yep, the HEQ5 should handle an 8" dob tube, just take the side bits off the dob if you think they weigh a bit and find some rings to mount to a dovetail.
I have an 8" 1000mm focal length BD200N on my HEQ5 and its fine for AP, once I get my guiding cranking, I can take some shots longer than 30 secs with my DSLR to really get some tight stars.
Stu, you are right on the limit before Flexure becomes a major problem.
HEQ5 - Max: 8" f5 - f6 Reflector
EQ6 - Max: 10" f5 Reflector
As for Astrophotoraphy you will need to attach your camera and see if you get enough 'IN' travel to get focus.
If you don't you will need to either:
- get a low profile focuser
or
- move the mirror up the OTA
or
- both
yep, the HEQ5 should handle an 8" dob tube, just take the side bits off the dob if you think they weigh a bit and find some rings to mount to a dovetail.
I have an 8" 1000mm focal length BD200N on my HEQ5 and its fine for AP, once I get my guiding cranking, I can take some shots longer than 30 secs with my DSLR to really get some tight stars.
Should be sweet.
Cheers
Chris
Thanks for all the comments guys.
With regards to guiding, as a total noob in this field, is this the mount doing it's thing via the goto functionality or do I need an extras bit of kit that I am unaware of ?
I might be naive but I thought
OTA + goto GEM mount + dslr = AP Setup
Guiding will more than likely be needed to get longer than 30 sec shots as no matter how accurate your polar alignment is, the drives will "wobble" slightly due to periodic error and due to the fact they arent the most precision mount gears around for AP.
My first (and only to date) pics of objects were quick and dirty 30 sec subs (times 8-9 stacked) using a DSLR with no guiding and to get these 9 I had to throw away about 10-15 more I took because the mount wobbled and drifted slightly and there was no guiding to bring it back on to the stars. Note, that I had VERY accurate polar alignment at the time.
I wont link them but you can check out the pics I took on the Beginner's Astrophotography forum.
I have to disagree with Chris, tho' from his avatar that might not be a good idea!
I had exaclty the same combo last year, and once "trained" over 3 nights and using the PEC functionality, the mount would track to well within advertised limits.
If you are going to use an auto guider, I suggest Synta / Orion's own.
These mounts don't like 3rd party software / bits in my experience (YMMV), but I feel a lot of 'problems' with the mounts are caused by not setting them up properly in the first place.
True, they aren't THE most accurate, but they aren't the worst either.
Stu, you are right on the limit before Flexure becomes a major problem.
HEQ5 - Max: 8" f5 - f6 Reflector
EQ6 - Max: 10" f5 Reflector
As for Astrophotoraphy you will need to attach your camera and see if you get enough 'IN' travel to get focus.
If you don't you will need to either:
- get a low profile focuser
or
- move the mirror up the OTA
or
- both
I put my camera on the dob mounted OTA last night and I don't get enough "IN" therefore it does indeed look like I need another focusser.
Long term, the best approach is to get the biggest and best mount you can and then the rest is relatively easy. The analogy is bit like the "weakest link" and you could have a million dollar scope and a million dollar camera and your results will still only be as good as the mount. If you already own the mount and scope give it a go, it wont hurt to try.
While you may not be in a shopping mood right now, spending as much as you can on a mount will always pay off in results and when you want to upgrade good mounts always keep their resale value very well.
If your DOB is an 8" Skywatcher then you can unscrew the 1.25" eyepiece holder apart. You'll see a thread that will fit into the T adapter. This gave me plenty of infocus. However I should repeat this is only on the 8" Skywatcher DOB as I have one which I've mounted on to a HEQ5 Pro mount. I also have an Orion ST80 with a QHY5 camera attached (as a guide scope combo) to the 8" and the HEQ5 Pro handles it all with no dramas.
I do an 8" Skywatcher, the 1.25 can be taken out and an adapter used for the 2" EP or Camera adapater So i dont understand fully what you mean. The low point with the Camera and T-ring is as low as it can go, but still not "in" enough
Maybe the low profile focusser is the way to go, but i pay for that and its still not low enough, i dont want to be messing with the Mirror
On my Skywatcher the tube part of the 1.25" eyepiece adapter can be unscrewed from the base, the part that goes into the focuser. If it's like my Skywatcher there is a thread on the outside of the hole where the 1.25" tube part screwed in to the base. A T adapter will screw onto this thread and then the camera gets attached to the T adapter. The whole assembly can then be put into the focuser. This should give you plenty of in-focus.
Let me know how it goes - I can always take a few happy snaps to show you what I mean.
Good to hear that you've worked it out. The picture you showed was the focuser collar. This will cause more pain if and when you decide to use a coma corrector, specifically the Baader MPCC. When you get to that stage give me a yell!!
Yes, some of us have been lucky enough to get it all to work by getting the 2" adaptor cut down, but its a close thing. You probably will want to buy an MPCC at some stage Stu - very reasonably priced option to kill off coma - but you can't just screw the MPCC in. Sorting out coma more important than focusers in early days I would suggest. There's a thread here somewhere - options are broadly:
1. Unscrew the piece Mario told you about
2. Cut down 2" adaptor
3. Move the mirror up (longer screws)
4. Cut down the end of the OTA (so mirror is closer)
5. Replace focuser
IMHO its worth persevering, because its a damn hard to get better bang for your buck when your starting out. You will find balance, guiding, wind, focusing a challenge, but its all very do-able with a bit of patience, and you can certainly learn all the important basics of AP to see whether its "for you" before really investing in mounts etc. Options 2-4 would let you use an MPCC.
Yep, I have the same issue with the 2" adaptor and the MPCC, the 2" adaptor is too tall and the DSLR cannot reach in-focus. I think I may have to try cutting down the collar mod.
Here is an example of the coma experienced on my 8" F5 scope into the DSLR, you can see how much of the screen shows coma, from about 50% to 60% off the middle, the stars blur like a zoomed shot.
Taken last night (read, this morning at around 5am) when testing my guiding using the toucam through the finder and PHD (got it working though! - woohoo, took some 5 minute shots with NO trailing)
This is a simply a 60 sec sub of the Eta Carinae Nebula showing the Homonculus.
Forget about the quality of the shot, there is a lot of work and fine tuning for me to do yet, but I thought I would post it to show you what the problem is when using the 1.25" adaptor screwed onto the T ring (gets focus OK) but shows a LOT of coma in the outer half of the image.
Keep this in mind. I have an MPCC and tried to use it last night, but was about 15mm from reaching in focus on the focuser, so the collar cut down is the most likely route I will take to bring the MPCC into play. Then, look out!
Don't worry about the Coma Corrector just yet!! Get out there and test your DSLR attached the way I suggested. Then you can decide if you want to get into the hobby/passion or spend up on a bigger Dob.
However, be warned, that once you've been bitten by the Astrophotography bug there is no cure!!
LOL - you better listen to Mario's advice about how addictive it can get too Stu.
Whatever you do, DON'T screw on the DSLR, point it at M42 and take a few subs of 30secs - 60secs. You'll slip over the imaging event horizon and all notes in your wallet >$20 will start to spontaneously levitate.
I forgot option 6 - some people have managed to ream out the inside of the fitting on the end of the focuser tube making it just large enough to take a 2" fitting. Goodness knows why they didn't just make it like that in the first place to save us all some gray hair...!
