HaruhikoT wrote:
The tape is not only for centering, but also to avoid from falling through.
Thanks, sorry for all the questions :-)
I've mounted the filter with a Contax G UV-filter and an Elpro4 retaining ring. The champagne color matching between the lens and filter frame is nice, but I don't have access to the 55mm thread since the filter is a bit to thin. So the downside is that I can't use the original cap or my 55mm polarizer.
The Elpro4 ring has an inner thread, but as far as I can tell it is not 49mm or 52mm... Does anybody know the thread size? (A cheap generic 52mm lens cap sort of works...)
HaruhikoT wrote:
1) For ZM25 I expect PCX 2.5m (SLB-50-2500PM) is optimal.
Interestingly, unlike the case with ZM35 and G21/28, ZM25 accepts very wide range of PCXs. Not only 2.5m but also 1.5m and 5m shows good MTF in my simulation. 5m seems to be a bit lack of correction, though.
Difference between 1.5 and 2.5 seems be small so I prefer 2.5m that should be easier to achieve infinity focusing.
ZM25 has 37.3deg chief (exit) ray angle that is smaller than G28 having 38.9deg, that's why ZM25's optimal filter is weaker than G28 despite 25mm is shorter than 28mm.
2) As I wrote in theprevious post, correction effects of the meniscus lenses such as Proxar and Hoya+1 are more complicated than that of PCX.
I can't tell exact difference of attributes between those meniscus and PCX in simple words.
But a sure thing is, not always but in some cases, meniscus gives weaker correcting effect to astigmatism and field curvature than PCX having the same diopter.
This may be the reason why @candreyo@'s Proxar 1m works on ZM25 and Proxar 0.5m works on ZM18, while PCX 1m and 0.5m should be too strong (over-correction) for those.
Also this should be why many close-up lenses are meniscus, I think.
For close-up usage, they need filters which give sufficient diopter but doesn't affect AST and FC. So meniscus is optimal.
In contrast we A7x + RF WA owners need filters give adequate correction to AST and FC but having less diopter which affects its FL and infinity focus. So PCX is preferable for this purpose in many cases....Show more →
Thanks again for the info..
If it isn't asking too much, wouldn't you mind doing also simulation for this ZM25 and Leica/Kolari UT filter stack (around 0.8-0.9mm) ?
As I've already ordered the PCX 5m. I'm interested to know how it would perform in a A7 with the UT Kolari mod.
@HaruhikoT
Your recommendation is actually consistent with the reports and real tests.
We knew that both PCX 1.5m and PCX 5m offered a good level correction and perhaps the optimal strength was somewhere in between.
PCX 2.5 makes total sense and thanks for sharing your simulation. That seals the deal. The good news is that we would probably have to remove less shims from the lens.
Also big thanks for doing the simulation. I already sent email on pricing and availability. No question Fred less shims to pull.
Fred Miranda wrote:
@HaruhikoT@
Your recommendation is actually consistent with the reports and real tests.
We knew that both PCX 1.5m and PCX 5m offered a good level correction and perhaps the optimal strength was somewhere in between.
PCX 2.5 makes total sense and thanks for sharing your simulation. That seals the deal. The good news is that we would probably have to remove less shims from the lens.
Btw I'm going to run another infinity test just for kicks , heading out now. I was not comfortable with results hand holding the PCX 5 from the ZM 35. So I put it in my ZM 25 mount for now to test. I'll do both the B+W and PCX 5 . I'll post the Raws here in a hour or so. This way we know better on the PCX 5 how close it is. It did correct very well
UPS should bring today my OptoSigma order. I ordered SLB-50-1500PM, SLB-50-3000PM, SLB-50-4000PM and SLB-50-5000PM. Most likely daylight is gone before UPS truck visits, but as soon as I have possibility I'll test the SLB-50-3000PM with ZM25.
@HaruhikoT thanks for ZM25 simulation - Question about lens reversing: SLB-50-1500PM reversed equals ~1200mm lens. Does SLB-50-3000PM reversed equal to ~2400mm? Or is the math more complex?
I honestly think taking out the front shims is causing me major issues with the right side soft when using a lens filter but without a lens filter its sharp as a tack. Im really baffled here. First set of 5 images was without any lens filter, second set is the B+W than the third set is the OptoSigma PCX 5000 from my ZM 35. I also used my Hawk adapter and put lens on infinity and focused with the adapter . This way no lens elements move.
Im seriously considering of putting back the front shims as i think they are directional shims so left right thing and the rear shims are for infinity. So Im going to put back the front shims and remove what i need in the rear becuase this is making zero f---king sense . Im so baffled by no lens filter the right side is perfect and with lens filter regardless which one i use its soft on the right side. Im about to drop this in the garbage can.
These raws 5 of each 2.8 to 11, First set no lens, second set B+W, Third set OptoSigma PCX 5000
I have to get this squared away because i can't confirm anything is working. I have never run into this
I decided to screw this. I put all shims back and ill wait until a proper solution is in my hands or someone else has a answer. Im wasting a lot of time and money on this and I have the Firin coming tomorrow to start testing
GMPhotography wrote:
I honestly think taking out the front shims is causing me major issues with the right side soft when using a lens filter but without a lens filter its sharp as a tack. Im really baffled here. First set of 5 images was without any lens filter, second set is the B+W than the third set is the OptoSigma PCX 5000 from my ZM 35. I also used my Hawk adapter and put lens on infinity and focused with the adapter . This way no lens elements move.
Im seriously considering of putting back the front shims as i think they are directional shims so left right thing and the rear shims are for infinity. So Im going to put back the front shims and remove what i need in the rear becuase this is making zero f---king sense . Im so baffled by no lens filter the right side is perfect and with lens filter regardless which one i use its soft on the right side. Im about to drop this in the garbage can.
These raws 5 of each 2.8 to 11, First set no lens, second set B+W, Third set OptoSigma PCX 5000
I have to get this squared away because i can't confirm anything is working. I have never run into this
Perhaps the ZM 25 behaves similarly to the ZM 35 on the Sony sensor stack where the main issue is really field curvature. Your latest infinity test seems to indicate there is no astigmatism induced by the thicker sensor stack. That is evident on your f/2.8 sample using no front-lens. The right bottom right side of the image is completely in focus with little astigmatism.
Aside from that, there is some evidence that your ZM 25 is not well centered Guy.
If I would do this from scratch, I would not use any meniscus close-up lens and get a ZM 25 + PCX 2.5m (or PCX 3m if you already have one). HaruhikoT's simulations have being confirmed to be right with real images.
Focus position compared to Proxar f=1.0m was gigantic change; with shim setting which allowed me to reach infinity (it was somewhere between 5m and infinity) now makes infinity ~1.2m. So I added back two gold (thin) and one bronze (thinner). Now at infinity (at room temperature) I was not able to reach infinity, almost thou - when lens was infinity hard stop focus distance was somewhere between 10m and 15m. So I removed the bronze (thinner) shim. Now lens reaches infinity little before the hard stop.
All focus adjustment was done by adding and removing shims, which directly change focus position. The other shims adjust back lens group distance from front lens group - I would personally NEVER touch these. Illustration of what to open to adjust the focus position - DO NOT TOUCH the ring pointed by red arrow, instead open the whole lens to adjust focus position, this is indicated by blue arrow:
After lens is opened, just remove shims, assemble lens again and test focusing.
I did shoot tilted horizon test twice with apertures f/2.8-f/11. Boring as hell, but I'll try to survive without passing out next to my computer tilted to both orientations to test all corners, whole images to illustrate:
Corners (focus using centerpoint of the image/sensor):
As I expected results are as HaruhikoT simulated. Looks good to me, but I'm not the best person to evaluate photos @ infinity as I almost never shoot with such technique, specially rare with wide angles. If you wish to check RAWs, see this directory - one 7z package for each aperture. NOTICE! A7r model was used to shoot these (I know many of you have A7r version II).
Lens seems to shoot fine nighttime cityscapes, thou sun stars are too crazy on A7r, not sure is it the lens or camera, but I think they are "too much", f/8 might be still usable, but f/11 and f/16 it gets really crazy. Also ray angle is too large for 7r or for anything else than A7r vII; there is magenta colour on edges of image.
f/8 - 4 shot HDR:
The real test will be how it behaves in real life shooting scenarios; I never shoot anything with infinity focus, so shooting something close by and observe does the lens pick random stuff from background into focus/contrast like it does without the front.
EDIT: corrected information about number of shims.
Focus position compared to Proxar f=1.0m was gigantic change; with shim setting which allowed me to reach infinity (it was somewhere between 5m and infinity) now makes infinity ~1.2m. So I added back one two gold (thin) and one bronze (thinner). Now at infinity (at room temperature) I was not able to reach infinity, almost thou - when lens was infinity hard stop focus distance was somewhere between 10m and 15m. So I removed the bronze (thinner) shim. Now lens reaches infinity little before the hard stop.
All focus adjustment was done by adding and removing shims, which directly change focus position. The other shims adjust back lens group distance from front lens group - I would personally NEVER touch these. Illustration of what to open to adjust the focus position - DO NOT TOUCH the ring pointed by red arrow, instead open the whole lens to adjust focus position, this is indicated by blue arrow: https://vahonen.info/secure/wiki/images/1/1e/CarlZeissZM25_ShimRemovalRearRings.jpg
After lens is opened, just remove shims, assemble lens again and test focusing.
As I expected results are as HaruhikoT simulated. Looks good to me, but I'm not the best person to evaluate photos @ infinity as I almost never shoot with such technique, specially rare with wide angles. If you wish to check RAWs, see this directory - one 7z package for each aperture. NOTICE! A7r model was used to shoot these (I know many of you have A7r version II).
Lens seems to shoot fine nighttime cityscapes, thou sun stars are too crazy on A7r, not sure is it the lens or camera, but I think they are "too much", f/8 might be still usable, but f/11 and f/16 it gets really crazy. Also ray angle is too large for 7r or for anything else than A7r vII; there is magenta colour on edges of image.
The real test will be how it behaves in real life shooting scenarios; I never shoot anything with infinity focus, so shooting something close by and observe does the lens pick random stuff from background into focus/contrast like it does without the front.
From end results point of view I would order 2500mm, because HaruhikoT recommends it. I ordered punch of lenses from OptoSigma and 3000mm just happened to be in order (it's for ZM 2/35).
tilted to both orientations to test all corners, whole images to illustrate:
