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What do I need to get smaller galaxies and nebula?


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I have a C5 sct a ED80 and a RCT 8" f/8, I also use a canon 600da and a asi120 as a guide scope and I wish to photograph as many objects in the sky as my setup would allow. I've been doing 10-20 3min subs on each object and the weather has been kind enough recently so I have a fair bit now but I'm running out of the bigger ones. The obvious method is just cropping in processing but that would give less detail, a good example of the perfect size is crescent nebula. A bad example is basically anything that takes up less than 10% of the picture like the box galaxy cluster, eskimo nebula, fetus, snowball, cat's eye etc. I tried a 2x barlow on my rct but I need so many extension tubes that it would cause many problems, maybe a dedicated CCD camera will have a shorter fov?

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Bigger aperture telescope with longer focal length (hope f number stays low). Better camera (dedicated astro CCD - can crop to smaller targets without losing too much detail). Better guide camera to deal with longer focal length telescope. Better mount to handle the increased payload. Lots of moonless, cloudless, windless skies and a very big wallet to pay for it all!!!! 

If I was to upgrade to achieve better imaging smaller DSO's then I would consider:

SW250PDS reflector telescope. EQ6-R Mount (belt driven). ASI2600MC camera (or ASI1600 at least). But up to you on OSC or Mono(+filter) cameras.

Can't think of a guide camera (can anyone else suggest one for the above).

Consider RORO Observatory??

That's off the top of my head for the main components.

Gerr.

 

 

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45 minutes ago, Gerr said:

If I was to upgrade to achieve better imaging smaller DSO's then I would consider:

SW250PDS reflector telescope. EQ6-R Mount (belt driven). ASI2600MC camera (or ASI1600 at least). But up to you on OSC or Mono(+filter) cameras.

I have an eq6 pro, i am currently deciding whether or not to upgrade to the rowan belt mod as every other image I take is unusable

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3 hours ago, Quetzalcoatl72 said:

I've been doing 10-20 3min subs on each object

I suppose it depends on what you are trying to achieve, but 30-60 minutes total integration time doesn’t seem very long for each image?

 

1 hour ago, Quetzalcoatl72 said:

i am currently deciding whether or not to upgrade to the rowan belt mod as every other image I take is unusable

This doesn’t seems right. I had an EQ6 pro and it really didn’t drop any subs due to the mount itself, but depending on the load, the wind would have an effect. 300s-600s were my normal duration.  I did the rowan belt and this improved the mount a little, reducing backlash etc. But I wouldn’t do the mod until you have worked out why you are losing 50% of your subs.

1 hour ago, Gerr said:

SW250PDS reflector telescope. EQ6-R Mount (belt driven).

Unless it’s calm, there is a good chance you will lose quite a few subs, been there done that, but in the dome it’s perfect.  The image scale is pretty low at 0.64”/px, not sure how the EQ6 would work out. But I love my SW250, it’s my galaxy imaging scope. 

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From what I read from the experienced guys on this forum, going below 1"/px is a waste of time for most people (with typical skies) as the seeing just will not allow you to use a resolution that high most of the time (or ever?!)

From what I found online, the pixels in your current camera are 4.3um, which gives you a sampling rate of 0.55"/px with the RC8 at native FL, which is already a very high sampling rate - it is unlikely the atmosphere will allow you to make full use of this resolution.

You may therefore consider binning your data in post; I'm not sure how easy this is to do with DSLR/OSC data as I'm strictly a mono+filters guy, but I'm sure others on here can advise. In an oversampled image, binning is preferable to just cropping away as it will increase your SNR - if you were to bin your images x2, this would take your resolution to 1.1"/px, which would probably be a good sampling rate.

The next thing you could do to improve your images would simply be more integration time. I've recently been using this online calculator to help me decide how long to spend on various targets, which I've found really useful: https://snrcalc.vercel.app/home

If you were interested in purchasing some new equipment, then I'd suggest a dedicated astro camera - l think this would give you a bigger benefit than a new scope, but happy to be corrected by anyone more knowledgeable than myself in this regard. In terms of which camera, well, that's a whole other thread in itself! 😉

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7 hours ago, tooth_dr said:

I suppose it depends on what you are trying to achieve, but 30-60 minutes total integration time doesn’t seem very long for each image?

 

This doesn’t seems right. I had an EQ6 pro and it really didn’t drop any subs due to the mount itself, but depending on the load, the wind would have an effect. 300s-600s were my normal duration.  I did the rowan belt and this improved the mount a little, reducing backlash etc. But I wouldn’t do the mod until you have worked out why you are losing 50% of your subs.

Unless it’s calm, there is a good chance you will lose quite a few subs, been there done that, but in the dome it’s perfect.  The image scale is pretty low at 0.64”/px, not sure how the EQ6 would work out. But I love my SW250, it’s my galaxy imaging scope. 

I'm pretty sure it's the gears, i can hear coffee grinding and knocking, the image wobbles pretty bad on rate 2*, second idea is the ground, it's not very stable. Waiting for a dry day without aclear night so i can fill 3 large holes full of cement and gravel in my garden as it would e much better than what i have atm. 

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