11 replies to this topic

[Flasheart]

Guys,

 

after several months of researching, I took the advice to get the best mount possible for your budget, before getting a telescope.  So I now have a Losmandy G11G with Gemini 2 system and heavy tripod. I like Scott Losmandy’s philosophy on building a mechanically precise system.

 

 I also have a very good camera - Canon EOS 5D Mark IV, not modified. I also have an older Canon EOS 60D that could be modified. Or is it better to get a purpose built Astro camera?

 

i want to do astrophotography, and visual, so maybe two different scopes.  And I would like to get it roughly right the first time rather than start cheap and work up.  I will be using this setup for many years.

 

Some questions on the mount - is the $300 illuminated polar alignment scope worth the investment?  What other add-ons recommended for the mount?

 

For the scope I have been looking at APO triplet refractors for astrophotography.  Astronomics has some great deals this month on Explore Scientific.  Any downside to going big with the FCD 100 127mm CF?   I know it is long focal ratio. Visual and astrophotography capable?

 

What about DSOs?  Any advice on selecting an OTA for DSO would be appreciated. 

 

 

 

[Mike W]

Get a Televue NP101is. (f5.4 flat field)

Edited by Mike W, 14 August 2019 - 09:19 PM.

[astro_1]

I think you would be happier with a pole master setup instead of the polar scope, assuming you would be carrying a laptop with you anyway for AP work.

[mlrtime99]

+1 on the pole master.  You'll be double and triple checking enough stuff if you're getting into astrophotography and the pole master "just works"

[scadvice]

+2 PoleMaster makes life so much easier.

[John Fitzgerald]

The ES scopes are fine.  I have one of their ED152 apo refractors on a G11.  Their ED80 is great also.   The Astrotech scopes are also highly recommended.

 

Can you give your location?  You might be within driving distance of a place you could pick one up and avoid the shipping hassle.

[scadvice]

When considering a refractor I think you need to look at what you want to image. You can do this by comparing the different scopes with flatteners and flattener/reducers. Larger aperture scopes put more photons on the camera faster but they also present more guiding problems along with the  higher cost.

 

I suggest using these tools below to help you in deciding what scope and F ratio to purchase but in general look to get as close as you can to an F/5 for DSO’s  like nebulas. F/7 IMHO is the highest ‘F’ ratio for beginner imagers (like me)and it can be a challenge starting out.

 

 

https://astronomy.to.../field_of_view/

 

or

 

http://www.blackwate...maging-toolbox/

 

Both are great tools…

 

I started out with a 81mm William Optic’s GTF with a built in flattener at F/5.6. I recently up scaled to a Stellarvue SVA130mmT at F/7 and I bought two flatteners. The first does not reduce the F stop but keeps it at F/7 great for galaxies, clusters and smaller DSO objects. The second flattener acquired is also a reducer.  That brings the F ratio down to F/5.1 for wider field objects like M31 and nebula fields.

 

For me it was the best option for a little of both worlds in one scope.

 

Others approach it differently than did by have more than one scope.

 

The most common approach for apochromatic triplets and the doublets is a flattener/reducer.

 

Example…and I’m just using a scope I know for the example (Nice scope though)

 

When buying a Stellarvue SVX102T your F ratio is F/7. For astrophotography you will want a field flattener. You have two options… leave the F/ratio at F/7 by just getting the standard flattener.  Or ... Flatten and reduce the field by x .74 to about F/5.2. Obviously you could buy both as I did for mine.

 

Other brands of scopes your going have to call the manufacturers or dealers to see what flatteners and flattener/reducers are available.

 

Just punch these number into one of the programs above add a DSO and see what is in the field.

Edited by scadvice, 14 August 2019 - 11:34 PM.

[tross]

On my G11, I'm using a Celestron 9.25 with a Stellarvue 80mm triplitt on top for both visual and AP .

 

I also have a SV130mm APO as well for AP and visual

 

Seeing that your mount is a recent one, did it come with the RAEX kit pre installed?

 

You might want to purchase some extra weights. Some times they come up used on the Classified or on other sites.

 

I keep mine covered with the Telegizmo 365 cover and then put another tarp over that.

[Rovert9988]

Another vote for a Polemaster. It will be more accurate than a polar scope and is very easy to use. Well worth it.

[Flasheart]

I am very grateful for the level of information the members contribute.  Definitely no one-word answers here. 

 

I am now sold on the Polestar system, which looks like it will bolt right into the G11G mount.

 

Have not decided on the first telescope yet. 4" or 5" Refractor? Would the Explore Scientific FCD100 options currently on sale be smart? 

 

What about the Celestron Edge 9.25" which is also on sale? Or the Skywatcher Maksutovs that seem to deliver fantastic DSO images  

 

Auto guider camera and guidescope? Do I need them?

[denny-o]

Couple of issues here.

The PoleMaster is a good idea. Without it, or something similar for making alignment easier, you are likely to get discouraged with AP and quit. And yes, the day will come where you can align to the pole almost in your sleep and will scoff at those "Needing" electronic aids.

You do not want to start out for AP with an SCT or other long focus scope - period. (Like the old maps say,  Here There Be Dragons )

The ES scopes have a good reputation and you could do worse.

Now, focal length of the imaging scope becomes critical as to what equipment you may need/want. Up to roughly 300mm focal length you can get by unguided for short subs. Use that with your DSLR and have fun learning AP ( lots of software you have to learn at first so make it easy on yourself)

Anything much longer in focal length and you will need a guide camera/scope (50mm or 60mm will do nicely - and you will be wanting to guide quite soon anyway so you can take longer subs)

Were I starting where you are I would get a 70mm or 80mm, F5 to F7 scope. For AP a bigger scope is not the improvement you think it will be. And the short scope will do nicely for large objects. The short scope will allow you to do large nebulae and galaxies that a 900mm, or longer, scope will have issues with framing the object. The short scope will do nicely for visual for now.

By the time you are ready to dive into a DSO scope you will have a far better idea of what you want/need.

stick to CMOS cameras.  Used equipment is a good idea for starting out - assuming you will ask the opinion of the folks on the imaging forum on here before spending the money.

You did make an excellent decision on the mount. Try to keep it going and not let enthusiasm steer you off into the weeds.

[denny-o]

Um, I just took a look at that line of ES refractors. They are not APO which may affect your choice for photography. (shrug)  I'm not going to do a dissertation on that. And, you will need/want a field flattener for AP.