Kenza

Here is a bicolor ( Ha + OIII) image of the Crescent  nebula.

Optics: Equinox 120

Mount: Astrophysics 900 GTO

Camera: QSI 690 ( Ha 120’ ; OIII 60’  + Flats )

Post processing: Pixinsight and PS

Crescent Nebula Bicolor by Aleksandar Topalov, on Flickr

For guiding i use a Lodestar and a 180 mm FL guide scope which gives me an image scale of 9.6 arcsec/pix. My imaging rig gives me 1 “/pix. I know that the guider image scale is way too high. I should probably bring it down to 3-4. Maybe use a barlow? Then i think is Lodestar a good choice for a guiding camera with such big pixel size? You need a really long FL scope to get reasonable image scale.

How much would lowering the image scale improve my images? 

On 19/09/2019 at 18:30, Highburymark said:

Here’s a pic of the MkV and the T2 adapter/ring. It doesn’t come with either a 1.25” or 2” nosepiece. If you want to use a 2” diagonal instead of a T2 prism/mirror, you would add a 2”/T2 nosepiece (Baader #T2-16), so the order would be:

Binoviewer with GPC screwed in - heavy duty ring - 2”/T2 nosepiece - 2” diagonal.

Worth making sure first that your refractor will reach focus with such a system. 

Thanks for the info. I know about the nosepiece. I don’t think there will be a problem to reach focus, CFF has 180 mm backfocus. I reckon that should be enough.

Hi everyone!

I plan to buy the baader mark V bino to use with a CFF 132 triplet and C11. I know that a prism, such as the baader T2 prisms, would be the best choice because of the short glass path. The thing is i already have a perfectly good TV 2” everbrite which i love because of the one piece body construction . My question is will i be able to use this combination at all and are there any restrictions to using this combination? 

Thanks!

Aleksandar

There is one issue that I haven't been able to resolve so far. I have problems when guiding and tracking an object that is near the zenith. Everywhere else in the sky guiding works fine (i can manage 20 minutes without star trails) but when I point the scope directly above I get trails after 3 minutes. I have tried both pulse guiding and ST4. Any thoughts?

Well, I've been imaging throughout the whole night without dew heaters and it was -1 degrees.

What does it mean when while guiding PHD reports and error like this: Mass (some big number) vs (another big number). Also the screen flashes red and beeps.

Right.  Fewer than 7-8 steps is likely to result in a poor calibration.  As you've found, it might work sometimes.  I'd decrease the step size a bit (maybe try 3,000 and see) before you change anything else.

I changed the rate to 3000 but the steps didn't go over 5. But I tested on more than 10 different regions of the sky for 10 mins each and the stars were perfectly sharp. I even imaged M52 with the Bubble Nebula. Any suggestions or should I leave at as it is?

Hard to say.  Even Craig Stark doesn't really say.  The bottom line is that bigger SNR numbers are better than smaller numbers. So when you are selecting a guide star, setting exposure/gain and focussing the guide scope just pick the combination that gives you the biggest SNR you can find that night.  If you get 'Star Saturated' errors then your chosen star is too bright, the gain/exposure is too high/long or maybe de-focus a tiny amount.  If you get 'Star Lost' errors a lot, then you need to do the opposite and try to get a brighter star, increase gain/exposure or focus better.  Make sure you don't have dew on the guidescope objective and check for high clouds.

Yes I'd say that somewhere between 3,000 and 4,000 is a good starting point for that pixel scale.  Remember 15-20 steps in each direction should give a good calibration.

I've set the Calib. Rate to 3500, but PHD only takes 3-4 steps in each direction. Nevertheless i managed to image for nearly 10 mins without star trails (Perseus Region). Next I slewed to Cepheus and had small trails. I presume that if i lower the rate more steps will be taken, right?

Hi! I calculated my pixel scale for my guiding rig and I get 4.28" ( Starlight Xpress Lodestar with ST-80). How big should my Calibration Step Size be? 4000?

Hi! Here is my first DSI (M51) taken three nights ago.

Lights 21x 60 sec. @ ISO 800 (but DSS used only 14)

Darks 15

Processed in Photoshop

M51 3.tif

No guiding