RayD

Crikey, I had trouble seeing the boxes, never mind reading the text, so there is definitely no chance of me ever seeing the difference.  Glad I image at 1.3"/p 😂

Very nice and super sharp.  Well done!

21 hours ago, mikeyj1 said:

thanks Ray,

I'm still wondering if the ADU max level  will change if I Bin 2x2 compared to 1x1?  

in any case i will aim for around 20k and 2 secs or less for the LRGB.

I will experiment some more tonight hopefully, looks like it may be clearing...!

cheers

Mike

 

No the ADU max level shouldn't change as the full well depth doesn't change. What it will mean is as you are now aggregating 4 pixels (at 2x2) the amount of time needed to reach the same ADU will reduce.

If you bin your lights you will also need to bin your flats to match. 

Just now, gorann said:

Yes, on our original Mesus that kind of balancing is not possible (no clutches), but a CEM120 is supposed to be able to carry 50 kg (I thought), so it should not matter much there either.

The CEM120 can definitely take that weight, but I think it's more about the guiding having to do less work than the weight.

I only linked the video to show what @Midnight_lightning was talking about as it can be a little hard to get your head around, so thought it would help.

1 minute ago, gorann said:

Well, I now saw the video. I never realized that this was so filddly - I may be saved by having an Mesu on one pier and an EQ8 on the other - I doubt they would bother about filter wheels sticking up or down. Hopefully, for Midnight Lightning this will not matter when he upgrades to a bigger mount.

Yes I have a Mesu too, Gorann, and it isn't really possible to get it this fine on the Mesu and certainly not a critical thing.  The CEM120 is very smooth as you will have seen, and it makes quite a bit of difference.

I think if someone is struggling with guiding at the zenith it is always worth checking, on a non friction drive mount.

Yes I think this is really only beneficial, as counter intuitive as it sounds, if your mount is pretty good and has very low levels of backlash on the dec axis.  If you have to balance one side heavy to engage mesh then this is going to largely negate the need for it.  The CEM120 is particularly good in this regard and it makes quite a difference when done.

1 minute ago, Skipper Billy said:

I was told way back to balance in all 3 axis and whilst the weight of the filter wheel off to one side makes little difference on my current rig on a previous rig which was a very light newt with an EFW2 and a heavy camera balancing the third axis made an enormous difference.

Yes indeed, David.  Like you, on my Mesu you wouldn't even be able to determine if there was a difference, but when I got the CEM120 it made it really easy to show the issue.

This video I did shows what he is talking about.  Off centre equipment affects the balance point on a third axis.

Post no longer relevant.

They all downloaded fine for me.

With friction drive it is very easy to get it very wrong due to the very specific nature of the materials that have to be used on the friction surfaces, and the very tight tolerances involved.  I suspect that unless you are using Chinese manufacturers to produce equipment to your own specifications, then their market is generally mass production stuff, which will be very difficult to do with friction drives and get it spot on, whilst keeping costs low.

The likes of 10Micron successfully manage to produce extremely high quality gear final drive mounts, but not for £4k.  Naturally there is a balance to be had, and at the very high end is direct drive using renishaw encoders (ASA), with the lower end being mass produced full gear driven using production machining, such as a Celestron AVX, which performs perfectly adequately for its intended use.

I think the friction drive mounts are an excellent middle ground offering performance knocking on the door of that from a 10Micron etc, but at a lower price.  Whether that performance is going to be long-lasting is down to the quality of the build and materials, and Mesu has proven this to be very good.  Obviously 10Micron uses a sky model rater than guiding, so the performance is probably more guaranteed as it removes the additional complications which can come with guiding.

Ultimately I think the reason this JTW mount looks so similar to a Mesu is because the Mesu is such a good design.  I had a really interesting conversation with Lucas when I was with him in his workshop about how he came about the design of the mount.  I suspect he will be flattered that the design is being copied, rather than upset by it, as it proves he got it right.

40 minutes ago, Adam1234 said:

No idea what Catalina is? 

I'm using PC with Windows 10

Catalina is a Mac OS so if you're on W10 it won't be that.

As Olly says, probably worth dropping a line to the author.

I'd say relish the fact that you can chuck it over a hedge and enjoy the wonders of a Bortle 2 sky!  Lucky you!

Just seen this.  That really is amazing.  Great job, both on the capture and excellent processing.

Personally I would wait until you have it and try it.  The standard one may work perfectly well, at least for some time.

I think there has been an issue with Catalina on Mac.  Not sure if you are using Mac or PC, but I had some real odd things happening and had to delete the set and reload them and all was fixed.

7 minutes ago, Northernlight said:

ok think we are really getting off topic now.

Just a tad 😲

Very good effort.  Agree with Tomato on DBE to each of the LRGB stacks, and I would say all that your image appears to be missing, which you don't show in your workflow is some background neutralisation.  This will help make things a little more neutral, which should help with the slightly red cast.

You can also run SCNR on the red channel which may help.

Great start though.

19 minutes ago, Davey-T said:

Will do, still trying to collimate the thing ATM and having read through the CN thread on it have now got a few mod's to perform 😁

Dave

Well if mods are what are needed it has come to the right person! 😂

38 minutes ago, Davey-T said:

Don't want to side track this thread but wondered if you have any thoughts on this filter Ray, I've got this Sharpstar HNT f/2.8 and supposedly fast scopes need filters that don't lose bandwidth especially when the light is turned through and angle, I don't pretend to understand the maths involved.

Planning on getting CMOS colour camera for it as focuser doesn't seem up to the task of supporting full frame and filters.

Dave

https://optcorp.com/products/radian-telescopes-2-inch-triad-ultra-filter

I have looked at this exact filter a number of times for DLSR imaging, Dave, and it has some really good reviews.  I've been a little skeptical of multi-band filters myself, especially on colour cameras, but this really does seem to do what it says it does, and is almost the holy grail of filters for NB imaging!

I can't see why it wouldn't work at f/2.8 as they seem confident it has been designed to work up to f/2, although that doesn't say if that is the f/2 range, or exactly f/2.0.  Like you I don't pretend to understand the maths, but maybe someone like @vlaiv who does, can chip in with reasons why this one may work well where others have failed.

If you do get one I'd be interested to see your results as it is high on my list to get.

46 minutes ago, mikeyj1 said:

Hi all, 

I have been trying to get flats using the 6120 and LRGB filters, but struggling to find an exposure, it's either ridiculously short for 20,000 adu (approaching bias frame speed!), or far too long (8-10sec) for 33,000, which is the 'default' in SGP.  i seem to only be able to get a max of around 31,000 adu even with a multi second exposure, into a relatively bright source. I have a stretched t shirt as my diffuser

What should i be aiming for, and does the binning level make a difference on the max level?

thanks

Mike

When I take my flats with my Sony sensored cameras I pretty much have the flat panel light off for the RGB filters.  They are very sensitive and I only increase the lighting levels to high when taking Ha flats (3nm).  Try them agianst just a white board or wall with only background lighting.

I aim for a time of around 2 seconds, and adjust the lighting level to achieve this.

Increasing the binning will reduce the time needed for the same ADU level, but only use that if your lights are binned also.

Not sure what the exact ADU level would be on your particualr camera as I believe the QSI6120 has slecetable gain, so on low gain it is around 50,000 ADU, so you would aim for around 20,000 - 25,000 ADU.

22 hours ago, gorann said:

Interesting thread, but I expect, as someone said, that the differece between expensive and very very expensive filters may be more apparent for NB filters. I wonder if anyone has any experience with the Baader Ultra-Narrowband 4.5nm OIII Filter? It is 40% of the price of the Chroma 5nm Oiii filter. Same question could of course be asked about the Baader 3.5 nm Ha filter (I have it but have no Astrodon or Chroma to compare it to).

I had the 2" Baader 3.5nm Ha filter and sold it as I now have the 2" Chroma set.  The difference was very noticeable, with much more fine detail for the same integration on the Chroma.  They both do a very good job on filtering moon glow etc. as would be expected with such a narrow bandwidth, but the Chroma data is just so much more detailed and defined, but the stars are tiny specs.

Is it worth £700+ , almost 3 x the cost of the Baader?  I'm not sure I can provide emperical evidence that it is but the difference to my eye in the data, as would be expected at this price, is very noticeable.

2 minutes ago, Gorr_77 said:

it must be good

thanks for that, i will order one now...

and probably new mount as well....!!!!!

The Celestron AVX is excellent, and with encoders will out perform the Mesu.................😂

Just kidding.  Be good to see what mount you end up getting.

7 minutes ago, Gorr_77 said:

Hi Dave-T,

Yes, but - would you see the difference?

Personally I think that if they were going to make a huge difference, Lucas would have added them.  A RMS value of 0.3"/p, which most of us with the Mesu200 see regularly, is perfectly adequate for most imaging the average amatuer is going to be doing on this class of mount.

1 minute ago, Davey-T said:

Well that would at least double the price of the mount  😂

Dave

I reckon you're about right there!