Mewlon 210, Vixen VC 200L

[Zuts]

Hi Guys,

I really want to get some extra focal length and go galaxy hunting. At the moment I have narrowed my choices to a Vixen VC 200 L or a Mewlon 210.

I would be using the scope with my SBIG 2000 XCM. Without a focal reducer the Mewlon would give me an image scale of 0.63 arcsecs/pixel and the Vixen 0.85 arcsecs/pixel.

Is this image scale to ambitious (on an EQ6), and which scope do you think would give better results.

Any input appreciated

Cheers
Paul

[marki]

Originally Posted by Zuts

I would be using the scope with my SBIG 2000 XCM. Without a focal reducer the Mewlon would give me an image scale of 0.63 arcsecs/pixel and the Vixen 0.85 arcsecs/pixel.

I think you would have lots of trouble with longer exposures and your mount would have to have near perfect tracking. I thought the best you could hope for was about 2 arcsecs/per pixel due to atmospheric turbulance, even on a very good night. Still they claim seeing is about 1 arcsec if you are sitting on top of a great big mountain like the himalayas .

[Zuts]

Originally Posted by marki

I think you would have lots of trouble with longer exposures and your mount would have to have near perfect tracking. I thought the best you could hope for was about 2 arcsecs/per pixel due to atmospheric turbulance, even on a very good night. Still they claim seeing is about 1 arcsec if you are sitting on top of a great big mountain like the himalayas .

Yes, but even an SBIG 11K or a full frame 5D would only give me 1 arcsec/pixel. People do attempt astrophotography with a Mewlon and they dont normally go to the Himalayas.

Cheers

[marki]

You could use binning ??? It works ok with the canon if I dont put in a focal reducer which is pretty rare. At F10 its just too hard to get the tracking right. Yes I have also seen some very nice images from Mewlons and VC 200's. Both are very desirable scopes.

[netwolf]

Better mounts and Adaptive optics may play a part in those images that you have seen.

[montewilson (Monte)]

Start a new thread called something like "EQ6 - what is the most accurate guiding possible?" That will flush out plenty of answers from the EQ6 fans. Most of them will not have noticed this thread.

[JohnH]

Hi Paul,

I have a VC200L on an SXW mount with a Canon 20D at prime this gives me 0.73"/pixel, I almost always use the FR and run at 1.16" per pixel.

Even then I find my images tend to look soft at full res and generally scale down 50% to get a pleasing on-screen appearance, prints easily bear examination at A4 size or bigger.

I think either scope is going to work very well for you but imaging at the scale proposed is going to be a real challenge, certainly I find myself limited by seeing/tracking which is typically +/- 1-2 ".

I think the rule of thumb is 2 pixels or less tracking error for a good looking image for me this means an image scale of 4" per pixel would be ideal though some suggest some oversampling is good so 2" would be better...I am not 100% convinced here but for me I would would prefer a little less scale and a wider fov. Perhaps a better mount would help me?



Rgds, John

Originally Posted by Zuts

Hi Guys,

I really want to get some extra focal length and go galaxy hunting. At the moment I have narrowed my choices to a Vixen VC 200 L or a Mewlon 210.

I would be using the scope with my SBIG 2000 XCM. Without a focal reducer the Mewlon would give me an image scale of 0.63 arcsecs/pixel and the Vixen 0.85 arcsecs/pixel.

Is this image scale to ambitious (on an EQ6), and which scope do you think would give better results.

Any input appreciated

Cheers
Paul

PS - You are not far from my place (Hornsby Heights) - you are welcome to have a stick beak at my VC200L if you like....

[marki]

Originally Posted by netwolf

Better mounts and Adaptive optics may play a part in those images that you have seen.

Seen one taken using QHY8 and a VC 200 on a EQ6 without adaptive optics. Not too bad for a first go. I think he has binned this one??? Check the link.

http://www.myastroshop.com.au/guides/vixen-vc200l.asp

[Dennis]

I understand that the reflective coating on the primary mirror of the VC200L actually forms part of the final figure of the “VISAC”. This means that the mirror needs to be returned to Vixen for any re-aluminising.

I did hear (on the rumour mill) that one VC200L owner in Qld didn’t know of this and had his mirror re-coated locally and as a result, I was told “he cannot focus” the telescope any more.

I don’t have names, dates and places, just word of mouth unfortunately.

Cheers

Dennis

[Terry B]

I use my VC200L on an EQ6 and either 9um CCD pixels or the 40D.
I can guide when facing the west within 2 arcsecs according to giudemaster. It isn't as good facing east. I haven't worked out why. This gives me round stars mostly with 5 min exposures with a FWHM of about 4pixels. If I use the focal reducer then the FWHM is about 2.8 pixels.
It is certainly possible to image small objects with this combination. Can't speak for the mewlon as I have never seen one.

[Dennis]

How important is backfocus? What accessories will you be adding – a Motorised Focuser? OAG?

The VC200L has an excellent R&P focuser with a fixed Primary mirror. The Mewlon 210 focuses using a moving Primary, similar to an SCT.

Cheers

Dennis

[Hagar (Doug)]

Hi paul, Very interested in this thread as I am looking at the same scope choices as you. I have a QHY8 and would like that bit of extra FL. What ssort of price is the Mewlon?
I also thought about the new RC scopes being produced by GSO but I am unsure as they don't make a field flattener or focal reducer as yet. Who knows they may neve get around to it. The initial release of the 8" is well overdue.

[Zuts]

Originally Posted by Hagar

Hi paul, Very interested in this thread as I am looking at the same scope choices as you. I have a QHY8 and would like that bit of extra FL. What ssort of price is the Mewlon?
I also thought about the new RC scopes being produced by GSO but I am unsure as they don't make a field flattener or focal reducer as yet. Who knows they may neve get around to it. The initial release of the 8" is well overdue.

Hi Doug,

I am very interested in this thread as well, I fully intend to reply to everyone who has posted, i am just waiting to get as many opinions as possible.

The Mewlon can be had for around 3000 AUD from AEC, click the link on the right. Another option I am considering is the VMC 260L. This gives 10.5 inches of aperture for the price of the Mewlon. However I cant find an internet price in Oz for this and am going by the OPT price list.

Cheers
Paul

[netwolf]

Paul, You could also try William in Hong Kong for pricing on Vixen gear. Nice guy and has been down here a few times to image under southern skies. He is a member here but have not seen him post in some time.
http://www.geocities.com/tatsco/OTA_set.htm

I saw a very good shot taken with the VMC260l on a G-11 at 3000mm on CN, follow this link.
http://www.cloudynights.com/ubbthrea...ype=&bodyprev=

[Zuts]

Thanks for all the comments everyone.

Pricewise I would opt for the Vixen VC200L, however the Mewlon given the Takahashi reputation and AEC price is hard to go past. I would love the VMC 260L just for the extra aperture and longer FL. On an EQ6 i may be biting off more than i could chew with the VMC though. I would like some more feedback on the VMC though as in the future I may get a better mount. It will never be possible for me to get an RCOS as i havnt got a permanent setup (or enough cash ). The VMC would be as big and portable as I could go so it is very tempting but I need to find the oz price and a bit more info before I decide.

Edit**

Out of my league but there is an Australian based 12.5 inch RCOS going for 12,500 AUD on Astro Mart at the moment ......

Originally Posted by marki

You could use binning ??? It works ok with the canon if I dont put in a focal reducer which is pretty rare. At F10 its just too hard to get the tracking right. Yes I have also seen some very nice images from Mewlons and VC 200's. Both are very desirable scopes.

Hi Marki,

Binning is certainly an option. However I dont have too many pixels to spare. Initially I guess I would look at a reducer. This i guess would leave with with a long but still manageable FL for my EQ6. Later on I could look at a better mount.

Originally Posted by netwolf

Better mounts and Adaptive optics may play a part in those images that you have seen.

Hi Fahim,

I have seen some images taken with the Vixen on an EQ6 so I believe it is possible. So initially I think I could get by using a reducer, guiding and without resorting to AO. At least with the SBIG I dont have to worry about the additional weight of a guide scope and cam, so that should help as well.

Originally Posted by montewilson

Start a new thread called something like "EQ6 - what is the most accurate guiding possible?" That will flush out plenty of answers from the EQ6 fans. Most of them will not have noticed this thread.

Hi Monty,

On a good night I can get sub-pixel guiding with no probs on the EQ6, so at least i know it is possible on my mount. However this is at a short 480 ml FL. I am not sure if subpixel guiding at 480 ml easily translates into subpixel guiding at a reduced 1.5 m FL. Does anyone know?

Originally Posted by JohnH

Hi Paul,

I have a VC200L on an SXW mount with a Canon 20D at prime this gives me 0.73"/pixel, I almost always use the FR and run at 1.16" per pixel.

PS - You are not far from my place (Hornsby Heights) - you are welcome to have a stick beak at my VC200L if you like....

Hi John,

It's good to know that you are getting good results with the Vixen. Secondhand Vixens go for 1200 AUD so maybe that is the way for me to go. One step up rather than going for the Mewlon or the VMC 260 straight up.

Also thanks for your kind offer

Originally Posted by Dennis

I understand that the reflective coating on the primary mirror of the VC200L actually forms part of the final figure of the “VISAC”. This means that the mirror needs to be returned to Vixen for any re-aluminising.

I did hear (on the rumour mill) that one VC200L owner in Qld didn’t know of this and had his mirror re-coated locally and as a result, I was told “he cannot focus” the telescope any more.

I don’t have names, dates and places, just word of mouth unfortunately.

Cheers

Dennis

Hi Dennis,

This probably doesnt concern me as hopefully it would be many years before I would need a mirror re-coating

Originally Posted by Terry B

I use my VC200L on an EQ6 and either 9um CCD pixels or the 40D.
I can guide when facing the west within 2 arcsecs according to giudemaster. It isn't as good facing east. I haven't worked out why. This gives me round stars mostly with 5 min exposures with a FWHM of about 4pixels. If I use the focal reducer then the FWHM is about 2.8 pixels.
It is certainly possible to image small objects with this combination. Can't speak for the mewlon as I have never seen one.

Hi Terry,

This gives me a lot of confidence that I would be able to get decent results on the EQ6. Together with the images I have seen on the net it seems that an EQ6 and Vixen VC200L is a workable combination.

Originally Posted by Dennis

How important is backfocus? What accessories will you be adding – a Motorised Focuser? OAG?

The VC200L has an excellent R&P focuser with a fixed Primary mirror. The Mewlon 210 focuses using a moving Primary, similar to an SCT.

Cheers

Dennis

Hi Dennis,

At the moment I have a OSC camera so dont need a filter wheel. Hopefully at the long focal length manual focussing will be far easier than on my TV85. Were I to go the motorised route I would probably opt for another robofocus motor. I get good results on the TV85 with this and it doesnt consume any focus.

Originally Posted by netwolf

Paul, You could also try William in Hong Kong for pricing on Vixen gear. Nice guy and has been down here a few times to image under southern skies. He is a member here but have not seen him post in some time.
http://www.geocities.com/tatsco/OTA_set.htm

I saw a very good shot taken with the VMC260l on a G-11 at 3000mm on CN, follow this link.
http://www.cloudynights.com/ubbthrea...ype=&bodyprev=

Hi Fahim,

The VMC 260L shot looks very very nice, thanks. Looking at the Hong Kong prices they are very similar to OPT. The mewlon pricewise seems very reasonable and compares well to OPT from the Australian supplier. Even cheaper considering that it includes GST.

[madtuna (Steve)]

Paul, if I remember correctly, when I was choosing between the VC200L and the VMC260L, I was quoted something around $4500 for the VMC from Astro Optical in Sydney with an 5 to 8 week waiting time

[Zuts]

Originally Posted by madtuna

Paul, if I remember correctly, when I was choosing between the VC200L and the VMC260L, I was quoted something around $4500 for the VMC from Astro Optical in Sydney with an 5 to 8 week waiting time

Hi Steve,

Can I ask why you opted for the VC200L over the VMC260L? Also, how well does you VC200L hold collimation and is it on a permanent setup?

Thanks
Paul

[madtuna (Steve)]

Originally Posted by Zuts

Hi Steve,

Can I ask why you opted for the VC200L over the VMC260L? Also, how well does you VC200L hold collimation and is it on a permanent setup?

Thanks
Paul

Apart from being near half the price, from my research on everything I could find on the two, the VC200L just came up as a better dedicated imaging scope.
Even the dealer told me that when he could have pushed for the dearer sale.

I also looked at and through a few while in the states and spoke with thier owners including one guy who had both.

Collimation I've never had to touch, and from what I understand I doubt I will for a long while yet. If it ever did need collimation it can be done from four points but unless I knew exactly what I was doing I would take it to the dealer and get him to do it.

I originally had it on an EQ6, steady as a rock and looked damn fine to boot!

Now I'm whacking it on a G11 side by side with a 140 refractor which will be both a permanent pier aswell as portable

[madtuna (Steve)]

Paul, also I've heard a lot negative talk about it having a R & P instead of a crayford, but 95% of the negative you hear is from people with no experiance with a Vixen R & P.

A good R & P is 100% better than a run of the mill crayford.
If I was to ever change it, it would only be to an electric focusor

[montewilson (Monte)]

Some people wonder about quality of the R&P on my two Takahashis.

The R&P's are first class, no shift, no slack just smooth movement. A good scope like a Vixen shouldn't be a problem either.