sorry for the countless questions advise over ccd and worth the cosr

[Wirral man]

6 hours ago, kens said:

Its a complex pursuit so getting the right balance between all the components, including your wallet, is difficult.

If you are interested in narrowband (a good idea under light pollution) then a cooled camera is pretty much a given. In cooled cameras the difference between ZWO and QHY is pretty minimal on cost/performance. Within each brand, for their cooled cameras, the main cost driver is the size of the sensor. There is not much difference in raw performance.

So you are mainly constrained on sensor size by your budget and that in turn determines the size of target you can image. Let's ignore mosaicing for now. Many of the best targets for narrowband, tend to be on the large side. In my sky, Tarantula nebula is 40 arcmin across, eta Carinae is 120 arcmin across. Sara's image was taken with a 328mm FL and a sensor with a 22.5mm diagonal so that gives just under 4 degrees! You've got a 600mm FL OTA and with the ASI178 at 9mm on the diagonal you can get 50 arcmin. With a 0.8x reducer, say, that could become 62 arcmin. The ASI183 is almost 16mm on the diagonal and the ASI1600 is bigger again at 22mm so they can fit correspondingly larger targets.

So you can see that you are paying to get ever larger targets. 50 to 60 arcmin will get you a good selection of narrowband targets. You can check if you can image your favoured targets.

In terms of narrowband filters, Ha is the most useful. If I were in your boots I'd get a set of LRGB (or even just RGB) and a Ha to start with. For the Ha filter aim for the narrowest you can get. Baader has a 7nm filter (I use Astronomik 6nm). With that set you can do regular RGB imaging on galaxies, globs etc and for the Ha targets you can use Ha alone for a B&W image or use it as luminance and red and add colour with G and B. Or you can play around with various combinations - there are no strict rules. 

Looking at the FLO website: The ASI178MM-Cool is GBP637. The manual filterwheel is GBP65. A set of Baader LRGB filters GBP211 and a Baader 7nm Ha filter is GBP 103. That comes to GBP1016 and the only thing that the DSLR beats it on is the field of view. If you can afford more, get a bigger sensor.

You might want to ask around about filters. Astrodon are regarded as the best but pricey. Astronomik are well regarded and mid-priced and I use the full set. I've not heard much about Baader other than that they are comparable to Astronomik. Some people are happy with the ZWO filters and Optolong but I've heard mixed reports. I have a set of ZWO LRGB on my "backup" rig. 

 

 

 

 

if i got the lrgb and a ha filter what would i do about light pollution the target i have always wanted to image is the horsehead nebula?

also based on fov i might take the plunge for the asi1600mm pro its a big outlay but will last me years hopefully 

[kens]

The narrowband filter gets rid of the light pollution. Light pollution is generally broadband so it covers much of the visible spectrum - some 300nm of bandwidth

So a 7nm narrow band filter will only catch around 7/300 of the light pollution. But the horsehead is strong in Ha so you'll pick up a large part of the photons from that. The result is a high contrast image. (For the pedants, the Horsehead itself is a dark nebula and the surrounding Orion Complex has the Ha signature). 

You can either stick with just the B&W image from the Ha filter or use it as the luminance and red channels combined with regular green and blue channels to make up the LRGB. Luminance is the channel that provides the detail so the extra light pollution in G and B channels will be masked. The alternative is to go the whole hog with OIII and SII filters but that starts to become expensive. If its a choice between the extra narrowband filters and a larger sensor I think you'd be happier with the larger sensor.

One caution though on the camera is don't overstretch yourself financially. Cameras can and do fail especially under the sorts of conditions we use them. Moisture and corrosion are problems and dropping things in the dark is always a risk. But with due care they should last quite a few years. On the plus side they don't have a heavy duty cycle - especially with all the cloud about. I've had my Atik420 for over 3 years with only one repair under warranty (fan bearing failure) and my ASI1600 has been going about 18 months with no issues.

[carastro]

Wirral Man, pleased to hear you have got/are getting a mono camera.

A manual filterwheel works fine, especially if you are going to do one filter per evening.  Where I found it a chore was trying to change the filterwheel during the same evening when I didn't want to move off the target, and often the scope would be angled in such a way that I couldn't see what filter I was choosing without some cortortions - even on one occasion lying flat on my back in the obsy (thank goodness it wasn't out in the open), with a torch trying to see the bit of the filterwheel where the filter was labelled).  

You do need to check the focus when you change filters, though what i tend to do (though some people would frown on it), is check the focus on all filters before I start and make a note if any does not appear to be par focal.  That way i can collect data from the matching filters without stopping to refocus.

Yes use the Ha, Oiii and Sii as the RGB channels.  they can also be used for the Hubble pallette as Sii Ha Oiii (Sii being in the red channel, Ha in the Green channel and Oiii in the blue channel), you'll need to tweak the colours a bit as the Green (Ha) will be a bit overwheming.

 

Quote

lrgb and a ha filter what would i do about light pollution the target i have always wanted to image is the horsehead nebula?

 Take a look at my recent Horsehead done from SE London, I used Ha as the luminance channel + RGB.  

https://www.astrobin.com/327655/C/?nc=user

Best of luck, and any problems we are always here.

Carole 

[Wirral man]

43 minutes ago, kens said:

The narrowband filter gets rid of the light pollution. Light pollution is generally broadband so it covers much of the visible spectrum - some 300nm of bandwidth

So a 7nm narrow band filter will only catch around 7/300 of the light pollution. But the horsehead is strong in Ha so you'll pick up a large part of the photons from that. The result is a high contrast image. (For the pedants, the Horsehead itself is a dark nebula and the surrounding Orion Complex has the Ha signature). 

You can either stick with just the B&W image from the Ha filter or use it as the luminance and red channels combined with regular green and blue channels to make up the LRGB. Luminance is the channel that provides the detail so the extra light pollution in G and B channels will be masked. The alternative is to go the whole hog with OIII and SII filters but that starts to become expensive. If its a choice between the extra narrowband filters and a larger sensor I think you'd be happier with the larger sensor.

One caution though on the camera is don't overstretch yourself financially. Cameras can and do fail especially under the sorts of conditions we use them. Moisture and corrosion are problems and dropping things in the dark is always a risk. But with due care they should last quite a few years. On the plus side they don't have a heavy duty cycle - especially with all the cloud about. I've had my Atik420 for over 3 years with only one repair under warranty (fan bearing failure) and my ASI1600 has been going about 18 months with no issues.

thanks your a wealth of information im  going to follow you thanks for the help

[Wirral man]

36 minutes ago, carastro said:

Wirral Man, pleased to hear you have got/are getting a mono camera.

A manual filterwheel works fine, especially if you are going to do one filter per evening.  Where I found it a chore was trying to change the filterwheel during the same evening when I didn't want to move off the target, and often the scope would be angled in such a way that I couldn't see what filter I was choosing without some cortortions - even on one occasion lying flat on my back in the obsy (thank goodness it wasn't out in the open), with a torch trying to see the bit of the filterwheel where the filter was labelled).  

You do need to check the focus when you change filters, though what i tend to do (though some people would frown on it), is check the focus on all filters before I start and make a note if any does not appear to be par focal.  That way i can collect data from the matching filters without stopping to refocus.

Yes use the Ha, Oiii and Sii as the RGB channels.  they can also be used for the Hubble pallette as Sii Ha Oiii (Sii being in the red channel, Ha in the Green channel and Oiii in the blue channel), you'll need to tweak the colours a bit as the Green (Ha) will be a bit overwheming.

 

 Take a look at my recent Horsehead done from SE London, I used Ha as the luminance channel + RGB.  

https://www.astrobin.com/327655/C/?nc=user

Best of luck, and any problems we are always here.

Carole 

wow great image i will be following tou aswell thanks for the info 

 i see you use a atik460ex will the asi1600mm be close as yours for quality as its double the price nearly

[Wirral man]

also forgot to ask do i use 1"25 filters?

2 hours ago, carastro said:

Wirral Man, pleased to hear you have got/are getting a mono camera.

A manual filterwheel works fine, especially if you are going to do one filter per evening.  Where I found it a chore was trying to change the filterwheel during the same evening when I didn't want to move off the target, and often the scope would be angled in such a way that I couldn't see what filter I was choosing without some cortortions - even on one occasion lying flat on my back in the obsy (thank goodness it wasn't out in the open), with a torch trying to see the bit of the filterwheel where the filter was labelled).  

You do need to check the focus when you change filters, though what i tend to do (though some people would frown on it), is check the focus on all filters before I start and make a note if any does not appear to be par focal.  That way i can collect data from the matching filters without stopping to refocus.

Yes use the Ha, Oiii and Sii as the RGB channels.  they can also be used for the Hubble pallette as Sii Ha Oiii (Sii being in the red channel, Ha in the Green channel and Oiii in the blue channel), you'll need to tweak the colours a bit as the Green (Ha) will be a bit overwheming.

 

 Take a look at my recent Horsehead done from SE London, I used Ha as the luminance channel + RGB.  

https://www.astrobin.com/327655/C/?nc=user

Best of luck, and any problems we are always here.

Carole 

wow great image i will be following tou aswell thanks for the info 

[kens]

1.25" filters will be fine. With the ASI1600 you might get some vignetting but it would calibrate out with flats.

[carastro]

Quote

i see you use a atik460ex will the asi1600mm be close as yours for quality as its double the price nearly

I can't answer that question as I know nothing about the ASI cameras, hopefully some-one else will know.  FOV is another question, you might find this website useful to compare cameras:

http://www.12dstring.me.uk/fovcalc.php

Or this one

https://dso-browser.com/telescope-simulator

Carole