Scope for more Galaxy imaging resolution?

[Notty]

I currently run an ED80 ds pro on an HEQ5, and although the ED80 is fine for wider field images obviously for galaxy season it's not ideal. I used to have a 200PDS reflector which (when collimated) gave a nice resolution, but was too large and heavy and the mount struggled a bit (and I hated the whole collimation faff).

My question is if anyone could recommend any other non-reflector type of scope my mount might be able to handle? Or maybe it doesn't exist but thought I'd ask. I image with ASI1600m+filters or unmodded EOS6D

thanks, Andy

Edited April 22, 2020 by Notty

[Skyline]

Certainly a longer focal length scope. What camera and mount will you be using?

Edited April 22, 2020 by Skyline

[Notty]

18 minutes ago, Skyline said:

Certainly a longer focal length scope. What camera and mount will you be using?

Thank for the reply, I'd realised I'd omitted my cameras, asi1600+fw or eos6d. Mount is an heq5. I'd assumed any larger refractors would be too heavy for my little mount?

[Skyline]

I am currently using a celestron 100ed with a tsred279 reducer which brings the scope down to f7.1 coupled with the ASI294MC Pro with my heq5 pro.

You can easily run something like a 6" f5 newt with other imaging kit on the heq5.

I think having anything above a 6" reflector without modifications to your mount is overkill IMO.

Another option is to use a camera with a smaller chip, like a Atik 314L+, ideally the more longer focal length with this camera, the better resolution. 

Edited April 22, 2020 by Skyline

[Notty]

Thanks, yeah as I said I used to have the 200PDS newt (which I think was f5) but it wouldn't hold collimation and caused me violent thoughts and words so I promised myself I'd not get another newt.

[Skyline]

RC scopes are all used for galaxy imaging, but for ease of use my own preference would be a long focal length refractor or a smaller camera chip.

[Skyline]

Since you have the filter wheel and filters, you be amazed at the images of what a mono 314 camera results give with your ed80 for galaxies.

314's are in the region of £500 s/h or cheaper.

[stevewanstall]

I was in a similar position to you and ended up buying a Celestron XLT 9.25 F10 (yes, I appreciate its a reflector but its a BIT smaller than a 200mm newtonian!). I also bought the focal reducer but with 'galaxy season' in full play, haven't used it much. I have been very pleased with the images taken (Canon 500D and recently a ZWO ASI1600 MM.  The images I have published on here havent been cropped much , usually just on the edges to remove overlaps, so they will give you an idea of the FOV. There is a lot more info on my equipment and set up  on my   (b)log page. 

[DaveS]

I think that for galaxy imaging you will need a better mount than an HEQ5 unless you're going for bigger targets or galaxy groups (Leo Triplet, Markarian's Chain). If you want FL *and* a refractor then the moment arm becomes an issue, especially when you hit the 1 metre range.

[ollypenrice]

7 hours ago, Skyline said:

RC scopes are all used for galaxy imaging, but for ease of use my own preference would be a long focal length refractor or a smaller camera chip.

No, a smaller chip just reduces the field of view. It has nothing whatever to do with increasing the resolution (also known as 'getting closer' or 'capturing more detail.') What you need are smaller pixels so that more of them lie under the projected image of the object. When shown at full size (1 camera pixel given 1 screen pixel) this will give you a larger object image on your screen.

8 hours ago, Notty said:

I currently run an ED80 ds pro on an HEQ5, and although the ED80 is fine for wider field images obviously for galaxy season it's not ideal. I used to have a 200PDS reflector which (when collimated) gave a nice resolution, but was too large and heavy and the mount struggled a bit (and I hated the whole collimation faff).

My question is if anyone could recommend any other non-reflector type of scope my mount might be able to handle? Or maybe it doesn't exist but thought I'd ask. I image with ASI1600m+filters or unmodded EOS6D

thanks, Andy

I would begin by thinking about resolution in arcseconds per pixel. Anything less than 1"PP is probably going to be unrealistic since it will be lost to seeing and guiding problems. Your ASI has much smaller pixels than your Canon. As things stand you're at about 1.3"PP in the ASI and about 2.2"PP in the Canon. If you binned the ASI 2x2 it would be close enough in effective pixel size for either camera to work in the same scope. If you don't bin the ASI there is no one scope which can work with both cameras at longer focal length. Your first decision would be which camera to choose.

To be honest you're not at a bad resolution already with the ASI. There will be plenty of nights when the seeing won't support more resolution than you have already. However, a little more focal length and aperture might be nice. Just don't overdo the focal length. I'd be looking for something that would take the ASI to about an arcsec per pixel. There's a calculator on FLO's website. When less experienced imagers discuss mounts they jump straight to payload. That does have to be respected but, most of the time, accuracy is a bigger issue. Your guide RMS in arcsecs needs to be no more than half your image scale in "PP. (Give PHD your guide cam pixel size and guidescope focal length and it will automatically give you your RMS in arcseconds.)

Olly

[Skyline]

28 minutes ago, ollypenrice said:

No, a smaller chip just reduces the field of view. It has nothing whatever to do with increasing the resolution (also known as 'getting closer' or 'capturing more detail.') What you need are smaller pixels so that more of them lie under the projected image of the object. When shown at full size (1 camera pixel given 1 screen pixel) this will give you a larger object image on your screen.

Olly

Yes you are correct Olly, it does mean you just reduce the field of view, I can see now what you mean by using smaller pixels.

Nadeem

[tomato]

I don’t know what your budget for the refractor is, but an Altair 102 F7 APO would give you 1.09 arcsec per pixel with the ASI 1600 and I’ve imaged with this scope on a belt modded HEQ5 guiding at 0.7 arcsec total RMS on a temporary set up.

[Notty]

Why thank you everybody for the tips and info I’d not thought so much in terms of arc seconds/pixel. I’ll have a look at the Altair 102 as well.

[discardedastro]

On the 200P, something like an ASI183MM with considerably smaller pixels will undersample (e.g. 0.5"/px on my setup) which imho is ideal for detailed imaging of galaxies, but Olly is right that actually using this requires perfect seeing and guiding which rarely happens - I guide around 0.8"/px and seeing is of course usually worse. But I find it works well for me overall.

[Lostone]

On 21/04/2020 at 23:56, Notty said:

I currently run an ED80 ds pro on an HEQ5, and although the ED80 is fine for wider field images obviously for galaxy season it's not ideal. I used to have a 200PDS reflector which (when collimated) gave a nice resolution, but was too large and heavy and the mount struggled a bit (and I hated the whole collimation faff).

My question is if anyone could recommend any other non-reflector type of scope my mount might be able to handle? Or maybe it doesn't exist but thought I'd ask. I image with ASI1600m+filters or unmodded EOS6D

thanks, Andy

I am currently using a Sky Watcher 120ED on a EQ6-R mount.  One thing you should be looking at is, how much weight can your mount handle and how much will the new configuration weight.  If weight is an Issue, I'd recomend one of the Carbon Fiber scopes.  Explorer Scientific has a dicent priced 102ED.