Why No 10mm Primes for Crop Sensors or 16mm primes for Full Frame?

Wouldn't it be cheaper to make a 10mm prime lens than a 10-20mm or similar zoom lens? I noticed that Samyang is putting out 10mm F/2.8, but why are they the first. Why is there not any 16mm or 17mm primes for full frame cameras that are cost effective, it must be cheaper to build a 17mm F/4 prime than for a 17-40 F/4 zoom lens. Am I thinking into to this too much or am I on to something.

Well there's several 14mm primes for FF. Zeiss make an 18mm.

jkokbaker wrote in post #15581533
Wouldn't it be cheaper to make a 10mm prime lens than a 10-20mm or similar zoom lens? I noticed that Samyang is putting out 10mm F/2.8, but why are they the first. Why is there not any 16mm or 17mm primes for full frame cameras that are cost effective, it must be cheaper to build a 17mm F/4 prime than for a 17-40 F/4 zoom lens. Am I thinking into to this too much or am I on to something.

I'm thinking that maybe there isn't enough perceived demand to justify it? Even a lens like the 10-22 is too wide for most casual users, and fills the ultra-wide slot for those who really want or need it. It's rare that one needs a fast ultra-wide, and a lens which can be zoomed from wide to ultra-wide is something that there is a definite but specialized market for. If there was a real market for a prime, then there would be more of them available.

I'd say the full frame sensor is reasonably well covered at the wide range.

Off the top of my head, there's a Canon and Samyang 14/2.8's, a Zeiss 15/2.8, a Canon 15/2.8 fish eye, the Zuiko OM 16/3.5 fish eye, Canon TS-E 17/4L, Zeiss 18/3.5, Zuiko OM 18/3.5. Several of these are out of production but they are still available in the used market.

You should also remember the TS-E 17 can also work like a 10.8mm or 12mm (depending on how you orient the shift.)

On crops - I suspect the reason is that zoom lenses are quite adequate and it's difficult to make a prime significantly faster than the available zooms.

Edit - on re-reading the question
Why are there no less expensive options? I'd venture that the cost of manufacture of most lenses with a given optical quality is the same - give or take 20%. Of course, this doesn't apply to lenses with huge optical elements - optical glass is very expensive - but design, prototyping, manufacture, assembly, test, distribution and retail all requires the same infrastructure.

The cynic in me might also comment that there's less money to be made selling cheap items that are "good enough."

It would certainly be cheaper to build the lenses you suggest as a prime rather than a zoom but would there be a market for them?

People investing in wide zooms are fully prepared to accept the optical shortcomings in favour of the flexibility that they offer. The purchasers in the wide prime market demand that the lenses are well corrected for all aberrations. ...the developement and production costs escalate to achieve this.

Bob