252 of 269 people found the following review helpful
Would be a bargain at twice the price,
This review is from: Rokinon 85M-P 85mm f/1.4 Aspherical Lens for Pentax (Black) (Electronics)
Image quality from wide open
Image quality doesn't improve a lot stopping down the aperture
Included 72mm lens cap is junk
Hood not positive feeling
Focusing at 85mm f/1.4 is difficult
About 1/3rd stop darker than my other 85mm lenses
Buy this lens now if you want a superb manual focus long portrait lens of modern design and don't want to empty your pocket book. It performs like a name brand 85mm f/1.4 at a fraction the price. You must be proficient with manual focus to use this lens at f/1.4 (or be willing to learn).
The lens produces nice usable portraits from wide open. There is a pleasing softness too it, but the eyes appear nice and sharp and the bokeh transitions are smooth. Specular highlights in the bokeh are smooth and fairly uniform with minimal rings or donuts. The modern aspherical lens design takes care of most spherical aberration. I bought this lens solely for f/1.4-f/5.6 usage. If I want to use the f/4+ range I will use my f/4 zoom, so wide open performance of the 85mm was critical too me, otherwise it added nothing over my slower zoom. I would not be afraid to use this lens at f/1.4 for portraits.
Wide open it does show a small amount of purple fringing around very high contrast subjects, but it almost has to be blown out next to a darker object for it to be noticeable. The lens also has your typical green/red chromatic aberrations (CA) visible in the bokeh, which I think is longitudinal CA. This is actually fairly typical of large aperture lenses, even good lenses. It is generally not intrusive. The lens is also a tad darker than my other 85mm lenses, maybe 1/3rd f/stop.
Focus is critical at 85mm f/1.4 as the depth of field is shallow, and most dSLR focus screens are designed to focus for f/4. I think the one in my K-7 is a bit better but still doesn't show the true DOF at f/1.4, so it is impossible to focus totally precisely less than f/2 or so, but with practice you can get really close. Also, for slower subjects live view is useful. The focus feel of the lens is excellent with a heavily weighted focus ring that feels high quality.
Lens construction is equivalent to any Canon L lens or Pentax DA*. It is a metal body at the base with a quality feeling plastic focus ring/upper body (this feels like the Plastic in DA* or Canon L lenses). The only part that feels cheap is the rear lens cap, the front lens cap, and the hood. At least they only cut costs with the non-critical items.
This will make an excellent manual focus video lens too, because of the pleasing bokeh wide open and the shallow depth of field. This is one of the reasons I wanted the good bokeh wide open.
Overall, this is a great lens for a superb price. The maker is Samyang, but it is sold under the Vivitar, Opteka, Bower, Rokinon, Polar, and other names. Image quality is supposedly the same between any make, but accessories might differ depending on what the brand wants to include with the lens. The Vivitar Series 1 lens has a slightly different look to it.
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Showing 1-10 of 27 posts in this discussion
Initial post: Oct 7, 2009, 5:59:12 AM PDT
Amazon Customer says:
Thanks for your review! Very informative.
In reply to an earlier post on Nov 16, 2009, 6:14:12 PM PST
You see red chromatic aberration? That's not good as you also say your lens shows green and blue. That covers three of the four major Fraunhofer color lines and suggests that your lens does not even meet the definition of an achromate. Visible color at those wavelengths implies that you have more than 1/4 wave of color in each of the three lines, C, E, and F.
In reply to an earlier post on Nov 16, 2009, 7:23:08 PM PST
I didn't say anything about blue, but it does show the typical green/magenta longitudinal CA that nearly every large aperture lens shows. I don't notice much lateral CA, but haven't looked too closely. Overall the CA looks a lot like what you would see on the Nikkor 85mm f/1.4 (based on the review at Photozone.de). I can't imagine anyone who is not designing lenses cares anything about C-E-F lines.
In reply to an earlier post on Nov 16, 2009, 7:44:01 PM PST
Last edited by the author on Nov 16, 2009, 7:46:24 PM PST
In reply to an earlier post on Nov 16, 2009, 8:11:48 PM PST
Last edited by the author on Nov 16, 2009, 8:15:10 PM PST
I am not reviewing the lens from an optical physicists perspective, and using Fraunhofer lines would obfuscate my review. I am proficient in evaluating lenses for taking pictures, which is what matters to the end user. Colloquial techno babble is exactly what you are doing as well, just from an optical physicist stand point. Pontify somewhere else please.
Purple fringing can be caused by the micro lenses on the sensor and even the Bayer arrangement of the sensor. The lens performs similarly to other (quality) 85mm f/1.4 lenses. What is your point?
Posted on Nov 16, 2009, 8:48:08 PM PST
Just to add, I am not trying to be a jerk, just wondering what your point of posting was other than to berate me?
As you state, "your lens does not even meet the definition of an [sic] achromate", I think you are in error. I think it is showing that it is an achromat. I think there is just some confusion. Longitudinal CA is visible in the out of focus regions specifically. Green/Magenta is common to show in the out of focus region for longitudinal CA, with red/magenta in front of the focus plane and green/cyan behind. If an achromat is assumed to focus red and blue light on the same plane, and we focus on the red blue focus point, you will see that behind the focus point everything out of focus will have a green tint (the green is most defocused behind the focus plane), and everything in front will have a red tint (the red is most defocused in front of the focus plane). Also, since an achromat focuses blue and red light together, those combined produce purple. So I think all the CA can be explained by the fact that it is likely an achromatic lens (as most photo lenses are).
In reply to an earlier post on Dec 8, 2009, 11:38:46 AM PST
Last edited by the author on Dec 8, 2009, 11:39:44 AM PST
In reply to an earlier post on Dec 8, 2009, 12:17:57 PM PST
Last edited by the author on Jan 8, 2010, 10:29:17 AM PST
"This "an achromat focuses blue and red light together, those combined produce purple" is not how you evaluate chromatic aberration of a lens. Try reading Warren Smith's Modern Optical Engineering and Daniel Malacara's Optical Shop Testing."
By the, way, if you look on page 83 of the Warren Smith book you mention, you will see that purple fringing can be caused by Longitudinal CA as I pointed out.
Posted on Jan 3, 2012, 3:31:36 PM PST
Deal or No Deal says:
What do you mean it's darker than your other 85mm lenses? How many lenses and which ones? How did you measure it? Are you just saying the pictures are darker?
In reply to an earlier post on Jan 4, 2012, 2:40:40 PM PST
Lenses are labeled in f/stops, but that is a number that indicates how large the aperture is. There is something else known as a t/stop which is how much light actually gets to through the lens (transmission). You lose light from reflections off the lens elements, etc. I am saying the t/stop for the lens is maybe a bit darker than an equivalent lens, but it should still be acceptable. I don't have the lens any more so I can't compare it again.