Moving the frame a little - A quick and dirty way please?

[swag72]

OK, this sounds like such a beginner question, but it is driving me mad. I have asked before about framing the image in the same place night after night, but this is even more basic.

Last night, while I was taking short images just to see targets, so only 2 min subs (with no intention of taking anymore to stack, just a bit of a visual fest really!), I found that for example M31 was slightly too low in the frame and I wanted to move it upwards and across the the right a little. Well, could I work out what way to move the damn thing? No!!

I usually resort to liveview in this instance and find a star bright enough, and then watch the star as I move the scope with the handset - Bingo! Well, no bright star in that area for me to find.

So, alternatively I think I could use my guidescope - Would make sense. I can see the star moving instantly on the screen in PHD Capture, but it moves in totally different directions to the image through the scope!! Grrrr!!

Is there something simple I am missing? I only wanted to move the frame up and across a bit! Can I use my guidescope? (finderscope and QHY5) Does my scope show an image upside down and so I need to work in opposites? Will it be different according to what part of the sky I am pointing? While I have got everything else pretty clear in my head, the most fundamental and surely simplest thing of all has me utterly stumped time and time again.

Thanks for reading this and managing to get through to the end, I hope you can shed some light on a easy and idiotproof method for this!!

[johnb]

Same problem I really get confused which way so move the scope to adjust the framimg, I tend to use a 5 sec exposure and move the mount a touch and look for a star thats moved.

John B

[ncjunk]

Not sure i understood but what i do to move over and up a bit is test the direction buttons on the controller against the camera orientation. Take a pic press the W button then take another pic and see which way it moved. Once i know which way the buttons move it on the camera the rest is easy. I can do it a bit easier with the ccd in that i can take a 20sec exposure and hit the W for the last couple of seconds so that i see a star and a trail on the picture with the trail away from the star indicating movement.

The other thing i do is use astrmetry.net to tell me where i am if i get lost then dial in a correction on eqmod ;if you right click on the dec a box appears with ra and dec and you can type in the new values and hit a slew button rather than mucking around with the controller.

I hope some of that was understandable!

[Merlin66]

The orientation of the FOV can change with the positioning of the camera...I always have the label on the camera body in a "fixed" position relative to the Dec axis.

A couple of minutes practice then allows the N-S-E-W directions to be noted.

A Post It note helps to keep this on record.

(My set-up is a bit more complicated - I use the 8 x 50 finder with cross wires, then a 135mm telelens with an Atik camera as an electronic finder, then a guide beamsplitter set up at the prime focus of a f10!, then finally I have a 3mm high x 20 micron wide slit that I want to position onto the target star! - I have the slit sitting in the Dec direction - so I just need to "drift" the target across in RA..but which way is which? Finder/ electronic finder/ guide???? Interesting......)

[swag72]

Cheers for that - Can I just ask then for a little further clarification. Is the image that my scope / camera combo produces actually upside down or right way up? If it is the right way up, then surely if I want to move things up, I shuld be able to go to capture on PHD and move the stars in real time upwatds? But never seems to work.

I need to get the directions sorted really. If I point my scope at M31 say and the camera is horizontal in the focuser - Will my image be upside down or not? If I even understand this bit I'll have a fighting chance!! Actually, does it matter about camera orientation at all?

**Cross post!! So camera orientation does matter!!**

[swag72]

Ken, you say that you have the camera fixed with the DEC axis - Would it be beneficial then for me to do this? So, when I set the scope to home and the DEC axis is always in the same direction, make sure that I put the camera in the same position each time, then resist the option of rotating my focuser as I do regularly to get a better frame!!

[ollypenrice]

Because my imaging cameras have square chips I don't ever have much choice in terms of framing orientation (45 degrees covers all possibilities.) For this reason I run them orthogonal to RA and Dec, which I check by doing a slow slew during an exposure. When the star trails are horizontal or vertical I'm done.

This then means that your handset buttons will correspond to up-down, right/left on the picture. Much easier, and much, much, MUCH easier when you want to add more data next month/year etc. You will still have to note which button moves in which direction and this will, of course, change when you flip the mount. But trying to frame when the camera is not orthogonal is very tricky.

Olly

[swag72]

OK, so lets see if I've got this right - I need to run my camera chip orthogonal to RA and DEC - Is this a different position as you go to different targets? Or can I get it orthogonal pointing at Polaris for example and it will then be orthogonal full stop?

When you say about adding data at a later stage for example, how can you be sure that you have the camera in the same way if you have imaged a 100 things since and moved the camera many times?

And - Is there another name for orthogonal? It's a pain to type as I can't spell it!!!

[Merlin66]

Sara,

Once the camera is set up square in RA/ Dec it will always be square, where ever you point the scope!

Registration between images I think we discussed on another thread.....

[swag72]

Sara,

Once the camera is set up square in RA/ Dec it will always be square, where ever you point the scope!

Registration between images I think we discussed on another thread.....

Excellent, so I can go and have a play tonight then - No need to align and stuff to start with, I can just point the scope at the home position and use polaris and play from there.

Let me get this clear. I want the camera placed so that trails as I move the handset left and right are horizontal and up and down the trails are vertical.

It's as easy as that?!! Then where ever I point in the sky, up will be up and down will be down? Regardless?

Yep, we discussed framing on another thread, I've tried that with OK success, but lots more to come!!

[AndyUK]

Hi Sara - Using the ATIK, I follow Merlin's method of always putting the camera label the same way each time (for me, it's right way up and parallel with the OTA). This way, the handset buttons move pretty much in line with left/right and up/down on the screen. Regarding which button relates to which way, I use a similar method to Nick - a 20s exp and a few very quick rate 4 presses which leave a trail on the screen.

However, regarding what's flipped and what isn't in which application... well, that's a secret I'm still looking for an answer to! I think it's just one of those things I'm going to have to try and wrap my head around and think about each time. To adjust framing though, I first centre the object as I want it and then rotate the ATIK, although in my (very limited) experience, this is quite tricky with nebula when there aren't many major stars / star patterns to go by and using an NB filter. I currently use 20s exp, 3x3 bin and play with the log slider and squint at the screen a lot to try and see the nebulosity... (If anyone has a better way of doing this, then I'd be very interested to know!)

[ollypenrice]

Atiks, as said, have a sticker aligned to the chip. Sight this so it's aligned along the line of the counterweight bar, for instance. As Ken says, it will always be square on to RA and Dec if this is accurateley done. It gives no guarantee of which way up the image will be but that doesn't matter and will change when the mount swaps sides.

Artemis Capture allows you to roate the image 180 but I don't do this because I don't know what its changing and fear getting confused with my darks. I would rather rotate the pre-flip image and use that to re-locate the picture after the flip.

Olly

[martin_h]

As above, but if you want to watch live view through the guide scope you will need to align it the same way as your main camera, or you may have the star moving left/right in the guide scope and up/down on the capture CCD !!

[Helen]

If you wanted something automatic rather than manual Maxim has a Centre command. You calibrate it and then click on a point on the image and it centres it (well, usually!). Its under the telescope command in the Observatory Tab

Helen

[swag72]

Cheers all for your input. I'm not with the Atik yet, so still on the DSLR at the moment. Will try tonight to get it nice and straight. Horizontal lines during a slew / exposure with left and right handset buttons and vertical lines during a slew / exposure with up and down buttons.

Sounds easy - Bet it isn't!!

[ncjunk]

If you wanted something automatic rather than manual Maxim has a Centre command. You calibrate it and then click on a point on the image and it centres it (well, usually!). Its under the telescope command in the Observatory Tab

Helen

Well thats ruined my fun! I carefully calculate how far out i am and then move it in the wrong direction. But your saying i can just click on the image in maxim? A mere click? Any idiot can click on an image, it takes genius to overly complicate things and slew it in the wrong way....

[swag72]

.... it takes genius to overly complicate things and slew it in the wrong way....

Thanks for clarifying that Neil, I knew I was a genius!!!

[Helen]

..but you'll be pleased to know there's still scope for genius (particularly after a meridian flip )

Helen

[swag72]

For me, the genius is avoiding the meridian flip!!

[ncjunk]

For me, the genius is avoiding the meridian flip!!

I´m with you on that...I image East side only. It´s an East side story for me.