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Archive 2008 · Zoerk vs. Mirex TS adapters?
  
 
msshea
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p.1 #1 · p.1 #1 · Zoerk vs. Mirex TS adapters?


I've read various archived threads on the Zoerk and Mirex adaptors from a couple of years ago, but I'm still unsure as to the relative strengths and weaknesses of each. I'm wondering if folks have some new thoughts, based on subsequent experience. I'm thinking of using one or the other on my 1Ds3 with a Pentax FA35, which Hubsand seems to think is the best wide angle available for this configuration. I'll mostly use it for architectural work.

Thanks for any thoughts.
Merrill



Sep 07, 2008 at 03:50 PM
dennishh
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p.1 #2 · p.1 #2 · Zoerk vs. Mirex TS adapters?


Hi Merrill,
I can only comment on the Zork PSA, the one I have been using for 3 or 4 years. If you can find a FA35 it's the way to go. It's an incredible combination that gives you about a 17mm field of view with almost a 21/2 times the resolution of a straight 17mm lens. Even more your final file will be closer to an 8x10 format that is great for architecture. The shifting is very fast with almost 20mm on each side. The other Pentax lenses I use are the 120macro,75mm and 55mm, these are usually available at KEH very cheap. The FA35 is as sharp if not sharper than any 35mm lens. Photoshop CS3 has no problem with stitching these images.
Dennis
Image 273520 not found



Image 273521 not found





Sep 07, 2008 at 04:37 PM
marcwilson
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p.1 #3 · p.1 #3 · Zoerk vs. Mirex TS adapters?


Yes.
For architectural work the zork setup will give you the best amount of shift on a 'wide' focal length lens available. The mirex I think gives less shift but does give you tilt...but for your uses...

In fact the whole set up is one I will be looking at putting together again fairly soon. Wether the pentax is sharper than say the olympus / contax 35 focal length shift lenses I do not know but frankly for the amount of shift you can get even without the thought of stitching thsis et up is invaluable...so why did I ever sell my set up...no idea!

Edited on Sep 07, 2008 at 04:46 PM



Sep 07, 2008 at 04:45 PM
jcolwell
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p.1 #4 · p.1 #4 · Zoerk vs. Mirex TS adapters?


The Mirex gives +/- 15mm shift and 10 deg tilt. The Mirex rotates around the mount with 15 deg clickstops. If you're set up for side to side shift, then the Mirex tilts the lens up or down. The Mirex tilt movement is similar to front standard base tilt on a bellows camera, so you have to recompose the image after tilting. I generally use a Manfrotto 410 geared head (like the one Dennis shows) to make this easier.

The Mamiya 645 C 35/3.5 N, 45/2.8 N, and 55/2.8 N are all very sharp lenses. The Hasselblad CF 50/4 is a bit sharper wide open than the 45N and 55N, but these Mamiyas are equal or sharper at f/8 (centre and corners of 5D and 20D). I'd love to try the SMC Pentax-FA 645 35/3.5, but it's not a simple task to adapt the P645 to M645 - you need to modify the lens, as Mark Hubsand did with the one he tested.

From the Zoerk setup photos Dennis posted, it appears that the lens is mounted on the tripod, as opposed to the camera body (which is what you have to do with the Mirex). Mounting the lens on the tripod avoids shift-induced parallax for panos with relatively close subjects. In order to avoid this problem with the Mirex, I have to mount the camera body on a slider, so I can shift the lens one way, and then move the body back, to have the same pre- and post-shift positions for the lens with respect to the subject.

Despite the compromises, I really like the Mirex and use it with M645 lenses whenever I need some movements, but it really can't do very much in comparison with an old LF bellows camera.

Edited on Sep 07, 2008 at 08:25 PM



Sep 07, 2008 at 08:24 PM
shirozina
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p.1 #5 · p.1 #5 · Zoerk vs. Mirex TS adapters?


IMO both are now rendered obsolete (if you just want shift) by the latest stitching programs. A good pano head and an app like PTGUI will give you far more flexibility and it's cheaper.


Sep 07, 2008 at 08:27 PM
jcolwell
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p.1 #6 · p.1 #6 · Zoerk vs. Mirex TS adapters?


The stitching programs won't provide tilt (if you want more than just shift), nor will they eliminate perspective distortion optically.


Sep 07, 2008 at 08:50 PM
shirozina
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p.1 #7 · p.1 #7 · Zoerk vs. Mirex TS adapters?


They totaly eliminate perspective distortion opticaly if the lens is rotated around it's nodal point.


Sep 07, 2008 at 08:54 PM
dennishh
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p.1 #8 · p.1 #8 · Zoerk vs. Mirex TS adapters?


I use PTGUI and it's great, but doesn't always work 100%. The Zork with the camera moving is 100% all the time. Nodal point is also not always accurate, no matter how much you try, especially with wide angle subjects close to lens. I have found for commercial architecture work panning can produce very large hi-res files but can be overly time consuming and when it goes bad your dead.


Sep 07, 2008 at 09:10 PM
shirozina
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p.1 #9 · p.1 #9 · Zoerk vs. Mirex TS adapters?


You have to set up the camera on the pano head very accuratley - then there is no misalignment. I have gone over exclusivley to this method of capture for my commercial architecture and interior work just using a Nodal Ninja head, 5D and CZ 50mm and 28mm lenses.


Sep 07, 2008 at 09:25 PM
montespluga
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p.1 #10 · p.1 #10 · Zoerk vs. Mirex TS adapters?


Here, the PSA remains at home, since I stitch - for architecture as well.


Sep 07, 2008 at 10:05 PM
 

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dennishh
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p.1 #11 · p.1 #11 · Zoerk vs. Mirex TS adapters?


Nice work! I probably just don't have your patience with the complexity of this. The 1dsMKlll gives such a high res image with just 3 frames, I would only consider stitching in an unusual situation. For the past few weeks I've been having great results with the Nikon 14-24g, causing me to get a little more lazy.


Sep 07, 2008 at 10:44 PM
jcolwell
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p.1 #12 · p.1 #12 · Zoerk vs. Mirex TS adapters?


shirozina wrote:
They totaly eliminate perspective distortion opticaly if the lens is rotated around it's nodal point.


It won't optically remove convergence of vertical parallel lines when the lens isn't horizontal.



Sep 08, 2008 at 12:01 AM
montespluga
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p.1 #13 · p.1 #13 · Zoerk vs. Mirex TS adapters?


dennishh wrote:
Nice work! I probably just don't have your patience with the complexity of this. The 1dsMKlll gives such a high res image with just 3 frames, I would only consider stitching in an unusual situation. For the past few weeks I've been having great results with the Nikon 14-24g, causing me to get a little more lazy.


Thanks dennishh

Stitching isn't to complex anymore; thanks to the smarter apps. You' re much more flexible

Still, I can't wait for Marks adapter, i might become lazy, too



Sep 08, 2008 at 12:36 AM
montespluga
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p.1 #14 · p.1 #14 · Zoerk vs. Mirex TS adapters?


jcolwell wrote:
It won't optically remove convergence of vertical parallel lines when the lens isn't horizontal.


Yes, it will; its done out of 15 frames.





Sep 08, 2008 at 12:46 AM
pookipichu
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p.1 #15 · p.1 #15 · Zoerk vs. Mirex TS adapters?


The 35FA is a wonderful, wonderful lens. I've compared it to the 35L, 28-25 Tamron and it just rocks the focal length. No vignetting obviously and even sharpness through the frame. Bokeh is rendered beautifully and great coatings, contrasty.


Sep 08, 2008 at 01:20 AM
shirozina
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p.1 #16 · p.1 #16 · Zoerk vs. Mirex TS adapters?


jcolwell wrote:
It won't optically remove convergence of vertical parallel lines when the lens isn't horizontal.

You clearly have no understanding of how it works - this is exactly what it does.



Sep 08, 2008 at 06:38 AM
hubsand
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p.1 #17 · p.1 #17 · Zoerk vs. Mirex TS adapters?


The FA35 is fantastic: it's the Zeiss 21mm of the MF world, but with less distortion. On a Zörk PSA, it's untouchable.

So why don't I use one now? Because I succumbed to the discreet charms of the Mirex and those oh-so-cheap Mamiya 645 lenses. However you choose to stitch, using the same MF lenses (especially the Macros) with tilt movements is a big plus.

Much to my amazement, the later N version of the Mamiya 35mm is actually OK. It might not have the ultimate resolving capacity of the Pentax but the microcontrast is excellent and at working apertures it doesn't struggle to live with the 1Ds III at all: especially when you consider that the monstrous image files typically end up down-res / sharpened. I was expecting captures to look conspicuously soft next to the Zeiss and Olympus 35mm shift lenses, but they stood up very well. One day I'll get round to writing up the test . . .



Sep 08, 2008 at 09:58 AM
jcolwell
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p.1 #18 · p.1 #18 · Zoerk vs. Mirex TS adapters?


shirozina wrote:
You clearly have no understanding of how it works - this is exactly what it does.


I understand how shift works to eliminate convergence of parallel lines; you use the wide image circle of the lens to shift up within the image without having to point the lens up from the horizontal. I thought that rotating a lens about its nodal point (a.k.a. entrance pupil), was a technique for eliminating angular parallax, not perspective distortion. If you do a pano with some shots taken with the lens horizontal, and others taken with the lens pointing up, then do not those with the lens pointing up have converging parallel lines?

In the attached composite image, the left side was taken with the lens pointing horizontal, and the right side had the lens pointing up approx. 10 degrees, using a 24-70L on 20D with a Nodal Ninja set for the 24-70L nodal point. The images were taken of a long, slender photo montage, with the same part of the montage shown in both sides of the attached image, the tripod wasn't moved, only tilt was used. You can't observe the lack of angular parallax, as there are no foreground/background objects, but you sure can observe the convergence of parallel lines for up-tilt (compare the cyan vertical reference line to the edge of the black frame, on the left and right sides of the comp).

Please, explain to me how to use a pano head to eliminate perspective distortion optically (i.e. before the photo is taken) - I know how to do it in post-processing.

Image 273734 not found




Edited on Sep 08, 2008 at 10:37 AM



Sep 08, 2008 at 10:33 AM
shirozina
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p.1 #19 · p.1 #19 · Zoerk vs. Mirex TS adapters?


Obviously you can't do it BEFORE the photo is taken. But by rotating the lens exactly around the nodal point in a multi row panorama the image data is available to reassemble the image in PTgui in perfect 2 point perspective which will exactly match an image taken with a shift lens. Infact it will be better because as you know PTgui corrects any optical distortion which the lens has and depending on how you shoot it you end up with more pixels and a greater coverage/shift than can be had from any shift lens.


Sep 08, 2008 at 10:50 AM
jcolwell
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p.1 #20 · p.1 #20 · Zoerk vs. Mirex TS adapters?


The shift lens allows you to optically correct for perspective distortion before taking the photo, provided the lens image circle is sufficiently large to cover the image while keeping the lens horizontal. That was my sole point. Perhaps the lack of understanding was on your part, when you decided that to "optically remove convergence of vertical parallel lines" could be done in software; that's more often called digital processing.


Sep 08, 2008 at 11:47 PM
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