105mm VR Focusing "Problems"

[fv18m]

Hello Guys & Gals,

got my 105mm recently. Seems to have an issue when I am shooting a subject from a 45 deg angle (e.g. an item placed on the table, and the lens is 45 deg diagonal to the subject). Problem is ONLY 1/3 of the frame is sharp although I have stopped the aperture down to f/11.

However, when I place the lens perpendicular to the subject (i.e. 90 deg to the subject) even at f2.8, the edges appear sharp. Is there a problem with my lens? Anyone can advise?

Thanx in advance

P.S. Can't seem to find any previous thread on this. Perhaps someone can point me in the right direction. If there are already threads discussing this, Moderators - please advise. I'll close this thread ASAP. Thanx again..

[cichlid]

Originally Posted by fv18m Hello Guys & Gals, got my 105mm recently. Seems to have an issue when I am shooting a subject from a 45 deg angle (e.g. an item placed on the table, and the lens is 45 deg diagonal to the subject). Problem is ONLY 1/3 of the frame is sharp although I have stopped the aperture down to f/11. However, when I place the lens perpendicular to the subject (i.e. 90 deg to the subject) even at f2.8, the edges appear sharp. Is there a problem with my lens? Anyone can advise? Thanx in advance P.S. Can't seem to find any previous thread on this. Perhaps someone can point me in the right direction. If there are already threads discussing this, Moderators - please advise. I'll close this thread ASAP. Thanx again..

probably u are too near the subject?

[psychobiologist]

depends on how close you are,

do an aperture blade check, i.e. press the DOF button to see if the blades close in properly.

if the object's small, and you are too close, sometimes F11 is not enough for the amount of depth of field that you require. try f16, 22 etc

[Jack Chen]

Well, yr lens is perfectly alright, pls don't worry.
As this is an Macro lens, the focal lenght has to be very precised, even the distance is different by 0.5mm, subject will be out of focus.

[calebk]

Originally Posted by fv18m Hello Guys & Gals, got my 105mm recently. Seems to have an issue when I am shooting a subject from a 45 deg angle (e.g. an item placed on the table, and the lens is 45 deg diagonal to the subject). Problem is ONLY 1/3 of the frame is sharp although I have stopped the aperture down to f/11. However, when I place the lens perpendicular to the subject (i.e. 90 deg to the subject) even at f2.8, the edges appear sharp. Is there a problem with my lens? Anyone can advise? Thanx in advance P.S. Can't seem to find any previous thread on this. Perhaps someone can point me in the right direction. If there are already threads discussing this, Moderators - please advise. I'll close this thread ASAP. Thanx again..

Your issue is with depth of field. Depth of field is parallel to the sensor, hence when your lens is perpendicular to the subject (sensor is parallel to subject), you're able to get the subject wholly sharp, most of the time.

[ExplorerZ]

Originally Posted by fv18m Hello Guys & Gals, got my 105mm recently. Seems to have an issue when I am shooting a subject from a 45 deg angle (e.g. an item placed on the table, and the lens is 45 deg diagonal to the subject). Problem is ONLY 1/3 of the frame is sharp although I have stopped the aperture down to f/11. However, when I place the lens perpendicular to the subject (i.e. 90 deg to the subject) even at f2.8, the edges appear sharp. Is there a problem with my lens? Anyone can advise? Thanx in advance P.S. Can't seem to find any previous thread on this. Perhaps someone can point me in the right direction. If there are already threads discussing this, Moderators - please advise. I'll close this thread ASAP. Thanx again..

to full understand this, i recommand you search DOF either in this forum or around the web...

[fv18m]

Roger. Just tried. Subject was my HP's buttons. Gotta stop down to f/40 for an overall sharp pic. At f/22, top & bottom 1/4 is still much more blur than the middle 1/2. So I guess it is really a case of too shallow a DOF resulting in the blurry images mentioned in my earlier post.. Thanx for the advice.

[fv18m]

Thanx alot Bro. I did some read-up on DOF before. And I thought f/11 - f/16 was just about right. Well, now that I've been given this insight, it seems my earlier assumption about DOF being just about right at f/11 - f/16 was wrong. Once again, Thanx to all the "Dark & White Knights" for your guidance. Cheers

Originally Posted by ExplorerZ to full understand this, i recommand you search DOF either in this forum or around the web...

[nyxx88]

OT: If you not satisfied with your lens, pass it to me. I can live with the 1/3 OOF issue

It's a nice lens .

[fv18m]

Good try Bro... I can also live with f/40 shots... Maybe get an R1C1 as my flash unit (then that would be BEST). See if there's any news of "Ah Gong" giving me pocket money tomorrow. If he decides to give me..

Originally Posted by nyxx88 OT: If you not satisfied with your lens, pass it to me. I can live with the 1/3 OOF issue It's a nice lens .

[zac08]

Originally Posted by fv18m Thanx alot Bro. I did some read-up on DOF before. And I thought f/11 - f/16 was just about right. Well, now that I've been given this insight, it seems my earlier assumption about DOF being just about right at f/11 - f/16 was wrong. Once again, Thanx to all the "Dark & White Knights" for your guidance. Cheers

Not when you're shooting real close-up... as the working distance reduces, your DOF drops dramatically...

You'll get the hang of it as you shoot more of such macros.

[calebk]

DOF is affected by focus distance. The closer you focus, the thinner your DOF. Hence, for macro, your DOF is usually paperthin.