[Wesbo]

Keep in mind that the sensor on your Fuji s100fs is 2/3", so it has a MUCH easier job of keeping things in focus than does the K-X, which has a sensor about 9 times as big.

This link has a comparison of sensor sizes...

Digital Camera Sensor Sizes: How it Influences Your Photography

I was a little startled when I first got a DSLR as well... I finally figured out that I had almost never seen any of my film images larger than 4x6 or 5x7, so it was unfair to compare them to a 10mp image blown up to 100% on my monitor.

[Nightwings]

I don't understand any paranoia. It's just a camera, not some sort of magic box. Relax a little.

I know ....

And you do understand that the end-to-end sharpness you are seeing with your Fuji may have as much to do with the vastly deeper depth of field you get out of a smaller point and shoot's sensor than any wonderfulness of the Fuji AF.

Absolutely, but it doesn't take away from the fact that I have zero fear that my image will be out of focus when I pick up the "pig" as I like to call it.


I also presume that you have been conducting your K-x AF tests with spot focus (ie using the centre AF point only), not any other mode. You need to do it that way for your results to be reliable and consistent.

Yes sir, as a matter of fact, I shoot Center AF all the time.

[kyteflyer]

Thanks for the tips guys .... I guess I will have to use a target further away. ... And depending on the type of target .... seems to affect the results. But yes, I will be doing further tests outside. The K-x is my first digital DSLR and now that I can pixel peep, I guess it gets me paranoid .. the type of paranoia I never experienced with my film SLR's. On the other hand ... My FUJI S100fs is smack on ... razor sharp focusing one end of it's 14x zoom to the other. As much as I like the K-x .... they'll have to pry my S100fs from my cold dead hands

Be aware also that the move from a bridge camera to a DSLR can be trying, at first. I switched from a Fuji S8000fd to a Pentax K200D and it was 3-4 months before I realised that my expectations needed to be different, as did my way of shooting. Once I got that, I just concentrated on doing the best shots I could. I sold the Fuji 6 months after the purchase. I have a new bridge cam but its only for those times when I really don't feel inclined to carry the full kit, or when it would be inappropriate to do so.

[Nightwings]

Be aware also that the move from a bridge camera to a DSLR can be trying, at first. I switched from a Fuji S8000fd to a Pentax K200D and it was 3-4 months before I realised that my expectations needed to be different, as did my way of shooting. Once I got that, I just concentrated on doing the best shots I could. I sold the Fuji 6 months after the purchase. I have a new bridge cam but its only for those times when I really don't feel inclined to carry the full kit, or when it would be inappropriate to do so.

Yes, I've come to that realization as well.

I did notice that you have the tammy 18-250. Part of my reasoning for holding on to my s100fs is that ..... I haven't seen an all in one zoom for the Pentax that I can be happy with. ... though I've only been going by resolution specs/reviews. The Fuji's 28-400 has stunning tack sharpness throughout it's range. How happy do you think I'd bee if I took the plunge to the 18-250? According to the review's I've seen (resolution tests) .... it drops off significantly on the soft side in the upper zoom range.

[Marc Sabatella]

So does the Fuji. Photzone is just pickier than you about resolution. But the Fuji will continue to present the illusion of higher sharpness both because it has much larger DOF but also because it probably has extremely high in-camera sharpening settings.

[Wesbo]

I really, really like my 18-250... It is on the camera almost all the time. Here's its section on PPG:

PENTAX Photo Gallery

You can actually rent one of these from cameralensrentals.com if you'd like to give it a spin before putting out the $$.

[dtsui]

I had similar experience on my K7. I used to adjust the AF under tungsten light using a focus chart. However on field tests of far away objects focus is always off by a margin. I found that a better way is to adjust AF using far away subjects (just tune AF until subject is the sharpest, I usually focus on number plates), it is then good under tungsten light as well (haven't recheck whether it is exactly spot on with a focus chart) but at least it is sharp under field conditions.

David

[Nightwings]

I really, really like my 18-250... It is on the camera almost all the time.
You can actually rent one of these from cameralensrentals.com if you'd like to give it a spin before putting out the $$.

Well, this is not my first copy of the K-x - I did have for a couple of days a Pentax 18-250 and a Pentax 55-300 - I found them both to be soft lens at the high end.

[Marc Sabatella]

You'd have to post controlled comparison shots aganst your Fuji if you expect anyone to believe the 55-300 actually performs worse.

[Internetpilot]

All of this is a little over my head (just a little -- I'm following it), but are we sure this is a focus problem or is it a soft lens issue? Again, I'm not expert in this, but wouldn't it be a bit more logical for it to be a soft lens issue when the focus only "malfunctions" at one end of the zoom or only on one lens?

My 18-55mm kit lens was soft, which is saying a lot because I don't tend to notice these things. I replaced it with a Sigma 18-50mm f/2.8 and I have no "focus" or "soft" problems with that lens or the 55-300mm kit lens.

Just throwing things out there -- feel free to disregard or correct me on my opinion.

[Nightwings]

Now that I've done the focus tests correctly .. about 3 to 5 meters ... outside ... I've found that the 18-55 was in focus all along as well as my F 50mm 1.7 prime. ..... End conclusion.. the 18-55 is soft at the 55mm mark. When I had the two long zoom Pentax's, the softness at the high end of zoom was worse than the kit. Sorry I don't have comparative samples... I erased them all in disgust

[Marc Sabatella]

Chances are, then, you simpy did not perform a well-controlled experiment (eg, you missed focus, didn't have a steady enough tripod, too low a shutter speed or too high an ISO, etc).

[rawr]

I haven't used the 18-250 but have the DAL 55-300. I have also had a frustrating experience with telephoto zooms. Over the last year I've used 4 different consumer-grade zooms in the 300mm-ish focal range (2 Sigmas, 1 Tamron, and the Pentax). One of the Sigma's and the Pentax were good performers and are my keepers.

At 300mm the DAL 55-300 is reasonably sharp wide-open but it is sharpest at about f8-f11, focal lengths at which you also get a workable DOF out of it too, which improves the impression of sharpness. I'd have another look at that lens if I were you.

With telephoto focal lengths like 250 to 300mm (and above), the biggest contributors to lack of sharpness may not always be (a) the optical properties of the lens so much as (b) the greater scope for blur due to camera shake with lenses of that length, as well as (c) the greater scope for missing focus due to the razor thin DOF telephoto lenses can have, and (d) the image softness that comes from the high-ISO the camera will sometimes select when using a stopped-down slow zoom in order to meter the scene correctly. It can sometimes be hard to separate (a) (b) (c) and (d) with long telephotos in assessing which lens is working well.

[orlovszki]

Thanks for the tips guys .... I guess I will have to use a target further away. ... And depending on the type of target .... seems to affect the results. But yes, I will be doing further tests outside. The K-x is my first digital DSLR and now that I can pixel peep, I guess it gets me paranoid .. the type of paranoia I never experienced with my film SLR's. On the other hand ... My FUJI S100fs is smack on ... razor sharp focusing one end of it's 14x zoom to the other. As much as I like the K-x .... they'll have to pry my S100fs from my cold dead hands

I also had a Fuji, a Finepix s7000. Much older than yours. It is also razor sharp. Even from 1 cm distance made brilliant macro pics. Only concern was the slow AF. But if compared with Pentax K-x in live-view mode, the good old S7000 is many times faster. (Sometimes i feel pity why not choosing the finepix S100Fs instead). Plz do not throw stones over me. I like my Fuji is I like my Pentax. I am a Pentaxian as this is my 5th slr. And yes, it is nonsense to compare apples and pears.
My former K-m had the same - slight - focusing problems too. might be because of lens quality. Anyway, my best lens is an old manual 55mm. It takes time to select aperture, speed and focus, like in the good old days, but the result is much nicer.