I expect there is no visible performance difference between PCX 2.5m and 3m. Also reversing those will make quite small changes. Will post sim results to show how small they are.
For Kolari UT modded cameras, ZM25 will greatly work without PCX. PCX 5m may give small improvement on extreme corner. Will post those MTFs.
Thanks everyone for your help. Really really appreciate everyone jumping in on the ZM25 been fighting a real confusing battle. Being de centered has thrown me off my game. I usually get this stuff right away. I'll wait till they contact me I'll get the 2500 if in stock or the 3000.
I'm going to test it out and if good than I won't send it in. Bad it's going in.
Not wanting to add confusion but, as per HaruhikoT simulations of the ZM25, PCX1500 gives slightly better center and midfield performance than PCX2500, while the later beats the PCX1500 in the edges/corners. Maybe the sweet spot is between these two i.e. PCX2000 (or PCX2500 reversed ) ?.
It occurs to me also that the inherent FC of each lens plays a big role in this game, Simulations show the behavior of a perfect lens but the final correction depends on how much FC has the main lens and in which direction. So, in some cases the theoretical best front filter isn’t the correct one. In the end, only real life tests with different PCX filters are gonna tell us the whole story. This is good for Optosigma’s business but not so good for our pockets and patience.
artur5 wrote:
Not wanting to add confusion but, as per HaruhikoT simulations of the ZM25, PCX1500 gives slightly better center and midfield performance than PCX2500, while the later beats the PCX1500 in the edges/corners. Maybe the sweet spot is between these two i.e. PCX2000 (or PCX2500 reversed ) ?.
It occurs to me also that the inherent FC of each lens plays a big role in this game, Simulations show the behavior of a perfect lens but the final correction depends on how much FC has the main lens and in which direction. So, in some cases the theoretical best front filter isn’t the correct one. In the end, only real life tests with different PCX filters are gonna tell us the whole story. This is good for Optosigma’s business but not so good for our pockets and patience. ...Show more →
I also still wonder if a 10m PCX lens might be the better choice for the midframe of the ZM 35mm 1.4 ...
Midframe looks bad wide open while corners look already quite good, a weaker filter might even out things a bit.
Or am I completely wrong here, @HaruhikoT ?
If you think I might be right I may give that 10m filter a try.
BastianK wrote:
I also still wonder if a 10m PCX lens might be the better choice for the midframe of the ZM 35mm 1.4 ...
Midframe looks bad wide open while corners look already quite good, a weaker filter might even out things a bit.
Or am I completely wrong here, @HaruhikoT@ ?
If you think I might be right I may give that 10m filter a try.
Interesting idea. Also, I can't seem to find the post (maybe I imagined it) where someone was going to try inverting the PCX to compare to double check this same issue of theory vs reality. Did that happen?
Here are additional sim results for ZM25. First one is for Stock A7 and Second is for Kolari UT 0.8mm. Also show PCX-induced distortion in the first one.
Some of you notice 2m looks better than 2.5m but both are better across frame than Zeiss publised original MTF so such difference should be meaningless.
PCX 2.5m requires less infinity adjustment, less changes FL and induces smaller distortion curve that's why my choice here is 2.5m.
Reverse orientation do almost nothing in these case so I don't care about it.
PCX 5m is great for Kolari UT as you see.
As always I'm not sure how well these results match with reality.
I still can't replicate such midzone dip using my sim model for ZM35 but I agree with you, 10m might work.
From my simulation experience, midzone dip sometimes occurs when PCX is too strong, that implies 5m may be slightly over-correction particulaly for ZM35's midzone.
If the guess is true, weaker PCX should make better midzone in exchange for some residual field curvature at extreme corner.
Forgive me if I would be wrong.
If anything it would need more corners. Centerally it's very sharp. I put a order in but they want me to call this morning. I'll find out available lenses in stock. I put a order in for a 2500. Are they stronger effect going up or down
artur5 wrote:
Not wanting to add confusion but, as per HaruhikoT simulations of the ZM25, PCX1500 gives slightly better center and midfield performance than PCX2500, while the later beats the PCX1500 in the edges/corners. Maybe the sweet spot is between these two i.e. PCX2000 (or PCX2500 reversed ) ?.
It occurs to me also that the inherent FC of each lens plays a big role in this game, Simulations show the behavior of a perfect lens but the final correction depends on how much FC has the main lens and in which direction. So, in some cases the theoretical best front filter isn’t the correct one. In the end, only real life tests with different PCX filters are gonna tell us the whole story. This is good for Optosigma’s business but not so good for our pockets and patience. ...Show more →
HaruhikoT wrote:
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.
Thanks for posting such detained information for the ZM 25. It looks like PCX 2m is optimal for center while still great for mid and corners. A slightly weaker PCX 2.5m seems to be the best compromise as you wrote with great results across the field. (center and corners)
Question: Is the ZM 28/2.8 a different beast? I tested it with a PCX 1.5m filter and was not that impressed and decided selling this combo. Perhaps I could try a different PCX with it. Optically, the ZM 28 is not as great as the ZM 25 to begin with though.
I have my Zeiss 35mm f/1.4 Distagon ZM lens with PCX filter setup completed. I followed the Fred Maranda and Guy Mancuso method which starts with a 49mm blank tiffen UV filter so I can still mount the Zeiss lens hood. Then I used a 49 to 55 step up ring > 55mm tiffen blank UV filter > a optimasigma .5 than the ELPro 3 retaining ring. I find it is much better across the frame and into the corners even wide open and really excellent when stopped down to f/2.8 and higher. There is a bit of CA at f/1.4 - f/2.0 but it is easily corrected in LR. After f/2.8 the CA is not a problem. I've tested it out and vignetting is not a problem even with the screw in CPL filter and ND filter with a 55 to 58 step up ring. I also have tried it out with the Lee Seven 5 ND filter with no issues. I've attached some pics of the set up with various filters and the lens cap for those of you that may want to do a similar setup.
I did have to remove 1 of the 2 shims in order to get to infinity focus with both my Hawk's factory Helicoid adapter and my TAP adapter.
A big thanks to everyone on this thread for all the great experimentation and sharing of information!
Chuck
BastianK wrote:
I also still wonder if a 10m PCX lens might be the better choice for the midframe of the ZM 35mm 1.4 ...
Midframe looks bad wide open while corners look already quite good, a weaker filter might even out things a bit.
Or am I completely wrong here, @HaruhikoT@ ?
If you think I might be right I may give that 10m filter a try.
Bastian, this is a very interesting idea. I agree with you about the mid-zone dip of the ZM 35, although stopped down, it's not much of an issue. If you do test the PCX 10 filter, I will be very interested in seeing the results. Do you know if it is the same diameter and thickness as the PCX 5? It would be very nice if it fits in the same setup.
Chuck Coyne wrote:
I have my Zeiss 35mm f/1.4 Distagon ZM lens with PCX filter setup completed. I followed the Fred Maranda and Guy Mancuso method which starts with a 49mm blank tiffen UV filter so I can still mount the Zeiss lens hood. Then I used a 49 to 55 step up ring > 55mm tiffen blank UV filter > a optimasigma .5 than the ELPro 3 retaining ring. I find it is much better across the frame and into the corners even wide open and really excellent when stopped down to f/2.8 and higher. There is a bit of CA at f/1.4 - f/2.0 but it is easily corrected in LR. After f/2.8 the CA is not a problem. I've tested it out and vignetting is not a problem even with the screw in CPL filter and ND filter with a 55 to 58 step up ring. I also have tried it out with the Lee Seven 5 ND filter with no issues. I've attached some pics of the set up with various filters and the lens cap for those of you that may want to do a similar setup.
I did have to remove 1 of the 2 shims in order to get to infinity focus with both my Hawk's factory Helicoid adapter and my TAP adapter.
A big thanks to everyone on this thread for all the great experimentation and sharing of information!
Chuck...Show more →
Thanks for posting that. I didn't think about adding a 58mm step-up to be able to use square filters even with the hood!
You didn't get any vignetting?
I also found out that the original Zeiss cap (49mm) fits perfectly into the 55mm ELPro retaining ring.
So, we can have both original hood and original cap.
Thanks for posting that. I didn't think about adding a 58mm step-up to be able to use square filters even with the hood!
You didn't get any vignetting?
I also found out that the original Zeiss cap (49mm) fits perfectly into the 55mm ELPro retaining ring.
So, we can have both original hood and original cap.
Fred,
It's even better than that, I can actually screw the Seven5 55mm adapter ring directly onto the 55mm blank filter without any step up ring. There is just enough threads on the 55mm filter ring so the Seven5 adapter screws on nice and tight up to the lens hood. The square filters work great with it. Also, I have the Seven5 CPL but I haven't tried it out yet so I don't know if there will be any vignetting problems. I do have to use the 55 to 58 step up ring for the Firecrest ND filters that I have since they are in the 58mm size. I need to do some more testing with that setup but it doesn't appear to be causing any vignetting either. The Firecrest ND's are in a fairly thin ring so that helps.
robgo2 wrote:
Bastian, this is a very interesting idea. I agree with you about the mid-zone dip of the ZM 35, although stopped down, it's not much of an issue. If you do test the PCX 10 filter, I will be very interested in seeing the results. Do you know if it is the same diameter and thickness as the PCX 5? It would be very nice if it fits in the same setup.
Rob
Optosigma does not list a 10m filter, only Eksmaoptics does.
Unfortunately someone bought the last one they had in stock a few hours before my order got through,
so delivery time is now also 5 to 6 weeks even for the uncoated filter...
BastianK wrote:
Optosigma does not list a 10m filter, only Eksmaoptics does.
Unfortunately someone bought the last one they had in stock a few hours before my order got through,
so delivery time is now also 5 to 6 weeks even for the uncoated filter...
Parariss wrote:
Interesting idea. Also, I can't seem to find the post (maybe I imagined it) where someone was going to try inverting the PCX to compare to double check this same issue of theory vs reality. Did that happen?
As reported earlier, I have tried the 5000 Optosigma both ways on my ZM 35/1.4, and there is very little difference - perhaps the slightest edge for it inverted, i.e., with the curved face towards the lens. That's the way I'm currently using it, and I'm very happy with it.
