In regards to the statement of buying a UV filter for this lens.............
Why do we put inferior glass in front of superior glass? Doesn’t any glass degrade the quality of what the manufacturer worked so hard to achieve??
I’ve not fully understood the benefits of filters.
Good old school is a UV filter and you will forget about the problem, or playing with software is new school. You can always use all kinds of profiles etc. But why create something new when everything else works well.
I'm doing it to solve a specific problem I see with certain lenses. I definitely would never suggest anyone must or absolutely should use a UV filter (a very specific type in this case), especially if they don't see any problems.
But for me, there is enough reason to do it with the CV 50 APO. I also see the same behavior on the CV 65 APO, and expect to see it on the CV 35 APO. Haven't noticed on my CV 110, but I suspect I will see it there as well.
And to be clear, not any UV filter will do. It needs to have a hard cutoff around 410nm or higher to be effective.
I'm not sure CV was trying to get magenta shading on Sony as a feature. Any perceived degradation seems to be outweighed by the reduction in the magenta I see in the corners. But I would not suggest that this is something that would bother the majority.
YMMV (or everyone's really)
Karl Witt wrote:
In regards to the statement of buying a UV filter for this lens.............
Why do we put inferior glass in front of superior glass? Doesn’t any glass degrade the quality of what the manufacturer worked so hard to achieve??
I’ve not fully understood the benefits of filters.
tsdevine wrote:
I'm doing it to solve a specific problem I see with certain lenses. I definitely would never suggest anyone must or absolutely should use a UV filter (a very specific type in this case), especially if they don't see any problems.
But for me, there is enough reason to do it with the CV 50 APO. I also see the same behavior on the CV 65 APO, and expect to see it on the CV 35 APO. Haven't noticed on my CV 110, but I suspect I will see it there as well.
And to be clear, not any UV filter will do. It needs to have a hard cutoff around 410nm or higher to be effective.
I'm not sure CV was trying to get magenta shading on Sony as a feature. Any perceived degradation seems to be outweighed by the reduction in the magenta I see in the corners. But I would not suggest that this is something that would bother the majority.
tsdevine wrote:
I'm doing it to solve a specific problem I see with certain lenses. I definitely would never suggest anyone must or absolutely should use a UV filter (a very specific type in this case), especially if they don't see any problems.
But for me, there is enough reason to do it with the CV 50 APO. I also see the same behavior on the CV 65 APO, and expect to see it on the CV 35 APO. Haven't noticed on my CV 110, but I suspect I will see it there as well.
And to be clear, not any UV filter will do. It needs to have a hard cutoff around 410nm or higher to be effective.
I'm not sure CV was trying to get magenta shading on Sony as a feature. Any perceived degradation seems to be outweighed by the reduction in the magenta I see in the corners. But I would not suggest that this is something that would bother the majority.
So which UV filters have hard cutoffs at 410nm? I was looking at the Breakthrough X4 graph on their site and it looks like there's a falloff under 450nm.
Yes, I believe more than just CV lenses are susceptible. My Tamron 35mm Di III is probably the worst in this regard. Sony has a lower frequency cutoff in their sensor stack than other camera manufacturers. I'm not sure 3rd party lens makers fully realized that difference when they did lens design. If you look in that link to the thread I posted above, I have some links to sites that discuss Sony's sensor stack and at what frequency it starts filtering.
Oddly enough I don't see this problem in pretty much any of my old legacy manual glass.
Fred Miranda wrote:
Tim,
It looks like this could be a general phenomenon. (Not restricted to Voigt lenses)
Here is the 35/2 DG DN without the Zeiss filter (left) and with the Zeiss filter (right):
I have some BT X4 UV filters and they don't really have any effect on this. There are few options that I've found where the filter has multicoating. I have links to Lensrentals tests in that link I posted above. I personally have found Zeiss UV filters having a positive impact. I also have a Kenko Zeta L41 UV filter on order, it looks like it might also be a good solution.
Check the graph of the last page of this Zeiss brochure...
I find it interesting that the case the Zeiss filters come in is very similar to the one the Kenko comes in. Maybe I'm reading too much into that.....
At the end of the day, if there isn't a pretty hard cutoff at 410nm or somewhere higher, I don't think you'll see much impact in terms of reducing the effect. Kolari believes the cutoff on the Sony stack generally seems to be around 409nm, so that gives you an idea.
There is quite a bit of good comment and content on that other thread, with links to external references. Might be good to pick up commentary over there vs high jacking this thread. Definitely didn't mean to do that.
saxguy wrote:
So which UV filters have hard cutoffs at 410nm? I was looking at the Breakthrough X4 graph on their site and it looks like there's a falloff under 450nm.
There are good explanations for your observations but none has anything to do with the Sony UV/IR cut filter on their sensors. No UV or IR gets through them. They are very strong.
The problem is with this (50 APO) Cosina lens . Once I have my spectrometer setup again, I will post about this in detail.
tsdevine wrote:
Yes, I believe more than just CV lenses are susceptible. My Tamron 35mm Di III is probably the worst in this regard. Sony has a lower frequency cutoff in their sensor stack than other camera manufacturers. I'm not sure 3rd party lens makers fully realized that difference when they did lens design. If you look in that link to the thread I posted above, I have some links to sites that discuss Sony's sensor stack and at what frequency it starts filtering.
Oddly enough I don't see this problem in pretty much any of my old legacy manual glass.
Let us hope that Cosina have rectified this issue in their 35/2. It will be tragic if they have not and keep selling these as “APO” lenses.
realVivek wrote:
There are good explanations for your observations but none has anything to do with the Sony UV/IR cut filter on their sensors. No UV or IR gets through them. They are very strong.
The problem is with this (50 APO) Cosina lens . Once I have my spectrometer setup again, I will post about this in detail.
Let us hope that Cosina have rectified this issue in their 35/2. It will be tragic if they have not and keep selling these as “APO” lenses.
I ordered the CV 35/2 APO to replace my Leica APO Summicron-SL lenses (selling off my SL2-S) for black and white photography. I have always found that even though APO lenses had color benefits they were very good for high contrast/high sharpness black and white images. I imagine that the UV filter on the 50 (which I was planning to order) will be necessary to get the performance closer to my APO Summicron-SLs.
I'd definitely be interested, I know you've commented on some of my posts that you believe you could provide some some insight into this. Note that I've seen this on more than just CV lenses, so it would be interesting to see how this has nothing to do with Sony at all, and it's all on the lens manufacturers.
realVivek wrote:
Is that the final word or would you be interested in reading about what I find? You are the Admin.
I’ve seen this magenta fringing on several of my non Voigtlander lenses. My Loxia 25 and Tamron 35/28 both have it. Also I don’t see this on my Voigtlander 110/2.5 APO.
I have bought Zeiss uv filter now for my Loxia 25 and Tamron 35/2.8 and that has largely fixed the problem.
Good to know, I know i haven't noticed it on my CV 110....but I haven't tested it explicitly either. I do notice it on my Loxia 21 as well (although maybe more subtle.)
TakenWild wrote:
I’ve seen this magenta fringing on several of my non Voigtlander lenses. My Loxia 25 and Tamron 35/28 both have it. Also I don’t see this on my Voigtlander 110/2.5 APO.
Just to clarify, you're saying the Sony sensor stack blocks UV at a lower frequency (deeper into the UV portion of the spectrum) than those of other brands? And that some lenses, such as the Voigtlander 50 APO, transmit more UV than other lenses? Hence the color shift due to too much UV light contamination?
If this is the case, it sounds like the opposite problem of Leica's M sensor stack that doesn't filter out enough IR light (some models are worse than others) and results in color contamination.
My working theory, which I believe realVivek will maybe correct or provide different insight into, is that Sony's sensor stack filters (in general) below 409nm. Other camera manufacturers filter at higher frequencies, therefore allowing less UV spectrum though. Some lens manufacturers may not realize this, being used to dealing with Canon, Nikon, etc. And even though Sony licensed the mount specs, they may not have not gotten into this type of detail.
I don't know if certain lenses transmit more.....or in reality it wasn't realized at design time and attention wasn't paid in how the optics performed at near 410nm frequencies because it was believed the sensor stack would take care of it.
But there are few multicoated UV filters that filter out UV at 410nm or above. The Zeiss happens to be one of them and does seem to reduce the effect.
I'd love to REALLY know the reason, but am happy I found something that mitigates it somewhat.
rscheffler wrote:
Just to clarify, you're saying the Sony sensor stack blocks UV at a lower frequency (deeper into the UV portion of the spectrum) than those of other brands? And that some lenses, such as the Voigtlander 50 APO, transmit more UV than other lenses? Hence the color shift due to too much UV light contamination?
If this is the case, it sounds like the opposite problem of Leica's M sensor stack that doesn't filter out enough IR light (some models are worse than others) and results in color contamination.
