glojo Loc: South Devon, England

Many apologies for the time out but I doubt there was much in the distance between gull and squirrel shots. I do have lots of images of squirrels that I have shot with this lens and they are fine. This one however just looks wrong so in the software I use I switched on the optional 'Show Focus point'. This then caused even more confusion.

Final thought.
Could the double glazing influence the focus abilities of the camera?

I am someone that tends to learn from their mistakes so I end up being my own worse critic (my wife hates it when I moan so much about the photographs I have taken)

THANK YOU very much for the input and please feel free to offer any further observations. :thumbup:

glojo Loc: South Devon, England

I thought I would post this just so you know I was not spinning a line and how easy it would be for me to blame my lens. Just look at the bottom right of the image and see how sharp the grass is??

Software as Nikon users will recognise is NikonView NX2

Gidgette Loc: Boerne,Texas

Beautiful picture. Is there any way you can put a wide board across the arms of your chair and then use a short tripod on it? Or how about a table with the tripod? The tripods don't don't have be tall, just close for your use. Hope these ideas will help make your life easier. Wishing you the best.

glojo Loc: South Devon, England

Hi Gidgette,
What a very kind suggestion but sadly I have steel rods in my spine and always have to lay down. I use a wheelchair that is fully reclining so I can manage to raise myself a little. I have tried a few ideas to support the camera but none have been practicable. The tripod must be solid and not prone to any type of movement. To support my lens the legs would have to be spread out and I would always be afraid it might move or slip off of any heavy board??

It cannot be placed by the side of my chair as that means leaning to one side which I cannot do... I tend to accept that a number of my attempts end up in the recycle bin.

This problem we are discussing is the red box which I believe is NOT highlighting the correct area of focus??

I did not put that box where it is.... I believe the Nikon software detects the point of focus from the downloaded camera file and then it highlights it by the use of that box??

I am also of the opinion that the correct location the box should show is down at the bottom right section of the image?? I have NO idea why I would have aimed the lens at that location but it could be the camera was predicting where the moving animal should have been?? (see how I am trying to deflect the blame) Bottom line though is why is that red box where it is?

Thank you very much for the suggestion and if you hear of anything that might meet my requirements of holding this VERY heavy lens then please feel free to give me a shout (it's the Nikon 500mm prime lens which is definitely quite heavy)

Gidgette Loc: Boerne,Texas

Check your camera and make sure "face detection" is off. Put it on "center point". I have the Nikon D90. Go to menu and scroll down left side to Autofocus, then go to Live View center and click on it, then select "center view" for stationary movement or "wide view" for moving subjects. See if that will help it from moving on you. The "face detection" choice is in "Live view" section. See if that will keep the box from moving. I think it is just trying to follow a face or what it detects as a face. Good luck. I'm still learning, but if you moved you f4.5 to about f8, wouldn't you have a farther depth of field? Try it and see if you need to go to f16, just play around with it to see what goes best. Can always delete what doesn't work, at least you will know. Then more than grass would be sharp.

glojo Loc: South Devon, England

Good point Gidgette and thank you for taking the time to respond. My bad for not declaring the name, rank and number of the camera.... note to moderators should we all list in our profiles what equipment we have? :) Fortunately my camera does not have your face detection gizzmo.. It's the D300, I say fortunately as it sounds like something I would not want or perhaps would not use even if I did have it (I'm not into portrait stuff).

I take onboard what you are saying regarding 'F' stop numbers but I use a long telephoto lens and to me I sacrifice depth of field for shutter speed. Hand holding a telephoto lens is not the easiest of skills and I tend to grab as much speed as possible and if the odd image comes out blurred then sadly that is the cost I have to pay.

My only issue with this specific image is where the camera is telling me the focussing point is. That software does not suggest where it should be, it is saying where it is.

Hopefully folks will look at these points as questions as opposed to me stating 'facts'. There will always be a loss of detail as I usually have to shoot through to thick panes of glass. (The double glazing fitted to our patio door)

rpavich Loc: West Virginia

That's not a long way....possibly 3/8" or so between the focus point and the grass that's in focus.

From that one picture , it would appear that your lens front focused a bit.

glojo Loc: South Devon, England

I totally agree but surely the red box should be at the point with the highest degree of focus?

That 3/8" is clearly enough to get the focussing wrong and that is always going to be a challenge. I am wondering if I am failing to describe the issue correctly as I accept the point of focus is NOT the fist, I totally accept that, plus your estimate of just being 3/8" of movement out is more than fair but to me the software is giving incorrect information.

I am not someone that will jump to a conclusion and if the lens is at fault, then trust me, I would be bending the ear of the shop's proprietor. These items are not cheap (how I wish we had US prices). I have just taken a picture of our weather station which is slightly further away than the location of that squirrel but the red box states I have focussed on the writing and to me that looks about right? (question)

Am I being too critical and should I just accept it is 'one of those things' or should the software say what it means and means what it says?

Handheld 500mm 1/500th F8 ISO200

rpavich Loc: West Virginia

Actually no. It tells you where the focus point was.

The auto focus doesn't pick the point of "most focus" it just does it mechanically, and if the lens is slightly mis-matched in dimensional tolerance, then the focus point will be different than intended.

Just yesterday I got my 50mm back from Canon repair service.

I shot a few pics and realized that the point of focus had changed due to the repair.

So I had to adjust it to get it sharp again. (I adjusted my camera's AF adjustment)

glojo Loc: South Devon, England

But surely the fault would be consistent if the lens is mis-matched?

The image I posted of the eye of that seagull is as sharp as you can get and that is where the red box tells me the point of focus is located. Note these are questions and I am NOT disagreeing. All my experience has been that a misalignment or an incorrectly set screw, adjuster etc will not correct itself and then go wrong again unless you are EXTREMELY unfortunate.

This image tells me the point of focus is all but on the eye, the shot was taken through two panes of thick glass, (the double glazed patio door) plus the usual hand held factor. I am quite pleased with this focussing and is it as accurate as I need? (question)

1/500th second F4 and ISO of 800

I am someone that simply takes snaps and am not after a perfect picture but I do not like the 'unexplained'

If you believe this is a case of misalignment and others agree then so be it as I have a very open mind regarding this issue and I am EXTREMELY appreciative of all the excellent advice folks are kindly offering.

I have never really used this focus point referencing before and only used it this time as I was curious as to where I was pointing the lens to get such an awful result.

Is it possible that the camera was doing its predicative tracking, I was following or tracking the squirrel and then milliseconds before I pressed the button, the pesky thing stood still? I would still be lining up on this 'tree rat' but could the camera be anticipating where the rodent should be?? I have only just thought of this explanation but it does make sense

This is a cropped sho of the beak of the latest picture and it might indicate the degree of focussing

bull drink water Loc: pontiac mi.

did i miss world war 2.8 ?

rpavich Loc: West Virginia

Yes, it would be consistent. But...there is slop in the focusing mechanism also...it's not unusual to take 3 shots back to back and have them have a bit of front or back focus....I hate to say that but it's true. Some lenses are worse than others.




You are correct...your results are spotty. The point to operator error rather than the adjustment.

BUT...it's possible that you do have a slight front focus so when you "lean forward" slightly you actually put the focus point farther back and thereby IMPROVE the focus and think that you nailed it... :)




yes...that is very nice for hand held and I'd have no complaints.




You and me both! :)




Thank you very much...It's no problem. It might just be a matter of getting more practice with this lens...it IS a large long lens...





Well...it was only one out of many.






With focusing, it's EASY to have you or your subject or both sway just SLIGHTLY and mess up the focus...trust me...I know. I shoot multiples of EVERYTHING because of this.




Thats pretty good. Especially on something that small.

glojo Loc: South Devon, England

Thank you very much for the excellent and very detailed reply. I am also tending to lean toward human error but it is just that stupid red box telling me where the focus point was on that one, very specific shot. I take aboard what you say about play, or was it slop.

I read on a different thread some criticism of images that are downloaded and I note all the wavy lines and other issues on that last 'beak' shot. They are definitely not on my image but could that be down to the small size of the file? Bottom line though was it highlights how the image is in focus and camera shake is noticeable by its absence! :D :thumbup:

Thanks again for the very constructive observations

John
from the English Riviera :oops:

rpavich Loc: West Virginia

Not a problem John...take a bunch of shots and weed out the bad ones!!

Weddingguy Loc: British Columbia - Canada

Here are a few facts that might help you understand what you are up against with your evaluation of the focal point of the squirrel image.

1) Shooting through any kind of glass can effect your focus, depending on how close to the glass the camera is situated and how clean the glass is. This is NOT the problem here as it would cause the image to be much more OOF.
2) The camera focuses on an area much larger than the little red square that you see in your viewfinder, so trying to focus on a squirrel's eye at that distance is at best a waste of time.
3) Auto focus uses several vertical rows of pixels on the sensor for adjusting focus. These pixels are sensitive to detail and contrast especially in lines that run perpendicular to the rows. If what you have in the little red box area has no vertical lines, or little contrast or detail, then the camera will search elsewhere for those vertical lines, detail or contrast. (like the grass which has lots of lines, lots of contrast and lots of detail. This has nothing to do with your lens, but the method the auto focus uses to focus.
4) Your camera has a number of pre-set focus points. When you ask for the focal point of an image with your software it picks the little red square that was used at the time of exposure by the camera . . . whether it was in or out of focus. It cannot just pick a spot anywhere on the image.
5) If you are trying to focus on a subject with little detail or contrast (that the camera can see) and you have surrounding contrast and detail, especially lines that are running perpendicular to your sensor pixel rows, then the answer is to pick a point of focus with detail and contrast that is the same distance from the camera as the subject, lock in the focus by pressing your shutter button half way . . hold it there . . . recompose your image . . . then press the button the rest of the way to capture it. The other way is to switch to manual focus under those situations.
The reason your gull shot is so tack sharp is because the camera had no other detail in the area to challenge the detail of the gull.

Hope that helps. By the way, great suggestion you received about checking the focus mode on your camera. Center spot focusing is how my cameras are always set.