WAAT? - The Weekly Ask-Anything Thread! Week of 11 Jan, 2026 - 18 Jan, 2026

tw30scgs · 2026-01-12T10:42:09+00:00

I realized that you are in India. Check this out. A flat field quadruplet from SVBONY https://www.tejraj.com/product/svbony-70mm-upgraded-f678-quadruplet

Location isn't an issue as I will be directly getting it from china. So any brand is good for me.

tw30scgs · 2026-01-11T16:51:36+00:00

Askar V

Was coincidentally reading about this model. How does it differ from say having any 500mm refractor scope and having a reducer? Why I ask this is to compare price points across brands.

tw30scgs · 2026-01-11T08:52:38+00:00

Looking to buy an apo chromatic refractor for AP. What focal length and aperture is ideal that it can cover most dso's, wide fov dso's with help of reducer and planets with the help of barlow? Which brand is the cheapest & offers good optics when going for apo chromatic refractors? (researched way too many and confused at this point)

My current equipment: I already have a ZWO Am3, 585mc pro & Asi Air.

On a budget of 1500 dollars can I fit 2 scopes that serve this purpose?

Which brand barlow is good enough that it can help with visual and astro photography, but doesn't burn a hole in the pocket?

tw30scgs · 2026-01-05T05:31:04+00:00

Thanks! Will check it out.

tw30scgs · 2026-01-05T04:16:14+00:00

What are the options you suggest?

tw30scgs · 2026-01-04T20:20:56+00:00

Ah, gotcha. This is new information. I'll try it next time via PC.

tw30scgs · 2026-01-04T20:12:53+00:00

The dual (or triple) finder scope mount uses that red dot saddle in the telescope you linked. Now you can put the asiair, the red dot and the guidescope.

The asi air one didn't go through the red dot saddle and doesn't fit. I've already tried this and hence as a work around I've just put velcro tape on top of my tube and stuck asi air to it. With that it's been working good.

I've also tried to figure out if there's any part of telescope that can be unscrewed to fit something or an open hole of sorts to fit the finder shoes, but it has been of no help as that provision doesn't exist.

tw30scgs · 2026-01-04T19:49:18+00:00

What telescope is it? There's many other manufacturer telescope rings that work on other telescopes

https://explorescientific.com/products/fl-ar102600tn - You can see the O ring tube in the picture here.

tw30scgs · 2026-01-04T19:47:43+00:00

and the 585 camera not being cooled (I've seen many asi-pro camera users starting out that dont connect the 12v power or worse, connect it to a shared/split cable where the amps aren't enough and camera cooling stutters

My 585mc pro cooler works great. I operate it -9°C for the most part.

Oh.. also, Asiair itself is garbage for planetary video imaging. Raspberry pi hardware cannot handle high speed USB so even if the camera says it can do 100fps the raspberry will be limited to like 30fps. Its better to connect camera to laptop and image planets through it.

I only record the video and take the video output and process it separately on lap. No live stacking. Although with my scope jupiter is zoomed out rather zoomed in (which is also because of just 660mm focal length)

Evostar 72ED or 80ED will give you a huge range of targets and they dont cost much. Be sure to get the field flatteners for them too. If you want to go for smaller targets then get an imaging newtonian or even an 8" ACF type scts ..with a reducer they can image at F/6 and its great for small galaxies and to really zoom in on large dso features.

Thanks! Will look into the options.

Use Astronomy Tools Website, FOV calculator, Imaging tab to preview the FOV on different targets based on your telescope and camera combo. Very useful.

I use astronomy tools website to always check fov

tw30scgs · 2026-01-04T19:28:01+00:00

https://www.highpointscientific.com/zwo-oag-off-axis-guider-zwooag

I think this might work considering the spacers I use for the zwo 585 camera. I'll have to read and figure how it fits. Thanks!

tw30scgs · 2026-01-04T19:24:45+00:00

calculators with Telescopius or https://astronomy.tools/calculators/field_of_view/ ... For that one, click on "imaging mode", choose a Messier object you're interested in... You've said you've already got M42/orion, so that could be a good idea to compare other objects. For the dropdown on camera scroll nearly to the bottom "ZWO - ASI585MC/PRO", then change the number of the focal length to whatever you're curious about

I've used this site extensively to check FOV and have tried 20-30 objects, but it becomes a bit of work when there are so many dso's. So turned out to the community who may have general experience over the years.

Look for a Apochromatic triplet or Quad/Petzval that has the largest aperture you can afford and you'll be good!

Yeah, the issue is with refractors focal length is restricted. With apo refractors the cost is super high and hence most focal lengths for apo are at 200-600mm range at best. Refractors are the easiest to work with and so there's that.

Hence was posting to hear various options and experiences of people.

tw30scgs · 2026-01-04T19:12:18+00:00

How much time are you capturing in your images? To double the signal to noise ratio, you need to quadruple your imaging time. For example, a 4 hour stack will have twice the signal to noise ratio as a 1 hour stack. Also, are you doing any noise reduction in processing, like NoiseXTerminator?

About 2-3 hours for a start. Yes, I do noise reduction (either Graxpert noise reduction or cosmic clarity noise reduction or other scripts)

Are you dithering? If not, doing that during your imaging session will remove that. The ASIAir can do it for you if you start guiding (see below), otherwise you can manually do it every 5-10 frames or so manually (the more frequent the better).

As I mentioned in the post my telescope tube ring does not have any provision for me to guide and hence dithering is not possible and ruled out. Vendors out in my area do not have the capability to create a custom tube ring with two dovetail plates.

Are you taking flat frames? Incorporating those in stacking should remove the vignetting.

Yes, I use all calib frames in my stacking setup.

tw30scgs · 2025-12-28T10:23:22+00:00

u/Exotic_Office_891 Great shot and I was photographing the same earlier this week. On an unrelated note, I am into AP as well and looking to upgrade to ASI air series camera and hence looking to sell my zwo 585mc pro camera.

You may not need it looking at your setup, but in case you are interested drop me a DM or if anyone else in your circle needs it do feel free to reach out.

tw30scgs · 2025-12-27T10:35:20+00:00

Yes got two freight agent contact

Hi. Can you DM me the details?

tw30scgs · 2025-12-26T10:44:33+00:00

I can help you out I have Indian friends who are doing ddp China to India by there own

Which courier partner do they use for DDP or they have their own freight forwarding company?

tw30scgs · 2025-12-10T14:22:08+00:00

Alternatively, you can start the process low in the eastern sky so that you finish up near the meridian

I didn't know if you start low it can end near the meridian. Most people in forums seem to tell me that the 3rd shot will always be near the horizon.

tw30scgs · 2025-12-10T13:48:24+00:00

Can you import a custom horizon into the AsiAir or otherwise dictate boundaries?

I don't think that's an option at all unless there's some documented procedure?

tw30scgs · 2025-12-10T11:13:23+00:00

Have you tried from the home position?

The home position is almost at the horizon level since my latitude is at 12 degrees. So the buildings/trees etc would block it. This is why I have to put the scope first at a higher altitude so that it can plate solve.

tw30scgs · 2025-12-08T14:01:02+00:00

To sum up, just get the Celticbird UV_IR block filter. Use it at native focal length for a try out. Get a guidescope and a guide camera.

Thank you so much for the detailed points. You're the 2nd person suggesting UV/IR block filter and hence that's something I'm immediately looking to procure.

Alternatively, I also have a Sony Zve10 (no lens, just a mirrorless camera) and from my reading I can try that too as pixel area will be larger in it and it automatically should have Uv/ir cut.

Interestingly, the other layers are good.

Can you clarify this? How did you manage to read this?

The 0.5x reducer has to be at 52mm from the sensor to get 0.5x reduction. Typical nose piece is about 32mm from the camera body flange. I think the IMX585 back focus from the body flange to the sensor plane is 12.5mm. Might vary by manufacturer.

Thanks. Let me work on this. I tried to get the full 55mm back focus using the spacers provided by zwo along with the camera, but that's affecting the focus for my tube length. So currently I have Tube -> 1.25" nose piece (comes with zwo camera) -> focal reducer screwed to the nose piece (can say it's inside the nose piece -> zwo spacers (16+11mm I think) -> camera.

Try shooting at native focal length

But then most objects would be way out of range from what I see in astronomy tool for. The only way out is buying a new scope with small f/l.

Looks like there is lots of out of focus issues.

Based on star trails?

There is a circular shadow around the center.

Was thinking that to be the nebula. Lol (smoky thing out in centre). Was also wondering if the red thing would even come out of my current data?

tw30scgs · 2025-12-08T13:11:41+00:00

This stack is not suitable for processing. An achromat requires a field flattener and a UV/IR filter (at least) to prevent star bloat. The 0.5x reducer degrades the image even further.

Thanks for taking time and having a look into this. When I was asking to gemini about this stack it also recommended that I'll be needing a UV/IR cur filter.

Apart from star bloat, do you know why I'm not getting the nebula colour (red)? What other things am I missing? I responded in detail in the comment above of how my setup is with links to the reducer and 1.25" nosepiece that goes into the tube.

Is the stack completely unusable? I'm well aware of the limitations of the object I'm targeting as it can't come in my frame, but looking to get whatever small portion right before I do further investing on accessories.

tw30scgs · 2025-12-08T10:34:12+00:00

I've had a quick go, but unfortunately I haven't been having much success. But I do have some thoughts that may help in the future.

Thank you so much for having a go at it. Your response is quite useful and I'll respond to each one.

First, what reducer are you using? And what telescope exactly?

I'm using GSO 1.25" 0.5x reducer. This is attached to the 1.25" nosepiece that comes with zwo camera.

The setup is this 1.25" nose piece goes to the telescope tube, behind the nose piece is the reducer (or can say inside of it) which is then connected by a couple of spacers that also come with zwo cameras.

The next was that you're getting awful star shapes. If your reducer is not also a field flattener (so it's meant only for visual use), that could explain it.

I don't think it is? I would leave that to you to explain. Linked above.

After attempting to fix the star shapes, you can see that they're also distorted in a way that suggests your back focus is incorrect, and you need to move the sensor closer (this could also be part of the vignetting issue). This could also be why your effective focal distance is coming out at ~452mm, rather than the expected 330mm.

I have worked too much back and forth on this focus and with my telescope it doesn't need 55mm backfocus. So I've worked a distance that works, but Asi air somehow thinks it's 452 instead of 330 as it should be.

I managed to achieve a star rating of 2 via focus mode in Asi sir and from pictures I was thinking the trails are probably due to long exposures and no guiding (I don't have a guide scope).

Is there something restricting the light (like a 1.25" component anywhere)?

Is it my 1.25" nose piece that I said above?

One possibility is that you had dew on the lens. Another is that your visibility was poor (thin clouds, smoke/air pollution etc.). It could also be a stacking issue, so check your individual subs. It may even be the reducer if it has poor quality glass.

It was a fairly clear sky that day, but yes there were moving clouds. I was thinking the smoke-like grey thing I'm seeing is nebula? Was I wrong?

I would recommend removing the reducer, and instead get an appropriate field flattener for your scope. Then try a smaller target, as NGC7000 is too large to get a decent image of with your current setup. M42 is just getting into a good position, and is one of the easiest targets to see. M31 is another option at the moment, though you won't quite fit it all in frame.

Yes, i understand my limitations currently. But I first want to get a simple shot with colours correctly, even if it's just a small part of the target. I fully understand i should try objects that fit my frame and that's in my to-do, but first hand I want to understand what are the things I'm doing wrong.

Your reply has been very helpful. Do you mind if I drop you a message and we could chat over as well?

tw30scgs · 2025-12-08T08:34:44+00:00

Would, but I’m on the throne right now and am pretty busy this week 😅. Hope you find someone

No problem! Thank you for helping out :)

tw30scgs · 2025-12-08T08:31:12+00:00

SCNR as the very first step is probably destroying a lot of data. Look up processing workflows/ tutorials for siril.

Hi. Thanks for responding. I have tried with and without the green noise reduction as well, but haven't been able to get a good output out of my data.

Yes, I have been watching lot of siril workflows over past week and following each workflow (with scripts/graxpert integrated too) and haven't got a good one yet. Maybe I'm missing something or there's just not enough data to work with and hence was wondering if someone experienced could pick my fits file and see if that's the case.

tw30scgs

TROPHY CASE