p.7 #1 · Kolari Mod's Improvements: A Summary of Tests
First off, let me backtrack and say kudo's for the testing comps work.
Looking at the side by side corner crop comps (pg. 4), three things are apparent to me (in the realm of push / pull). First and second are the color / contrast variances. Third is the field of view / perceived size diff.
It seems like the stock fov is wider, and simultaneously, the image features seem larger than compared to the modded counterpart. It seems as though by moving the point of refraction more distant, the projection is enlarged, but since the capture area is the same, you are losing some of the projected image, as well as making it smaller (i.e. capture area smaller than projection area). Not sure I'm fully following what is the reason behind the diff (noting my explanation as a question, not an answer).
Probably an "insignificant" difference in fov for better corners, but isn't that kinda like cropping out the extreme offending corners?
The effect seemingly being somewhat like using a .7mm extension tube ... which goes back to my question @ making the adapter .7mm thicker, instead of modding the stack. It would seem that the stack mod is creating a color variance, whereas I'm not sure if a .7mm thicker adapter would induce that (retaining the OEM design stack). Sony is pretty good at understanding color. I'm not sure that modding the stack and creating profiles is the better route to color. Would be very curious to see the diff between a .7mm stack mod, vs. an AA removal (likely accountable for certain diffs) with replacement glass to retain 2mm OEM stack thickness vs. stock with a .7mm thicker adapter.
I guess my perspective is that by modding the stack thickness, we are making a globally applicable adjustment that can result in correction for non-native optical projection design ... which could simultaneously incur over / under correction for native optical projection (note Otus comps). However, if we left the stack thickness stock (replacing AA with cover glass maybe), then we are no longer tampering the OEM (i.e. color) design refraction angles between lens / stack / sensor for OEM design glass. By making the .7mm adjustment via adapters (vs. stack), we can selectively apply correction vs. non-correction application.
Push / pull / compromises ... choose your poison(s).
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.7 #2 · Kolari Mod's Improvements: A Summary of Tests
RustyBug wrote:
First off, let me backtrack and say kudo's for the testing comps work.
Looking at the side by side corner crop comps (pg. 4), three things are apparent to me (in the realm of push / pull). First and second are the color / contrast variances. Third is the field of view / perceived size diff.
It seems like the stock fov is wider, and simultaneously, the image features seem larger than compared to the modded counterpart. It seems as though by moving the point of refraction more distant, the projection is enlarged, but since the capture area is the same, you are losing some of the projected image, as well as making it smaller (i.e. capture area smaller than projection area). Not sure I'm fully following what is the reason behind the diff (noting my explanation as a question, not an answer).
Probably an "insignificant" difference in fov for better corners, but isn't that kinda like cropping out the extreme offending corners?
The effect seemingly being somewhat like using a .7mm extension tube ... which goes back to my question @ making the adapter .7mm thicker, instead of modding the stack. It would seem that the stack mod is creating a color variance, whereas I'm not sure if a .7mm thicker adapter would induce that (retaining the OEM design stack). Sony is pretty good at understanding color. I'm not sure that modding the stack and creating profiles is the better route to color. Would be very curious to see the diff between a .7mm stack mod, vs. an AA removal (likely accountable for certain diffs) with replacement glass to retain 2mm OEM stack thickness vs. stock with a .7mm thicker adapter.
The problem isn't the register distance. Kolari does its best to adjust the registration distance properly. A .7mm thicker adapter would still leave the thicker cover glass that curves the tangential curves and creates astigmatism in the corners. Such a thicker adapter wouldn't help at all, it would just prevent full infinity focus.
p.7 #3 · Kolari Mod's Improvements: A Summary of Tests
Steve Spencer wrote:
Rusty,
The problem isn't the register distance. Kolari does its best to adjust the registration distance properly. A .7mm thicker adapter would still leave the thicker cover glass that curves the tangential curves and creates astigmatism in the corners. Such a thicker adapter wouldn't help at all, it would just prevent full infinity focus.
+1 @ distance vs. infinity
I'm confused then (what else is new ).
How are we making a thinner stack without increasing the distance from the exit pupil to the stack? Are we offsetting the thinner stack by shimming the sensor / stack with the corresponding .7mm?
p.7 #4 · Kolari Mod's Improvements: A Summary of Tests
RustyBug wrote:
+1 @ distance vs. infinity
I'm confused then (what else is new ).
How are we making a thinner stack without increasing the distance from the exit pupil to the stack? Are we offsetting the thinner stack by shimming the sensor / stack with the corresponding .7mm?
Kolari moved the sensor forward to counter the thinner filter effect (less light bending). You could also adjust on the lens front only (i.e. adapter), but that would mess up a lot of things.
And Rusty, the slight shift in framing is not due to the mod but due to mounting on and taking off the two cameras from my tripod. I guess lever Arca Swiss clamp is not good for this kind of test. There is no other trick at play.
Regarding color profile, the default Adobe profiles are not particularly good so using Xrite profile is not a problem to me. You can still get good color with the Adobe profiles if you can WB your scene properly (either while shooting or in post). It's the same amount of work regardless.
p.7 #5 · Kolari Mod's Improvements: A Summary of Tests
hiepphotog wrote:
Kolari moved the sensor forward to counter the thinner filter effect (less light bending). You could also adjust on the lens front only (i.e. adapter), but that would mess up a lot of things.
Okay, thanks.
And Rusty, the slight shift in framing is not due to the mod but due to mounting on and taking off the two cameras from my tripod. I guess lever Arca Swiss clamp is not good for this kind of test. There is no other trick at play.
I would understand a shift in framing ... but the features look larger (or is it only an illusion because of the contrast / color shifts).
p.7 #6 · Kolari Mod's Improvements: A Summary of Tests
RustyBug wrote:
I would understand a shift in framing ... but the features look larger (or is it only an illusion because of the contrast / color shifts).
, now I look at them, it does seem to be a bit larger. But I think it's mainly because of the lighting angle. The mod (on the left - bluish cast) has flatter lighting.
Next round, we will probably go with the knob clamp to have less shift and indoor test with constant lighting so it would be easier to see.
Reduction in field curvature and astigmatism is easily experienced. On the stock camera, you need to focus much closer to get the corner at infinity in focus. On the modded cam, sometimes you don't even need to refocus to get that corners in focus. This physical evidence has to be experienced in person ,
Nov 22, 2015 at 01:20 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.7 #7 · Kolari Mod's Improvements: A Summary of Tests
RustyBug wrote:
+1 @ distance vs. infinity
I'm confused then (what else is new ).
How are we making a thinner stack without increasing the distance from the exit pupil to the stack? Are we offsetting the thinner stack by shimming the sensor / stack with the corresponding .7mm?
Yes, Rusty, I believe Kolari repositions the sensor to make up for the thinner sensor stack.
p.7 #8 · Kolari Mod's Improvements: A Summary of Tests
FWIW, I checked the Batis 25 on Lloyd's comparison between the stock and modded cam. Without saying too much, personally, I wouldn't worry too much about the degradation with native lenses.
p.7 #10 · Kolari Mod's Improvements: A Summary of Tests
So, could someone please describe for me how the register, i.e. the flange to focal plane distance, is defined and measured for a stock and Kolari modified A7 type camera? TIA.
p.7 #11 · Kolari Mod's Improvements: A Summary of Tests
k-h.a.w wrote:
So, could someone please describe for me how the register, i.e. the flange to focal plane distance, is defined and measured for a stock and Kolari modified A7 type camera? TIA.
K-H, I think the registration distance is published for each mount. It's the distance between the mount to the sensor/film plane. FYI, Sony E-mount has an 18mm flange distance. For the mod, I think KolariVision went through a trial and error process to re-position/shim the sensor until they got it right with their ZM 50 and an adapter combo. I don't imagine they need to move a lot to get it right.
p.7 #12 · Kolari Mod's Improvements: A Summary of Tests
hiepphotog wrote:
K-H, I think the registration distance is published for each mount. It's the distance between the mount to the sensor/film plane. FYI, Sony E-mount has an 18mm flange distance. For the mod, I think KolariVision went through a trial and error process to re-position/shim the sensor until they got it right with their ZM 50 and an adapter combo. I don't imagine they need to move a lot to get it right.
Thanks Hiep. This is my question.
18mm measured from flange to the front of the sensor surface or to the front of the cover glass?
Which is it and why? TIA.
p.7 #13 · Kolari Mod's Improvements: A Summary of Tests
k-h.a.w wrote:
Thanks Hiep. This is my question.
18mm measured from flange to the front of the sensor surface or to the front of the cover glass?
Which is it and why? TIA.
I believe it should be measured to the surface of the sensor with only air gap in between. It's probably only a conventional thing since only until recently, this stack thickness issue has become more apparent to the public.
p.7 #14 · Kolari Mod's Improvements: A Summary of Tests
Thanks Hiep, I agree. The distance of 18mm should be the same, whether it's film, stock sensor stack, or Kolari modified stack. So, that's different from the post by Steve Spencer above p.7 #7.
Of course, the issue that has surfaced (pun intended) is that the cover glass with its optical properties has to be part of the optical calculation. I am sure that is done correctly for the new FE lenses. But, of course not for none-native lenses. Thinning the cover glass is just a fudge, that seems to work pretty well for some lenses though. Thanks again.
Nov 23, 2015 at 04:36 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.7 #15 · Kolari Mod's Improvements: A Summary of Tests
k-h.a.w wrote:
Thanks Hiep, I agree. The distance of 18mm should be the same, whether it's film, stock sensor stack, or Kolari modified stack. So, that's different from the post by Steve Spencer above p.7 #7.
Of course, the issue that has surfaced (pun intended) is that the cover glass with its optical properties has to be part of the optical calculation. I am sure that is done correctly for the new FE lenses. But, of course not for none-native lenses. Thinning the cover glass is just a fudge, that seems to work pretty well for some lenses though. Thanks again.
K-H,
I think Kolari needs to reposition the sensor because the glass they use has different refractive properties than the stock glass. I think the 18mm is to the sensor with the refractive properties of the stock glass included in the path. Different glass requires a slightly different register distance to get the focus optimized on the sensor. As Hiep noted, Kolari had to figure this out with trial and error. In any event they have been clear they do reposition the sensor.
p.7 #16 · Kolari Mod's Improvements: A Summary of Tests
hiepphotog wrote:
FWIW, I checked the Batis 25 on Lloyd's comparison between the stock and modded cam. Without saying too much, personally, I wouldn't worry too much about the degradation with native lenses.
Hi Hiep,
k-h.a.w and Hiep, fantastic work!
I just reviewed Lloyd's tests with the Batis 25 on the A7rII mod and unmoded version, and there is quite a difference which I was not expecting. In all the test results it shows that until f/5.6 in most cases the Kolari modded version is not really suitable with the Batis 25. It is appears that if we decide to proceed with the Kolari modification, we really need to make a choice as to which series of lenses we wish to run with.
p.7 #17 · Kolari Mod's Improvements: A Summary of Tests
Steve Spencer wrote:
K-H,
I think Kolari needs to reposition the sensor because the glass they use has different refractive properties than the stock glass. I think the 18mm is to the sensor with the refractive properties of the stock glass included in the path. Different glass requires a slightly different register distance to get the focus optimized on the sensor. As Hiep noted, Kolari had to figure this out with trial and error. In any event they have been clear they do reposition the sensor.
Many thanks Steve.
So, the optical length, not just the physical length, matters, and Kolari adjusts for that.
Is that the point? Does Kolari say by how much they need to adjust the physical lemgth?
If so, why not reposition the existing sensor stack, unless of course, there is not enough extra space available?
Also, how does Leica solve this problem, e.g. in the M9, taking into account their thinner cover glass?
Thanks again.
p.7 #18 · Kolari Mod's Improvements: A Summary of Tests
charles.K wrote:
Hi Hiep,
k-h.a.w and Hiep, fantastic work!
I just reviewed Lloyd's tests with the Batis 25 on the A7rII mod and unmoded version, and there is quite a difference which I was not expecting. In all the test results it shows that until f/5.6 in most cases the Kolari modded version is not really suitable with the Batis 25. It is appears that if we decide to proceed with the Kolari modification, we really need to make a choice as to which series of lenses we wish to run with.
Many thanks Charles.
I, sort of, have already resigned myself to the fact that one would need two cameras, one modified for M lenses, and a stock one for native FE lenses.
With kind regards, K-H. (K-H is short for Karl-Heinz)
p.7 #19 · Kolari Mod's Improvements: A Summary of Tests
charles.K wrote:
Hi Hiep,
k-h.a.w and Hiep, fantastic work!
I just reviewed Lloyd's tests with the Batis 25 on the A7rII mod and unmoded version, and there is quite a difference which I was not expecting. In all the test results it shows that until f/5.6 in most cases the Kolari modded version is not really suitable with the Batis 25. It is appears that if we decide to proceed with the Kolari modification, we really need to make a choice as to which series of lenses we wish to run with.
I guess I have lower expectation so it looks fine to me. The Elmar 24 improves a lot more than the Batis 25 degrades.
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k-h.a.w wrote:
Many thanks Steve.
So, the optical length, not just the physical length, matters, and Kolari adjusts for that.
Is that the point? Does Kolari say by how much they need to adjust the physical lemgth?
If so, why not reposition the existing sensor stack, unless of course, there is not enough extra space available?
Also, how does Leica solve this problem, e.g. in the M9, taking into account their thinner cover glass?
Thanks again.
K-H, optical length matters, but what Kolari does is to simply replace the original thick stack with a much thinner stack. Then they need to move the sensor closer to the mount to achieve infinity focus. The stock Sony is already using shims to position their sensor to the right location and make sure it's flat. Kolari just removes some of the shims, at least that's what I remember Ilija told me. I didn't ask how much closer he moved the sensor to the mount, but he said it's quite close to the mechanical curtain.
The sensor stack has to be glued on top of the sensor so I'm not sure how they can reposition without moving the sensor. Also, that wouldn't change the total refractive power of the stack, which is the important factor for the performance of short-flange rangefinder.
p.7 #20 · Kolari Mod's Improvements: A Summary of Tests
Steve Spencer wrote:
Yes, Rusty, I believe Kolari repositions the sensor to make up for the thinner sensor stack.
If you don't want to trust their reposition of the sensor, just send in one of your own adapter/lens combo that you trust, like I did. They will be close in compensating the register distance of the coverglass replacement.
).
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