What is your standard prime?

Started 3 months ago | Discussions thread
blue_skies
blue_skies Forum Pro • Posts: 12,127
Re: What is your standard prime?

José B wrote:

Martin_99 wrote:

José B wrote:

WhoKnow wrote:

Why FF lenses will be faster in AF? I always thinking it have slightly bigger and heavier glasses, which is harder to move for focusing and thus it should be a bit slower.

P. S. Very interesting rating, because Sigma 60 2.8 I could get here used only for $100, compared to $320 for Sigma 56 1.4 and $200 for Sony 50 1.8 also used.

I don’t know if I could come to a conclusion on this with only one lens. But my 50/1.8 OSS was slow to focus and thus I ended up trading it in for the Sony Zeiss Sonnar 55/1.8 which is a FF lens. The Sonnar focuses fast and it is clearly my fastest lens when it comes to focusing. Not only I use it for model shoots but also for sports and indoor entertainment.

I would say, that it more relate with price than format. You are comparing $360 VS $1000 lens.

I still have 50mm OSS, on newest gen. body is AF speed fine IMHO. Surely not on the level of of newer lenses with linear motors, but better than eg. new Tamron f2.8 primes or old Sigma f2.8 primes.

For sure it’s one of the perks of the premium lens. I also love the rendition of this lens certainly one of my faves.

+1, sharper than the 50mm, but again, no OSS.

As to focusing speed, yes, lens pricing is a good indicator - the higher the price the faster the focusing.

Lens focusing motors for mirrorless, afaik, come in 3 types:

SAM - Smooth AutoFocus Motor

SSM - Super Sonic Motor

XD LM - eXtreme Dynamic Linear Motor

XD is only found on the new FE24GM/1.8 and FE400GM/2.8.
SSM is both faster and more silent than the SAM, which in itself is speedy and quiet, just not at the same level. SAM also indicates plastic build and parts - ie. cheaper lens (construction).

Sony does also mention the STM (Rokinon uses this), RDSSM (FE70200GM/2.8, FE85GM/1.4), DDSSM (FE100400GM), as sub-types.

https://www.sony.com/lr/electronics/alpha-lens-technology

also consider:

https://briansmith.com/sony-a7-a7r-a7s-lens-guide/

Yes, the more expensive the lens, the faster, more silent, and more precise the motor will be.

For AF at small apertures, yes, the aperture will open up first, measure the AF, then reset and focus - there is a minimum delay for this - on all lenses.

The AF method changed with the A6000 model and beyond, albeit that some upgrades came in firmware upgrades. It resulted in faster focusing for all lenses.

Macro lenses tend to focus slower, as they have more precise control, and some faster lenses may also focus slower because of the extra precision needed (using a bigger lens element to focus).

The focus algorithm, CDAF, PDAF, C-AF, S-AF, etc., also plays a role. As does lighting and subject placement as well as focus zone method.

BTW - pricing relates to AF performance in non-Sony branded lenses as well. The more expensive the lens, the more likely it has a faster and quieter motor.

Below is a technical explanation between stepping and linear motors: stepping motors rotate in fixed increments, whereas linear motors move in fixed delta (linear) wrt/ the lens:

https://www.fredmiranda.com/forum/topic/1694901

There are more posts as to durability of all such lenses. I still have mechanical lenses that work fine after 30+ years, and one wonders if electronic lenses will do the same.

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Cheers,
Henry

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