8" SCT or 6" Maksutov or 4" APO or 6" Ritchey-Chretien?

[Analysis Paralysis]

4 hours ago, RobertI said:

I found that 'piggybacking' even a small refractor on my C8 created a surprising amount of extra 'leverage' and I needed to load up extra counterweights, putting extra load on the mount - this is not ideal for imaging especially on the smaller mounts, but ok for visual, as long as you have enough counterweights! Probably better to mount the refractor directly on the mount for imaging and keep things light and unstressed. As for doing visual through the SCT/Mak at the same time as imaging through the piggybacked refractor, I wouldn't have thought its a good idea as one touch of the scope and you have ruined an exposure, also you will have to look at the same object for hours while you are imaging. 

Some very good points, especially staring at the same object for a long time! I guess I can do some visual first then set up for the imaging. Or get a second mount... Mmm... Many things to consider, one has.

[Sp@ce_d]

54 minutes ago, Analysis Paralysis said:

Some very good points, especially staring at the same object for a long time! I guess I can do some visual first then set up for the imaging. Or get a second mount... Mmm... Many things to consider, one has.

and so the journey down that long slippery slope begins... with AP there's the "black hole" to eat up your finances to contend with as well... I've 3 mounts so far. If you can afford to it's best to keep AP & visual separate. A lot of the time if I'm actually outside imaging (I'm normally indoors, remotely imaging from my Obsy these days) I'll just use a pair of Binoculars to have a good look around, its a great way to find your way about & learn star hoping etc if you've never tried.

[michael.h.f.wilkinson]

Regarding mushy views with an SCT: I have had very sharp views with my C8, although the contrast of the image was a bit lower than with the 6" "planet killer" Newtonian at the same exit pupil. The latter is important. If I take my APM 80mm triplet APO, and stick in a 5mm XW, that gives about the same exit pupil as using the 8mm Delos in the C8 (0.83 vs 0.8). Both images have the same surface brightness, and the contrast in the 80mm is better. However, the amount of detail in the C8 is much better, as I am using 256x magnification vs 96x in 80mm. At the same magnification, the SCT provides far brighter images. CO does affect contrast, but much less resolving power. An 8" APO will give better views of course, but they cost an arm and a leg (and at least a kidney too). I have looked through some pretty good fracs (including Olly's TEC 140), and I must say that for me in planetary observing and imaging, aperture is king. The visual impact of the image in a good refractor is massive, but if you take your time getting used to the slightly more muted contrast of the SCT, you will see a lot more. For planetary imaging, the SCT is great (ask Damian Peach), although as many (apart from me) have said for DSO imaging, a short frac is clearly better, unless you are interested in small, bright targets like some planetary nebulae.

Regarding DSO observing, my SCT again hits the APM 80mm F/6 triplet for six on almost all targets, because it gathers so much more light. Only for a handful of large objects like the North America Nebula, the Andromeda Galaxy, the Double Cluster, the Pleiades and M33 does the APM 80mm shine in its role as wide-field scope. BTW, for observing wider objects in the SCT, I used to go for the 0.63x reducer, but have since abandoned that approach, and simply added a 2" visual back. With my Nagler 31T5 I get 1.25 deg true FOV, and with the Vixen LVW 42mm I can reach 1.34 deg. At those low magnifications, stars look pretty sharp to me. When using my favourite DSO observing EP, the Nagler 22T4, the views are very sharp too.

[Analysis Paralysis]

55 minutes ago, Sp@ce_d said:

and so the journey down that long slippery slope begins... with AP there's the "black hole" to eat up your finances to contend with as well... I've 3 mounts so far. If you can afford to it's best to keep AP & visual separate. A lot of the time if I'm actually outside imaging (I'm normally indoors, remotely imaging from my Obsy these days) I'll just use a pair of Binoculars to have a good look around, its a great way to find your way about & learn star hoping etc if you've never tried.

Yes. I can feel my feet sliding down that slope. Resistance is futile. Any suggestions on the cheapest goto tracking mount for a 180 mm mak? Please don't say heq5, as I still need to buy that for the astrophotography, and can not afford/justify a second one. 

[rocambol]

On 1/5/2018 at 17:38, michael.h.f.wilkinson said:

Regarding DSO observing, my SCT again hits the APM 80mm F/6 triplet for six on almost all targets, because it gathers so much more light. Only for a handful of large objects like the North America Nebula, the Andromeda Galaxy, the Double Cluster, the Pleiades and M33 does the APM 80mm shine in its role as wide-field scope. BTW, for observing wider objects in the SCT, I used to go for the 0.63x reducer, but have since abandoned that approach, and simply added a 2" visual back. With my Nagler 31T5 I get 1.25 deg true FOV, and with the Vixen LVW 42mm I can reach 1.34 deg. At those low magnifications, stars look pretty sharp to me. When using my favourite DSO observing EP, the Nagler 22T4, the views are very sharp too.

You mean adding 2" eyepiece?

What about adding 2" eyepiece+ a reducer? will it give the maximum performance?

[rocambol]

On 1/5/2018 at 17:46, Analysis Paralysis said:

Yes. I can feel my feet sliding down that slope. Resistance is futile. Any suggestions on the cheapest goto tracking mount for a 180 mm mak? Please don't say heq5, as I still need to buy that for the astrophotography, and can not afford/justify a second one. 

I think this is what you ask for:

https://www.amazon.com/dp/B013TPZEAI/_encoding=UTF8?coliid=I29O1L0VVPYLRE&colid=2VS4T2535WNG1&psc=0

[25585]

Don't know if reducers for Maks are made, or cheaply enough.

Choosing a SCT will open up fork mount options if you go for Meade or Celestron. SCTs are better general purpose scopes, and there is a big 2nd hand market of gear and accessories for them.

[Louis D]

On 1/6/2018 at 14:11, rocambol said:

You mean adding 2" eyepiece?

What about adding 2" eyepiece+ a reducer? will it give the maximum performance?

Based on many CN/SGL reports of using an SCT reducer + 2" visual back combination on an SCT, you'll certainly gets lots of vignetting with a Mak as well.  This assumes you can find an appropriate focal reducer for a Mak.

[RT65CB-SWL]

20 hours ago, 25585 said:

Don't know if reducers for Maks are made, or cheaply enough.

Choosing a SCT will open up fork mount options if you go for Meade or Celestron. SCTs are better general purpose scopes, and there is a big 2nd hand market of gear and accessories for them.

Here is my 're-modded' Meade ETX105 with a Celestron 0.63 focal reducer/flattener and a 1.25" visual back. I have not done any comparisons as to whether it does work or not, though it does focus when using 1.25" low to medium power eyepieces on terrestrial targets.

At present I use it as a spacer so I can use my 2" SCT Crayford focusser, (not shown), as the locking ring/collar is close to the ETX focusser when attached. It is not necessary as a spacer when using my 2" SCT star diagonal.

[25585]

Got a x0.63 for my C8. Optical function aside it is a protection for the tube's interior.

Could such as that be made suitable for Maks with other rings or optics?

[Louis D]

2 hours ago, 25585 said:

Got a x0.63 for my C8. Optical function aside it is a protection for the tube's interior.

Could such as that be made suitable for Maks with other rings or optics?

GSO used to make such a tube protection filter: Skylight Filter for SCT, but it has reportedly been discontinued.  If you have SCT threads on the back of your Mak, and you could find one in stock or used, it would probably work.

[The Admiral]

There is a discussion on collimation of RC scopes in the latest video from the Astro Imaging Channel. I've no experience of doing it, and frankly, by the sound of it, nor would I want to. Probably worth a quick check-out to at least appreciate the potential issues involved with this class of advanced instrument.

Ian