Torn between the 35mm/f1.8 to the 40mm/f2.5, autofocus differences?

Started 10 months ago | Discussions thread
JpGomez Contributing Member • Posts: 550
Re: Torn between the 35mm/f1.8 to the 40mm/f2.5, autofocus differences?

eeran wrote:

I know, and Im sorry in advance for opening yet another thread about those two lenses.

I read them all. at least twice.

Im super conflicted.

I have no where where I can rent and try at my area, unfortunetaly, so that all sums up to buy and try.

I own the a7c with the marvelous, yet heavy-duty (for me), sigma 28-70/f2.8.

I love the camera, I live its functionality, I love the sigma performance. I really do.

I take photos of my kids/family, the main purpose is general all-purpose use for events, family trips etc.

I hate using a flash, I love natural light.

I shoot indors quite a bit, or during the evening and night where big aperature is key.

I do alot of short videos, nothing too professional (relying on the gyro to stabilize), but I dont know how critical focus breathing is for me in this case (which is the benefit of the 35mm compared to 40mm that really changes focal length)

I love the flexibility of the zoom lens, yet f2.8 sometimes makes me need to bump the ISO quite a bit, and with the weight/size of the zoom I thought of getting a single prime at a focal length of 35mm or above, but not too much above, because it may be too much since usually - given that most of my pictures are either enviromental portraits, and indoors, 50mm or above would be simply too much.

So my conflicting sums up to this:

1. The 35mm being widely known to be excellent lens, larger aperature, good autofocus, which is very important to me due to having my kids running around, I want a good fast af motors to deliver. and from reviews it seems to be very sharp in center even wide open.

2. the 40mm is super compact and small, 2cm shorter and 100grams lighter seems significant to me. its wheather sealed, it has dual af motors, which sounds to me even a more significant upgrade to the focusing speeds (or does it not come into real world difference?). Problem is that I feel that being "just" f2.5, is too close to the light performance of my current sigma, so I benefit only weight/size, which is nice but I dont know how substantial difference it is in reality.

I think that if the 35mm had the dual linear motors as the 40mm it would be simply a debate on the extra 2cm/100grams, but the 40mm does have that edge.

Aperature ring - not too bothered about having it or not. programmable button exists for both. focus ring as well.

Do you think the AF speeds is significant between the two?

Now that Sony started to release lenses with focus on size/weight and improved focusing technology, it makes me feel that maybe its not the most wise decision to get a lens dated to 2019, maybe soon enough they will refresh the line with something else?

Not to mention, that it is still highly priced at 750$.

Regarding other lenses in the market like the samyang or sigma - I read other reviews, and I feel that I want a sony prime simply for its better performing focus and simply because the reviews seems to be very positive on these two.

I would pay an extra 100$ right now to have a 40mm/f2 or something, with the same size/weight (+-) just to free me from this debate with myself about what lens to by

I have FE35 1.8 but also have Samyang 35/2.8 (its dirt cheap) for the occasional ultra portable setup.

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The best gear is the one you have at that moment.

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Sony a9 Sony 1.4x Teleconverter (2016) Sony 2x Teleconverter (2016) Sony FE 100-400mm F4.5-5.6 Samyang AF 85mm F1.4 FE +2 more
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