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Minus Violet Filter

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#1 RGM

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Posted 04 October 2003 - 06:22 AM

I have a 120 mm f8.3 on a Vixen SP mount. I started using a minus violet filter at the front of my 2" diagonal and have just left it on. Do others leave it on, or just use it for bright objects? The telescope seems to focus better on all objects, regardless of brightness. Am I loosing much in way of light gathering ability? The filter passes around 95%. This means my 120 mm is equivalent to a 116mm objective. Thanks for your input. Bob


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Posted 04 October 2003 - 09:28 AM

Hi Bob,
When I had my Meade 6" achro I too left it on the scopes diagonal also. I didnt really notice anything dimming just much better focusing with no halo or flaring anymore tho 6" aperture did take filters well. It was a must use at all times on my scope even low powers worked better with the filter. They should just package em with the big achros I think. Dave

#3 jrcrilly

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Posted 04 October 2003 - 09:50 AM

Yes; I keep one installed on my Celestron 6" all the time also. Even when it isn't obvious that it's doing any good, it is!

#4 Don W

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Posted 04 October 2003 - 01:23 PM

I realize this thread is a little old, but what brand Minus Violet filter do you guys use?

#5 Jacques

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Posted 04 October 2003 - 02:56 PM

Hi Don,

I use Baader's contrast booster on both achromats I own (4" and 6"). Someone who used this one in a reflector said:'it almost mimics good seeing'. I agree. It completely removes the violet fringing but has a colour shift to green/yellow which does not bother me at all. Al's MV filter (Sirius) works great for photography too it seems. I chose the Baader cause I'm a visual observer only and cause the price here in Europe was too good to pass. Very little chance of going wrong this way. According to client feed-back, Al's filters do a great job. None of them perform miracles tho.

Regards,

Jacques

#6 EdZ

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Posted 04 October 2003 - 03:14 PM

I gotta get me one o those for my CR150. Got the itch to buy something new anyway.

So there's the baader, where do you get that one?

Is that the same as the ?MV1? or is it ?MV2?. Where do you get those?

Are these worth about $75? $100?

thanks,

edz

#7 Jacques

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Posted 04 October 2003 - 03:50 PM

Hello Edz,

When you search the web, you will get some reports about the Sirius filters used in CR150's as well as ohter achromats (at the site of APM telescopes USA f.i.). I can only comment on the baader. It seems to have more colour shift to green/yellow than the Sirius which would have more neutral colour rendition. It needs an additional filter for digital imaging, the Sirius does not.

Anyway, the difference with and without (especially at higher/high powers) on bright objects is quite spectacular. Since you also like double star observing, it will bring you much joy (whatever brand of MV filter you choose). Stars 'snap' into focus (whithout filter they also do that in my CR150, but at higher powers there's a noticable difference. Light transmission in the Baader is 95% so leaving it on all the time including DSO observing is usefull indeed. I only have the 1.25" version of it since I don't have a 2" setup and I don't feel ready for this other addiction yet!

Anyway, buying an MV filter (regardless of brand) will be a good investment for your CR. Let's see what other folks come up with.

Good luck,

Jacques






#8 RGM

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Posted 04 October 2003 - 04:12 PM

I use the Lumicon version. Not sure if there is something better. This was the one that my favourite store suggested I use. Bob


#9 Don W

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Posted 04 October 2003 - 05:12 PM

Thanks guys. I just picked up a use Celestron 150 OTA from Astromart. I'm not a huge lunar/planetary observer, but I'd like to get decent images when I do look that way. I picked up a Celestron ASC mount last month and needed an OTA to ride it, so I snapped up the 6" refractor. :money:

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Posted 04 October 2003 - 06:31 PM

I was using the Orion V block filter myself, it seemed to work very well tho I havent tried any other V block brands. You really have to try one tho to see how much it really did help, especially at hi-mag. Dave

#11 jrcrilly

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Posted 04 October 2003 - 10:16 PM

I picked up a Celestron ASC mount last month and needed an OTA to ride it, so I snapped up the 6" refractor. :money:


Hi, Don.

To anser your earlier query; I'm pretty sure mine's the Sirius model. I'll take a look next time I'm in the barn.

As an LXD55 fan and a former user of the AR-6 I'd be very interested in your opinion of hiw well that mount handles that optical tube.

#12 Don W

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Posted 05 October 2003 - 12:18 AM

From what I've seen of the LXD55 mount, the Celestron should do a much better job. A club member has a 10" LXD55 and it shakes like Little Eva on a Friday night. The ASC mount is much sturdier mainly due to the 2" tubular legs.

#13 jrcrilly

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Posted 05 October 2003 - 05:10 AM

Hi, Don.

I never use the tripod that came with the LXD55; it's really crap. The mount, even though it's a Chinese clone of a Chinese clone, deserves better. On a solid platform the mount begins to show just a little slop with the 150mm refractor. I'm wondering if the ASC version of the mount will be a little better yet.

#14 Guest_**DONOTDELETE**_*

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Posted 06 October 2003 - 06:34 AM

JR, what is the original mount that the LXD55 was copied from?

#15 jrcrilly

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Posted 06 October 2003 - 08:19 AM

JR, what is the original mount that the LXD55 was copied from?


Hi, Schultze.

It's a copy of the Chinese CG-5, which is a copy of the Japanese Vixen Great Polaris Deluxe (usually referred to as the GP-DX mount), which is a heckuva nice piece of equipment.

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Posted 06 October 2003 - 08:25 AM

Thanks.

#17 SAL

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Posted 30 October 2003 - 11:17 AM

Baader contrast-booster -vs.- Orion V-Block -vs.- MV1 -vs.- MV20 filters…yikes! I am really confused about which filter to purchase for my Orion 120mm (f8.3) scope. The Baader claims better quality glass and coatings. It is also the least expensive of the group. But it sounds like it might have the greatest amount of green/yellow color shift. I know a lot of folks report being very happy with the MV1, but others feel the newer MV20 has better color balance. I think the Orion is very similar to the MV1. Has anyone ever had the opportunity to actually look through all of these filters before? I’m leaning towards the MV20 as my f8.3 should theoretically have less CA than the f5 models. Thoughts???

#18 Trever

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Posted 30 October 2003 - 03:07 PM

You think thats confusing, try buying a Chromacor...

www.astrobuffet.com

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Posted 30 October 2003 - 03:31 PM

Sal,
Thats a real good question. Ive been wondering about all the comparisons myself but I dont want to be a test Mule either. I think its going to be hard to do a comparison simply because you dont need all these similar filters to do the same job so getting a reliable comparison is going to take someone with access to all of them at once to really judge them against ea. other unless somebody has a better idea. Dave

#20 SAL

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Posted 30 October 2003 - 11:29 PM

Dave: I was hoping perhaps someone had been to a star party where a group of folks tried several of the filters on a common scope to compare them. Since they all claim to do roughly the same thing, I doubt if anyone would own more than one or two of them at a time. Maybe one of the astronomy magazines will do a comparison between them. In the meantime I think I’ll take the plunge and purchase one. Now, if only I could decide which one to buy… (Scott)

#21 Jacques

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Posted 31 October 2003 - 04:53 AM

I don't think that there's a risk of really going wrong in buying an MV filter. I expect every filter to sharpen things up. There's a page on the web of Jefferson Tang (owner of your type of scope) which has pictures with and without MV1. Your search engine should lead you to it. Hope this helps.

Jacques

#22 Jacques

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Posted 31 October 2003 - 05:06 AM

Oops, it's Jefferson Teng. Sorry.

#23 SAL

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Posted 31 October 2003 - 08:49 AM

Thanks Jacques...

#24 Jacques

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Posted 31 October 2003 - 09:42 AM

You're welcome Scott

In case that doesn't work, try http://www.geocities...goteng/one.html



#25 IDONTSEEIT

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Posted 01 November 2003 - 01:56 AM

Hi Sal, et al,

I have both the V-block, and the baader contrast booster.

On my scopes(80mm f5, 102mm f5, refractors), the contrast booster seems to work better "to my eyes of course". The V-block causes a much more noticeable change in the color of stars, etc., it causes them to look yellower, and/or greener, if that makes any sense to you? The contrast booster, once again, "in my eyes", doesn't affect the color of objects nearly as much, however, it does not remove much of the false color on the brightest objects, where as the v-block does a good job of that.

Overall, I would say that I prefer the contrast booster over the v-block(wanna buy a slightly used 1 1/4" v-block filter?...lol). How long can you stare at a bright star like vega, sirius, alderbaran, etc., anyway? I haven't really found the false color on things like jupiter to be very bothersome to me, on my scopes. I think that for things like planets, the contrast booster is better, as it does remove a little bit of the false color, and does improve the contrast some.(I think my filthy NYC skies actually do a good job at dimming the brighter planets so that there really isn't much false color on them). It's helpful enough, that you probably would just leave the contrast booster in your diagonal, for most objects, where as you probably wouldn't leave the v-block filter in too long. Hope my rambling helps you guys!

I've never tried both together:question:

Good luck!!!

P.S. The contrast booster is like 1/2 the price of the v-block. :yay:


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