From: Mark Gaffney <markgaffney@mac.com>

Date: January 31, 2009 11:26:18 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: M37 Image


Hi Milton something I found here about the Meade OAG mentions a 90 degree tilt; " a small part of the light at the edge of the telescopic field is diverted at a 90° angle to the unit, where it is observed on the crosslines of an illuminated reticle eyepiece to detect any change of position."

What is the range of prism tilt in your Celestron Radial Guider?

All I can find about the Orion Deluxe OAG is; "Features prism tilt adjustment and more than 100 degrees of radial adjustment for easy guide star location"

I`ll see how I go with the Meade for a start! It has 360 degree rotation at least; "The slip ring allows 360-degree rotation of the guider body for guide star selection."

I got out the other night to re-do my polar alignment but found out my illuminated reticle eyepiece was low on the batteries & wouldn`t stay alight. I`ve renewed them now but the weather looks no good for tonight at least. I made an attempt to use the Analyse RA/DEC Tracking option in Astro IIDC that night but couldn`t obtain a star image with the Flea 2 (neither with a bright star like Sirius which I tried later) Poor PA is hampering the centreing of the star I imagine,(so it`s catch 22!) & attempting to achieve focus & correct exposure simultaneously proved too difficult for me. Mark.

On 01/02/2009, at 4:49 PM, Milton Aupperle wrote:

Hi Mark;


I would not recommend the Meade OAG, even if it is cheap.


You can not tilt the prism, which means your area for finding guide

stars is far narrower than with either the Celestron OAG or the Orion OAG.


HTH..


Milton Aupperle


--- In Astro_IIDC@yahoogroups.com, Mark Gaffney <markgaffney@...> wrote:


Hi Alberto, I was asking about f3.3 FRs before buying anything but the  

general consensus I got both here & the SCT & Autoguiding groups was  

that getting things into focus might be difficult. The set-up I`ve  

decided on with the OAG I`m about to purchase is an f6.3 FR (probably  

Antares as they`re supposed to be as good as Celestron maybe better  

for a cheaper price.) Also I was looking at a 0.6 Mogg FR attaching to  

the imaging camera along with a 0.3 extender from the same place. I`ve  

been offered a barely used second-hand Meade OAG for only $90 +postage  

of $10 which is a great deal I think! Here`s the site for the Antares  

f6.3 FR as given to me by a guy called Don D`Egidio;

http://www.agenaastro.com/Antares-f-6-3-SCT-Focal-Reducer-p/ofr-an-sctfr.htm

& here`s the Mogg site in Adelaide Australia where I live;

http://moggadapters.com/astro/adapter.asp

just click on Focal Reducers on the left. I was thinking also of  

another 0.6 Mogg FR & a TM- 1.25. F adaptor also from Mogg to connect  

to the OAG T-thread. Just go to accessories on the left & scroll down  

the page. In the Future perhaps I may even get a Moonlite CS focuser  

but things tend to move glacially in the land of Mark Gaffney  

purchases! Mark.

On 01/02/2009, at 1:03 PM, albe albo wrote:


Very nice,  patient and ICY work!

I noticed you used a OAG (i'd like to try it too) but i also figured  

out that the OAG should work at its best into a star  cluster!

Normally I heard that the OAG is terrible in order to catch a star.

Example around M51 or M82 i guess that it should be very hard.

Is it?

In addition i would use the OAG on a f. 3.3 reducer but it is less  

forgiving  than the 6.3reducer.

Time ago i read that even Mark Gaffney would use the OAG on a f 3,3  

reducer but i couldn't read if he or someone else succeeded in this  

task.


Ii fully agree about decent RGB even if it seems impossible.

All my color images done with TIS DMK exploited very old color  

imagery i did years ago (at my beginning) with my EOS300D.

They were absolutely filthy, noisy and blurry  but they worked fine   

as RGB!

http://www.makina.it/SAA/DSO_%28DMK+EOS%29.html


For this reason now i'm experimenting the double TIS camera  

grabbing: DMK =Luma  + DBK binned = one-shot-RGB (i did only M1  

because since i own the DBK  the sky is permanently cloudy here).

The result was  encouraging in order to continue further experiments.

This is the link with the reprocessed M1:

http://www.makina.it/SAA/DSO_%28DMK+DBK%29.html


About M37: I guess that you correctly left the natural result  "as  

is" so I did a little aesthetic experiment trying to reduce the  

already small horizontal ovalization of the stars .

I tried with 0,67 px at center but it is different at the corners.

Do you want to see it?


TTYL







From: Milton Aupperle <milton@...>

To: Astro_IIDC@yahoogroups.com

Sent: Saturday, January 31, 2009 11:18:13 PM

Subject: [Astro_IIDC] M37 Image


Hi Folks;


I think I finally have my L R G B exposure times and processing

figured out for the EXHAD Grasshopper camera.


Check out M37 (taken at -22°C ambient temperature) :


http://groups. yahoo.com/ group/Astro_ IIDC/files/ DSO/M37_20090125  

_MJA.jpg


Details are embedded in the image. I did have an electric blanket

turned on and wrapped around the gear box of the HEW 5 mount, which

eliminates the "grinding gears" issues below -15°C when slewing at

900x times siderial for the GotTo.


I found that when using the Hutech IDAs LPR filter with the AstroDon

"E" series LRGB filters, I need to use exposure times of roughly 1.3

Red, 1.0 Green, 1.0 Blue. I may increase the blue color channel a bit

more in future imaging session (I think it's a bit low), if the wind

ever stops blowing.


It's amazing how much you can underexpose, blur and soften the RGB

color channels and still get decent colors out in the LRGB combined  

image.


TTYL..


Milton Aupperle









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