CA K Module Purchase

[Mike]

Greetings to the group.
I am looking at purchasing a Lunt Ca K B1200 module. Current scope are a Celestron 102 (made by Vixen ) 1000mm focal length, Televue 101 540mm focal length, and a Televue 102 880mm focal length.

Does anyone know of any problems with these combinations? Possible not enough back focus? Would the B1800 be a better purchase for imaging?

Any advice is appreciated.

Mike

[Derek Klepp]

Mike I have the B1200 and use it on a 714mm FL 102ED Doublet .Focusing should not be an issue on any scope as the unit has a couple of inches or more to move in and out of the diagonal.I think Pedro uses one with his 101.

[Pedro]

Hi Mike:

I have a LUNT 1200 CaK module. I use it with a TV101 and an Ikharus 102 F/7 with great results. Both are apo refractors. Not all OTAs are adequate for imaging in the near UV.

Here are a couple of images obtained today

http://re.apaaweb.com/sun_20130912_IK10 ... mosaic.jpg
SUN (20130912) WL & CaK (16:00 UTC). IKHARUS 102 F/7, 2" Lunt Solar Wedge, LUNT 1200 CaK Module, ANTARES 0.5X Reducer, DMK51

http://re.apaaweb.com/sun_20130912_TV10 ... mosaic.jpg
SUN (20130912) WL & CaK (16:00 UTC). TV101 F/5.4, 2" Lunt Solar Wedge, LUNT 1200 CaK Module, DMK51

Pedro

[Cschur]

Hi Mike, Id like to add that if money was no object Id have a B1800 myself, since as the focal lenght goes up, you will start to cut off the edges of the frame rather soon. Like looking through a porthole at the sun.

Chris

[brianb11213]

I am looking at purchasing a Lunt Ca K B1200 module. Current scope are a Celestron 102 (made by Vixen ) 1000mm focal length, Televue 101 540mm focal length, and a Televue 102 880mm focal length.

Does anyone know of any problems with these combinations? Possible not enough back focus? Would the B1800 be a better purchase for imaging?
Back focus will not be an issue providing there are no baffles in the focuser which might restrict the 90mm long nosepiece on the unit. I can't use my B1200 CaK diagonal with my 80mm f/6 achromatic for that reason. Works fine with the FLT 110 though.

There is some reason to suspect that the unit will work a little better with a larger focal ratio, though as Pedro says his works with a f/5 scope you should find it OK with any of yours.

B1200 is probably more than adequate ... you'd really only need a B1800 if you wanted to do one-shot full disk imaging with a scope with a focal length greater than 1000 mm.

[Pedro]

I always use the 1200 CaK LUNT module at F/10. You will surely need an aperture reducer.

Pedro

[sullij1]

The B1800 is awesome, you would not regret the purchase. We have tested it with the C102 and it has performed surperbly in that combo. We also tested it in the Explore 102 and my 127mm F5 set up. YMMV but the units seem to work in just about any scope less the caveat Brian mentioned.

[astroshot]

I have the B1800 CaK and use it on my TEC140.
No issues with getting it to focus.

[Mike]

Hello Pedro
Trying to make sure that I get this right. When to mention F10, My C102 is an F9.8 so it is close to F10. As you know the TV 101 is F5.4. Would that mean that I could use a 2X power mate to get the F10. I have one of the 2X and 4X powermates.

Love to see your photography.

Thanks Mike

[Pedro]

I usually reduce aperture to have a f/10 focal ratio. With the TV101 I reduce it to 72mm (FD prime focus imaging). In your case you already have the right focal ratio.

Pedro

[marktownley]

Hi Mike,

Welcome to the group

I would try the module with all 3 scopes and see which gives the best image. What camera are you going to be using?

Mark

[astroshot]

Why the need for f/10?
The only restriction that Lunt places on it is to limit the aperture to 100mm.

[swisswalter]

Hi Mike

the B1200 is a great Piece, You will be very happy. I don't see the need for a B1800. You can always work with larger FL then 1000 mm through a simple mod using the Cak filterstack and another hotmirror system ;-)

[brianb11213]

Why the need for f/10?
The only restriction that Lunt places on it is to limit the aperture to 100mm.
Yeah ... given that the atmosphere attenuates UV quite heavily and the sun never gets close to the zenith here at 55.2 N, I've been using my Lunt B1200 CaK diagonal with my (f/7) William Optics FLT 110 at full aperture with very good results. Stopping down to f/10 may reduce the badwidth pass very slightly (a bit more contrast) but this is more than offset by a loss of resolution providing the seeing is average or better.

Of course I'm not risking my eye ... only the scope & camera, which are replaceable.

[Pedro]

I've tried imaging at different focal ratios and F/10 always gives better results (better contrast, better resolution...). LUNT recommends using their CaK modules at F/10 but I have never seen this written..

Pedro

[brianb11213]

LUNT recommends using their CaK modules at F/10 but I have never seen this written..
Yet if you buy one of their 60mm CaK scopes you get an f/8 system.

If you go too short then the components in the CaK module may start to restrict the effective aperture but as I've indicated the module "works" at f/7 .... I wish it was possible to put a tele-extender of some sort in front of the diagonal but the long nosepiece on the CaK module really interferes with this.

[sullij1]

F10 is not a requirement! Just depends on how you want your image to look.

We tested this here in the "does F10 matter thread". One side of the coin is the answer is No -as long as you don’t mind a lil softer looking image when shooting at shorter focal lengths. We were also able to eek out similar detail to f10 by using more aggressive processing techniques. On the other side of the coin, at F10 Yes- you get a nice contrasty image that requires very little processing.

Does the module work at almost any focal length? YES! It seems to not matter much. It is like processing technique and color; it goes back to personal taste in the image and what you are willing to settle for. All the imagery we got was still excellent imagery at most all focal lengths.


Some folks just like a lil higher contrast.

If you want examples, all the imagery we took is still in the thread I mentioned.

Here:http://solarchat.solarastronomy.org/ind ... ter-in-cak

[Mike]

I am using Imaging Source DMK 21 and DMK 41 USB cameras.

Thanks for all of the replies. This is a good group!

Mike H

[MapleRidge]

Hi Mike...

I use the B1200CaK on the same C102, f9.8 OTA and it gives very good results (seeing conditions permitting).

I found some of the standard focusers do not have sufficient in-focus...the diagonal assembly in the Lunt Blockers takes up more travel than you might think. My C102 had been shortened before trying it with the module, so not sure how the stock focuser will work. The Celestron CR-150 stock focuser would not allow either the CaK or WL filters to focus...very close, but not quite.

BTW, there was a used B1200CaK on Astromart earlier today I believe.

Brian

[Mike]

I just sent Rikki an e-mail to place me in the line for the Ca II filter. She said that it will take about two months.
In the mean time I still have the 80mm PT Ha scope, Thousand Oaks glass filter, and Baader wedge to play with.

Thanks to everyone in the group for the replies and advice!!! Good group!!!

Mike

[solarchat]

my friend Tim Nix has a brand new Lunt CaK B1200 sitting on his shelf as of yesterday that he would be glad to sell any US residents and ship out tomorrow.

404-873-4513

[Mike]

Hello Steve

Thanks for the tip.

I called Tim at Camera Bug. He has one in stock but he has already taken a deposit on it. He doesn't know when he will get another one.

Thanks
Mike