[iudex]

2 things: 1) choice of focal length/aperture is possibly more to do with the fact that Pentax already have the optical design for prettysimilar (if not identical )lens from film days, rather than any machievellian scheme to make anyone purchase a much more expensive zoom and 2) don't write-off the IQ of this lens yet - the DA 16-85 is a lens that is very useable wide open, with good sharpness across the frame from the get-go, so if Ricoh can come up with similar for the FF version, the advantage over a constant F4 lens is reduced.

Nobody denies the qualities of 16-85, it´s pretty sharp across the range, but f5,6 is f5,6; e.g. you actually cannot make portrait shots with this lens. And from a universal walkaround lens (main point of which is that I do not bring other lenses) I expect to handle almost all types of shots from landscapes to portraits (at least to some acceptable degree, of course I do not expect portraits like from 77mm/1,8). F4 at 85mm would be acceptable (so-so), however f5,6 is not. And the same applies to shutter speeds: f5,6 at 85mm requires (general rule, not concidering the IS) 1/120s, while f4 needs only 1/60s.
So I do not say the 28-105 won´t be optically decent, but it won´t be very suitable for landscapes (28mm is not wide enough), nor for portraits.
But enough whinning, it´s a kit lens and nobody expects it to make miracles. I believe in the future there will be 3 lines of FF zooms, just like there are for the APSC: 1. fast constant f2,8, 2. constant f4 (or medium-fast f2,8-4) and 3. variable aperture slow zooms (f3,5-5,6). And in the meantime maybe Sigma makes it´s Art 24-105/4 with K-mount.

[Digitalis]

but f5,6 is f5,6; e.g. you actually cannot make portrait shots with this lens.

....really?

it won´t be very suitable for landscapes (28mm is not wide enough)

...really?

[Giklab]

f5,6 at 85mm requires (general rule, not concidering the IS) 1/120s, while f4 needs only 1/60s

U wot m8
85mm is 85mm, whether it's f/5.6 or 1.4.

[D1N0]

you actually cannot make portrait shots with this lens

Ricoh has patented a subject removal algorithm. If you shoot portraits with an unsuitable lens they will remove the subject hence preventing disappointment about insufficient bokehliciousness.

[Kharan]

U wot m8
85mm is 85mm, whether it's f/5.6 or 1.4.

That's the most bizarre interpretation of exposure I've yet seen Not yours, Giklab, but the post you quoted.

Again, this lens makes sense in two broad ways: it'll be the most compact and cheap modern zoom for FF, and also sealed and silent in AF, which will make it a preferred choice for many different use cases and scenarios. It doesn't hurt that in no way will it compete with the new 24-70mm f/2.8.

[iudex]

Ricoh has patented a subject removal algorithm. If you shoot portraits with an unsuitable lens they will remove the subject hence preventing disappointment about insufficient bokehliciousness.

Good one, I gotta say.

[beholder3]

....really?

...really?

Forum posters can only express their own skill level.
Not all people have the same specs.

[iudex]

That's the most bizarre interpretation of exposure I've yet seen Not yours, Giklab, but the post you quoted.

It should have been vice versa, so (given the same ISO) at f5,6 you need 1/60s whereas at f4 you need only 1/120s. My mistake.

[VoiceOfReason]

Nobody denies the qualities of 16-85, it´s pretty sharp across the range, but f5,6 is f5,6; e.g. you actually cannot make portrait shots with this lens. And from a universal walkaround lens (main point of which is that I do not bring other lenses) I expect to handle almost all types of shots from landscapes to portraits (at least to some acceptable degree, of course I do not expect portraits like from 77mm/1,8). F4 at 85mm would be acceptable (so-so), however f5,6 is not. And the same applies to shutter speeds: f5,6 at 85mm requires (general rule, not concidering the IS) 1/120s, while f4 needs only 1/60s.
So I do not say the 28-105 won´t be optically decent, but it won´t be very suitable for landscapes (28mm is not wide enough), nor for portraits.
But enough whinning, it´s a kit lens and nobody expects it to make miracles. I believe in the future there will be 3 lines of FF zooms, just like there are for the APSC: 1. fast constant f2,8, 2. constant f4 (or medium-fast f2,8-4) and 3. variable aperture slow zooms (f3,5-5,6). And in the meantime maybe Sigma makes it´s Art 24-105/4 with K-mount.

You're doing it wrong then.

Also, remember on FF the lens will have the same FOV as an 18-70 would on APSC.

[iudex]

....really?



...really?

Dont act like you don´t únderstand. I meant typical portrait with blurred background. F5,6 on APSC doesn´t really give you much of a background blur.

[pathdoc]

F5,6 on APSC doesn´t really give you much of a background blur.

But we're ultimately talking about a lens (the 28-105) which is specifically designed for full-frame. And for the same focal length, you have to get closer to fill the frame with your subject in the same way - and standing closer is going to decrease your depth of field. Combine that with a distant background, and you should be able to produce an acceptable result.

If you want professional grade portrait quality, buy a professional grade portrait lens.

[Digitalis]

Forum posters can only express their own skill level.

A more global version: some people cannot see beyond their own expectations.

I meant typical portrait with blurred background.

You know not all portraits need blurred backgrounds. And if you've ever taken a portrait with more than one person in it, you need to stop down anyway. At 105mm f/5.6 there will be shallow enough DOF for reasonable amount of separation for decent portraits. Remember we are talking 105mm on full frame, not on APS-C.

[awaldram]

Dont act like you don´t únderstand. I meant typical portrait with blurred background. F5,6 on APSC doesn´t really give you much of a background blur.

Mmmm were discussing FF but to demonstrate your lack of understanding.....

on FF

105mm @ f5.6 subject 10Ft away

Subject distance 120 in

Depth of field
Near limit 114.8 in
Far limit 125.7 in
Total 10.9 in

In front of subject 5.2 in (48%)
Behind subject 5.7 in (52%)

But on AP-c at same distance

Subject distance 120 in

Depth of field
Near limit 116.5 in
Far limit 123.7 in
Total 7.25 in

So for the same shooting distance DoF is 3inches shorter on APs-C fro the same 105@f5.6

for completeness shoot FF 105 f5.6 @10ft and APc 105 f5.6 @12ft and you'd have pretty much identical DoF

[Kharan]

It should have been vice versa, so (given the same ISO) at f5,6 you need 1/60s whereas at f4 you need only 1/120s. My mistake.

Ok.

However, claiming that portraits don't work because you shot them at 105mm and f/5.6 simply doesn't make any sense. You will have less DoF control, sure, but from this to that there's simply an ocean of drama. "Blurred backgrounds", "bokeh", "magical point of light sources" and other maligned words and overused expressions actually depend of two things primarily - how close the photographer is to the subject, and how far away the background is from both. That's it. All this talk of focal lengths and apertures is absolutely irrelevant if you can't first control the other two aspects (in the interest of transparency, I will say that the impact of those two factors becomes exponentially greater with tiny sensors, but is simply moot with a 35mm frame).

[iudex]

A more global version: some people cannot see beyond their own expectations.



You know not all portraits need blurred backgrounds. And if you've ever taken a portrait with more than one person in it, you need to stop down anyway. At 105mm f/5.6 there will be shallow enough DOF for reasonable amount of separation for decent portraits. Remember we are talking 105mm on full frame, not on APS-C.

Oh, now I get it. In the original post I was talking about 16/85mm lens and the f5,6 referred to APSC and you talk about FF. I am of course aware that f5,6 on FF is something different (equals to f3,7 on APSC).
And I was talking about portraits with a background (environmental portraits, is it correct expression?), not studio portraits (I am not a pro with own studio), so fast lens comes handy. So let´s finish this with statement that f4 would be nicer in more ways, that´s all.