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M43rds user question about sensitivity


dabateman

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Andrea B.

We shouldn't forget that in a certain range (years), the digital cameras also have anti-aliasing filters. While a type of BG glass might be used for blockiing IR, you also have to understand what the anti-aliasng polarizer is blocking. I don't know what is used for those filters.

 

 

Shane Elen has some transmission charts for a few older internal cut filters. You can those here. Some of them appear to be BG glass on two of the old models. But the rest cut some UV.

http://www.beyondvis...m/BV3a-ICF.html

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dabateman

@Cadminum

I looked through the link to Enrico's website that Andrea provided. My 35 mm kuri clone looks almost exactly like the image for the Galaxy 35mm f3.5 here:

http://savazzi.net/photography/35galaxy.html

mine does have one small difference, being that the Open close ring is black and not silver as in the Enrico's image. But that is the only difference.

 

@Andrea thank you for the ICF spectra plots. That is interesting. The Kodak 760 was also available as a Monochrome camera, but I don't know if the block filter was also removed. Olympus said the Olympus EM1 does not contain an anti-aliasing filter on chip in its press release. I think it was the first Olympus not to include an AA filter, but I might be wrong.

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So the question is - under this lighting, with this lens and filter ((or with any fixed lighting/lens/filter))

 

How many stops difference in UV sensitivity should we see between a full spectrum conversion and a stock camera?

 

Good question, and I personally don't have an answer because I've always used conversions for UV/IR work. But let's see if other members have some input on that. And I will ping Bjørn because I think he might have some observations on this......

 

 

I'll go now and see if I can find Bjørn Birna (nfoto). And please, anyone who might have some data to answer the primary question, please let us know.

 

We might somewhere actually have an answer already posted. But after writing almost 6K posts myself, I've long ago lost track of where everything is on UVP !!!! :lol: :lol: :lol:

 

I had bookmarked this conversation on that question. I am sure there are others.

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Hi,

I have two E-M1's, one off-the-shelf and one converted to full spectrum. Yes, with a 385nm LED and a StraightEdgeU filtet there is little if any difference between the two. I am writing this of the top of my head. I'll have been doing some tests, but I can only post details tomorrow. It is getting late here in Finland.

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@Cadminum

I looked through the link to Enrico's website that Andrea provided. My 35 mm kuri clone looks almost exactly like the image for the Galaxy 35mm f3.5 here:

http://savazzi.net/p...y/35galaxy.html

mine does have one small difference, being that the Open close ring is black and not silver as in the Enrico's image. But that is the only difference.

 

Yes, it may look the same physically, but does your lens show a brand name on it? There are a number of those lenses that look almost identical physically, which is a good sign, but not functionally conclusive .

You may not be able to see a brand name on the picture of the lens you ordered, but I will wait until you get it, maybe it has a brand name on it, then I will stop wondering what it is, and stop complaining.

Maybe it has a brand name on it that is one of the ones Enrico shows...

Calling something a clone, without providing the exact brand, or maybe even removing the brand... not saying the brand has been removed, just saying that either of those to me seems fishy.

Time will tell... :)

 

You will not know what you have until you take that step up ring off the lens and see what (it anything) is written under it on the lens.

https://i.ebayimg.co...STM/s-l1600.jpg

 

It seems like the clones on Enricos's page have front labeling which look like they would show up in a photo even if a step down ring was installed on the front.

I don't see any brand name, just a white label applied to the step up with with the words Kuri and clone.

Here is the Kuribayashi 35mm f/3.5. Labeling is in the same location as the Kyoei version.

post-87-0-64574200-1525223555.jpg

 

post-87-0-26329400-1525223761.jpg

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Andrea B.

The bookmarked link which John has posted above tells us that there are 10-13 stops difference between a UV exposure and a Visible exposure made outdoors in good sunlight.

 

Apparently we don't have any information about the number of stops gained between an unconverted UV exposure and a converted UV exposure.

 

Given the serious lack of UV in sunshine illustrated by that 10-13 stop difference, you can surely understand why I encourage conversion. Even if you only gain one stop in UV, that's an improvement. However it has to be more than one stop with most of the current crop of cameras. I was getting almost nothing at all in UV with my Nikon D610 or D810. Apparently some of the Olympus digicams are anomalous and do not block much UV? But I wonder why that is? It surely cannot help with atmospheric haze ("UV haze")??

 

If some users do not wish to convert their cameras, then perhaps the next best thing is to convert a Metz (or other) flash to improve its UV output. In UV photography, illumination is everything. :D That almost sounds profound. But really it is simply the practical take on UV exposures.


 

Cadmium, interestingly I have a W. Acall 35/3.5 which is quite good for UV. There were so many different lens models made by multiple manufacturers that sometimes it is impossible to know whether the 35/3.5 you've just gotten on the 'Bay is going to be good or not.

 

Added Clarification: I was told the preceding statement might be misleading, which I hope everyone knows is never my intent. So let me add the following.

 

If you dig into lens history (a fascinating and time-devouring topic) you will find that lenses with the same labeling and basic design were often manufactured at different times by different manufacturers for later re-branding by a vendor. So we can, and certainly do, encounter two otherwise identically labeled lenses which might perform differently due to -- perhaps -- different coatings, different glues, different glass pours. Sometimes lenses even look alike externally but actually have different element design within.

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Apparently we don't have any information about the number of stops gained between an unconverted UV exposure and a converted UV exposure.

 

 

As I said elsewhere, that is extremely camera-dependent. For example, some older Canons change only 0.5-1.5 stops. The SD14 hot mirror, on the other hand, blocks 10+ stops of UV (fortunately, that one is hand-removable.) It depends on whether UV blocking was deemed a priority by the engineers when the camera was designed.

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dabateman

Hi,

I have two E-M1's, one off-the-shelf and one converted to full spectrum. Yes, with a 385nm LED and a StraightEdgeU filtet there is little if any difference between the two. I am writing this of the top of my head. I'll have been doing some tests, but I can only post details tomorrow. It is getting late here in Finland.

 

Excellent, if you could test them side by side and provide the exposure values, I would be very appreciated.

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Cadmium, interestingly I have a W. Acall 35/3.5 which is quite good for UV. There were so many different lens models made by multiple manufacturers that sometimes it is impossible to know whether the 35/3.5 you've just gotten on the 'Bay is going to be good or not.

 

Andrea, your statement is misleading.

It is actually VERY possible to know what to expect from certain brands and models of lenses that have been tested.

That is what Enrico's tests are about, and that is what my Sparticle tests are about, and many other people have tested these lenses also.

People should expect something when they purchase a certain lenses that has been repeatedly tested by multiple people.

You should build your self a Sparticle, or get a spectrometer, to back up such a statement, otherwise, the tests people have done are there for the people who want to know what to expect.

People have put a lot of work into testing various lenses, and to say they shouldn't know what to expect disregards a consensus of work that many people have invested in for the larger community.

Now, someone walks away thinking they don't need listen to those who have tested these lenses, because it will not matter, because you said they can't know what to expect.

They can.

 

W. Acall is also on the label of the second Kyoei lens (second from left). Both of the lenses on the left end are W. Acall Kyoei 35mm f/3.5, only one works good for UV.

If you mean you have that very exact same lens on the left and it works well for UV, I think you might be mistaken, those are not that good for UV.

See the photo below, both lenses on the left hand side are labeled W. Acall. The second one works the same as the Kuri.

The W. Acall on the left end has been tested by various other people. It will transmit 360nm, but 350nm and 340nm are completely black,

whereas the other three lenses will show some hint of transmission as low as 325nm, so not the same at all, and not what I call a very good lens for UV,

it will work (but then so does a Nikkor 18/4), but definitely not a lens to buy for UV.

By the way, the lens the left end will not work for anything except extreme close up shots with a Nikon. Even with an infinity adapter, you will have to be a few inches or less to focus using a Nikon.

I warm people not to buy that style of W. Acall Kyoei, thinking it is as good for UV as the others shown.

All of the lenses pictured below are made by Kyoei, at least the optics, and at least the first three on the left are probably entirely made by Kyoei.

post-87-0-56570600-1525239100.jpg

 

The W. Acall on the left will transmit almost as well as a newer plastic version of the El-Nikkor 50mm, but not even as good, because it will not have any hilt of light transmitting through 350nm.

So avoid that lens. Some people buy it thinking it works the same as the Kuri/Kyoei, but no.

post-87-0-44579500-1525242322.jpg

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The Kyoei objective on the left seems to be one of those on Leica LM39 mount, which are known to absorb quite a lot of UV.

 

The short answer for the camera comparison is: using a 385nm LED and the StraightEdgeU filter the difference between the cameras is 1/2 stop or less, and about 1 stop with the Baader U-filter. With a 365nm LED filtered with SWB1, and either filter on the objective, the sensitivity of the converted camera is between 4 and 5.5 stops better, with the largest difference in the red sensor channel. The difference between cameras is different for the different sensor channels, so the conversion also affects the "false colours" after white balancing.

 

The long answer is to read the draft reports from my "adventures" into testing lenses and the two cameras.

 

I have been playing for several months and have a method working for testing UV transmission of objectives using LEDs. I have a semi-polished draft report at https://photo.r4phot...otebook.nb.html (Andrea: believe it or not, I have made some progress, and you may even find some useful information for the sticky post on lenses. :-) )

I have applied the same method to compare my two E-M1 cameras, for this I have only a rough draft at https://photo.r4phot...ras-report.html

The data is good in both reports, but text is not yet fully polished. I also intend to test a couple of additional objectives. In the case of the comparison between cameras, I have quite a few more LEDs to play with in the VIS and NIR.

 

Update: I forgot to tell that the "full-spectrum" conversion was done by DSLR AstroTEC (http://www.dslr-astrotec.de/) in Germany. They have been a little bit secretive about the replacement glass used, but the explanation looks convincing to me.

 

"First of all the clear glass that we are using for conversion is specially coated for us and our purpose. The supplier for such special glasses is our great business secret - so I am sorry that I can not tell you our supplier for the clear glass - I don't want to make it too easy for my competitors. But here it is what I can say: The supplier is a German company and the clear glass has a coating on both sides. It is a wideband coating (visual & near infrared) to archive a transmission of at least 99,0% within 400-750 nm.

 

The sensor can detect up to around 1100-1150 nm in the IR range. The UVB/UVC range is more difficult, because the optical design (selection of substrate) and the coatings on the lenses are a big influencing factor. In general we can say that the cheaper the lens is, the larger is the UVB/UVC proportion on your image. The imaging sensor itself can detect UV light up to around 280 nm. So the total range of a clear glass converted camera is around 280 nm - 1150 nm."

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Andrea B.

Pedro, thank you so much for all the good information.

Whenever I find relevant information, I do try to add it to the Stickies so that we can build a reference base accessible to everyone.

 

QUESTION for Pedro: For the camera experiment you reference please verify that the camera is the Olympus EM-1 as you did not reference it in the preceding post. Also, could you mention what lens you were using? And finally what is an SWB1? Thanks!!!

 

To summarize, so that I can add it to the Stickies:

  • Olympus EM-1 Stock vs. Full Spectrum Conversion
    • [Lens + StraightEdgeU ] + 385 nm UV-Led: 1/2 stop difference
    • [Lens + BaaderU] + 385 nm UV-Led: 1 stop difference
    • [Lens + StraightEdgeU or BaaderU] + [365 nm UV-Led + SWB1]: 4 - 5.5 stops difference, largest in R channel.

That data lends weight to a suspicion of mine that there might be a bigger difference depending on peak wavelength being imaged?

 

Andrea: believe it or not, I have made some progress, and you may even find some useful information for the sticky post on lenses.

Good for you on the progress! I will certainly look it over. I'll check with you later on Sticky usage.

 

QUESTION for Pedro: DSLR AstroTEC (http://www.dslr-astrotec.de/) in Germany

I would like to add this conversion shop to the Stickies because the current listings are too US-centric. Would you consider Astro TEC to be a reputable converter? I have the strong belief that a conversion shop should provide the transmission data for any internal filter and Astro TEC has done this. So kudos to them.

On a side note, as a practical matter, I think that 280 nm is a bit optimistic for sensor sensitivity??? We have had 290 nm mentioned before. These might be achievable in "laboratory" conditions, but as mentioned, practically I don't think this is easily achievable.

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Andrea B.

Cadmium: Andrea, your statement is misleading.

It is actually VERY possible to know what to expect from certain brands and models of lenses that have been tested.

That is what Enrico's tests are about, and that is what my Sparticle tests are about, and many other people have tested these lenses also.

People should expect something when they purchase a certain lenses that has been repeatedly tested by multiple people.

 

I think you might have missed my point? Two lenses with the same labeling and basic design were often manufactured at different times by different manufacturers for later re-branding by a vendor. So we can, and certainly do, encounter two otherwise identically labeled lenses which perform differently due to -- perhaps -- different coatings, different glues, different glass pours. Sometimes lenses look alike but actually have different element design within.

 

So, while the various lens tests are absolutely terrific, useful, relevant and greatly appreciated by all of us, we should all keep in mind that there is a possibility that a specific lens might perform differently from a tested lens even if they appear to be the same.

 

However, I will go look and see if what I wrote is misleading......

 

 

EDIT: I removed a reference to my UAT lens because I cannot find the bookmark about it. If I do, then I'll repost.

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Andrea B.

Clark: As I said elsewhere, that is extremely camera-dependent.

 

Yes, indeedy. We've tried to make folks aware of this by listing some cameras in the Stickies which could be used without conversion. Now I'm going to go add some info about the EM-1. :D

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Andrea: my bad, I meant ZWB1 2mm thick on the LED (SWB1, I guess may not even exist). https://www.aliexpre...2311.0.0.5JEzH2

 

I think DSLR AstroTEC is fine. Seems to be a small shop. Sometimes answers to e-mails are a bit too concise but this camera has been in use for a couple of years.

 

Yes, your summary about the camera is fine. Above I did not mention that I also checked the difference in sensitivity at 930 nm and there the difference is 7.5 stops for the three R G B channels. Yes, the cameras are both Olympus E-M1 (the original one, not the current mk II). The conversion retained the sensor cleaning function. I will add more details to the report I linked to when I find time to polish it. If you follow the link to the report there is additional information about some of the other questions frequently discussed here, like the balance between the RGB channels. There is quite a lot of information to go through and I have tried to also describe the method used in full detail (but surely there is something still missing).

 

In the lens tests, I think there are objectives which could be added to the sticky. Of these, the Sigma 30 mm f:2.8 DN A (Art) in MFT mount has become my favourite objective for non-macro UV. It transmits, I would guess down to around 340-350 nm, but it is a design from 2013. Image quality is surprisingly good in UV with the diaphragm fully open to f:2.8. Auto focus works most of the time, autoexposure requires only a bit of compensation and even sensor image stabilisation must be to some extent functional as I can manage 1/4 s and sometimes 1/2 s handheld. Its UV transmission is better than the 19 mm f:2.8 in the same series (of which I learnt about here from Enrico's answer to one of my earlier posts). The Sigma 30 mm surpasses slightly in my tests the Olympus OM Zuiko 35 mm f:2.8, listed in the stickies and tested by Klaus to transmit down to 340 nm. On top of it, it is rather cheap, 180 € new, while I paid 120 € for mine as second-hand.

 

I agree with Andrea about the objectives, or rather I have learnt the lesson here and also the hard way by buying the wrong Kyoei objective before joining this site. In the report I give serial numbers for all objectives tested and year of introduction and/or manufacture when such information could be found.

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Andrea B.

the Sigma 30 mm f:2.8 DN A (Art) in MFT mount has become my favourite objective for non-macro UV.

 

Pedro, wow!! That is a good discovery. And thank you for letting us all know about it. This will certainly go into the Sticky.

And I think I need to pick up one for myself. :D

 

I'm rather surprised because it has 7 elements in 5 groups non-quartz, non-fluorite yet you are getting good UV in the upper range with it. This just proves that it is very difficult to predict what lens going to be useful for UV. I think a lot of people will be very happy to learn about this Sigma A.


 

 

I agree with Andrea about the objectives, or rather I have learnt the lesson here and also the hard way by buying the wrong Kyoei objective before joining this site. In the report I give serial numbers for all objectives tested and year of introduction and/or manufacture when such information could be found.

 

That's the rub! It is quite difficult to discover who actually manufactured some of the older lenses - and when. Providing a serial number can certainly be helpful, and I think most here try to do that.

 

As an example --- here is a link to Soligor history: https://www.apotelyt...soligor-catalog

"Soligor concentrated on the marketing, while it commissioned its lenses from Japan-based producers. The company collaborated with a number of different optics manufacturers, and some lenses, such as the popular 28mm f/2.8, are available in slightly altered versions from several manufacturers. The identity of the producer (Kawanon, Kino, Komine, Sun Optical, Tamron, or Tokina) can be derived from the serial number on the lens."

 

Unfortunately for us, not every re-brander thought to be so careful with the serial numbers.

But thank you, Soligor for doing so. :D

 

A funny twist on the lens manufacturer mystery:

"Soligor lenses were also sold under alternative brand names in different geographical markets. This alternative naming includes lenses branded as Aetna, Beroflex, Derek Gardner, Elicar, Flexar, Hanimar, Infotar, J.C. Penny, Mirage, Pallas, Porst, Prinzflex, Reflex, Super Carenar, and Weltblick."

 

So your Hanimar 135/3.5 might really be a Soligor made by Tokina?? Tell me that is not the road to confusion when trying to figure out what you've got!! Geez!!


 

NOTE TO EVERYONE: Please put your lens photos in the Lens Gallery so they can be easily found by everyone. Nobody can find them in the middle of a long topic like this!!! Thanks.

 

.

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dabateman

Excellent, thank you so much Pedro.

This answers my question.

Your summary here is great. However the linked document is a little confusing, as the materials do not match the data charts. But you did say this was a rough draft and it looks like you have lots of good data to present.

 

To clarify is your Sigma 30mm f2.8 the first one (EX DN) or the second one (DN Art)?

Update: just reread your article and see its the later 30mm f2.8 DN Art. Thank you.

 

I am also interested in the Olympus 30mm macro, as I have a feeling it might be good. But will have to save up for it. I also own the Thingy pinhole lenses, the pro in Nikon mount and the S in m43rds. I look forward to your comments on them.

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The one I have is the newer one, DN Art.

I do not have the 30 mm M.Zuiko macro. I have tested the 60mm M.Zuiko macro and it transmits almost no UV.

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dabateman

Yes that doesn't surprise me about the Olympus 60mm f2.8 macro. It is 13 elements in 10 groups. So alot is going on there. The Olympus 30mm macro is 7 elements in 6 groups. Also some reviews have shown a strong purple blob in flare tests. That is why I think it may transmit well, as the purple blobs may be due to internal uv reflections. The purple blob problem with the Panasonic 7-14mm f4 lens was solved with a 2E or 2A filter needed when used with Olympus cameras. Panasonic cameras do not have the purple blob problem with the 7-14mm. This is why I think its a Uv issue.

 

I also have the Olympus four thirds 35mm f3.5 macro and it transmits ok in uv with Baader filter. Today on the EM1, with mmf3 adapter and Baader venus 2 filter I was able to do some hand held Uv shots in the back yard. I wasn't even using my Canon 199a flashes. With the IBIS and rapid fire shutter I actually got one or two images. So I am happy with the stock Em1. A tripod would be better and the flashes, but I was "watching" the kids.

Thank you for your tests. Looks like the straightedgeU may be a better investment than full spectrum conversion. Unless I win a quartz lens. Only if I get a good lens would the conversion seem beneficial.

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Andrea B.

Enrico Savazzi tells me that he has no details to offer for the difference in stops between the converted and unconverted models of the same camera. Like others of us, his pre-conversion cameras were basically unsuitable for UV photography so there's no pre-conversion UV exposures to use in a comparison.

 

To summarize, at this point we have that the difference in stops is very camera model dependent and may vary from between 1 - 5 stops for those cameras which are useable (more or less) for UV photography in their unconverted state.

 

I have added the Olympus EM-1 to the Sticky with a link to this discussion.

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  • 2 months later...
This is an old thread. However, I have been experimenting a bit more with E-M1 cameras, so for completeness I write a short update. The E-M1 camera off-the-shelf is usable for UV with either StraightedgeU or UG1 filters. With a BaaderU exposure difference to an identical camera converted to full spectrum is in sunlight more than 1 EV, with 365 nm LED as source, difference is about 5 EV. With StraightedgeU and Godox AD200 flash converted as suggested by Enrico the unconverted camera yields similar but less saturated false colours than the converted camera. A friend found that the E-M10 unconverted is also sensitive enough to UV to be used in sunlight with a Schott UG1 filter (Heliopan, thickness unknown). She also commented that some Fuji mirrorless camera she tried was also sensitive to solar UV transmitted through the UG1, while her own Canon DSLR is almost blind to UV transmitted by the UG1. She is using an adapted Soligor 35mm f:3.5. At least, with the unconverted E-M1, the UG1 stacked with Hoya R72 yields in sunlight an almost black EVF image, so IR leak is rather well controlled by the internal filter. In conclusion, an unconverted E-M1 can be used for UV photography if combined with a filter that transmits the longer UVA well and if one is mainly interested in monochrome UV images. As RAW converter for UV the free Olympus Viewer 3 does a very good job, better than PhotoNinja that struggles with the demosacing, at least with very colour imbalanced Olympus raw files (ORF).
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Thank you for the update.

Since this I have done some more controlled tests. The maximum my stock EM1 can see down to is 370nm. Too see this far I am using f8, 1600 for 30seconds with 365nm led and 370bp10 filter. This is abot 5 stops less than a full spectrum converted camera, but I don't think that conversion was done well on the converted camera.

A solar spectrum look also seems to correlate with 370 to 375nm depth.

However with a 390bp25 filter UV video and hand held photography is possible.

 

So Anyone wanting to dip there toes into UV. My recommendation would be:

1. Buy used Em1, go for about $400

2. Buy used sigma 30mm f2.8, go for around $100

3. Buy a SEUmk2 or S8612 2mm + U360 2mm filter stack.

Then you will be able to do autofocus, video and photography in uv on the cheap.

 

 

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  • 1 year later...
Two years later. Concerning the conversion, I wrote two years ago "I think DSLR AstroTEC is fine". The sensor had gradually accumulated dirt that I was finding impossible to clean. I sent the camera to be cleaned to a camera repair shop (the last one in Finland) and the verdict was that the filter had been installed without proper sealing of the edges and dirt had worked-in between the sensor and filter. Cleaning would require taking out the filter and reassembling and adjusting the sensor. Cost of cleaning would have been between 200 and 300 €, so I must conclude that the conversion by DSLR AstroTEC was not properly done! (I write this as a warning, in-case someone visits this thread.)
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