This topic is in the 2016 archive. You can read it and like its posts here. It is read only.
Archive 2016Front-End Filter Improves Corner Smearing
p.56 #1Front-End Filter Improves Corner Smearing
rji2goleez wrote:
Thanks in advance!Bob, I found that the best way to tell the surfaces apart was to lay it down on the tissue wrapping on a flat surface and press the edges to make it rock side to side - if the flat surface is on the tissue, you will see it creating even pressure across the whole surface, but if the curved surface is down, you will be able to shift the pressure on the underneath tissue around different parts of the lens. It's subtle but works. That curved surface needs to face the lens.
Sorry I can't help on the other...
-JohnWow, that's a subtle difference isn't it? I can feel the difference but the rocking side to side is so small that if you lay it on something like a this micro fiber cloth, there is no rocking on either side. However, once I laid it on the tissue paper on a hard surface the difference can be felt.
Thanks John.
Bob
Just place a pencil/pen on top one of the surfaces. The convex side will have more space on the edges. The plano side will be 100% flat.
navmannz wrote
rji2goleez wrote
I just received my opto-sigma lens for my 35/1.4ZM and have a few questions. Can the lens be inserted in either direction? If not, how do I know which side should be facing out? Also, my current setup using a 49-55, 55-52 and 52mm retaining ring results in the Opto-sigma having some play where the retaining ring doesn't quite tighten down to keep the opto-sigma secure. Do I need to try other rings?Thanks in advance!
Sorry I can't help on the other...
-John
Thanks John.
Bob
Just place a pencil/pen on top one of the surfaces. The convex side will have more space on the edges. The plano side will be 100% flat.
Feb 28, 2017 at 02:35 PM
p.56 #2Front-End Filter Improves Corner Smearing
Just ordered my SLB-50-5000PM today, I was able to order it from the Canadian distributor Optikon, great service from these guys! Turnaround time is fairly long according to my contact however, there is no Canadian stock and apparently none in Japan aswell so it's a 5-7 week wait period.
Keh had the ElPro 3 in stock so I ordered one of those, thanks Fred for the setup for the OEM hood.
Keh had the ElPro 3 in stock so I ordered one of those, thanks Fred for the setup for the OEM hood.
Feb 28, 2017 at 03:50 PM
p.56 #3Front-End Filter Improves Corner Smearing
navmannz wrote:
. . . That curved surface needs to face the lens.
-John
This is contrary to other orientation statements in this thread.
. . . That curved surface needs to face the lens.
-John
This is contrary to other orientation statements in this thread.
Feb 28, 2017 at 04:05 PM
p.56 #4Front-End Filter Improves Corner Smearing
JimBuchanan wrote:
-JohnThis is contrary to other orientation statements in this thread.
Wow - can you point me to them, Jim? if so, it means that performance is independent, as it certainly has the desired effect this way.
-John
edited - just found KaruhikoT's post on this here, and you are right - I'll have to test more. The advantages of a group
Edited on Feb 28, 2017 at 04:50 PM · View previous versions
navmannz wrote
. . . That curved surface needs to face the lens.-John
Wow - can you point me to them, Jim? if so, it means that performance is independent, as it certainly has the desired effect this way.
-John
edited - just found KaruhikoT's post on this here, and you are right - I'll have to test more. The advantages of a group
Edited on Feb 28, 2017 at 04:50 PM · View previous versions
Feb 28, 2017 at 04:31 PM
p.56 #5Front-End Filter Improves Corner Smearing
navmannz wrote:
-JohnThis is contrary to other orientation statements in this thread.Wow - can you point me to them, Jim? if so, it means that performance is independent, as it certainly has the desired effect this way.
-John
edited - just found KaruhikoT's post on this, and you are right - I'll have to test more. The advantages of a group
second edit - just back from a quick test, and it appears that with the curved face towards the lens, there is a slightly weaker effect than with it facing the subject, as assessed by focus distance anyway.
Do you have any comment on this, HaruhikoT?
JimBuchanan wrote
navmannz wrote
. . . That curved surface needs to face the lens.-John
-John
edited - just found KaruhikoT's post on this, and you are right - I'll have to test more. The advantages of a group
second edit - just back from a quick test, and it appears that with the curved face towards the lens, there is a slightly weaker effect than with it facing the subject, as assessed by focus distance anyway.
Do you have any comment on this, HaruhikoT?
Feb 28, 2017 at 04:47 PM
p.56 #6Front-End Filter Improves Corner Smearing
Mine faces out to subject. Now you guys got me all confused. Lol
Feb 28, 2017 at 04:51 PM
p.56 #7Front-End Filter Improves Corner Smearing
GMPhotography wrote:
Mine faces out to subject. Now you guys got me all confused. Lol
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...
-John
Mine faces out to subject. Now you guys got me all confused. Lol
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...
-John
Feb 28, 2017 at 05:03 PM
p.56 #8Front-End Filter Improves Corner Smearing
navmannz wrote:
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...
-John
I've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...
-John
GMPhotography wrote
Mine faces out to subject. Now you guys got me all confused. Lol-John
I've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...
-John
Feb 28, 2017 at 07:06 PM
p.56 #9Front-End Filter Improves Corner Smearing
navmannz wrote:
navmannz wrote
GMPhotography wrote
Mine faces out to subject. Now you guys got me all confused. Lol-John
-John
Can you see a difference in infinity focusing?
Feb 28, 2017 at 07:41 PM
p.56 #10Front-End Filter Improves Corner Smearing
rji2goleez wrote:
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...
-JohnI've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...
-JohnCan you see a difference in infinity focusing?
Very, very slight, Bob - based on my experience, when the curved face is towards the subject, the shimming needs to be reduced slightly more than when it is faced towards the lens - but the difference is very minimal! That suggests to me that when the curved face is towards the subject, it is inducing a slightly stronger correction effect, increasing the focal length just a tiny bit more.
-John
navmannz wrote
navmannz wrote
GMPhotography wrote
Mine faces out to subject. Now you guys got me all confused. Lol-John
-John
Very, very slight, Bob - based on my experience, when the curved face is towards the subject, the shimming needs to be reduced slightly more than when it is faced towards the lens - but the difference is very minimal! That suggests to me that when the curved face is towards the subject, it is inducing a slightly stronger correction effect, increasing the focal length just a tiny bit more.
-John
Feb 28, 2017 at 08:09 PM
p.56 #11Front-End Filter Improves Corner Smearing
navmannz wrote:
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...
-JohnI've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...
-JohnCan you see a difference in infinity focusing?Very, very slight, Bob - based on my experience, when the curved face is towards the subject, the shimming needs to be reduced slightly more than when it is faced towards the lens - but the difference is very minimal! That suggests to me that when the curved face is towards the subject, it is inducing a slightly stronger correction effect, increasing the focal length just a tiny bit more.
-John
I would love for HaruhikoT to weigh in on this subject. On my setup, I have the convex side facing forward. With a single bronze colored shim left in place, I can reach a hard stop infinity focus, but just barely.
Rob
rji2goleez wrote
navmannz wrote
navmannz wrote
GMPhotography wrote
Mine faces out to subject. Now you guys got me all confused. Lol-John
-John
-John
I would love for HaruhikoT to weigh in on this subject. On my setup, I have the convex side facing forward. With a single bronze colored shim left in place, I can reach a hard stop infinity focus, but just barely.
Rob
Mar 01, 2017 at 10:29 AM
p.56 #12Front-End Filter Improves Corner Smearing
robgo2 wrote:
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...
-JohnI've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...
-JohnCan you see a difference in infinity focusing?Very, very slight, Bob - based on my experience, when the curved face is towards the subject, the shimming needs to be reduced slightly more than when it is faced towards the lens - but the difference is very minimal! That suggests to me that when the curved face is towards the subject, it is inducing a slightly stronger correction effect, increasing the focal length just a tiny bit more.
-JohnI would love for HaruhikoT to weigh in on this subject.
Rob
In the case of the Contax 28G, based on @HaruhikoT's simulations, reversing the 1.5m front-lens changed its strength to about 1.3m.
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
navmannz wrote
rji2goleez wrote
navmannz wrote
navmannz wrote
GMPhotography wrote
Mine faces out to subject. Now you guys got me all confused. Lol-John
-John
-John
Rob
In the case of the Contax 28G, based on @HaruhikoT's simulations, reversing the 1.5m front-lens changed its strength to about 1.3m.
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
Mar 01, 2017 at 10:33 AM
p.56 #13Front-End Filter Improves Corner Smearing
Fred Miranda wrote:
-JohnI've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...
-JohnCan you see a difference in infinity focusing?Very, very slight, Bob - based on my experience, when the curved face is towards the subject, the shimming needs to be reduced slightly more than when it is faced towards the lens - but the difference is very minimal! That suggests to me that when the curved face is towards the subject, it is inducing a slightly stronger correction effect, increasing the focal length just a tiny bit more.
-JohnI would love for HaruhikoT to weigh in on this subject.
RobIn the case of the Contax 28G, based on @HaruhikoT@'s simulations, reversing the 1.5m front-lens changed its strength to about 1.3m.
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
Is that last suggestion of yours based on actual testing, Fred? My comparison did suggest the opposite, but I'm keen to establish a bit more evidence for whether there is one way that delivers better performance than the other.
-John
robgo2 wrote
navmannz wrote
rji2goleez wrote
navmannz wrote
navmannz wrote
I think that you're probably right, Guy - interestingly I went back to your post to check on shims for the ZM 35. When I removed the rear mount on mine I found two gold shims (c. 0.2 mm), and removing one doesn't quite get me to infinity, but removing both is way too much. Looks like I'll have to buy some shim material and get out the nail scissors...-John
-John
-John
Rob
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
Is that last suggestion of yours based on actual testing, Fred? My comparison did suggest the opposite, but I'm keen to establish a bit more evidence for whether there is one way that delivers better performance than the other.
-John
Mar 01, 2017 at 01:42 PM
p.56 #14Front-End Filter Improves Corner Smearing
navmannz wrote:
-JohnCan you see a difference in infinity focusing?Very, very slight, Bob - based on my experience, when the curved face is towards the subject, the shimming needs to be reduced slightly more than when it is faced towards the lens - but the difference is very minimal! That suggests to me that when the curved face is towards the subject, it is inducing a slightly stronger correction effect, increasing the focal length just a tiny bit more.
-JohnI would love for HaruhikoT to weigh in on this subject.
RobIn the case of the Contax 28G, based on @HaruhikoT@@'s simulations, reversing the 1.5m front-lens changed its strength to about 1.3m.
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)Is that last suggestion of yours based on actual testing, Fred? My comparison did suggest the opposite, but I'm keen to establish a bit more evidence for whether there is one way that delivers better performance than the other.
-John
John,
It's based on his simulation. A PCX 5m is perfect for the 35/1.4 ZM. See here:
https://www.fredmiranda.com/forum/topic/1453834/13#13843876
Reversing the front-lens would change these numbers and affect the simulation but honestly I didn't test it.
Did you get better results reversion the 5m front-lens?
Fred Miranda wrote
robgo2 wrote
navmannz wrote
rji2goleez wrote
navmannz wrote
I've just done two sets of four images infinity focused with the camera tripod-mounted and using apertures in the range F/1.4 through F/4 in one-stop increments - I had the curved face towards the lens in the first set, and towards the subject in the second. After importing them into Lightroom and using its compare facility zoomed into 1:1, I can possibly see slightly better resolution in the first set than the second. Based on that result, I'll be sticking with the curved face towards the lens. YMMV...-John
-John
Rob
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
-John
John,
It's based on his simulation. A PCX 5m is perfect for the 35/1.4 ZM. See here:
https://www.fredmiranda.com/forum/topic/1453834/13#13843876
Reversing the front-lens would change these numbers and affect the simulation but honestly I didn't test it.
Did you get better results reversion the 5m front-lens?
Mar 01, 2017 at 02:07 PM
p.56 #15Front-End Filter Improves Corner Smearing
Fred Miranda wrote:
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)Is that last suggestion of yours based on actual testing, Fred? My comparison did suggest the opposite, but I'm keen to establish a bit more evidence for whether there is one way that delivers better performance than the other.
-JohnJohn,
It's based on his simulation. A PCX 5m is perfect for the 35/1.4 ZM. See here:
https://www.fredmiranda.com/forum/topic/1453834/13#13843876
Reversing the front-lens would change these numbers and affect the simulation but honestly I didn't test it.
Did you get better results reversion the 5m front-lens?
In a word yes. When I discovered that I had mounted it the 'wrong way' round, I inverted it and shot some more images, which seemed very little different. I then did a more careful test (here) which suggests a very slight edge to those shot with the curved surface facing to the lens. It would be interesting to see results from a simulation done with it in this mode.
-John
navmannz wrote
Fred Miranda wrote
In the case of the Contax 28G, based on @HaruhikoT@@@'s simulations, reversing the 1.5m front-lens changed its strength to about 1.3m.For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
-John
It's based on his simulation. A PCX 5m is perfect for the 35/1.4 ZM. See here:
https://www.fredmiranda.com/forum/topic/1453834/13#13843876
Reversing the front-lens would change these numbers and affect the simulation but honestly I didn't test it.
Did you get better results reversion the 5m front-lens?
In a word yes. When I discovered that I had mounted it the 'wrong way' round, I inverted it and shot some more images, which seemed very little different. I then did a more careful test (here) which suggests a very slight edge to those shot with the curved surface facing to the lens. It would be interesting to see results from a simulation done with it in this mode.
-John
Mar 01, 2017 at 02:10 PM
p.56 #16Front-End Filter Improves Corner Smearing
navmannz wrote:
For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)Is that last suggestion of yours based on actual testing, Fred? My comparison did suggest the opposite, but I'm keen to establish a bit more evidence for whether there is one way that delivers better performance than the other.
-JohnJohn,
It's based on his simulation. A PCX 5m is perfect for the 35/1.4 ZM. See here:
https://www.fredmiranda.com/forum/topic/1453834/13#13843876
Reversing the front-lens would change these numbers and affect the simulation but honestly I didn't test it.
Did you get better results reversion the 5m front-lens?In a word yes. When I discovered that I had mounted it the 'wrong way' round, I inverted it and shot some more images, which seemed very little different. I then did a more careful test (here) which suggests a very slight edge to those shot with the curved surface facing to the lens. It would be interesting to see results from a simulation done with it in this mode.
-John
Thanks for the info John. Now I got curious and will test this out.
Fred
Fred Miranda wrote
navmannz wrote
Fred Miranda wrote
In the case of the Contax 28G, based on @HaruhikoT@@@@'s simulations, reversing the 1.5m front-lens changed its strength to about 1.3m.For the 35/1.4 ZM, the 5m front lens seems to be a better correction when not reversed. (Meaning, convex side facing away from the camera)
-John
It's based on his simulation. A PCX 5m is perfect for the 35/1.4 ZM. See here:
https://www.fredmiranda.com/forum/topic/1453834/13#13843876
Reversing the front-lens would change these numbers and affect the simulation but honestly I didn't test it.
Did you get better results reversion the 5m front-lens?
-John
Thanks for the info John. Now I got curious and will test this out.
Fred
Mar 01, 2017 at 02:33 PM
p.56 #17Front-End Filter Improves Corner Smearing
I was wondering why this thread doesn't show up in the alternate gear thread, being the epitome of alternate lens use on a non-native camera body?
Mar 01, 2017 at 08:51 PM
p.56 #18Front-End Filter Improves Corner Smearing
ZM 25
Very poor results from a test with a Hoya 46mm +1 diopter. Even after removing 3 shims from the rear of the lens, the focus would not reach to infinity.
Using the Optosigma 2000 lens however gives very good results. Removing 2 shims wasn't enough but with 3 shims out the focus reaches past infinity and gives a MFD of 7"! This is an unexpected bonus.
The only downside is no hard stop for infinity.
I used both a Techart and Hawk's adapter to check for infinity results on an A7Rii
Very poor results from a test with a Hoya 46mm +1 diopter. Even after removing 3 shims from the rear of the lens, the focus would not reach to infinity.
Using the Optosigma 2000 lens however gives very good results. Removing 2 shims wasn't enough but with 3 shims out the focus reaches past infinity and gives a MFD of 7"! This is an unexpected bonus.
The only downside is no hard stop for infinity.
I used both a Techart and Hawk's adapter to check for infinity results on an A7Rii
Mar 01, 2017 at 09:04 PM
p.56 #19Front-End Filter Improves Corner Smearing
Hi John, Rob and Fred,
Regarding that 35mm + PCX 5m, orientation of the corrective lens made no visible difference in my simulated MTFs. No difference in infinity focus position, too.
Something that my simulation doesn't take into account may cause John's experimental results but I'm not sure.
Curious about how does the difference looks like. Comparison images would be appreciated.
Haruhiko
Regarding that 35mm + PCX 5m, orientation of the corrective lens made no visible difference in my simulated MTFs. No difference in infinity focus position, too.
Something that my simulation doesn't take into account may cause John's experimental results but I'm not sure.
Curious about how does the difference looks like. Comparison images would be appreciated.
Haruhiko
Mar 01, 2017 at 09:07 PM
p.56 #20Front-End Filter Improves Corner Smearing
polylepis wrote:
ZM 25
Very poor results from a test with a Hoya 46mm +1 diopter. Even after removing 3 shims from the rear of the lens, the focus would not reach to infinity.
Using the Optosigma 2000 lens however gives very good results. Removing 2 shims wasn't enough but with 3 shims out the focus reaches past infinity and gives a MFD of 7"! This is an unexpected bonus.
The only downside is no hard stop for infinity.
I used both a Techart and Hawk's adapter to check for infinity results on an A7Rii
Do you mean poor results *and* it won't focus to infinity, or poor results *because* it won't focus to infinity?
It's perfectly possible for the best results to come with a filter which won't focus to infinity on your adapters, depending on a combination of facts about the filter, the adapters and the tolerances of the lens.
Ideally you would test for the best results focussed as far away as you can focus, and use the filter that gives that best result, and then mess with adapters and or shims to get infinity focus.
ZM 25
Very poor results from a test with a Hoya 46mm +1 diopter. Even after removing 3 shims from the rear of the lens, the focus would not reach to infinity.
Using the Optosigma 2000 lens however gives very good results. Removing 2 shims wasn't enough but with 3 shims out the focus reaches past infinity and gives a MFD of 7"! This is an unexpected bonus.
The only downside is no hard stop for infinity.
I used both a Techart and Hawk's adapter to check for infinity results on an A7Rii
Do you mean poor results *and* it won't focus to infinity, or poor results *because* it won't focus to infinity?
It's perfectly possible for the best results to come with a filter which won't focus to infinity on your adapters, depending on a combination of facts about the filter, the adapters and the tolerances of the lens.
Ideally you would test for the best results focussed as far away as you can focus, and use the filter that gives that best result, and then mess with adapters and or shims to get infinity focus.
Mar 01, 2017 at 09:16 PM