out of focus parts of the frame, the aesthetic is no longer noticeable.

 

I think one of the main reasons anamorphics like the SLR magic 1.33x have had such a bad time is that firstly it works best with wider lenses and smaller sensors, and slower apertures (meaning dof is so deep the already weak 1.33x look is even less obvious). - it's a disaster combination and why such lenses don;t command much respect from anamorphic purists.

 

I feel if a anamorphic requires the taking lens to be closed to f5.6, on an m4/3 sensor the anamorphic is not up to the task of the sensor it is being used on, the user loses a lot of the 'look' from anamorphic.  And adds hassle, weight, and unpleasant optical degradations into the equation.  The end result often just looks like spherical cropped to 2.35 with a gaussian blur and CA added in post.

 

to me a rough guide / criterion similar to this should be considered in order to make the job of shooting anamorphic a worthwhile choice (without unpleasant degradations to resolving power, CA, etc), while maintaining some type of anamorphic 'look' :- 

 

1. using full frame the anamorphic needs to be able to accommodate an 85mm @f5.6 or faster, or a 50mm @f4 or faster 

 

2. using aps-c / s35 a 50mm @f4 or faster, or a 35mm @f2.8 of faster

 

3. using m4/3 a 35mm @f2.8 or faster, or 25mm @f2 or faster

 

4. gh4/4k mode will need a 30mm at f2 or faster, or a 18mm @ f1.4

 

5. s16mm (bmpcc) will need a 20mm at f1.4 or a 12mm at f1.0

 

 

The lens speed can be 1 stop slower for every lens focal length step, for instance using an f-135mm lens on full frame would still look anamorphic set at f8.  a 200mm lens would still look anamorphic when closed down to f11.  

 

a separation between in/out of focus areas is a critical attribute you need for anamorphic shooting to be beneficial for most uses.  

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@richg Always the expert at anamorphics!  I agree with using the fastest lenses available for the GH4.  I'm shooting F1.4 or faster with speedbooster.  Especially effective with longer focal lengths for closeup shots.

 

I have a Sankor and Kowa B&H, and my Helios still has to be at F2.8 to get a "sharp" picture.  To get a softer picture with more glow and less contrast, then I'll keep it wide open at F2.  I think the only anamorphic I haven't had a problem is the Iscorama.  Damn thing is sharp no matter what lens at the widest apertures.

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Imo, first need to consider the taking lens front diameter. 16h is 50mm. So taking lens filter thread is better not bigger too much. 55 & 58mm are the best. 62mm is still usable. More than 72mm might have difficulty. So usually is not easy to use large aperture lens. Small aperture lens may get wider angle view. Especially, if using zoom lens, you will loose some wide angle.

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Only lenses over 85 need large front diameters to have large apertures. I have a nikkor 85 1.8 with a 52mm filter diameter, and since we are talking about Micro43, large apertures are no problem with smaller than 50mm front elements. Remember, Focal length / Apparent Aperture Size =  f stop number

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Thanks, everyone, for your replies to my post. It's all very useful information.

 

Bioskop asked if I was speaking about the Kowa for Bell & Howell. Mine doesn't say Bell & Howell on it, just "Kowa Prominar Anamorphic 16-H."

 

I had been eyeing up a Berogon 35mm f//3.5 lens because its zebra-pattern matches my anamorphic, and so seemed aesthetically suited to the lens (e.g., '> ).

 

I've decided instead on an SMC Pentax-M 35mm f/2 lens because it'll open wider — plus I'm oddly partial to Pentax lenses ever since getting my first film camera, a Pentax ME-Super, as a teenager.

 

This 35mm lens arrives soon, so I can see how it works for my purposes. ;-)

 

Stefan

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Stefan and to all others that are wondering about the Kowa. The 16-H, 8Z, and Bell & Howell are the same lenses. The 16-H I believe was for the American market and the 8z was labeled that way for the Japanese market. The Bell & Howell version is also identical to the 16-H/8Z.

 

The only distinction you can make between these lenses is that there's two different rear connector sizes. Some will come with M52-thread and some will have M50-thread x 0.75. 

 

You can look up the other Kowa versions here

 

http://super8wiki.com/index.php/Anamorphic_Lenses

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  • 5 years later...
On 11/8/2014 at 7:30 AM, nahua said:

Is it in focus though?  Some lenses require F5.6 or F8 to be in focus.  Even the coveted Helios 44-2 requires F4-5.6 to be sharp on some anamorphics.  If possible try the lens before you buy.

Very true... did several tests to get to same result. I´m struggling to get a good infinity focus on longer lenses... From 200mm - 300mm  it gets very hard.

I´ve tried as a Taking Lens on a Schneider Kreuznach:

Canon 300mm F4L IS

Result: Impossible to focus at the moment. Anyone knows to explain a possible optics incompatibility?

Takumar 200mm F3.5

Result: Quite ok but not perfect - See de video...

Takumar 120mm

Good result at F8-F11

Helios 44M-6

Perfect focus from F5.6

 

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