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Change from DOB to EQ mount or get an astrocamera?

EQ Dob Beginner Astrophotography
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#1 pahgo

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Posted 18 September 2021 - 10:58 AM

Hi there!

 

So I got my first scope, a big and beautiful SkyWatcher 8'' Dobsonian (203/1200). I've been taking some pictures of the moon and the big planets with my phone (on a holder) and also tried to get some Messier objects and there comes my bit of frustration. I love to look at the eyepiece but, the feeling of getting a sharp image of an object is way better, I guess I am more into AstroPhotography than I am into just looking at the EP. At first I thought of getting an astrocamera but then thought, how long is the maximum exposure I can take without tracking? I think the number is 500/1200=0.416s for my case, is that right? There's not much that can be done with 0.416s exposures! and manually keeping the object in place... 

 

Therefore, I first need to upgrade my mount to a tracking one. Being my purpose to do AP, getting an Alt/az tracking mount would not make much sense, would it?

 

One thing I did not consider when getting my scope is its weight. Just the scope, with no attachments, sits at 11kg (24lb).

 

So my questions are...

  1. Where do I go from here? Camera or mount first? 
  2. If camera, Skywatcher newtonians don't need a new focuser, right? (please say no) Which camera would you choose with a 300/400€ (350/470$) budget? and with a more flexible budget?
  3. If as I believe mount comes first, which one? Looking at the prices I am truly scared of this new hobby, what's the minimum you would put that scope on top of (for AP)? 

 

Many many thanks for reading me so far! Looking forward for answers! 



#2 Henry Decker

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Posted 18 September 2021 - 12:22 PM

Hi there!

 

So I got my first scope, a big and beautiful SkyWatcher 8'' Dobsonian (203/1200). I've been taking some pictures of the moon and the big planets with my phone (on a holder) and also tried to get some Messier objects and there comes my bit of frustration. I love to look at the eyepiece but, the feeling of getting a sharp image of an object is way better, I guess I am more into AstroPhotography than I am into just looking at the EP. At first I thought of getting an astrocamera but then thought, how long is the maximum exposure I can take without tracking? I think the number is 500/1200=0.416s for my case, is that right? There's not much that can be done with 0.416s exposures! and manually keeping the object in place... 

 

Therefore, I first need to upgrade my mount to a tracking one. Being my purpose to do AP, getting an Alt/az tracking mount would not make much sense, would it?

 

One thing I did not consider when getting my scope is its weight. Just the scope, with no attachments, sits at 11kg (24lb).

 

So my questions are...

  1. Where do I go from here? Camera or mount first? 
  2. If camera, Skywatcher newtonians don't need a new focuser, right? (please say no) Which camera would you choose with a 300/400€ (350/470$) budget? and with a more flexible budget?
  3. If as I believe mount comes first, which one? Looking at the prices I am truly scared of this new hobby, what's the minimum you would put that scope on top of (for AP)? 

 

Many many thanks for reading me so far! Looking forward for answers! 

Do you have a DSLR? The 1.25" adapter on the skywatcher dob has a t-thread built in, and I have been able to get my DSLR into focus without much of an issue before. 

 

As for a mount the EQ6-R Pro has a payload capacity of about 18kg (~40lbs) So it could attach to there, but you would need tube rings, and the weight and length of the scope might be pushing that mount to its limits.


Edited by Henry Decker, 18 September 2021 - 12:33 PM.


#3 pahgo

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Posted 19 September 2021 - 08:07 AM

Do you have a DSLR? The 1.25" adapter on the skywatcher dob has a t-thread built in, and I have been able to get my DSLR into focus without much of an issue before.

As for a mount the EQ6-R Pro has a payload capacity of about 18kg (~40lbs) So it could attach to there, but you would need tube rings, and the weight and length of the scope might be pushing that mount to its limits.


Thanks for your reply Henry! No, I don't have a dlsr. Would you recommend getting one before getting a tracking eq mount? I have read about the eq6r-pro before, do you know the differences it has with the neq6-pro? They have a price difference of 250€ (200$) and, although I am ok with that amount of money I am not willing to 'waste' (where I live that's a considerable amount). I want to take one step at a time in a reasonable way.
Still, say I get a dlsr or a dedicated camera (not just planetary), wouldn't I still have the problem of long focal length/short exposure time?

Again, thanks for answering!

#4 CassGuy47

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Posted 19 September 2021 - 08:36 AM

Hi,

 

There's a reason why many people own more than one scope, and your story is a perfect example.  IMO, instead of trying to modify your 8" DOB optical tube for astrophotography, it would be far more practical to purchase a 2nd scope/mount combination for that specific purpose. 

 

By the time you add tube rings and a guide scope to your DOB optical tube, it's going to weigh at least 50 lbs. and you'll need a 100 lb. mount setup to support it.  The required mount system will be expensive and heavy, and if you don't have a small observatory, the breakdown and setup time can grow old very quickly.  Although there are folks who use Newtonians successfully on GEMs, their ergonomics tend to be more problematic than other scope designs. 

 

Just my two cents!

 

Good luck!


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#5 MikeECha

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Posted 19 September 2021 - 09:11 AM

Hi there!

 

So I got my first scope, a big and beautiful SkyWatcher 8'' Dobsonian (203/1200). I've been taking some pictures of the moon and the big planets with my phone (on a holder) and also tried to get some Messier objects and there comes my bit of frustration. I love to look at the eyepiece but, the feeling of getting a sharp image of an object is way better, I guess I am more into AstroPhotography than I am into just looking at the EP. At first I thought of getting an astrocamera but then thought, how long is the maximum exposure I can take without tracking? I think the number is 500/1200=0.416s for my case, is that right? There's not much that can be done with 0.416s exposures! and manually keeping the object in place... 

 

Therefore, I first need to upgrade my mount to a tracking one. Being my purpose to do AP, getting an Alt/az tracking mount would not make much sense, would it?

 

One thing I did not consider when getting my scope is its weight. Just the scope, with no attachments, sits at 11kg (24lb).

 

So my questions are...

  1. Where do I go from here? Camera or mount first? 
  2. If camera, Skywatcher newtonians don't need a new focuser, right? (please say no) Which camera would you choose with a 300/400€ (350/470$) budget? and with a more flexible budget?
  3. If as I believe mount comes first, which one? Looking at the prices I am truly scared of this new hobby, what's the minimum you would put that scope on top of (for AP)? 

 

Many many thanks for reading me so far! Looking forward for answers! 

I hear your struggle. I am what I consider an intermediate hobbyist and went thru where your are not too long ago. So my opinion is framed by that. 

 

Let me start by #3:

In a larger picture, the AP hobby requires accuracy and exacting performance from your equipment and optics. That is expensive. Any peripheral/accessory you buy is in the $$$.$$ range and as you already see main equipment prices are "astronomical" (at least for my budget).

 

#1

If you are convinced that AP is what you are going to do, the mount comes first,. No question about it. That is as important for your AP results and enjoyment as a good foundation for your house. Buy the best (and highest load capacity) mount you can afford. You will use it, trust me. If you later realize AP is not for you, a good quality mount retains its resale value very well. Bad, lower quality ones do not. You may see suggestions like "...start on the low end and then latter... ". From my experience, I would say do not fall on that trap. (see #3)

 

SW EQ6R-Pro (as already suggested on this thread) is in my opinion the best deal out there for the price/performance ratio. At 44lb capacity you can throw just about any scope and imaging train package with reasonably long fl. I have one that now, after very simple tweaking(s) regularly tracks at .35 arc-sec RMS with an OAG @ fl 1370mm. DEC is most of the time at .2" or below.

 

#2 Focusing manually, and assuming a focuser with no alignment issues is possible but, it is time consuming and not so exacting and repeatable. AP, in addition to accuracy will require time-efficient imaging sessions. There is a limited amount of clear sky nights/time that changes with location and your own available time. I tried using my 300mm F2.8 camera lens focusing manually but I gave up. What I am getting to here is that you will soon be wanting to go automated and that brings you back to cost (#3). Except that you may have spent money trying to achieve good manual focus with a minimalist approach.

 

Those are my thought based on my short time trying to do good AP and my "perfectionist" personality.

 

Bottom line, my suggestion is that if you are going to go in at all, because of my answer #3 I would go all the way in (your budget is the limit). 


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#6 pahgo

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Posted 24 September 2021 - 09:07 AM

Thanks for taking your time and answering me! For what you are saying I am in a bad spot, ain't I? I understand there are two options here

  1. Getting a lighter scope with its eq tracking mount.
  2. Start throwing money into a rig that can hold this 24lb 8'' (f5.9) monster. 

Lets say I decide to throw money into a heavy sturdy mount! 

 

The SW EQ6R-Pro seems to be the best mount in a relation of payload capacity and price at 44lb capacity and around 1500$ (maybe a little bit more). Put on that my 24lb scope, counterweights and, in the future, a camera and we are in the limits of its capacity, right? Two questions here... 

  • Playing with the distance I put my counterweights means I need less mass, right? is there a problem with putting all the counterweights as far as possible? I'm supposing not.
  • Does the focal length of the scope matters on the maths? I understand mounts are not entirely perfect and so they deviate from the object given enough time, that is a bigger problem the longer our focal length is. correct? 

Trying to find anything more capable than a SW EQ6R-Pro I see there's a big gap until we get to the 4k$ mounts and I haven't been able to find anything in between. Do you know of anything stronger than a SW EQ6R-Pro that doesn't require a loan? 

 

Clear nights y'all!



#7 Pauls72

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Posted 24 September 2021 - 10:34 AM

1) A regular visual type reflector scope will generally not come into focus with a camera. They require more inward focus than is there. You may be able to get away with changing to a low profile focuser. But more likely you will have to remount your primary mirror further up in the tube. This is why there is astrograph style reflectors for imaging.

 

2) With any mass produced mount used for imaging, the general rule of thumb is the maximum capacity is about 50% of that rated for visual use. So your EQ6-R rated at 20kg (44lbs) for visual use is only good for 10kg (22lbs) load when imaging. There is more to the issue than just weight, it is where the mass is located. With a long scope the weight is further away from the pivot point making it harder for the mount to handle. The larger the scope. the more apt it is going to act like a sail in just a slight breeze. This is why small scopes are easier to image with.

 

You can do AP with a DSLR, lens and tracking mount without a scope.

If you want to use a scope, their are 2 paths you can take:

 

a) Long exposure images (images over 30 seconds), then the mount becomes the most important piece of equipment. You will most likely need to guide the mount too. So this means a guide scope, guide camera an computer of some sorts to control it.

 

b) Short exposure images (images under 30 seconds), also referred to as lucky imaging. You take lots of images and stack them.

 

Either way, you still need the same amount of image integration time to get the same results. So for a 90 minute integration time image you can have 9 - 600 second images, 18 - 300 second images or 1080 - 5 second images. If you have a 10MP camera, that is 20MB per image times the number of images. So disk space and stacking time become an issue.

 

 

This is 20 images of 120 seconds or 40 minutes if integration time. The mount is an Orion Atlas EQ-G (Skywatcher EQ-6) unguided. The scope is an Orion Short tube 80mm doublet refactor (ST80) that I bought used for $75. Being it's a cheap low end scope there are some faults with the image. A field flattener would help it, but it would cost more than the scope. But it shows you don't need a large or high cost scope to produce decent images. But a good mount makes it much easier.

 

get.jpg?insecure

 


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#8 MikeECha

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Posted 24 September 2021 - 04:57 PM

Thanks for taking your time and answering me! For what you are saying I am in a bad spot, ain't I? I understand there are two options here

  1. Getting a lighter scope with its eq tracking mount.
  2. Start throwing money into a rig that can hold this 24lb 8'' (f5.9) monster. 

Lets say I decide to throw money into a heavy sturdy mount! 

 

The SW EQ6R-Pro seems to be the best mount in a relation of payload capacity and price at 44lb capacity and around 1500$ (maybe a little bit more). Put on that my 24lb scope, counterweights and, in the future, a camera and we are in the limits of its capacity, right? Two questions here... 

  • Playing with the distance I put my counterweights means I need less mass, right? is there a problem with putting all the counterweights as far as possible? I'm supposing not.
  • Does the focal length of the scope matters on the maths? I understand mounts are not entirely perfect and so they deviate from the object given enough time, that is a bigger problem the longer our focal length is. correct? 

Trying to find anything more capable than a SW EQ6R-Pro I see there's a big gap until we get to the 4k$ mounts and I haven't been able to find anything in between. Do you know of anything stronger than a SW EQ6R-Pro that doesn't require a loan? 

 

Clear nights y'all!

I do not think the CWs count on the weight capacity. When the mount is balanced, the weight of the equipment and the CWs cancels out. With the use, I have come to be able to tell if I have a good balance just by feeling how heavy the RA feels when I try to rotate it with the clutch released.

 

I think the weigh spec is because of the torque the motors would have to produce to start, move/accelerate and stop or decelerate the axes. That would depend of how far the load is from the center of the axes. I just do not know what is that max distance at 44lb load. I assume they use some reasonable distance for scopes mounted on a standard dove tail. But that is just my assumption.

 

I can tell you that even with my mount loaded (I have about 35lb), if I am not careful and a cable get tangled it would snap it with no sweat. In addition, there are a lot of people with 8" f5 Newt astrographs mounted on EQ6R-Pro and the whole imaging train and the mount handles it with no problems. Just youtube for Cuiv The Lazy Geek (he is around in the forum too). He has EQ6R-Pro with that combo. You will get an idea.

 

Those 8" f5 as the name hints, are made for AP with a focuser with the right in-out travel. And they are reasonably priced.

 

As already pointed out by Cassguy47, I would not try to dismount your Dob. Every tool in this hobby has its use.


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#9 cuivienor

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Posted 01 October 2021 - 03:51 AM

 

I can tell you that even with my mount loaded (I have about 35lb), if I am not careful and a cable get tangled it would snap it with no sweat. In addition, there are a lot of people with 8" f5 Newt astrographs mounted on EQ6R-Pro and the whole imaging train and the mount handles it with no problems. Just youtube for Cuiv The Lazy Geek (he is around in the forum too). He has EQ6R-Pro with that combo. You will get an idea.

 

Hey! That's me! The EQ6R is a great mount, but there is some variability between samples (I recently found out that mine is one of the good ones overall). The big advantage of the SW mounts is the ability to use EQMOD, or GreenSwamp Server (I use the latter). GSS in particular has a lot of neat features to really optimize the mount in a (mostly) user-friendly way.

 

That being said I hear a lot of good stuff about other similar payload mounts (CEM40, CEM60, etc.), but EQ6R does seem to hit the sweetspot.



#10 MikeECha

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Posted 01 October 2021 - 06:40 AM

Hey! That's me! The EQ6R is a great mount, but there is some variability between samples (I recently found out that mine is one of the good ones overall). The big advantage of the SW mounts is the ability to use EQMOD, or GreenSwamp Server (I use the latter). GSS in particular has a lot of neat features to really optimize the mount in a (mostly) user-friendly way.

 

That being said I hear a lot of good stuff about other similar payload mounts (CEM40, CEM60, etc.), but EQ6R does seem to hit the sweetspot.

Hello Cuiv,

 

I hope your recovery is going well. 

 

Yes, there are always options in this hobby. As for variation between copies, the design of this mount is very simple and in my opinion, problems mostly come down to two issues: gear meshing and stiff axes. Both issues are very simple to fix if one has just minimal mechanical aptitude. There is nothing else to adjust.

 

Let me take this opportunity to thank you for the work and the video content you put out. I really enjoy the touch of comedy you sometimes add to the explanations and I check Youtube frequently looking forward to finding new content from you.

 

You have a vid on  how expensive this hobby is that may be good fit for the topic the OP is evaluating. It is a fun vid, specially the part where you tried to quit AP and went to paragliding. The timing on the delivery of the punch line was brilliant. Have consider standup comedy about AP. I think you would bee great

 

Thanks for your hard work and get well soon.




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