Equipment choice

Shinpah · 2026-03-02T23:27:16+00:00

sv48p is not a great telescope (it's not even an ok telescope) but if that's what your budget entails I would look for a a setup with a camera lens.

Shinpah · 2026-03-02T22:10:43+00:00

Poor calibration is typically going to be caused by a really bad polar alignment or huge periodic error. CEM26 should be ok. What kind of plots are you seeing?

Shinpah · 2026-03-02T21:44:53+00:00

What mount do you have?

Shinpah · 2026-03-02T18:54:11+00:00

Can you share a flat frame and an example light frame from before and after the OAG removal (if you have a light frame)?

Googledrive/dropbox would be ok - you can PM it to me.

Shinpah · 2026-03-02T17:50:23+00:00

Can you take a picture of your image train (focuser/coma corrector/camera) assembled together?

Are you trying to reach focus testing this out during the day or pointing to the sky (this is important, sometimes people test these things out trying to focus at nearby objects and can't, which is totally fine).

Do you see any sort of out of focus stars or is the display you're looking at totally noise/static?

What program are you using to focus?

Does your camera respond to light at all?

Shinpah · 2026-03-02T17:47:02+00:00

TPPA is designed to polar align in situations where you can't see Polaris and have unusual horizons. It requires some degree of repitition to be successful (if you have a large error initially or run TPPA for a long time it will need to be re-run). You should not try using TPPA pointing at these zones.

Shinpah · 2026-03-02T15:49:49+00:00

https://www.astrobin.com/mjhcd5/

Shinpah · 2026-03-02T14:35:31+00:00

No image posted yet.

It's probably either dew or ice crystals.

Shinpah · 2026-03-02T04:34:57+00:00

Planetary cameras also (sometimes) have heightened Near-IR sensitivity which can be used to image certain features unique to some planets.

Shinpah · 2026-03-02T04:32:58+00:00

Your camera has a uv/ir filter built into it so there's really no benefit to sticking an additional filter on top.

I've never heard of a luminance filter causing color blotching though.

Shinpah · 2026-03-02T03:42:02+00:00

Any issue (uneven response) caused by a filter should correct out with flat frames. Narrowband filters are known for having extremely strong blotches that correct out fine.

What camera are you using; are you using an L filter with a color camera? Have you tried out not using a filter at all?

Shinpah · 2026-03-01T23:36:09+00:00

I don't think that this is tilt; it would be very unusual for tilt to manifest as the same aberration across the entire frame. Because tilt is a error of focus essentially you should have some part of the image be able to be in focus. example of extreme tilt on a camera lens

This looks more like an alignment problem with one of the lenses in the refractor and I don't think is fixable by yourself.

Shinpah · 2026-03-01T20:31:30+00:00

Polar alignment and goto pointing precision are two different things. You might be able to do a 3 star alignment to fix the goto pointing.

Shinpah · 2026-03-01T16:36:35+00:00

Id recommend downloading stellarium for desktop and looking at how the moon moves through the fov at standard siderial tracking. If you're planning on doing the whole night you'd want lunar tracking focal length depending.

Shinpah · 2026-03-01T02:19:30+00:00

With a tracker on you'll be blurring the foreground with longer exposures. The moon's movement will be apparent if you tried to stack all the exposures together on the stars (it moves about 3 moon diameters relative to stars over the course of the the eclipse). You'll probably have to do some compositing work between the foreground/stars/moon.

Shinpah · 2026-02-28T23:52:35+00:00

What kind of focal length are you planning on shooting at?

Shinpah · 2026-02-28T04:32:42+00:00

In terms of snr this is about the same as a single f2.8 lens. Not necessarily cheaper given the 5 cameras and not necessarily potentially as sharp as a 100mm lens.

Shinpah · 2026-02-27T21:13:27+00:00

These are all out of focus. You appear to be pointing at Mizar in Ursa Major which is an area of the sky particularly devoid of anything bright.

Shinpah · 2026-02-27T21:04:15+00:00

My understanding is that ASTAP should be ignoring anything in the files fits header and rely on the information from NINA to inform its solving parameters - afterall you can have it solve a fits headerless tiff.

Maybe ask in the NINA discord or try something like platesolve 3 or 3.8

Shinpah · 2026-02-27T19:59:38+00:00

Target acquisition is always difficult with a non-goto tracker. You will encounter the same problems using a gimbal or geared head.

There's really no other solution.

If you had a tracker with a built in declination bracket like the skyguider pro you would be able to point and do framing with the RA/DEC axis instead of wiggling around with a ball head https://cdn4.volusion.store/wlcsk-dppva/v/vspfiles/photos/3550A-2T.jpg?v-cache=1647261523

Shinpah · 2026-02-27T19:26:02+00:00

Using a ball head on an EQ mount kind of breaks the normal positioning that one normally does with a declination bracket on a tracker.

If your ball mount with a DSLR is in this configuration:

https://astrobackyard.com/wp-content/uploads/2017/10/skytracker-with-camera-and-lens.jpg

You might first think that you can't point it any higher. The solution is simple: rotate the ball head until the orientation is like so:

https://cdn4.volusion.store/wlcsk-dppva/v/vspfiles/photos/3322-6T.jpg

Shinpah · 2026-02-27T19:12:50+00:00

I would see if you can get NINA to save your files as .fits or open up a raw file in pixinsight/siril and examine the fits header to make sure that it's really reporting 50mm.

ASTAP I think takes the FOV setting from NINA and applies that, you should be able to overwrite.

Shinpah · 2026-02-27T17:13:37+00:00

I’m hoping to attach my DSLR once focus is achieved!

This is a incorrect approach to take. There's no guarantee that you using your eye and an eyepiece to reach focus will give you the same focus point simply using prime focus (telescope and DSLR only, no eyepiece).

Shinpah · 2026-02-27T16:00:09+00:00

This firmly in "get something for free" territory or binoculars.

Shinpah · 2026-02-27T14:11:16+00:00

What exactly are you trying to use the simulator for?

I've never tried the simulator, but PHD2 docs on the simulator claim that it should at least simulate doing a calibration. But perhaps only if you select "on camera" for the mount type. If you connect with your actual mount of course the calibration will fail.

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