So What Would You Do if You Were Me?

So where do i go from here then guys if the shoe was on your foot?

Lots of tests have been done now and its pretty obvious that once again there are issues with some or all of my gear.

50mm f1.4 improves greatly at -10 Focus Adjust but still seems to be begging for more.

16-45 - seems to want -8 focus adjust.

Sigma 120-400mm or is it 70-200 f2.8 or is it 150-500mm - Seems to be no improvement with Focus adjust at any setting but in order to get acceptable results it really needs a minimum f8-f9 which if we are being totally frank you would get great results with any lens at those apertures.

I was looking over some older pictures when i was doing the Photome Lens ID test and came across a few Sigma 100-300mm f4 EX DG pictures.
The 100-300mm is a lot sharper at f4 than my 120-400 is at f8.
I realise its not a proper comparison due to several factors but when you see how good sigma lenses can and should be it makes you wonder whats gone wrong.

Having rad your various posts I'm not sure if you have successfully used the in camera adjustments to get any/all lenses sharp. I thought you could get at least one to focus sharply and reliably. So adjust for that lens then move onto the next as you have under 20 lenses?

That's the only facility the the K20D has that would make me want to change from a K10D as I'm sure some of my lenses would look better if I could adjust the camera focus for each of them.

Also for what it's worth I thought my primes (apart from the beloved 35 f2) were all out on focus until I realised how careful you had to be to establish a good focus each time. You definitely couldn't just point and shoot. The same is true of the 10-20 Sigma. It will say it has a focus but with a bit of bullying it gets a better focus that's actually very sharp.

I think I'd be much more analytical in your position and spend ages assessing each lens and applying adjustments until it works to my satisfaction. I know you've done a cereal packet test but have you done a brick wall test. On sturdy tripod, no breeze, 2 second delay, ideally fire with remote can you ever get the bricks all sharp? Bear in mind the cereal packet is slightly reflective.

Camera shake is a killer in these situations in my albeit limited experience.

Mike

i think you have to try another camera seems to me all your lenses are way out, maybe try find someone who has a pentax, or pick your self up a cheap second hand body, always comes in handy for this, but i cant see all the lenses being that fare out,

I really dont think you can compare the 100-300mm f4 to the 120-400mm in any way shape or form. As I said in the other thread I have the 135-400mm Sigma which is the predecessor to the 120-400mm and was never that impressed with it .. especially when you compare it to my 50-500mm DG EX .. its like night and day.

If you want me to do some test shots with my 135-400mm I am quite happy to do so then you can compare them.


Saying that if you think the 50mm needs more adjustment than the K20D can give then I would be chucking it back for a replacemet (the camera body).

Maybe you could be the first to try whether the 'Apply to all' or 'Apply to one' adjustments are cumulative? That might fix your problem if they are.

Also, I know you've taken pics of cornflake boxes but what about other 'real world' images? What are they like.

Personally, I'd continue testing, adjusting, and retesting with just one lens until I was happy with it.

FWIW, my FA50mm front focusses quite badly wide open and the images look very soft. The softness is expected, the front focus is adjustable and needs -10 to sort it.

Also, if you do have a real problem and you need to refer to Pentax, make sure you have a totally Pentax combination as I doubt very much that they will have any sympathy for results from the Sigma.

I have sevearal DA* lenses and they all focus differently and require individual adjustment. The K10D just can't deal with them all and I've set it to suit my walkabout lens, the DA* 50-135mm.

This issue is not peculiar to Pentax, all the DSLR manufactuers have the same problem but AFAIK only Pentax and Nikon have a facility to deal with it in-camera. I just wonder if we always had it in the days of film.

PS: As Mike-P says, you can't compare the prosumer Sigma 100-300mm EX to your other consumer Sigma lenses. They are like chalk and cheese.

I agree with Scott start with a new body and go from there, it's a pity no one lives near you with a K20D..

Some tests with the 135-400mm would be nice.

I wasnt comparing the 100-300mm with the 120-400mm, i was just pointing out how vastly different they were. I wouldnt expect the 120-400 to compete with the 100-300 f4.

The 50mm was 100% spot on with the other 2 cameras i had so i dont think its the lens.

Took the 120-400mm out into the garden this morning. Lovely sunshine, lots of birds feeding. Took over 50 shots at f5.6, f8 using 0, -10 and +10 focus adjust..All deleted, none worth even trying to PP. NB.. Will go shoot some more as i just noticed i had SR on while on a tripod.

I dont think theres much point in doing any more tests on cereal boxes, charts, bricks etc as the lenses will never be used for that purpose so they need to be able to perform in the Real World.


Can only wait until tomorrow and give Sigma and Pentax a call and ask their thoughts.

Canon have the AFA in camera as well, up to 20 lens +or-20,

Sorry, changed my post , obviously meant the K20D

Didn't know that, thanks.

That just shows how sloppy they make Canon bodies if they need to allow that sort of compensation.

well if the lenses were ok with the other 2 cameras both k20ds, now the third k20d there way of, it says to me that the camera is at fault, and you must be the unluckiest person i know

Its actually quite interesting that the new Pentax fit Sigma HSM lenses seem to be having a lot of manufacturing problems, especially when compared to their older models.

Take Scotts 150-500mm compared to the older 170-500mm, totally different in every respect, When I bought my SIgma 70-200mm f2.8 I went for the older APO EX version rather than the new HSM version because it is reportedly soft at 200mm wide open.

There is a lens rental company that does mainly Canon and they have all but stopped buying the long Sigma zooms because they were getting somthing like a 70% fault rate .. the worst one being the 150-500mm.

thats right the 150-500mm i had i didn't find sharp at all, also slow focusing, on both my k200d and k20d, and both the 170-500mm have been sharp as a tac on both cameras, it will be interesting when i get the 150-500mm back to see what that is like, not holding my breath,

If you are having to make such "large" alterations in settings for "all" your lenses, I would say it's a camera fault!.....I would take it back, fullstop!...........Ken