Sirius Optics VFS

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Brand and Model:

Sirius Optics VFS

Price ($USD):

$295

Type:

Variable Filter

Filter Position:

.96"	1.25"	2"
Visual Back	Full Aperture

Description:

Sirius Optics Variable Filter System - (VFS)

Telescope used: Skywatcher 6" Achromat Refractor-f/8.

Description

This is one nice piece of equipment. It has a simple and elegant design. It is anodized aluminum with a flat black finish. A small portion of the wheel protrudes out of a flattened side of the circular metal housing that contains the filter. This housing has 1.25" in-out barrels. It feels like it weighs a little over a half a pound. There is also a really nice red engraved plate.

Vote Highlights

Sirius Optics VFS

Superb, very versatile unit. Extremely well built and engineered. Does all it is advertised to do.

Overall Rating: 10
Optics:10 Value:10
Weight: 1 (Unreliable Vote)
Date: 03/30/2004 02:02:00 pm PST
By: Anonymous (xxx.xxx.132.221)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=350497

Reply Replies: 0

Sirius Optics VFS

Hi,

I thought I would post a vote regarding the VFS. As an optical aid I am not aware of anything that can approach the versatility of this filter. Commenting on its value,(price performance ratio), since that's a "relative" value. That said, for me its a 10. BTW, that's my review that the webmaster inserted in the product description. Armed with the VFS, I can't wait for the 2003 Mars opposition.

To the folks at Sirius Optics, thanks for making this thing.

Sol Robbins

Overall Rating: 10
Optics:10 Value:10
Weight: 1 (Unreliable Vote)
Date: 07/26/2002 09:31:48 am PST
By: Anonymous (xxx.xxx.118.98)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=116037

Reply Replies: 0

Sirius Optics VFS

[webmaster note: review moved from description]

M42, M43, and Running Man

20 mm Plossl 60x, 15 mm Plossl 80x, 11 mm Plossl 109x

The filter's rotation really changes M42's appearance dramatically. You could start at the blue part of the spectrum and roll through to the red. Without describing every view one can get, I have to say that I was able to dial in 3 very different, but very good views of these objects. Settings for M42 can really bring out the nebula as a whole with very black voids or, as I found out, bring out striking variations in the "wings". I got a very diaphanous and quasi-layered rendition of this part of the nebula. In the red regions, (broadband hydrogen alpha), stars and nebulosity shrank with what was left being M42's brighter central area. In this region of the filter's rotation, the nebula's extent looked like a view from a smaller scope. What was interesting was that the portion of the nebula presented here gave a look that was like thick cloud-webs with red stars. Strange. This "web-like" texture reminded me of images of M1.
The Running Man had a really good sweet spot. In this range, I was able to see a broken, but apparently connecting strand of nebulosity between this object's extremities. I don't recall seeing this extension before in my 6" scope. This object appears blue in astro-images
I guess the question is; were the views as good as the nebula filters that are currently available? Yes, even though there was one setting, on M42 that I thought really "nailed" it. This setting showed the greatest amount of nebulosity as it sailed right out the FOV at 60x, away from M43. The void between M42 & M43 was jet black. I also felt that there was quite a bit of depth at this setting. This "depth" is something I look for in filters and is analogous with the sensuality I associate with great oil paintings.
My impression is that scrolling through the filter's range would present only a few really good views on these objects. Since I didn't know where I was in the filter's rotation, I can't say the one position brought out the best view regarding both the emission and reflection nebulae. There was a difference as to where the filter was adjusted.
In short, I had all the beneficial filter types available to me. Just to recap, the "sweet spots" were the ones that held my interest. Other views/settings throughout the filter wheel's rotation were interesting in curious ways, but in a narrow range of rotation was where I got the fully awesome LPR effect.

M78
20 mm Plossl 60x, 15 mm Plossl 80x, 11 mm Plossl 109x

This is a reflection nebula. M78 had a small amount of contrast boost. I find M78, like M1, doesn't take to filtration in any dramatic way.

M45

At what I felt to be the best setting, the view is similar to Orion's Broadband LPR filter. This view presented stars with a blue/green, not green/blue, color cast. I make mention of the color cast because there are little variations in each small tweak of the filter wheel. For example, there is an area where stars turn a yellow/green and then a green/yellow.

M76 Little Dumbbell
20 mm Plossl 60x, 8 mm Plossl 150x, 7 mm Orthoscopic 171x

I found a point in the filter wheel's rotation that gave me one of the better views. Maybe the best view I've ever had of this object through this scope. I saw the usual 2 lobes. In the past I always tried to struggle to see any peripheral nebulosity to no avail with the filters I have in my arsenal. Tonight I succeeded using the 2 higher magnifications listed above. Although I didn't mention this as of yet, this filter can bring stars to a very sharp focus, even at high power.

M46 & NGC 2438
20 mm Plossl 60x, 15 mm Plossl 80x, 11 mm Plossl 109x, 8 mm Plossl 150x, 7 mm Orthoscopic 171x

This is the open cluster with the superimposed planetary nebula. The rotation of the filter wheel presented lots of different renditions of these adjacent objects. For example, I could see the cluster without the Planetary Nebula, or I could simply watch the PN grow in size. At the higher magnifications, the PN started to present that "smoke ring in the sky" look. The light-green/blue to green/yellow area of the spectrum had the highest intensity for showing both objects best. Still, I could choose the level of "naturalness" of the viewing-feel. This was beneficial since the object was in a light pollution dome at my observing site.

Jupiter
7 mm Orthoscopic 171x, 6 mm Orthoscopic 200x, 5 mm Orthoscopic 240x

This was one of the bigger and best surprises. When presented with a "neon lime-green" rendition, disc details on Jupiter were simply awesome. The amount of detail seen in this range surpasses any kind of visual aid I've ever used. All manner of Jovian details are held with ease visually. I really can't say enough about this. BTW, the VFS gave a multitude of renditions on Jupiter. When I tried the VFS in different scope types, the range of benefit/color renditions increased dramatically.

Filter Caveats

The first thing was that none of my eyepieces could come to focus while using the VFS inserted in a 2" or 1.25" diagonal. Consequently, all observations were done "straight through" on my refractor's stock Synta focuser. I calculate approximately an extra 2" of inside focus is needed to achieve focus. This made for a revamping my tripod's height. I also added some extra counterweights to the focuser end of my OTA as to move its balance position skyward.

Conclusion

My experience with various interference filters has made me sensitive to what I call filter artifacts. The Variable Filter System had no such artifacts present anywhere in the wheel's rotation. I believe that any strange and wild looking views were a consequence of my scope's design, (achromat), having chromatic aberration. For example, when the filter was adjusted to having a blue and red peak, high power views did not "resonate" well. This didn't happen in the 12" reflector.

As I said at the beginning, this filter can dramatically change an object's appearance. This can range from high visibility to complete invisibility. I think that some people might find this "hide and seek" to be fun. I personally found the filter to be most engaging when attempting to fine tune the better views that this filter is capable of. Small rotations allowed me to adjust it on the best views. Usually there were at least 2 or 3 so-called interesting views in addition to the best one.

As with any filter I've gotten from Sirius Optics, my initial experience is that they don't do what I thought they would. It took a little time to get used to the idea that I could wildly change the presentation of any object. That said, I really tried to "get over it" and tune the filter to where I thought the best possible views were. When other observers adjusted the wheel, I found that some folks had a different filter range than the one I had. At times, this was a not so slight variance. I know that doesn't sound simple, but I guess that's the point of a variable system. My guess is that the VFS could really change astro-imagers' methods and thoughts on how objects/features can be captured.

In regard to my 6" achromat, I found it best to have the filter's setting somewhere in the green/yellow zone to start out with. This makes finding and seeing most objects easier. I recommend this because I can easily imagine having the filter set so an object could be invisible. I also found that some small amount of refocusing was necessary at different points of the filter's rotation. Having said this, I almost wish there was a clear portion of the wheel to make finding and/or centering objects a little easier. There is also the convenience of having several filters in one device that can be inserted in the optical path much like a Barlow. I appreciated that since I didn't spend much time touching metal when I was viewing at 21 degrees F.

Overall Rating: No Vote
Weight: 1 (Unreliable Vote)
Date: 03/10/2002 02:15:17 pm PST
By: Anonymous (xxx.xxx.243.243)
Link to this vote: http://www.excelsis.com/1.0/displayvote.php?voteid=73977

Reply Replies: 0

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