Pitch Black Skies

Yeah but if the grapefruit were the same distance as the stars they would actually be tiny.

58 minutes ago, vlaiv said:

Ok, so first thing to do is to register both images against same sub, they need to be aligned.

I don't know how to do this.

Thanks,

M42 18 min 30 s, calibrated.FTS 30 seconds exposures

1 hr 6 min M42, fully calibrated.FTS 120 seconds exposures

How do I integrate short exposures of the stars into the main integration. I tried to do it with M42 before but was unsuccessful. I was using DSS and it gave an error message stating the exposure lengths differed. I've seen a few people mention Affinity Star but haven't gotten round to checking it out.

What is the definition of optimum exposure time?

In my mind, it is collecting as much signal as possible without blowing out the stars.

That makes me think, why not just take looong exposures, let the stars blow out, and then take some short exposures of just the stars and amalgamate the two.

On 13/06/2022 at 14:33, ollypenrice said:

The Baader LRGB are so reliable, and used by so many well known imagers, that I would look no further

That sealed the deal for me, thanks.

Yes, but the 5 position one.

On 13/06/2022 at 20:41, oymd said:

The Baader ones are a bit cheaper, but not in stock at FLO or anywhere else. 

I know someone who is selling the 2" LRGB Baader ones. He is selling a 2" filter wheel too.

On 31/05/2022 at 20:17, edarter said:

It does come out if the back focus yes, but a 10mm extension ring solves that and moves the recessed part of the baader out of the way of the securing screws on the focus tube. That's one of of the causes of slight tilt with the baader.... So kills 2 birds with one stone.

I'm sure there must be a way of working out how much of the primary you would lose by pushing it up the OTA 10mm but I can't figure out the maths on that.

I'm also researching whether a screw in fixing on the end of the focus tube is lower profile than the original, if so it would further reduce the focus tube protrusion meaning even less requirement to move the primary up the OTA.

Sorry, just seen your message now. Yes, that's a very good idea actually.

Yes I would be interested to know the maths on that too. Why not just try the longer screws and see how you find it? You can very easily revert back if it doesn't work out well.

42 minutes ago, Elp said:

Another option though it might be a swine to get the rest of the set individually, is get the ha and get a luminence filter

I think it might be best just to buy her whole set of LRGB SHO. It's a good offer and I think some of these filters are no longer available.

Well that's really nice, and you're using the filters I received the offer on. I see your Bortle is a little lower but not much. What sort of integration is this?

The set of CCD LRGB SHO Baader filters sounds like a good deal but the SHO is around the 8nm range and I don't know if they would be good enough for very heavy light pollution.

So just to clarify, getting the LRGB from the Baader set is a good move but if I want to go NB opt for a 3nm instead?

5 minutes ago, peonic said:

https://www.rothervalleyoptics.co.uk/antlia-pro-ultra-narrowband-3nm-h-alpha-filter-2.html

 

 

You've read my mind. This is exactly the filter I was thinking about.

I just can't decide on whether to buy the Baader LRGB or the Antlia 3nm Ha.

My gut is saying the Antlia but as I know nothing about mono yet I need someone to steer me in the right direction.

I don't want to make a costly mistake and get fed up with mono before I've even begun.

Still not really sure on what the best approach might be.

I have an offer for a set of Baader LRGB + SHO (all ~8nm range).

Given my Bortle scale (8/9), I'm wondering if it might be more sensible to just dump the whole budget on a Ha 3nm and build the collection very gradually.

I suppose the question is, would it make more sense to opt for narrowband filters over LRGB given my circumstances?

Looks great 👍

I wonder if something similar would be possible from Bortle 8/9.

I had given up on the idea of LRGB but maybe there's still hope.

Okay, I'm almost there.

So I will be imaging from Bortle 8/9.

Is it even be possible to image LRGB from a heavily light polluted city with mono?

I'm trying to decide on whether to buy a set of LRGB with a filter wheel, or simply just buy a single Ha instead and add an Oiii and Sii later down the road.

Thanks all, really helpful advice there.

I watched a video by Cuiv about narrowband filters from a reputable brand and was a little spooked. The quality control seemed to be non existent.

I have a friend who is selling these and these. They are labelled CCD but I will be using a CMOS. Will this make any difference? She said she uses CMOS with them too.

I'm considering going mono soon but I am overwhelmed by the options (and prices) of filters.

Can someone give me the heads up on what they think is garbage and what produces very good results for a reasonable price?

Astrodon and Chroma seem to be some of best from what I have read so far. Unfortunately, a set of them are out of my budget price range if buying from new.

Please PM me if you feel uncomfortable criticizing any specific brands.

18 minutes ago, Rodd said:

No. I was just saying that if you felt they would be visible then you were correct and that your answer to A would then be no.

So you believe A is sufficient so?!

I'm only joking 😁👍

4 hours ago, Rodd said:

And you are correct—guiding errors would be visible a 1” rms and a sampling rate of .2”.

Apologies, I thought you were telling me your position on it when you stated the above. I figured that if you believe guiding errors would be visible with (A), surely that would suggest you believe (A) to be insufficient.

2 hours ago, Rodd said:

And you are correct—guiding errors would be visible a 1” rms and a sampling rate of .2”

What's the person's reasoning as to why A would be sufficient/not show guiding errors?

Did you mean to write 500mm for A? Either way, I suppose the focal length is irrelevant as you have given the sampling rate.

A = 0.2"/pixel

B = 3.5"/pixel

If seeing is not the limiting factor, I'm confused as to how guiding errors wouldn't be visible at 1" total RMS if the sampling rate is 0.2"/pixel.

Cool little piece of kit!

I can see its use for detecting binding, but is it not better practice to deliberately imbalance the axis to keep the gears constantly meshed?