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Front-End Filter Improves Corner Smearing
  
 
Fred Miranda
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p.91 #1 · p.91 #1 · Front-End Filter Improves Corner Smearing


If anyone is considering selling a PCX 2m or 2.5m, please let me know.
Best,
Fred



Oct 08, 2017 at 04:38 PM
sychan
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p.91 #2 · p.91 #2 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
If anyone is considering selling a PCX 2m or 2.5m, please let me know.
Best,
Fred


I'm going to order one from Opto-Sigma. If I read HaruhikoT's message right, the one to order is the SLB-50-2000PM, right? I should probably take a picture of the CV 21/1.8 and see if Haruhiko can recommend a lens for that one as well.


Edited on Oct 09, 2017 at 08:16 PM · View previous versions



Oct 09, 2017 at 03:07 AM
BastianK
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p.91 #3 · p.91 #3 · Front-End Filter Improves Corner Smearing


sychan wrote:
I'm going to order one from Opto-Sigma. If I read HarihikoT's message right, the one to order is the SLB-50-2000PM, right? I should probably take a picture of the CV 21/1.8 and see if Harihiko can recommend a lens for that one as well.

You will probably run into problems attaching a lens to the 21mm 1.8 as it has a higher filter diameter
(Most of the PCX lenses are only readily available up to 50mm).



Oct 09, 2017 at 06:30 AM
sychan
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p.91 #4 · p.91 #4 · Front-End Filter Improves Corner Smearing


BastianK wrote:
You will probably run into problems attaching a lens to the 21mm 1.8 as it has a higher filter diameter
(Most of the PCX lenses are only readily available up to 50mm).


Ugh, yes. Even looking at cutting down the lens as someone mentioned elsewhere, it looks like they only go up to 1m in the larger sizes. Would it be possible to try a 58mm->52mm reverse macro adapter and sandwich a 50mm lens in there and suffer the vignetting?
Assuming the edge sharpness was needed for stopped down landscapes, any guesses if the vignetting from the narrower correction lens and step down adapter mostly be gone by around f8?



Oct 09, 2017 at 05:34 PM
Samuli Vahonen
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p.91 #5 · p.91 #5 · Front-End Filter Improves Corner Smearing


sychan wrote:
Assuming the edge sharpness was needed for stopped down landscapes, any guesses if the vignetting from the narrower correction lens and step down adapter mostly be gone by around f8?

No, mechanical vignetting just gets sharper (=faster/sharper transition to black corner) when closing down.

Optical vignetting usually improves when closing down.

Samuli



Oct 09, 2017 at 05:42 PM
hanay78
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p.91 #6 · p.91 #6 · Front-End Filter Improves Corner Smearing


Hi Bastian,

than you recommend Hawk's adapter for the ZM lenses in order not to have to modify them instead of Voigtlšnder one? Or it is better to remove sims in the lens and use Voigtlšnder?

Regards



Oct 10, 2017 at 07:50 AM
BastianK
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p.91 #7 · p.91 #7 · Front-End Filter Improves Corner Smearing


hanay78 wrote:
Hi Bastian,

than you recommend Hawk's adapter for the ZM lenses in order not to have to modify them instead of Voigtlšnder one? Or it is better to remove sims in the lens and use Voigtlšnder?

Regards

Hawk's adapter:
Infinity can be somewhat adjusted, but I don't know if there is enough room so you don't have to adjust the shims.
I haven't used one yet as in Germany you have to import them for rather high prices.

If you have a Zeiss lens where shims can easily be adjusted I would do that and go with the VM-E close focus adapter.



Oct 10, 2017 at 07:55 AM
hanay78
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p.91 #8 · p.91 #8 · Front-End Filter Improves Corner Smearing


Thank you Bastian,

by the way, how did you order the OptoSigma lens? It looks like Laser2000 only accepts orders from companies...

Regards



Oct 10, 2017 at 12:34 PM
 

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Slalom
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p.91 #9 · p.91 #9 · Front-End Filter Improves Corner Smearing


https://europe.optosigma.com/plano-convex-lens-50mm-diameter-5000mm-focal-length-400-700nm.html?___SID=U

They opened this up about 2 months ago.



Oct 10, 2017 at 12:48 PM
GMPhotography
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p.91 #10 · p.91 #10 · Front-End Filter Improves Corner Smearing


I have a PCX 2000 coming for my CV 28 Ultron. Iím changing my name to Guinea Pig. Have lens in hand going to do some limited testing today but looks like I have a good copy. I probably wonít post todayís test but wait for front filter test when I get it.


Oct 10, 2017 at 01:42 PM
jhinkey
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p.91 #11 · p.91 #11 · Front-End Filter Improves Corner Smearing


Now that the 65/2 APO is on its way, the 35/1.7 needs to find its way into a shopping cart soon . . .

I very much appreciate the Guinea Pigs among the participants in this thread!



Oct 10, 2017 at 02:54 PM
Fred Miranda
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p.91 #12 · p.91 #12 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
I have a PCX 2000 coming for my CV 28 Ultron. Iím changing my name to Guinea Pig. Have lens in hand going to do some limited testing today but looks like I have a good copy. I probably wonít post todayís test but wait for front filter test when I get it.


Yea, you got the last PCX 2000 they had!
I was the guinea pig this time but you didn't let me!!

No worries, I picked up the PCX 2500 and will test it on Friday. There should be no visible differences especially after f/4.



Oct 10, 2017 at 04:18 PM
GMPhotography
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p.91 #13 · p.91 #13 · Front-End Filter Improves Corner Smearing


Lol

Yea I jumped on it quick. I want to take the lens to NY next Tuesday.

The good news is Iíll be testing the PCX 2000 and Fred the PCX 2500. When I get back from NY Iíll probably sent the PCX 2000 so he can do a quick test between them but I feel also that it may not make any difference. But we certainly canít be using the PCX 5000 as Its ,just not strong enough.

I tested that yesterday with the PCX 5000 and you can see itís better than native already but not enough. Iím hoping to have the PCX 2000 by Friday so I can test before I leave.


I am thinking of starting a thread on the Ultron 28mm and show it in its native state the Big Bronco test just to show where it is without a PCX front filter



Oct 11, 2017 at 01:09 PM
nehemiahphoto
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p.91 #14 · p.91 #14 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
Lol

Yea I jumped on it quick. I want to take the lens to NY next Tuesday.

The good news is Iíll be testing the PCX 2000 and Fred the PCX 2500. When I get back from NY Iíll probably sent the PCX 2000 so he can do a quick test between them but I feel also that it may not make any difference. But we certainly canít be using the PCX 5000 as Its ,just not strong enough.

I tested that yesterday with the PCX 5000 and you can see itís better than native already but not enough. Iím hoping to
...Show more

Anyone else have the g21+PCX that can test for coma? My results at 2.8 shooting stars was pretty ok in the center, a midzone dip where stars got worse and more blobby/smearish, and then improvement towards the edges of the frame. I am wondering if it's a sensor stack/pcx result. I am going to try flipping my filter so it favors the mid zone and gives in the corners and see if that reverses the behavior. I gave mine for Derek to test on his UT sensor, but am curious if anyone else has tested for coma on a stock sensor with filter.



Oct 14, 2017 at 03:15 AM
GMPhotography
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p.91 #15 · p.91 #15 · Front-End Filter Improves Corner Smearing


BTW anyone needing a PCX 2000 I have one I just got for the CV 28 that is too strong for it. Itís on the B&S board. I only tested it this morning. So itís new

I need to ship Monday so grab it



Oct 14, 2017 at 07:59 PM
maxxprofex
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p.91 #16 · p.91 #16 · Front-End Filter Improves Corner Smearing


Hello everybody,

here's my results from testing the Voigtlšnder Color Skopar 25mm, based on Haruhiko's recommendation to use a 1200mm PCX lens (thanks again so much, Haruhiko!!!). Without filter the CV25 performs just horribly on the A7. With the PCX filter the lens becomes quite usable on my A7, albeit not perfect. The difference that PCX filter makes is quite impressive. (As a side note: with my Nikon AIS 24mm F2.8 I get better corners, but the center is better with CV25; also, the CV25 produces nicer colors).

These were shot at F8:
With PCX: https://ibb.co/cknLt6
Without: https://ibb.co/dHqUmR






Oct 17, 2017 at 03:52 PM
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