New Chinese U-venus filters.

[dabateman]

I saw the odd dpreview announcement about some Astrophotography cameras. Odd in that the ones mentioned by some new Chinese company called Player One aren't exciting.

But what caught my attention was that this New Chinese company also is releasing a U-Venus filter.

 

Then in trying to track down any information on it I found what might be a Similar or Same Chinese company called Antila and they too have a U-venus filter and a posted spectrum.

 

Antlia Filters U-Venus Filter 1.25-inch

 

Technical Data:

Schott optical substrate.

1.25-inch (2 mm+/-0.05 mm).

Surface Quality: 60/40 (Refer to MIL-O-13830).

2 sides fine-optically polished to ensure accurate 1/4 wavefront.

30 arcsec parallelism.

Transmission ＞80%

2 sides Multi-layers anti-reflection coating.

Single / Non-glued substrate.

Filter Ring: 1.25-inch (M26*0.6 thread). Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture. Black Anodized Finish.

Laser Engraving No Fading.

Size: Mounted; 1.25-inch.

 

Optical Substrate

 

1.25” mounted (2mm+/-0.05mm)

Surface Quality: 60/40 (Refer to MIL-O-13830)

2 sides fine-optically polished to ensure accurate 1/4 wavefront

30 arcsec parallelism

Tave＞80%

OD3（＞0.001）@ 200-1050nm

2 sides Dielectric multi-coating

Single / Non-glued substrate

 

The spectrum makes it look like 1 or 2mm UG1 has been used instead of UG11 that has been used for the Baader venus u.

 

 

I wonder if anyone has tried this cheaper filter, currently $200 for 1.25inches size.

Unfortunately IR is not indicated on their spectrum. If anyone has tried it does it leak IR like the Optolong filters?

 

One day I would like to test an Astrodon filter as its just coated quartz and should have the best UV transmission. But there seems to be mixed reports on IR leakage, which may depend on batch.

[ulf]

I saw the odd dpreview announcement about some Astrophotography cameras. Odd in that the ones mentioned by some new Chinese company called Player One aren't exciting.

But what caught my attention was that this New Chinese company also is releasing a U-Venus filter.

 

Then in trying to track down any information on it I found what might be a Similar or Same Chinese company called Antila and they too have a U-venus filter and a posted spectrum.

 

Antlia Filters U-Venus Filter 1.25-inch

 

Technical Data:

Schott optical substrate.

1.25-inch (2 mm+/-0.05 mm).

Surface Quality: 60/40 (Refer to MIL-O-13830).

2 sides fine-optically polished to ensure accurate 1/4 wavefront.

30 arcsec parallelism.

Transmission ＞80%

2 sides Multi-layers anti-reflection coating.

Single / Non-glued substrate.

Filter Ring: 1.25-inch (M26*0.6 thread). Ultra-thin filter cell to minimize vignetting by maximizing possible clear aperture. Black Anodized Finish.

Laser Engraving No Fading.

Size: Mounted; 1.25-inch.

 

Optical Substrate

 

1.25” mounted (2mm+/-0.05mm)

Surface Quality: 60/40 (Refer to MIL-O-13830)

2 sides fine-optically polished to ensure accurate 1/4 wavefront

30 arcsec parallelism

Tave＞80%

OD3（＞0.001）@ 200-1050nm

2 sides Dielectric multi-coating

Single / Non-glued substrate

 

The spectrum makes it look like 1 or 2mm UG1 has been used instead of UG11 that has been used for the Baader venus u.

 

 

I wonder if anyone has tried this cheaper filter, currently $200 for 1.25inches size.

Unfortunately IR is not indicated on their spectrum. If anyone has tried it does it leak IR like the Optolong filters?

 

One day I would like to test an Astrodon filter as its just coated quartz and should have the best UV transmission. But there seems to be mixed reports on IR leakage, which may depend on batch.

"OD3（＞0.001）@ 200-1050nm"

 

Not good enough, even if it is true.

Normally the leakage in IR is seen at the typical IR peaks for UG1 or UG11

[JMC]

Not overly impressed by the Astrodon details for the UVenus - https://farpointastro.com/shop/astrodon-uv-imaging-filters/

 

Quote "Another vendor recently discontinued a 1.25″ mounted UV filter due to NIR light leakage, but offers a 2″ unmounted version that only reaches 80%T. Astrodon offers you both sizes and higher performance.". And then lower down the same page "<0.01%T 285-305 nm; <0.1%T 420 – 1100 nm". So OD3 from 420nm to 1100nm.

[dabateman]

Yes just reread Enrico's review of the Astrodon and I don't like the IR leakage.

 

http://www.savazzi.net/photography/primalucelab_u.html

 

I didn't realize that he had the most recent one in that test. I thought it was the earlier one.

 

Yes I don't know what to make of the claims. The Optolong was found to leak too much IR. These newer Chinese single filter solutions might be similar.

The Baader is just too expensive and many of the 1.25" one are bad for IR leakage. I was hoping to get a small thin single filter solution for reverse mounting with wide angle lenses.

 

[Andy Perrin]

The options for UV filters have always been pretty bad. Most of them have IR leaks. The ones that don't are pricey. I do think Schott/Hoya filter glass (obtained from a reputable source...) is the current best option for beginners, or possibly one of Reed's filters. I still don't own a Baader, after all these years. I very much miss Omega Bob in his two eBay incarnations.