Completely Dejected (auto focus K5)

It's all good stuff by the sound of it.

link

I don't have a K5 but I do have the other two. Interesting that the Pentax JPEG engine is seen as the best, I only shoot JPEG and both my Nikons are tweaked to match the my Pentax JPEG's (colour wise).

Best regards

But that article isn't about focusing is it?

It was the low light side of it that seemed specific. The K5 gets a good review.

However, your K5 may be faulty. Back to the dealer?

The testing you have done should provide conclusive results, to you at least. No end of comments or input from members here will change your findings.

Best regards

You are correct that the testing is conclusive. Unfortunately, the more I read the more I suspect that it isn't a fault with my camera and therefore returning it will not sort the problem, it seems it's just that the K5 is crap at focusing.

I dare say that a lot of K5 users may not be affected by it, for instance it will not manifest itself in the majority of shots, but I shoot at wide aperture and usually portraits. This means that the bad focusing is pretty evident and I usually try get the person's iris as the focus point but when I typically try that I get blurred eyes and usually a sharp tip of nose or hair in front of the forehead.

But not peer-reviewed

Give us an idea of the EV values you're actually using, the focal length, the distance from subject, and the apertures, and I expect there are a few here that would be up for attempting to duplicate your conditions.

Since without actually returning it, you can't check this bit on your own:

Chris, will do, I'll post some examples tomorrow.

A compact camera with it's small sensor and massive relative depth of field will always 'pee all over' any DSLR when it comes to focussing in the type of situation you refer to. This is one of the primary reasons a compact camera is so much easier to use (but correspondingly much more limited) than a DSLR. Most of the time you don't even need to consider focus because you will simply never achieve a shallow enough depth of field to get an eyeball out of focus when the tip of the nose is in focus. With the depth of field it has to play with, the AF system simply doesn't have to be very accurate.

Of course, if you are talking about one of the interchangeable lens Lumix models which has a 4/3 sensor that's a bit different - but you still can't compare it to a DSLR as the lack of an optical viewfinder allows it to use contrast detect AF all of the time (and last time I read up on it - which granted was a few months ago - these G and GF series Lumix cameras had the fastest contrast detect AF system on the market, by a fair margin. i.e. They 'pee all over' most other cameras in this respect).

I'm a member of 3 different local photography groups, which means I get out and about on photographic field trips with a variety of different photographers on a very frequent basis. My personal experience from working with people using other brands and getting the chance to use them occasionally myself suggest that the Nikons have a slight edge when it comes to AF. The Canons fare about the same as my K-5. This, of course, is purely my personal impression.

I know one particular photographer who owns and uses a pair of Canon 5D MkIIs. He also does a lot of low-light portraiture. He considers the AF to be worthless in this situation and generally gets an assistant (i.e. whoever happens to be around) to shine a torch on the model's face while he focuses manually! Funnily enough his complaint is exactly what you've said in your posts - the camera tends to focus on the tip of the subject's nose.

---If you're still thinking of switching to Canon you might want to think about borrowing or hiring one and testing it first.

This isn't a new issue and it's not an issue that relates only to Pentax, I am on enough non-camera specific forums to note that it is an issue that DSLRs in general seem to have problems over-coming in low light. At least the consumer/prosumer cameras, probably the people using the top of the range CaNikon cameras already know how to over-come this issue.

You can set a global adjustment (and switch it off later) or lens specific adjustment if you spend a lot of time shooting in one particular environment, as it seems you do. If you do a lot of wide-open shooting then you should already know that MF can't be beaten and therefore this particular focusing issue is not therefore an issue at all. I love low DoF and now have two 1.2 lenses to go with the few 1.4 I have .... I rarely use AF for these except when shooting in environments I have no control over.

Accurate focusing with any DSLR just isn't possible

See:
http://www.slrgear.com/articles/focus/focus.htm

I have a similar experience from work and would concur with your findings. Many of my colleagues use Nikon (1 Canon). I get to use a Nikon D3 on a regular basis, the owner now using a Leica M9. The D3 has a slight edge on my K20D AF wise but not enough to bother me, the latest addition to the "Nikon club" as I refer to them is a D7000, I've not a had chance to use it much but the AF system does appear far more sophisticated, whether this will be borne out with better results remains to be seen.

John

It's worth quoting

Also to note that their attempts to focus using magnified live view was within a hair of 'perfect focus' - and I think the camera's AF in live view would be similarly good as it uses the same 'tiral and error' method as your eyes/brain when manual focusing.

You know, several Canon users I know complain of focusing problems but they all seem to accept it as a general DSLR problem. It's only the Pentax users who seem to want to blame it on their brand...

That's an excellent point, actually. I know a guy who used to photograph dance events for a living, and he used Canon. He had a 1D and a 5D, IIRC, and whenever we got on to the topic of AF, his bitching and moaning about the utter uselessness of Canon AF would put the worst of our puny efforts to shame.

After reading this thread I decided to use a gap between family commitments to fine tune the AF of my lenses for use my recently acquired K5.
The ability to fine AF was one of the key drivers for me, as I was always compromised with the K10. On my K10 the DA*16-50 and DA*50-135 both back focused (by differing amounts), but my FA50 F1.4 and FA 31Ltd both front focused. Interestingly on the K5 the two primes required no adjustment, the DA*s were +4 and +6 respectively.

So to the test, firstly I admit that the methodology was rough and ready, but I did take multiple shots on different occasions so for my camera/lens combinations the results are valid and repeatable.

1. Having consulted an EV chart, I noted that EV1 equated to using ISO 3200 @ F1.4 would require a shutter speed of between 1/15th and 1/8th of a second.

2. The subject was a finely printed document from my bank, placed flat on the floor under the shadow of a table.

3. I used FA 50mm F1.4 and FA31Ltd 1.8 wide open at closest focusing distances.

4. I used the fine tuning adjustment on the K5 to monitor its effect.

4. For the 'night' shots the room was lit by a single 16W low energy bulb. Using AV mode with centre spot metering this gave a shutter speed of between 1/10th and 1/20th of a second.

5. For the 'day' shots taken around 7:30am in the morning I used the same setup and waited until the cameras meter indicated the same range of shutter speeds.

Results
1. Both combinations K5/FA50 and K5/FA31 produced acceptable in focus images in both day and night EV1 conditions.
2. Moving the the AF fine setting by + or - 2 produced noticably worse results. Moving the adjustment by + or -4 produced significantly worse results.

Conclusion
I accept that the methodology is not perfect, I did allow time for the lenses to lock on, but there was little if no hunting. The 31ltd was very quick, a big improvement on the K10

For my purposes the combinations are fit for purpose. It is unlikely that I will be shooting down at EV1 levels very often, but it is nice to know that for me personally the results are acceptable.

Regards - Steve

I agree with Mark T's and Pentaxophile's comments. I almost always use manual focus in artificial light, or alternative use the live view in magnified mode if focus is really difficult and critical. I have no complaints about the AF abilities of my Pentax DSLR's although I don't have a K-5, only K-x and K-m.

Regards
David