[Andi Lo]

Take a look at how deep the lens hood is on the FA31mm f/1.8 and FA43 - but you're right, i'm probably over-thinking it (I haven't slept for 33 hours) . But Keep in mind zoom lenses are complex - we don't know all the variables in this particular optical design, which lens groups move for focusing, how far the lens extends and which way it extends as the focal length changes. I agree with the APS-C lenshood can be made longer than what is needed for FX - my sigma 8-16mm f/4.5-5.6 proves this. However, I have an old AF-D nikkor 20-35mm f/2.8 lens from 1996 that has a substantial lens hood on it - with this lens, the deep hood is necessary to be effective at 20mm.

Ah, that just makes a bit more sense. Perhaps at 20mm most of the optical members are deep in the lens, making a hood unecessary.

[causey]

This is a classic Pentax lens. They have made plenty of not so fast lenses through their history with awesome builds, sharp from wide open. But the easiest way to make a lens smaller is to limit its aperture. People are a little obsessed with fast lenses these days, but not everyone needs a Sigma 18-35 f1.8 zoom.

As if everyone needed f1.8 at 18mm. The weight of the Sigma is pretty much equivalent to the combined weight of, say, the new DA 20-40, FA 50 f1.4, Samyang 85 f1.4.

[snake]

This is a classic Pentax lens. They have made plenty of not so fast lenses through their history with awesome builds, sharp from wide open. But the easiest way to make a lens smaller is to limit its aperture. People are a little obsessed with fast lenses these days, but not everyone needs a Sigma 18-35 f1.8 zoom.

Why shouldn't people be "obsessed" with fast lenses?

You also know that fast lenses have been around forever and also have other compositional aspects, outside even the DOF question.

Believe it or not, people are shooting in low light. This was something not possible years ago, but the body is only part of the equation.

[Digitalis]

Perhaps at 20mm most of the optical members are deep in the lens, making a hood unecessary.

It would offer a good explanation for why they made the hood so shallow, if the lens is at its minimum extension at 20mm f/2.8, then the hood should be perfectly adequate as it is - though you do get some lenses like the Canon EF 24-70mm f/2.8L that extend at the wide end of their focal range.

therefore the FF optimized hood must be made shorter.

Then the question is why did they put a hood ideally suited for a Full frame camera on a DX format lens? that would only make sense if the lens was a D-FA lens, but its a DA lens.

Why shouldn't people be "obsessed" with fast lenses?

Some people are obsessed with fast lenses because of the perception is that perform better than slower lenses - which can be disastrously inaccurate.E.G, The Pentax 50mm f/2.5 macro is considerably sharper @ f/2.5 than the FA 50mm is @ f/2.5. One also must take into consideration AF issues - slower lenses don't gain anything from cameras with High precision f/2.8 AF sensors, so using a faster lens is a necessity if you want reliable AF in challenging situations.

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Last edited by Digitalis; 11-06-2013 at 05:15 AM.

[Iberia]

Pentax continues to build on it's collection of foolish focal lengths…cute, but who needs an expensive 30-60mm f2.8-4 zoom?

They like weird numbers so why not make the much needed strandard primes: 19mm f2.8, 23mm f2, 34mm f1.4, 60mm f1.8?

R

[lytrytyr]

why not make the much needed strandard primes: 19mm f2.8, 23mm f2, 34mm f1.4, 60mm f1.8?

Because you can get the FA 20/2.8 and FA*24/2 from Pentax,
the 35/1.4 from Samyang, and the 58/1.4 from Voigtlaender?

[D1N0]

Pentax continues to build on it's collection of foolish focal lengths…cute, but who needs an expensive 30-60mm f2.8-4 zoom?

They like weird numbers so why not make the much needed strandard primes: 19mm f2.8, 23mm f2, 34mm f1.4, 60mm f1.8?

R

Foolish focal lengths do not exist. You choose not to understand the philosphy of the lens so you get angry at Pentax. I suggest you buy into m43's where you can find the primes you want.

[Winder]

It had better be an absolutely amazing lens with lightning fast AF.

[snake]

Because you can get the FA 20/2.8 and FA*24/2 from Pentax,
the 35/1.4 from Samyang, and the 58/1.4 from Voigtlaender?

The first two are not easily available worldwide, particularly in Europe. The former is impossible and horrifically expensive. The latter is typically only available from Japan, used, and very expensive. And, as mentioned by several to many here, it doesn't perform as well as one would expect on a K5. Check the search for examples.

So no, they aren't really available and, for the most part, don't even exist outside of sourcing from around the world as used for horrific prices (same is the case for the FA35 in Europe right now, as I've also posted examples previously of its price going above that of the FA31 and 700EUR used being now a norm).

[StigVidar]

cute, but who needs an expensive 30-60mm f2.8-4 zoom?

It's 20-40mm ........

[Digitalis]

and the 58/1.4 from Voigtlaender?

That lens was discontinued some time ago.. as a consequence, the prices for this lens have gone up.

[thibs]

This is a rich one and pretty hard to swallow, considering the years of LULZ that SDM failures are giving us (and counting).

Really? Pentax screwed up so others can't have issues with their own version of the tech?
He said the most common Canon lens repair reason is due to the motor failure, he never said the that Canon had proportionally any comparable or higher returns than SDM c**p. He only said it was the first reason for repair.

[Iberia]

Pentax continues to build on it's collection of foolish focal lengths…cute, but who needs an expensive 30-60mm f2.8-4 zoom?

They like weird numbers so why not make the much needed strandard primes: 19mm f2.8, 23mm f2, 34mm f1.4, 60mm f1.8?

R

Because you can get the FA 20/2.8 and FA*24/2 from Pentax,
the 35/1.4 from Samyang, and the 58/1.4 from Voigtlaender?

All those lenses are big and heavy full-frame designs.
Besides, the first two are no longer available and the other two are manual-focus.

R

[lytrytyr]

All those lenses are big and heavy full-frame designs.

You're taking a light-hearted response to a presumably light-hearted post too seriously.

But, since you mention it:

Besides, the first two are no longer available

They're both available right here:

Pentax Autofocus Fixed Focal Length Lenses - KEH.com

and the other two are manual-focus.

Indeed. Your point?

[Rondec]

Why shouldn't people be "obsessed" with fast lenses?

You also know that fast lenses have been around forever and also have other compositional aspects, outside even the DOF question.

Believe it or not, people are shooting in low light. This was something not possible years ago, but the body is only part of the equation.

I like fast lenses -- I own two of the FA limiteds and the DA *55. But just because a lens has f1.4 doesn't mean that it is sharp. My copy of the FA 50 f1.4 certainly wasn't sharp till f2.8. I owned a Sigma 30mm f1.4 that was really poor in the corners to f4.

Fast lenses were created to allow photographers to take photos in low light, but my experience in most situations with modern cameras is that you are better off stopping down a little and pushing your iso a little than the reverse.