keeerow wrote:
So theoretically, which glass should I use the 3000 like the one used for your 18 ZM? I am willing to try it out myself and report my findings.
Theoretically 3000mm. I don't remember why I ended up to Hoya +1; was it just because OptoSigma lens is hard to place to this lens, or did I like also optically better. Due to archiving I can't tell you, I documented my findings to this post, but the link does not work as thread is archived.
I'm thinking of having my camera modified to only have a total of 1mm in the optical path behind the lens before the sensor (Hot Mirror and Cover Glass removed).
I would then add a rear-mounted 1mm thick filter behind my 21mm Loxia.
In theory, other than the risk of reflections and decentering, this should give me the same performance as stock shouldn't it?
According to Daniel at Monochrome imaging, the last layer over the sensor is 0.7mm. Dust shaker is maybe .5mm+-, I don't have a caliper to measure exactly. If i recall the UV/IR filter sandwich was a bit over 1mm, so the 2.5mm ball park that is out on the web is probably close...
Kolari states it UT is 0.2mm, plus the 0.7mm cover glass that he does not remove would give you 0.9mm. FWIW, I like Kolari and just had some work done by him, but some who know what they're talking about are skeptical about the availability of good hot mirror glass with that low thickness. (I don't want to speak on their behalf, but you can PM me if you want to know.)
Could look at a STC or Astronomik clip in filter if you haven't. This is actually my setup on my A7R2. Kolari pulled the shaker and hot mirror, leaving the last 0.7mm cover glass. I have an STC 615nm OWB clip in filter, they state is 1.1mm thick, so my total is 1.8mm. AWB is better than Kolari's UT (which is why I skipped that), the VM 40/1.2 behaves quite well, and Contax G lenses with a 1500mm PCX are even better than with the filter on stock, I think I'm getting close to the performance with a 5000mm PCX on a Kolari UT camera, now I need another filter for the G21 so I don't have to swap. Added benefit, is pull the clip in filter, and I have a full spectrum camera if I feel like something different.
Saw a very slight change on the borders with this setup on the 28/2, but didn't have anything wider and native to try. Change wouldn't be noticeable without peeping, so it didn't bother me.
Good luck!
thrice wrote:
Bit of an odd question.
I'm thinking of having my camera modified to only have a total of 1mm in the optical path behind the lens before the sensor (Hot Mirror and Cover Glass removed).
I would then add a rear-mounted 1mm thick filter behind my 21mm Loxia.
In theory, other than the risk of reflections and decentering, this should give me the same performance as stock shouldn't it?
thrice wrote:
Bit of an odd question.
I'm thinking of having my camera modified to only have a total of 1mm in the optical path behind the lens before the sensor (Hot Mirror and Cover Glass removed).
I would then add a rear-mounted 1mm thick filter behind my 21mm Loxia.
In theory, other than the risk of reflections and decentering, this should give me the same performance as stock shouldn't it?
Very interesting question. I haven’t the required knowledge to answer but there’re several variables involved and your assumptions that 1+1=2 mighn’t be so simple in this case.
To start with, fitting a 1mm. filter right behind the Loxia 21 isn’t the same as adding that same thickness directly on top of the sensor. Besides, if you do the Kolari UT mod, as Mathieu18 says, the final thickness remaining seems to be a bit lkess than 1mm. Another thing is that you’re assuming a stock filter of 2mm. while HaruhikoT, the OP of this thread, takes 2.55mm. for his simulations of front filters.
Not counting the fact that optical thickness isn’t physical thickness either. Different types of optical glasses have different refraction indexes.
Too many variables involved. Maybe somebody with a good education in optics would be able to clarify. I’m not.
A practical test seems the best way to find out. What are you waiting for ?..
Would be getting Daniel @ Monochrome to remove everything (including coverglass) and replacing it with a L3 luminance filter from Astronomik. These are 1.1mm
I figure a 1.1mm total stack should play quite nicely with my RF glass.
You are right, there are a lot of variables. The Loxia has a bit of field curvature anyway. 0.35mm stack reduction may help...
Talked to Brandon Dube, I believe he does the Olaf optical testing with lens rentals. He said 1mm is 1mm, doesn’t matter if it’s a clip in or right on the sensor, it’ll have the same effect.
As to 1.1mm playing nice... tread lightly. Newer RF lenses might be degraded, though I don’t know how thick Leicas stack is. If I remove the clip in filter and use a front end hot mirror, the VM 40/1.2 seems worse than if I use the clip in filter. So 1.8mm is closer to ideal than 0.7mm, but then you’re kinda splitting that difference... I know you’re better versed in this stuff than I am but figured I’d share a data point.
thrice wrote:
Wouldn't be doing Kolari.
Would be getting Daniel @ Monochrome to remove everything (including coverglass) and replacing it with a L3 luminance filter from Astronomik. These are 1.1mm
I figure a 1.1mm total stack should play quite nicely with my RF glass.
You are right, there are a lot of variables. The Loxia has a bit of field curvature anyway. 0.35mm stack reduction may help...
M9 is 0.8mm coverglass, m240/M10 are 1mm. Most modern lenses post-M9 (including the 35mm ZM and new Leica wides) were designed with 1mm in mind. I think it'll be ok... Certainly better than with PCX.
My concern will be aligning the rear filter on the loxia and dealing with any potential colour issues from the L3 (~420-690nm). Will be a bit redder than Kolari UT I believe which transmits 20% of sulphur-II (672.4nm) vs 97% on the L3 filter. I can always use front filters for colour-critical stuff or a rear mounted OWB filter on the loxia.
If you’re ordering from Astronomik why not get one of their clip ins with clear glass or OWB? Can use that for the Lox 21 and you’ll have 2.2mm which should be close to stock. Can pull it for M lenses. My Contax G21 and 28 clear the STC version so the Lox should be fine. It’s a pretty good fit.
thrice wrote:
Good points all of those.
M9 is 0.8mm coverglass, m240/M10 are 1mm. Most modern lenses post-M9 (including the 35mm ZM and new Leica wides) were designed with 1mm in mind. I think it'll be ok... Certainly better than with PCX.
My concern will be aligning the rear filter on the loxia and dealing with any potential colour issues from the L3 (~420-690nm). Will be a bit redder than Kolari UT I believe which transmits 20% of sulphur-II (672.4nm) vs 97% on the L3 filter. I can always use front filters for colour-critical stuff or a rear mounted OWB filter on the loxia.
True! However I only have 21 Loxia, 35ZM and 85/1.8FE
The 85 will be unaffected in any appreciable way by the 1.1mm coverglass, it's just the 21 that needs the extra thickness hence my compulsion to filter just the back of that lens for ease of swapping. I may end doing what you suggest if the cheaper option of a filter on the rear of the loxia doesn't work out.
I have had my camera modified (sadly with dust permanently on the microlenses and no recourse). Total coverglass thickness is now 1.1mm similar to Kolari UT.
I mounted a 30.5mm B+W XS-Pro filter to the back of the 21mm loxia (~1.3mm thickness) and optical performance is as good as on a stock camera.
Originally I tried a 28.5mm Astronomik MC Clear filter which is 1.0mm thick. Whilst performance was ok, it was worse than on a stock camera and caused a slight vignette.
So if you do modify your camera for better RF wide performance, you can still get get performance from stock lenses with an appropriate rear-mounted filter.
I have had my camera modified (sadly with dust permanently on the microlenses and no recourse). Total coverglass thickness is now 1.1mm similar to Kolari UT.
I mounted a 30.5mm B+W XS-Pro filter to the back of the 21mm loxia (~1.3mm thickness) and optical performance is as good as on a stock camera.
Originally I tried a 28.5mm Astronomik MC Clear filter which is 1.0mm thick. Whilst performance was ok, it was worse than on a stock camera and caused a slight vignette.
So if you do modify your camera for better RF wide performance, you can still get get performance from stock lenses with an appropriate rear-mounted filter....Show more →
Thanks, great information. How did you mount the filter safely so that it doesn't fall accidentally in the body? Is ist permanently?
KlausJH wrote:
Thanks, great information. How did you mount the filter safely so that it doesn't fall accidentally in the body? Is ist permanently?
I used two layers of thick foam tape on the front threads of the filter, it then slips neatly over the rear element of the lens. It's a friction fit but i tried to shake it off and physically couldn't.
The only way it would drop off is if I dropped the camera or lens from a decent height in just the right orientation.
I have had my camera modified (sadly with dust permanently on the microlenses and no recourse). Total coverglass thickness is now 1.1mm similar to Kolari UT.
I mounted a 30.5mm B+W XS-Pro filter to the back of the 21mm loxia (~1.3mm thickness) and optical performance is as good as on a stock camera.
Originally I tried a 28.5mm Astronomik MC Clear filter which is 1.0mm thick. Whilst performance was ok, it was worse than on a stock camera and caused a slight vignette.
So if you do modify your camera for better RF wide performance, you can still get get performance from stock lenses with an appropriate rear-mounted filter....Show more →
Wow, great info! Thanks for sharing. Can you post a picture of the modded-loxia?
Fred Miranda wrote:
Wow, great info! Thanks for sharing. Can you post a picture of the modded-loxia?
Anything for you Fred.
Excuse the multitude of fingerprints on this lens. I have obviously been handling it a lot lately.
Also excuse the messed up colour temps in these images, I held a LED head torch off camera to try and get specular reflections on the glass layers and illuminate inside the lens.
A $30 mod to make the Loxia work with the dusty $1000 mod I have done to the camera haha.
thrice wrote:
Anything for you Fred.
Excuse the multitude of fingerprints on this lens. I have obviously been handling it a lot lately.
Also excuse the messed up colour temps in these images, I held a LED head torch off camera to try and get specular reflections on the glass layers and illuminate inside the lens.
A $30 mod to make the Loxia work with the dusty $1000 mod I have done to the camera haha.
So simple and ingenious solution for those with thin filter stacks but still want to use this lens without much IQ degradation. Perhaps this even improves its native field curvature.
I should do a field curvature test if I can ever get onto a hill, Australia is very flat. Took a bit of a risk that this would work, would have been quite depressed if I couldn't use my 21 lox to its full potential. The first filter I used certainly didn't work quite right and I had more LoCA, a little smearing and field curvature.
Fred Miranda wrote:
So simple and ingenious solution for those with thin filter stacks but still want to use this lens without much IQ degradation. Perhaps this even improves its native field curvature.
thrice wrote:
It is the best 18-24mm range lens I've ever used.
I should do a field curvature test if I can ever get onto a hill, Australia is very flat. Took a bit of a risk that this would work, would have been quite depressed if I couldn't use my 21 lox to its full potential. The first filter I used certainly didn't work quite right and I had more LoCA, a little smearing and field curvature.
Probably this mod should work with the Lox 25 and 35mm as well since you would be using the same thickness correction.
Yeah will probably work if the correct diameter/thickness filter can be found to slip over the rear cell of the lens. I struggled to find a good 30.5mm with the correct thickness.
If one didn't have a 35 or care about fully native glass the 35ZM makes more sense.
sebboh wrote:
probably better to just use the better performing and cheaper zm 35/2 on a thin filter modded camera than the loxia 35/2 with extra filter.
