Left edge blurred when using 1.4tc on 24mm ts lens

I've noticed that when I'm shooting with my 1.4 kenko tc on my 24mm ts lens, the left edge is blurry.

right edge looks fine.

without tc both edges are fine.

the tilt is set to O.

 

any ideas as to what might be happening?

 

shooting with the d810

 

 

thanks

owen

 

 

 

 

Edited August 27, 2019 by owen_dawson

Dare I ask which 24mm? (Samyang?) It looks like everything is blurry, but I assume you can't find a plane that's actually in focus, and this is field curvature? (What aperture are you using?) I'm assuming this is all one image at 0 shift as well as tilt? Just checking the optical path through the teleconverter. Just to rule it out - no large smudges on anything? (I've spent a while diagnosing a lens artifact before noticing crud on the filter. If it's just a fingerprint, it'll save a lot of pain to notice now.)

 

Generally I'm surprised that the right hand side looks as good at is does, but I appreciate that there's an argument for shifting on a teleconverter. Quality is unlikely to be perfect, though. I assume the teleconverter is okay with other lenses?

That's the question . . . Is the TC working well with other lenses? It's certainly possible that the elements in the TC are out of alignment. They are not usually optimized for wide angle lenses but should be uniform at both edges in any case.

I gotta say I'd never thought of using a TC on a T&S lens....

 

The left smearing looks similar to the results I got with an older 28mm PC on a D700 with any more than 5mm shift either way.

The lens is the nikon 24mm PC-E. most to the time i'm shooting around f11 as in this shot

 

i attached a larger image, not cropped.

 

TC is fine on my 70-200.

 

its unlikely, i'm guessing, that it would be a smudge due to the exactness of the blur along the left side.

 

I never would have considered using the tc on ts either until I went on a shoot with a friend who uses his tc on 24 all the time with great results. he's a canon guy and shoots a lot of commercial architecture

 

Edited August 27, 2019 by owen_dawson

I'd be a bit concerned about the depth the lens protrudes into the teleconverter. I know the manufacturers state you can use them with wide-angle lenses, but that's a lot of glass in near proximity to the glass on the teleconverter. Moving the lens elements off-axis might exacerbate the distortion.

i would think it would be symmetrical distortion if that was the case. not one-sided?

That's decentring in the lens-TC combo. All it needs is a little bit of opposite tilt in the lens and TC separately, and when you put 'em together; what have you got? Bibbitty Bobbitty Boo!

(Sorry, there are some earworms that re-surface long after they should have decomposed into landfill.)

 

Just tell your Canon-shooting friend that he's very lucky having a 24mm wideangle that matches a TC. I had to take an L series f/4 17-40 Canon lens back because it had dreadful decentring tilt all on its own. Much worse than your TS/TC combo.

 

BTW, if you're not going to use the TS ability with the teleconverter, why not just buy a cheap 35mm f/2.8 Ai-S Nikkor? You'll have no AF either way, and the MF prime will give you a faster aperture..... and hopefully no decentring. Plus it'll be a lot less front-heavy on the camera.

 

FWIW, there's an easy test for decentring. Shoot a scene with good detail in one corner - obviously making sure that the corner is in best focus. Then swing the camera upside down while holding the focus exactly the same, and frame the same. If the two corners don't match after inverting the upside-down image, then you have a decentred lens.

Edited August 27, 2019 by rodeo_joe|1

...or pick up an 'inexpensive' Nikkor 35mm 2.8 Ai-S PC, in-case you DO need shift. ;)

 

...or use it with a D7200 and get the same apparent FL via crop factor... and you can use as much T&S as you like.

 

That much edge blur @ f11 is serious! What's it like wide open?

Edited August 27, 2019 by mike_halliwell

...or use it with a D7200 and get the same apparent FL via crop factor... and you can use as much T&S as you like.

I'm not sure what the ergonomics are like on a DX body. I've tried using my PB-6 bellows on a D7200 for the front swing ability, and simply fitting the bellows to the camera is a MENSA entrance exam. I swear you could solve a Rubik's cube blindfolded in less time.

 

Maybe someone can tell us if the tiny body and prism overhang physically limits the T/S movement available? And don't get me started on Nikon's barmy decision to prevent shifting the tilted 'sweetspot' of the lens back into centre-frame by default! :eek:

And don't get me started on Nikon's barmy decision to prevent shifting the tilted 'sweetspot' of the lens back into centre-frame by default! :eek:

I'm just about to re-align my 85mm T&S (non -E) to that very aim. The factory default is plain crazy.

Full 'up' shift towards the flash overhang leaves a smallish trap-gap. Tilt doesn't impinge on much.

 

The 24mm may be worse, I don't have one to check!

I think I understood that the (a?) point of teleconverting a tilt shift is that it effectively magnifies the shift - so you have a wider shift range than the lenses tend to offer natively. I'd certainly expect a bit of quality drop off, though.

 

At f/11 it's not going to be tilt angle (unless its way off) or field curvature. Something is certainly off centre if the behaviour differs across the frame (and you've ruled out a smudge), but that's not being particularly insightful. I doubt Nikon will give you any support for this combination, though.

 

Does rotating the tilt shift change the behaviour in a diagnostically useful way?

...Does rotating the tilt shift change the behaviour in a diagnostically useful way?

That is what I wonder as well.

 

Looking at the photo of the house, I would say the corners to the right are sharper than the left corners. I know the distance is not the same, but f/11 should have you covered. Perhaps your lens does not center perfectly when set to zero tilt? Does it lock down ok? Perhaps locking it down creates a slight tilt? However, a lens problem would have to be quite severe since a TC only enlarges the centre of the image projected by the main lens, thus it should show up on a much larger part of the left half of the frame when used bare. Since you say the TC is fine on the 70-200, I would re-test the 24mm lens and rotate it and see if the problem remains in the same place. It might be that the depth of field at f/11 masks a problem with the lens. Try shooting at f3.5 in order to really see what is going on (zero til and shift, locked and unlocked).

i haven't tried this yet, but i may just try to shoot in 1.5 crop mode on D810 to make a 36mm. Still big file at 4800x3200.