Fred Miranda wrote:
How are you guys shimming your adapters? It must be a very precise process not to introduce tilt/swing. As Bastian wrote, as far as performance goes, it's not really needed for unit focus lenses.
I use the plastic sheeting that typically comes as 'windows' in boxes. I have several dozen bits salvaged from scrapped packaging, thicknesses vary so its useful to have a selection. Seems to be consistent thickness. I cut 'arcs' of it of suitable width and radius using a circle cutter, then use sections a tight fit between the screws holding the flange to body of adapter. Seems to keep everything sufficiently parrallel for subjective 'testing'. From memory thickness required has most commonly been between 0.12 and 0.18 mm, with some outside that.
gyoung143 wrote:
I use the plastic sheeting that typically comes as 'windows' in boxes. I have several dozen bits salvaged from scrapped packaging, thicknesses vary so its useful to have a selection. Seems to be consistent thickness. I cut 'arcs' of it of suitable width and radius using a circle cutter, then use sections a tight fit between the screws holding the flange to body of adapter. Seems to keep everything sufficiently parrallel for subjective 'testing'. From memory thickness required has most commonly been between 0.12 and 0.18 mm, with some outside that.
I usually use the aluminum from soda cans.
I've not tried that, do you get enough variety in thickness?
I would be a bit wary of getting burred edges when cutting, although tightening down the flange screws in a sequence would probably flatten it. Easier to cut styrene etc with a sharp blade I would think.
Photo cross posted in the Sony FE Image Thread and taken at 4:28 PM.
Looking downstream across Jordan Creek at the Autumn Color on the far bank and Autumn Color reflected in the water. Part of the Pedestrian Bridge is visible near the center along the right edge of the image.
Tripod mounted A7rII Kolari Vision UT sensor modified camera and Voigtlander 28mm f2 Ultron II Asph VM lens; silent shutter.
ISO 200, f8?, 1/160 second.
Exposure Corrected +0.09 Stops.
October 28, 2021
Along Jordan Creek, near the Ford, Trexler Nature Preserve, Schnecksville, PA.
Photo cross posted in the Sony FE Image Thread and taken at 5:04 PM.
Looking down stream along the roadway that runs along Jordan Creek lined with trees in Autumn Color.
Tripod mounted A7rII Kolari Vision UT sensor modified camera and Voigtlander 28mm f2 Ultron II Asph VM lens; silent shutter.
ISO 100, f8?, 1/80 second.
Exposure Corrected +0.79 Stops.
October 28, 2021
Along Jordan Creek, near the Ford, Trexler Nature Preserve, Schnecksville, PA.
Fred Miranda wrote:
How are you guys shimming your adapters? It must be a very precise process not to introduce tilt/swing. As Bastian wrote, as far as performance goes, it's not really needed for unit focus lenses.
I have used this, but in the end I settled on not shimming.
mapgraphs wrote:
The outward field curvature exhibited with the 2/28 Ultron II, wide open, shows up on both my M-240 and Z 7. Both cameras exhibit the same effects. The subject distance and distance to midfield and background are the deciding elements in how noticeable it is. (...)
That's really odd. My Ultron 28mm Asph II shows a very slight inward / regular field curvature, actually it's so close to being flat, that for practical purposes it's flat on my Kolari UT modded Z6. Your sample may behave differently from mine, Steve Spencer's and Fred Miranda's.
I have a stock Z7 on the way, so I will certainly compare it to the UT modded camera and see how the plane of focus behaves.
Okay, I have now received my (stock) Z7. The 28mm Ultron II actually isn't too bad on that sensor.
The Z6UT yields an impressively sharp image corner to corner wide open at infinity, while on the stock Z7 sensor it looks "decent considering it's wide open" so to speak. There is some softening outside the center, while the extreme corners are nothing short of awful. I haven't checked how field curvature is on the Z7 yet, but there definitely is a performance drop compared to the Kolari UT modded camera.
Mar 26, 2022 at 01:08 PM
Steve Spencer Online • • • • • • • Upload & Sell: On
LarsHP wrote:
Okay, I have now received my (stock) Z7. The 28mm Ultron II actually isn't too bad on that sensor.
The Z6UT yields an impressively sharp image corner to corner wide open at infinity, while on the stock Z7 sensor it looks "decent considering it's wide open" so to speak. There is some softening outside the center, while the extreme corners are nothing short of awful. I haven't checked how field curvature is on the Z7 yet, but there definitely is a performance drop compared to the Kolari UT modded camera.
I have used the lens on the Z7. There is quite a lot of field curvature. Fred has some tests on a Sony E mount camera (I forget which one) and it is pretty bad on that too. The Z7 isn't much if any better.
Steve Spencer wrote:
I have used the lens on the Z7. There is quite a lot of field curvature. Fred has some tests on a Sony E mount camera (I forget which one) and it is pretty bad on that too. The Z7 isn't much if any better.
My tests show that there is some field curvature on the stock Z7, but not what I consider a lot. When stopped down to f/5.6, the extreme sides are at their sharpest when focus is placed in the center at infinity. To me, that means it's usable for landscape photography, however with the note that the lens performs just as well at f/2.8 on a suitable sensor (digital Leica M or Kolari UT sensor mod camera). That said, it does not perform as well as it can at wider apertures on the stock Z7.
mapgraphs wrote:
The outward field curvature exhibited with the 2/28 Ultron II, wide open, shows up on both my M-240 and Z 7. Both cameras exhibit the same effects. (...)
After testing my 28mm Ultron II on both Z6 w/ Kolari UT mod and stock Z7, I think your sample of this lens needs an adjustment. I base this on two things:
1) My sample as well as others' don't show reverse field curvature on an M camera or Kolari UT mod sensor.
2) The 28mm Summicron Asph v2 I had was sent to Wetzlar for adjustment and came back with a completely different field curvature characteristic (sharply inward curving at f/4). I sent it back again, and it had a more normal plane of focus after the lens elements were put together properly. This means an improper assembly of lens elements can introduce field curvature that otherwise wouldn't be there.
The above is meant as a help (while there hopefully still is a warranty on it).
Photo cross posted in the Sony FE Image Thread and taken at 3:28 PM.
Looking at the inside of the Pantheon, Roma (Rome), Italy.
Monopod mounted A7rII Kolari Vision UT sensor modified camera and Voigtlander 28mm f2 Ultron II VM lens; silent shutter.
ISO 800, F4?, 1/10 Second.
Photo cross posted in the Sony FE Image Thread and taken at 3:29 PM.
Looking at a Shagbark Hickory Tree, footsteps through the snow, across the ice and snow covered Jordan creek to the far bank.
Tripod mounted A7rII Kolari Vision UT sensor modified camera and Voigtlander 28mm f2 Ultron II VM lens; silent shutter.
ISO 100, f8, 1/160 second.
January 30, 2022
Along Jordan Creek not far from the Pedestrian Bridge and the Ford, Trexler Nature Preserve, Schnecksville, PA.
Photo cross posted in the Sony FE Image Thread and taken at 12:29 PM.
Looking at the outside of the Colosseum (the usually seen side of the building was covered and under Renovation), Roma (Rome), Italy.
Hand Held relying on Camera IBIS, A7rII Kolari Vision UT sensor modified camera and Voigtlander 28mm f2 Ultron II VM lens; silent shutter.
ISO 100, F8, 1/250 Second.
March 7, 2022
At the Colosseum, Roma (Rome) Italy.
Photo cross posted in the Sony FE Image Thread and taken at 3:01 PM.
Looking at farmer's fields and a portion of a farm covered with snow.
Tripod mounted A7rII Kolari Vision UT Sensor modified camera and Voigtlander 28mm f2 Ultron II VM lens; silent shutter.
ISO 100, f8?, 1/400 second.
Exposure Corrected +0.18 Stops.
January 31, 2022
Near the intersection of Loch Valley Road and Stony Ridge Road, New Tripoli, PA.
Rich
Apr 02, 2022 at 07:23 AM
Steve Spencer Online • • • • • • • Upload & Sell: On
LarsHP wrote:
My tests show that there is some field curvature on the stock Z7, but not what I consider a lot. When stopped down to f/5.6, the extreme sides are at their sharpest when focus is placed in the center at infinity. To me, that means it's usable for landscape photography, however with the note that the lens performs just as well at f/2.8 on a suitable sensor (digital Leica M or Kolari UT sensor mod camera). That said, it does not perform as well as it can at wider apertures on the stock Z7.
I agree for landscapes stopped down to f/5.6 and especially f/8 the lens does pretty well on the stock Z7, but when I said a lot of field curvature I was referring to the lens as one might typically use it for portraits at 1 to 3 M and at wider apertures. The plain of focus isn't a plain anymore in that sort of situation and curves back toward the camera such that anything in the foreground towards the edges becomes in sharp focus and draws attention away from the subject. The field curvature for that type of shot I would say is a lot and makes the lens pretty unsuitable for that sort of photography on the Z7.
Photo cross posted in the Sony FE Image Thread and taken at 11:46 PM.
Looking at the Arch of Constantine and Palatine Hill, Roma (Rome), Italy.
Hand Held relying on Camera IBIS, A7rII Kolari Vision UT sensor modified camera and Voigtlander 28mm f2 Ultron II VM lens; silent shutter.
ISO 100, F8?, 1/400 Second.
March 7, 2022
Image taken looking out of the Colosseum near the Gift Shop, Roma (Rome) Italy.
I did a quick test in the living room with focus at about 7 feet (a little more than 2 meters) in the center with my Z6 w/ Kolari UT mod and stock Z7 camera. In the background, in the side and near the corner of the image, there is a minor difference, one that most likely wouldn't be noticed unless pointed out or seen side by side with the Z6UT (or digital M camera). The background was only 5 meters away, so this may of course explain it, but my view is that the Ultron II isn't too bad on a stock Z7. It's definitely not as good as on the modified Z6, even stopped down. I wouldn't recommend it for someone who intend using it solely on a stock Nikon Z camera, but for occasional use, knowing the implications, I think it's fine. That said, if I take the 28mm Ultron II from my bag, having both the Z6UT and Z7 with me, I would probably put it on the Z6UT at least 9 of 10 times because it's just terrific at all apertures with the intended sensor glass thickness.
Steve Spencer wrote:
I agree for landscapes stopped down to f/5.6 and especially f/8 the lens does pretty well on the stock Z7, but when I said a lot of field curvature I was referring to the lens as one might typically use it for portraits at 1 to 3 M and at wider apertures. The plain of focus isn't a plain anymore in that sort of situation and curves back toward the camera such that anything in the foreground towards the edges becomes in sharp focus and draws attention away from the subject. The field curvature for that type of shot I would say is a lot and makes the lens pretty unsuitable for that sort of photography on the Z7....Show more →
Apr 03, 2022 at 07:59 AM
Steve Spencer Online • • • • • • • Upload & Sell: On
LarsHP wrote:
I did a quick test in the living room with focus at about 7 feet (a little more than 2 meters) in the center with my Z6 w/ Kolari UT mod and stock Z7 camera. In the background, in the side and near the corner of the image, there is a minor difference, one that most likely wouldn't be noticed unless pointed out or seen side by side with the Z6UT (or digital M camera). The background was only 5 meters away, so this may of course explain it, but my view is that the Ultron II isn't too bad on a stock Z7. It's definitely not as good as on the modified Z6, even stopped down. I wouldn't recommend it for someone who intend using it solely on a stock Nikon Z camera, but for occasional use, knowing the implications, I think it's fine. That said, if I take the 28mm Ultron II from my bag, having both the Z6UT and Z7 with me, I would probably put it on the Z6UT at least 9 of 10 times because it's just terrific at all apertures with the intended sensor glass thickness.
Where you really notice the problems with field curvature is with environmental portraits in which you want to blur at least some of the background. It really is quite bad for that application on the stock Z7 at least in my opinion. If you aren't blurring the background or at least not blurring it much (a 28mm lens with 2M to the target and 5M to the background will have very little blur even at f/2) then you won't notice the field curvature, but if you are 1M away or have a more distant background you will. Some of this may be subjective, in terms of how much performance decrement we are willing to tolerate. I don't think we fundamentally disagree. The lens does better on a camera with a thinner sensor stack. The drop in performance includes field curvature in which the edges and corners are sharper at closer distances than the center. Increasing depth of field can compensate to some extent for this problem. I think we agree on all that, where we might disagree (and I am not even sure of that) is whether when field curvature affects the results the image is still acceptable. Perhaps we disagree and perhaps we don't but we would need to compare our views on a number of images to figure that out and it probably isn't worth it. I think we fundamentally agree.
