Testing Hoya U-340 and U-360 for visible leaks - funding request

[JMC]

Andy,

Remember this post:

https://www.ultravioletphotography.com/content/index.php/topic/3784-some-unusual-ug-filters-uk-supplier-h-v-skan/page__view__findpost__p__34575

 

I wonder if Jonathan might have a 0.5mm ug11 or ug5. I am atill unsure.

God, dont remind me of all that. I've still not had an answer from them, as to what that mystery filter was. I believe it was UG11.

[Andy Perrin]

Andy,

Remember this post:

https://www.ultravio...dpost__p__34575

 

I wonder if Jonathan might have a 0.5mm ug11 or ug5. I am atill unsure.

No, I don't think I ever saw that post (I certainly don't see any responses from me on it, and I don't recall it). Anyway, we probably shouldn't use a mystery filter to compare to.

[Cadmium]

For me, I will say it again, the comparison between the UG11 and the U-340 is most important, not even the U-340 missing section alone, and certainly not the U-360.

I am fairly confident of the Schott data for the UG11 and UG1, and I am fairly confident that the U-360 performs the same or better than than UG1.

I think it might be a little hard to compare UG11 data with a U-340 scan directly. Where as a scan of each would show a direct comparison.

Personally, I would rather see a comparison scan of UG11 vs U-340 than a scan of U-340 and U-360. Just me... I will shut up about it now.

[Andy Perrin]

Cadmium - those reference thicknesses probably are not the thicknesses that Schott scanned at[*], it's just how they chose to report the data. Jonathan's scan will be no different. I feel like I'm missing something here. Why would it be any harder to compaire UG11 data with U-340 data than comparing any other two spectra?

 

[*] if they scanned anything at all - I wonder if those Schott numbers were arrived at computationally based on melt composition parameters which are known to them but not us.

[SteveE]

I will contribute

[Cadmium]

Andy, I don't know how or what Schott uses to scan their data, or how much if their deeper data may be arrived at by interpolation, or what thickness they used for scanning.

I am not saying you can't compare a scan of Hoya U-340 with the Schott UG11 data.

I am saying that the comparison would be much more solid if both glasses were scanned the same way, then you have something the same to compare to,

and that rules out any inconstancy in the two.

[Andy Perrin]

Ok, I see, but I guess it still comes down to the money here.

[dabateman]

I know Jonathan doesn't want to talk about his mystery filter. But I think I am confident that it is UG11 at what ever thickness purchased at.

I think the U340 will look similar, but with more relative leakage at 500nm. I have the feeling that Hoya acts like a 1/3 stop faster than Schott, at same thickness. Thus being that much more leaky.

[Cadmium]

David, that is an interesting way of looking at it, "1/3 stop faster", that works for the UV end, but not for the red/IR end,

because both the U-340 and U-360 transmit more in the UV and transmit less in the red/IR (~700nm~ range) compared with the UG11 and UG1.

So, the "1/3 stop faster" doesn't apply to the 700nm end.

 

 

PS: I mix the solid and dashed lines in with the colors for those who might get some colors mixed up, hopefully the different dashed or dotted lines help with that.

[ulf]

If you are going to do this kind of test, then you would be best to compare directly with Schott UG1 and UG11 using the same thickness.

That is the best way to compare any differences.

 

That is absolutely true when comparing filters by taking photos.

 

When measuring the transmission with a spectrometer It is not so.

The same thickness is not important, as long as it is thin enough for the high OD spectrum to be detectable with the spectrometer.

In the end you have to recalculate the found values to some common base thickness.

 

With a thin sample, instead it will be difficult to measure the low-OD parts (closer to OD0) of the spectrum accurately.

 

I am rather confident that I can reasonably well measure UG11, 1mm as my spectrometer is rather stable, even if 0.5mm would be even better.

I have none of those thicknesses available for measuring

 

I suggest that we trust both Schott and Hoya about the low-OD parts and just fill in the missing gaps of high-OD parts and use their native base thicknesses.

[JMC]

I will contribute

Thanks SteveE, I'll add you name to the list.

[colinbm]

Ulf how can you trust the filter companies....

UV protection filters are a joke....

B+W 486 was discussed the other day & it was decided they have differences & now leaking more in IR...

There are others if I am sure....?

[Andy Perrin]

Colin, he said trust them about the low OD parts. Those are the easy parts where we know the filters do a good job by our experience using them every day.

[colinbm]

Thanks Andy

[Cadmium]

Jonathan, Add me to your list, you talked me into it, I will contribute also.

[JMC]

Jonathan, Add me to your list, you talked me into it, I will contribute also.

 

Ok Steve will do, and thanks.

[JMC]

Everyone.

 

A quick update. Thank you all for agreeing to help out with this. As of August 8th I have so far received enough pledges that I am going to place the order, which I shall do so this coming week.

 

Once ordered I'll pm you individually to sort out payment, as unfortunately payment is up front for custom filter jobs like this.

 

Delivery time is 2-3 weeks so if all goes to plan, data should be available around the end of the month, or early September. Given the nature of this, I want to do multiple runs with each filter to get a meaningful average for the transmission.

 

Once I've done the experiments, I'll start a new thread with the results.

 

Jonathan

[Andy Perrin]

And then put the glass in a safe place where you can't even breathe on it in case it's needed for future tests. 0.5mm has got to be FRAGILE!

[JMC]

Update on the filter situation. Spoke with the supplier today - one filter is done, the other is being polished. I have asked them to run the spectra on their setup as well, and to let me have a copy of the data - will be good to check my own spectrometer against theirs. In theory they should be sent out wednesday or thursday, so likely to be with me on the 11th or the 14th. When they arrive and I have some data I'll start a new thread with it.