Focal Reducer

[Graeme1858]

Hello

Does anyone know how to tell APT you are using a Focal Reducer?

I'm not able to Plate Solve and I think the reason is because I'm using a 0.5 Focal Reducer. I've tried halving the focal length in the Object Calculator in the Tools Tab.

Any other ideas?

Regardes

Graeme

[OhNo]

IF it is correct or not I just adjusted my focal length and gave it a new name. Tools> Camera: CCD/CMOS and Save.-

BTW I have a .5 focal reducer. It was too much and induced a terrible coma....

[Graeme1858]

Thanks OhNo

I tried that. My telescope focal length is 2350 so I changed it to 1175 in the Object Calculator in the Tools Tab but the Plate Solve still didn't work.

It might just be a case of not enough stars. The FOV is 0.14° x 0.08°. The camera is severely oversampled on that telescope, I should only use it for imaging with the guide scope really but I was just playing!

Regards

Graeme

[OhNo]

Which Plate Solving program are you using? I just up-dated APT to the latest version. A new camera, new up-date what could possibly go wrong!!!! The old version with PS2 just wouldn't solve no matter what I did. Used ASTAP with the new up-date and WOW (I am extremely difficult to impress) it solved in less than 3 seconds......

[Graeme1858]

I was using PS2. I use PS2 with my 600D and it works every time. I could never get the Blind Solve with ASPS to work!

I've not updated the APT version.

Regards

Graeme

[OhNo]

ASTAP is not ASPS.

[OhNo]

Whoops double post!!!

[Graeme1858]

ASTAP is not ASPS.

Yes, APT uses PS2 to Plate Solve a known image at a known location and ASPS to Blind Solve an unknown image (or known) at an unknown location (or known) But you probably already knew that !

I've used PS2 for solving quite successfully but have been unable to get ASPS to work.

I've not used ASTAP. Is it good?

Regards

Graeme

[Juno16]

Sorry to hear that you are having issues with the FR Graeme.

A few nights ago, I used a FR for the first time and all that I did was go into the Object Calculator and create a profile focal length for with and without the FR. Profiles can be accessed by clicking the button with the ....
I wouldn't think that a profile is necessary to create a profile at all though. That is just what I did.

I was concerned about plate solving too and it solved in the usual 10 seconds of so (I always use ASPS).

Of course, I only had to go from 714mm to 571mm. Also, thinking that the FR might change my focus, I set up in the daylight and focused on a distant antenna just to get close.

Maybe the drop in focal length dropped the F ratio so much that the solving is failing from too much exposure time. I found that with my dslr, ASPS doesn't like too much exposure and set the default exposure at 3 seconds at iso 3200.

Good luck and hopefully you will have success soon!

[Graeme1858]

Thanks Jim

It's not too important, that camera is not good with that telescope anyway! I am just trying to tick a box on the learning curve!

In the end I sat back in a chair looking at the stars, it was really clear. That's still a lovely thing to do if you don't let the constant stream of Starlinks moving across the zenith 15° apart wind you up!

Regards

Graeme

[asanmax]

I used to have the same issue with APT plate solving with a scope of 1350mm of FL.
I was shooting at 300mm and plate solving was taking about 10 seconds to resolve the image.
Then I started imaging at 500mm and a Canon cropped camera and plate solving was taking longer because of the narrower field of view.
When I started shooting at 1350mm and a Canon cropped camera, plate solving was sometimes taking up to 3 or 4 minutes in APT. This is just to solve the first image, i usually do 3 iterations.
So i guess with your focal length and a smaller sensor, it is just taking its time to solve your image.

Solution to this is to try and plate solve with your guide scope.
You need to have your imaging scope and guide scope aligned to perfection, you can do it during the day on a distant object.
Before you start imaging, connect APT to your guidescope camera (if this is possible) and plate solve on it. It will be waaaay quicker and you'll avoid the frustration over plate solving through your imaging scope.
Then just switch to your imaging camera and start imaging.

Hope this helps.

[Graeme1858]

Thanks Asanmax.

Yes that does make sense. Usually though I'm imaging with my 600D and plate solving works ok. I got the Altair 290C out because I wanted to attempt to capture the tiny galaxies in Virgo to add to my Messier tally (epic fail!) And also because Jupiter and Saturn are on their way to us. For planetary I won't need to plate solve. I'll try your method if we get another clear night. Or I'll try putting an eye piece in to locate the Messiers then swap back to the camera.

Regards

Graeme

[JayTee]

That's weird because last night I finally got to a place where I could use APT plate solve with the new scope (6RC, 1370 FL), the new camera (ASI294 MC Pro, sensor size just slightly smaller than an APS-C), and the new mount (CEM 60). My images were solved everywhere I imaged (Sag, Cyg, Herc) in 6 seconds or less. I may have downloaded more of the database for the solving software - I don't quite remember.

Cheers,
JT

[Graeme1858]

I think you might expect that with your combination JT. Does that come out with a FOV at about 0.7°x0.5°. Resolution about 0.6" arcseconds per pixel? Sound like a good match.

My GPCAM2 290C and 9.25 SCT gives FOV 0.14° x 0.08° and Resolution 0.25" arcseconds per pixel. Significantly over sampled. (from Bintel calculator)

Regards

Graeme

[JayTee]

Those numbers are right in the ballpark Graeme. From FOV Calc -- FOV=0.8° x 0.55°, Res = 0.7" per pixel.

JT

[Graeme1858]

I've been looking at camera specs, my birthday is coming up!

The ZWO ASI 294MC-PRO ticks a lot of boxes. But I've just seen Larry 1969's very excellent NGC 7023 taken with his ASI071MC Pro.

Regards

Graeme

[asanmax]

I should also add that the mount should be precisely polar aligned for good plate solving results.
Polaris is not visible from my backyard, so I had to do a drift alignment in PHD2. Nailed it in 40 minutes.

[Graeme1858]

I should also add that the mount should be precisely polar aligned for good plate solving results.
Polaris is not visible from my backyard, so I had to do a drift alignment in PHD2. Nailed it in 40 minutes.

I've not heard that the mount needs to be perfectly polar aligned for plate solving to work. I would have thought focal length and a good image were more important. Accurate PA is important for tracking but guiding is happy for a bit less than perfect to prevent hunting.

Still the good news is that I'm going to get a new camera for my birthday that matches my telescope focal length and I won't need to plate solve with the GPCAM2 any more!

Thanks for your input though.

Regards

Graeme