geordie85

On 25/08/2020 at 08:27, ollypenrice said:

Blue bloating is a form of CA but might have varying origins. It might be that the scope's focal length in blue doesn't closely match its focal length in red and green. This would be because it wasn't sufficiently apochromatic. However, the blue bloat might come from a failure of the filters to block she shortest blue wavelengths as they approach the UV. Or bloat might arise from a combination of the two.

I think the ED80 might be an awfully big scope to put on the guide scope carrier. You really do need a rigid attachment of the slave scope. This would be a lot better. https://www.firstlightoptics.com/misc/jtd-dual-rig-telescope-alignment-saddle.html  I know it's expensive but our Cassady cost nearly twice that second hand!

Olly

My original plan is well out of the window now as I bought an esprit 100 so definitely need something alot stronger than a guide scope mount.

Thanks for the explanation.

35 minutes ago, shirva said:

What about a mini guide scope,, orion mini for example 

I think you're missing my point of this thread. I was asking if CA would be an issue when using a mono camera and if it would matter if the 2nd scope used FPL-51 glass.

Until very recently I used both colour and mono cameras with the 183 sensor (albeit the QHY version and not ASI). Yes there is amp glow on the right hand side but it's always calibrated out for me. Luminance and narrowband I used 300 second exposures and RGB varied from 30 to 300 second exposures with mono. Almost always 300 second exposures with osc.

This thread shows my early attempts with the osc and here is a couple images taken in mono.

43 minutes ago, shirva said:

I  don't get your meaning,,,  twin scopes,, would require double saddle or stacked scopes,,  a second dovetail fitted to the top of first scopes  mount rings.. Is usually the way to go, 

That is my plan, but the 2nd scope will need to be aligned so it is pointing to the same place as my main scope. I already have a skywatcher guide scope mount for alignment, but skywatcher haven't said how much weight it can carry without any slippage. I could just use a standard dual saddle but that would result in a big crop after image integration.

Here is my main imaging scope, guide scope and the guide scope mount waiting to be filled.

2 hours ago, SamAndrew said:

If you're only shooting colour with a mono camera, then you can refocus for each colour, so colour correction is no longer important (although field flatness is still important) 

I did think that but I wasn't 100% sure hence me asking. Thank you.

1 hour ago, shirva said:

Skywatcher evostar ed80 and 0.85 reducer 

That was a consideration but I think it'd be too heavy for the skywatcher guide scope mount.

Hi

I've almost got all the pieces for a dual rig apart from a 2nd scope. I've been holding out for an esprit 80 but they're very rare on the 2nd hand market which has got me thinking of other potential scopes for the job.

My main imaging scope is a William optics flt98 carbon fiber OTA with 0.8 flattener, sx filter wheel, astrodon filters and a qhy183mm. I have a ASI zwo 183mm and zwo mini filter wheel which will be connected to my 2nd scope mounted on a skywatcher guide scope mount for alignment which is why I need a smaller slave scope, hence thinking of the esprit 80.

I've been wanting a triplet to reduce CA but then I thought, is CA mainly due to blue bloating? Could I get a doublet but keep the blue filter in my flt98 and almost eliminate the ca that way?

Another question I have is does glass matter? I know FPL-53 glass is superior to FPL-51 but does it matter as I'm only collecting colour data and all the detail will be collected with my main scope?

Is there anything else I should be thinking of? Or maybe suggestions of potential scopes?

I'd put my money towards a second hand heq5 or you might get lucky and manage to find an neq6

I remember having this problem before myself but I cannot remember how I fixed it. I think I had a box ticked that I shouldn't have.

I know this isn't much help but at least you know it's not your camera

Everything looks the way it should do. Now a test under the stars will tell you if you've got your spacing correct.

Do you dither during your imaging sessions?

A very nice composite you have there.

If your camera is unmodified then you'll really struggle to get an image like the one you posted.

Clouds

17 minutes ago, StamosP said:

Round stars everywhere in the field...

That shouldn't be a problem as long as you can eliminate all of the tilt.

This is a 2 pane mosaic I did. I still have slight tilt on the left which I need to eliminate

1 hour ago, StamosP said:

Hello all!

Has anyone tried combining the lens with an 183 camera?

I've tried 5 samples so far and i haven't found one performing as i would like. I know that this specific chip is very demanding due to the very small pixels (even though the chip's size is small) and it would be very helpful to know if i'm expecting too much...

What are you expecting? I've use this lens with a qhy183c

How about a 600d? You'll have change of your £400 

My guess would be walking noise. There may o ly be a slight drift between your first and last sub, but your light pollution ect would have moved alot further during your imaging session 

5 hours ago, Chris Wright said:

Now there is another good reason! As well as my modded Canon 600D I also have an Altair Astro 183M pro with RGB+Ha+OIII filters and have data across both camera options for a few targets. I can start combining that data! Thank you very much for the heads-up!

Yes it is very good at combining data. 

This is a mix from an atik 383L on a william optics star 71 (very widefield) and my qhy183m and William optics flt 98 (not very widefield).

App done this with minimal effort. 

I believe there is a problem with light leakage in your calibration frames, namely your flats.

Here is your master flat stretched

You should be able to get something decent. This is a single shot using the kit lens on my Canon 600d iso 800 10 second exposure.

I was actually lucky enough to catch a meteor too. 

So my light bulbs need tin foil hats too now

My set is finally complete. 

1 hour ago, ApophisAstros said:

QHY183c and a selection og spacers,

Looks like i am doing a Dark library until the weekend.

Roger

I have this camera and the mono version. Very happy with them, you'll need an ir/uv cut filter. 

That is incredible. Will you do a mosaic of the entire veil complex like that? 

19 minutes ago, Craney said:

I am so glad you said that.   I've been trying to wrestle the Squid out of the clutches of darkness for the last 2 weeks.

Even resorting to 10min subs for Oiii ...... unheard of !!!   

I may try a few more (short) nights and do a massive collective stack in APP.

This is the best I got in Oxygen..

This is 3 hours of 600s subs.  (Atik 414ex   which is an amazingly sensitive camera).

 

Its definitely there, you just need more data. 

Is that a pure O111 image? What are you using for stacking? 

I only ask because you've got coloured noise in what should be a mono image.