[vonBaloney]

You really need to test the other apertures to see what is going on. In theory this lens should be even better than the 250-600 at the same apertures -- if it isn't I'd say it definitely needs some adjustment. (I'd hate to send such a rare beast back if it only needs some competent tinkering.)

[osv]

Anyways, I started comparing the two lenses, and I found that indeed , I think there is a problem with this copy of the 600/4...
I checked for any back or front focus issues, and I found that the FA600/4 might have a need for a +4 Back focus adjustment, but anyways, this is not the problem I am seeing, it's the kind of softness, or "haze" I get that bugs me...

did you shine a flashlight through it? and bounce the light off of the inner elements at an angle, at both ends? if it's hazy, you should be able to see it... compare what you see with how your long zoom looks.

it should go without saying that testing a 600mm lens at 1/100th is not a good idea... you should be doing it at 1/1000th bare minimum, *no ibis*, to eliminate variables, which it looks like you finally did do in the last couple of pics.

[Weevil]

did you shine a flashlight through it? and bounce the light off of the inner elements at an angle, at both ends? if it's hazy, you should be able to see it... compare what you see with how your long zoom looks.

it should go without saying that testing a 600mm lens at 1/100th is not a good idea... you should be doing it at 1/1000th bare minimum, *no ibis*, to eliminate variables, which it looks like you finally did do in the last couple of pics.

Thanks for your comments
yes I know but I used those low shutter speeds were for indoor tests in not the best light conditions, but it was stable on the tripod, and triggered with a wired remote...
all outdoor were shot at 1/1000s or maybe some at 1/800, But not less than that..

[JeffB]

I appreciate you likely made a substantial investment in this glass. But I feel there is often misconception about the purpose of large aperture lenses. The primary purpose is not for background blurring bokeh and shooting tack sharp at maximum aperture. They are designed to improve autofocus performance by providing maximum light to the focusing system. Every lens I have ever heard of or used has better optical performance somewhere in the middle of its aperture range. I never shoot lens at their maximum open aperture unless I absolutely need to achieve a particularly high shutter speed. Fortunately current digital sensors let us shoot relatively high ISO so I normally shoot f/2.8 lenses at f/4, f/4 lenses at f/5.6, etc.

It is definitely worth taking the time to properly test your new glass for back or front focusing issues that you may be able to correct for in the camera.

[vonBaloney]

I appreciate you likely made a substantial investment in this glass. But I feel there is often misconception about the purpose of large aperture lenses. The primary purpose is not for background blurring bokeh and shooting tack sharp at maximum aperture. They are designed to improve autofocus performance by providing maximum light to the focusing system. Every lens I have ever heard of or used has better optical performance somewhere in the middle of its aperture range. I never shoot lens at their maximum open aperture unless I absolutely need to achieve a particularly high shutter speed. Fortunately current digital sensors let us shoot relatively high ISO so I normally shoot f/2.8 lenses at f/4, f/4 lenses at f/5.6, etc.

It is definitely worth taking the time to properly test your new glass for back or front focusing issues that you may be able to correct for in the camera.

That's all true, but all of the other Pentax premium long glass that I know of is decently sharp wide-open. However, f/4 is VERY fast for a 600 (relatively faster than f/2.8 at 300) -- the closest "equivalent" in another Pentax lens would be the Pentax-A* 400/2.8, of which I've heard is reasonably sharp at f/2.8, and of course the other 600/4 F version. (And I know from direct experience that the Pentax-A* 300/2.8 is very sharp wide-open, as well as the A*600/5.6.) So while I wouldn't expect miracles at 600/4, his examples look pretty soft and ghostly. I'm very much curious how the lens performs at f/5.6 - f/11. If not extremely sharp, then something is wrong. (There must be a few other people that have these monsters that can chime in?)

[oneill]

Yes please... I also asked @oneill to have a look...

Hi Weevil,

Further to my PM, I got off my iPad and I had a good look at your sample comparison images. This is a serious and unacceptable out of focus problem. I could not see anything in focus, but nothing had depth so I could see where it was focusing. judging by the small bird I would suspect front focus. I used my FA*600mm at F4.0 almost all the time, since about 1996, and although it was sharper at F5.6 or F8 it was still good wide open. When I did a LensAlign test on it I was right on the edge of the adjustment range at 9. Here are some suggestions that will take out the guesswork: You are using exceptionally good support equipment and I don't see many people using "long lens support" from Sunway, Hegnar, or Really Right Stuff. It makes a difference!

(1) Do a LensAlign test at a minimum of 50 feet (which they suggest for that lens)
(2) Definitely use their FocusTune software as it takes your subjective sharpness analysis out of the equation. Keep in mind that your DOF at that distance is just 4"
(3) Follow their "best practices" instructions, de-focusing between shots. THE SAME WAY EACH TIME
(4) Make your final micro adjustments and do a complete re-test.

When it is properly adjusted your wide open shots shout be acceptably sharp at 100%, particularly with the K3, and should be razor sharp at F5.6 and F8.0. If not there is something wrong with the lens. I don't think there is anyone in North America that will do a CLA on that lens. Eric said he will only do up to 500mm and I was told by Pentax that they do not have an optical bench to work on that lens in Canada, and I assume in the US as well, as when I dropped mine I had to send it to Japan, I don't even want to recall the freight cost, but it was more than the repairs..

It is older optical technology, but I always considered it "sharp" wide open. You are experienced, use best long lens practice and if the lens is properly micro adjusted, and not acceptably sharp, or if it can't be micro adjusted there is something wrong with the lens. As I mentioned in my PM I am using my DA560mm F5.6 a lot in the past year and like your FA250-600 it is incredibly sharp wide open and I think it has an edge on the FA600, not to mention the weight

If you want to talk send me a PM and I will give you my number.

Have a good one!

Murray

[osv]

Borrow a good mirrorless and manual focus using 10X/peaking etc and test again.

that's what needs to happen here, if nothing else do it with live view in the lcd.

doing lens align and af adjustments this early on is adding variables into the testing procedure... you need to first establish whether or not it's sharp, period, and mf is the best way to do it.

that said, shooting text objects at an angle should show something in focus, if the af is close to being right... i adjusted the tamron 150-600 that way, seen here at 200mm, after microadjusting at 600mm, it's pretty close... shooting text objects on a longer surface gives you more leeway, if the af is way out of adjustment.

when you shoot flat centered objects dead on square, it's hard to tell which way the af needs adjusting.

Attached Images

View Picture EXIF

File Date

 

[gmans]

that's what needs to happen here, if nothing else do it with live view in the lcd.

doing lens align and af adjustments this early on is adding variables into the testing procedure... you need to first establish whether or not it's sharp, period, and mf is the best way to do it.

that said, shooting text objects at an angle should show something in focus, if the af is close to being right... i adjusted the tamron 150-600 that way, seen here at 200mm, after microadjusting at 600mm, it's pretty close... shooting text objects on a longer surface gives you more leeway, if the af is way out of adjustment.

when you shoot flat centered objects dead on square, it's hard to tell which way the af needs adjusting.

A carpenter folding metre ruler makes excellent lens align tool, set up on a slope and use the centre hinge as the focus target.

[goubejp]

I remember that when I tuned AF I observed some focus shift when the lens was stopped down. So I calibrated focus for optimal performance at f7.1 or something.
Note that using this lens requires a good technique, it took me 6 month to get tack sharp shots in the field. I used bean bag to stabilize the lens and electric remote control.
I have sold the lens to go Nilon mainly to get much lighter lenses - the 600f4 FL series weights half the weight of the Pentax ! I now use mainly 400 f2.8 and 800 f5.6 lenses, both are sharp and usable wide open but have their optimal performance when stopped down 1 stop.

[Ducatigaz]

I have been using my FA*600mm mostly at f6.3 ,it is quite tricky to use ,keeping it still is the main problem also as mentioned above DOF is very shallow wide open.
When we get a sunny day I will take a few shots at f4 to see what its like.

[Weevil]

This PM I tried it again at a bird feeder, and I took 50 shots, between f5.6 and f11, 1/800 to 1/6000, iso 100 to 400, and none of them were sharp, except the ultimate shot I decided to take with the flash at 1/6000 F11 ISO400 that is acceptable...
It was a bit cold outside (-7C), but not that bad (I let the lens acclimate to the cold gradually in the case in my car for a while to make sure that there was no haze cause by possible condensation, and I always do the same thing with my FA250-600, idem for when I go back home... and there always a lot of silicagel pouches in the case to absorb any humidity).
I dont know if something could have happened in the shipping... or before, because that lens used to be dropped, because the lens hood has been notched (attached the photo from the listing)... Also, the screw drive system is doing a strange noise, especially under the cold (my 250-600 doesn't do that) so.... anyways, I am giving up on that lens and going to return it...I contacted the seller, and requested a return that was accepted
Yesterday I thought that I would maybe be better get the DA560F5.6 as a fixed long focal for the better portability, speed, and digital design and price advantages...
Thanks to all for your advices, I learned a lot again because of you and I appreciate very much all your knowledge!

[vonBaloney]

This PM I tried it again at a bird feeder, and I took 50 shots, between f5.6 and f11, 1/800 to 1/6000, iso 100 to 400, and none of them were sharp, except the ultimate shot I decided to take with the flash at 1/6000 F11 ISO400 that is acceptable...
It was a bit cold outside (-7C), but not that bad (I let the lens acclimate to the cold gradually in the case in my car for a while to make sure that there was no haze cause by possible condensation, and I always do the same thing with my FA250-600, idem for when I go back home... and there always a lot of silicagel pouches in the case to absorb any humidity).
I dont know if something could have happened in the shipping... or before, because that lens used to be dropped, because the lens hood has been notched (attached the photo from the listing)... Also, the screw drive system is doing a strange noise, especially under the cold (my 250-600 doesn't do that) so.... anyways, I am giving up on that lens and going to return it...I contacted the seller, and requested a return that was accepted
Yesterday I thought that I would maybe be better get the DA560F5.6 as a fixed long focal for the better portability, speed, and digital design and price advantages...
Thanks to all for your advices, I learned a lot again because of you and I appreciate very much all your knowledge!

Definitely sounds like it has some issues! Which means there still could be another copy in your future! Slightly but not completely off-topic, here's an interesting local (to me) craigslist ad:

The 'ULTIMATE' Photographic Shooting Platform!

[Driline]

Definitely sounds like it has some issues! Which means there still could be another copy in your future! Slightly but not completely off-topic, here's an interesting local (to me) craigslist ad:

The 'ULTIMATE' Photographic Shooting Platform!

I'm pretty sure that's a 5 chime train horn.........

Youtu.be

Youtu.be

[dane.dawg]

Well at least you get to return it.
No interest in the Sigma 500/4.5

[Marc Langille]

Glad to hear a positive outcome on this matter.

Feedback from Mark:
"The 600 f4 was always soft wide open. The only time it was ok for me to shoot f4 was when the target was not moving. It was very easy to misfocus when the depth of field was so slim."

EDIT: Mark also shied away from the 560mm for his needs: "...That thing could never be used for sports because it has misfocus issues and awfully slow"
Things may have improved on the focusing issue, he may have tried a bad copy, not sure?

I concur about the narrow depth of field issue, in addition anything else that may be going on with the lens.My subjects were often less than 6m/20ft away, often very small. I'll probably end up buying the 150-450mm as a excellent long lens option for travel.

Hope that helps!
Marc
PS. I had a focus issue happen after selling/shipping my FA* 300/2.8 to a forum member. It was well packaged, but one never knows how it was handled.