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Thread: Fast 25mm to 35mm prime?

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    Senior Member Rawfa's Avatar
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    Fast 25mm to 35mm prime?

    Hi,

    Ive been shooting most of the time with a cheap but very fun 35mm 1.7 with my NEX5, but Ive been finding my self more and more in situations where I need someting faster like 1.4 or 1.5. My first option is the Nokton 35mm 1.4 but I find it a bit expenssive considering the fact that Im not a pro, so I would like to know if there are less expenssive options out there. It could be from 25mm to 35mm, but its important that its compact, fast and less expenssive than the Nokton. What are my options?
    Last edited by Rawfa; 6th May 2011 at 06:56.

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    Re: Fast 25mm to 35mm prime?

    Try to find a Voigt 35mm f/1.7 Ultron - it's LTM and has been discontinued.

    I'm not sure why CV doesn't have a fast 24/25mm lens.

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    Senior Member Rawfa's Avatar
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    Re: Fast 25mm to 35mm prime?

    F 1.7 is what I have right now...Id like it to be at least f 1.5...

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    Re: Fast 25mm to 35mm prime?

    Quote Originally Posted by Rawfa View Post
    F 1.7 is what I have right now...Id like it to be at least f 1.5...
    My opinion: a third of a stop nets very little real gain.

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    Re: Fast 25mm to 35mm prime?

    Agreed, Godfrey. In fact, I'd bet that the difference between f1.7 and f1.4 is quite a bit less than even a third of a stop, since digital sensors have issues receiving light at the edges. There is only about a half stop difference between my SMC Tak 50 at f1.4 vs. f2.

    Rawfa, if you jump to the Nokton 35/1.2, you may be able to gain an extra half step, but I wouldn't bother with an f1.4, honestly.

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    jcoffin
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    Re: Fast 25mm to 35mm prime?

    Quote Originally Posted by douglasf13 View Post
    Agreed, Godfrey. In fact, I'd bet that the difference between f1.7 and f1.4 is quite a bit less than even a third of a stop, since digital sensors have issues receiving light at the edges. There is only about a half stop difference between my SMC Tak 50 at f1.4 vs. f2.

    Rawfa, if you jump to the Nokton 35/1.2, you may be able to gain an extra half step, but I wouldn't bother with an f1.4, honestly.
    Two points: first, it depends on why he wants a faster lens -- if he's after more light gathering, you're right, but if he's mostly after a thinner DoF, that's a bit different story.

    Second, the degree to which the extra speed is a benefit for a digital sensor depends heavily on the degree of retrofocus in the design. More retrofocus means the light rays are traveling closer to straight back when they get to the sensor, so the extra light can be absorbed better by a digital sensor. Unfortunately, it's virtually impossible to figure that out directly -- even assuming you can find a lens cross-section diagram, without specs on the index of refraction of each element, you can't do it (and I can't imagine them supplying that).

    Fortunately, there is a kind of cheap substitute: a retrofocus design tends to reduce light falloff at the corners/edges. The more retrofocus they use in the design, the less light falloff you tend to see. As such, a design that shows less light falloff at the corners (in general) will also show improved light gathering performance with a digital sensor as well.

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    Re: Fast 25mm to 35mm prime?

    Again, even the difference in DoF between f/1.7 and f/1.4 is virtually invisible. getting a better fast lens is what I'd be after, not necessarily a faster one.

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    Re: Fast 25mm to 35mm prime?

    Exactly, the difference between a 35mm f1.2 Nokton (which will run you about $1000 used by the way) and the $40 35mm f1.7 cctv lens both shot at f1.7 is as different as you can get.

    The Nokton will be razor sharp from edge to edge, while the cctv lens is only mildly sharp in the center of the frame with a heavy vingette.

    Its a cool look, and worth every dollar of the $40 I spent for it, but one I like to use sparingly.

    One really does need to mention what they are looking for, just speed, dof, optical quality etc

    Regarding the 35mm Ultron's, from what I've seen lately, they are selling for higher than the 35 f1.4 Noktons as well due to being quite rare.

    I sold one a few months back for $500 and it sold in a matter of hours after being listed.

    CV does have a 28mm f2.0 which isn't too bad a lens for around that same price


    Best bet would be a Zeiss 25mm, however your looking at around $900+ for one of those. It is however by far the best lens in that focal length you'll find. Much less color shift than the CV offerings

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    Re: Fast 25mm to 35mm prime?

    Quote Originally Posted by jcoffin View Post
    Two points: first, it depends on why he wants a faster lens -- if he's after more light gathering, you're right, but if he's mostly after a thinner DoF, that's a bit different story.

    Second, the degree to which the extra speed is a benefit for a digital sensor depends heavily on the degree of retrofocus in the design. More retrofocus means the light rays are traveling closer to straight back when they get to the sensor, so the extra light can be absorbed better by a digital sensor. Unfortunately, it's virtually impossible to figure that out directly -- even assuming you can find a lens cross-section diagram, without specs on the index of refraction of each element, you can't do it (and I can't imagine them supplying that).

    Fortunately, there is a kind of cheap substitute: a retrofocus design tends to reduce light falloff at the corners/edges. The more retrofocus they use in the design, the less light falloff you tend to see. As such, a design that shows less light falloff at the corners (in general) will also show improved light gathering performance with a digital sensor as well.
    The phenomena that I'm talking about even occurs with fast lenses on DSLRs, which are generally more retrofocus than rangefinder lenses. DxO recently published an article illustrating how the various makes include "secret" ISO boosts under the hood to to somewhat trick users into believing that the differences between wider apertures are linear: http://www.dxomark.com/index.php/Our...s/F-stop-blues

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    Re: Fast 25mm to 35mm prime?

    I'm not a super tech guys at all, so forgive me for my ignorance, but are you guys seriously telling me there in a dusk situation a 1.4 would would give me no extra light when compared to a 1.7??

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    Re: Fast 25mm to 35mm prime?

    Quote Originally Posted by Rawfa View Post
    I'm not a super tech guys at all, so forgive me for my ignorance, but are you guys seriously telling me there in a dusk situation a 1.4 would would give me no extra light when compared to a 1.7??
    Very little if any practical advantage in light gathering power. That's like going from ISO 100 to 130 at best.

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    Re: Fast 25mm to 35mm prime?

    I agree with Godfrey. You'll get 1/3 stop at best, but, depending on the lens/sensor combination, you may not even get that much.

    All of this being said, you may want to get a new 35mm lens for quality's sake.

    The Nokton 35/1.4 is at the top of the heap when it comes compactness, speed and price. However, it does have a classic character and various aberrations like barrel distortion, purple fringing, field curvature, etc. I use my ZM C-Biogon 35/2.8 most of the time and switch to the 35/1.4 Nokton for lowlight and occasional people shots.

    p.s. If you can go up to 40mm, the 40mm Nokton will save you some money.

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    Re: Fast 25mm to 35mm prime?

    Got to remember though that the 40mm 1.4 Nokton, while a little cheaper, has a bit of a harsher overall drawing style and even more of a jittery bokeh than the 35mm, which itself can be overly busy in many scenes.

    Comes down to why your looking for a given lens. If its simply because you need more light gathering ability, then perhaps its worth the tradeoffs, however, if your also going after a certain overall way of rendering, sometimes the faster lens isn't always the better lens.

    Counter intuitive to some, but sometimes a slower lens can actually have a much nicer way of rendering. Case in the ZM35 C vs the f2.0 version. One would assume that the faster lens would look better wide open, with its stop advantage but shooting them side by side, the f2.8 C version renders much smoother, with a better transition and actually gives "better" bokeh and subject isolation even though its slower.

    At the same time though, in a lower light environment, and/or with a camera with limited high ISO abilities, the f2.0 can still prove the more useful lens. When I had my Leica M8.2, which is pretty poor at higher ISO's I actually used the f2.0 lens because 1 extra stop was really make it or break it in terms of ISO settings. On a camera like the NEX which is quite good at higher ISO, pushing the ISO a stop is less of an issue and one can use a f2.8 lens in many more situations.

    Most any lens is going to be a tradeoff though. CV 35 1.2 being an exception I would say because its not only fast, but its also optically very very good. Perfect edge to edge sharpness yet also sharp wide open.

    Does have its disadvantage though in being a bit big/heavy on a camera like the NEX and its $1200 (as new) price tag.

    One might be best served to simply wait for the CZ 24mm f1.7 E mount lens though. Who knows it it will be a real bargin at $699 or if its going to be priced really high, perhaps $1299 ??

    Should perfect quite well though, at least based upon the A mount 24mm, and have a manageable size/weight and of course the advantage of auto focus and I would expect zero color shift and only slight vingetting.

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