HEQ5 and 10" DOB

[mangrovedutch]

G'day, Maybe a silly question, but will my HEQ5pro mount handle the weight of a Sky-Watcher 10" DOB ? I picked up DougMCs DOB, and it got me wondering whether I could make the DOB into a good GOTO and tracking scope by getting some rings and a dovetail. :shrug:

Depending on where you get your information from, an HEQ5pro will handle anywhere from 8kg to 14kg.

Am I kidding myself? I like to think outside the square, but some of my ideas have been somewhat retarded in the past :screwy:

Regards, Dutch

[ReaPerMan]

I have done exactly this in the past it will work well as a goto but.... Regardless of what you think now you will eventually slide into the addiction if taking astro photos. It is then the major weaknesses will come to light and as I did you will have to move up to a stronger mount EQ6 or better.

I hope this helps

Paul

[Screwdriverone]

Hi Dutch,

Paul is right, the 10" is getting a little large for the HEQ5. Visually it should be OK but it will struggle. My 8" on the HEQ5 struggles to pull up from the horizontal if I have the DSLR and binos on it and when I had the 5" reflector as well (only weighs about 2-3kg) the gears started slipping.

I would suggest if you did want to put the 10" on and then attempt AP with it, lighten the load as much as you can by putting the 10" on a diet. I have seen quite a few cut outs in tubes and lightweight finderguiders using the guidescope to keep the weight down.

Ultimately though, if you found it wasnt up to the task, you could always "upgrade" an EQ6 by selling the HEQ5 here and buying a second hand EQ6 and this would handle it much better.

I think my HEQ5 and the 8" reflector with my proposed finder/toucam guider and a DSLR will be the max I will have on mine and that's probably pushing the limits for stability and guiding/tracking accuracy....

Cheers

Chris

[ballaratdragons]

Dutch, it isn't the weight so much. It's the length.

Even though a 10" reflector on a HEQ5 is too much weight, you could get away with the same amount of weight in an SCT.

The length will give you flexure problems.
That doesn't mean that the tube flexes. But imagine your arm as a mount, now grab the end of a broom and hold it out at arms length. Now try to move the broom. Hard isn't it.
Now hold something short like a wooden spoon. Now try move the spoon.

Now think back to the broom and imagine what your mounts gears must be going through every time you slew the scope, or even a slight breeze pushes against your scope.
Not good.

I wouldn't recommend mounting a 10" dob OTA on a HEQ5 mount.

[mangrovedutch]

Thanks for the input guys, it was worth the question. I had the opportunity to buy the scope rings fairly cheap, and saw it as another option. Alas, the answers suggest that it wouldn't be the greatest idea, so the Dob stays a Dob, and the HEQ5 will retain the ED120 only. Back to the drawing board. Anyone want a 10" Dob?

Regards, Dutch

[jjjnettie]

:) maybe, if you can hang on to it for a few months before selling.

[ballaratdragons]

Dutch, as Chris mentioned, you can cut sections out of the OTA and make it:
1. lighter
2. not a wind barrier

If you cut it right it will look a bit like a Truss Dob and the wind can go sailing straight through it.
Then it will work OK.

[asimov]

Anything is possible. Check out this 16" on a Losmandy mount.

[mangrovedutch]

:rofl::rofl::rofl:, my DOB is a wee bit different than that 10 inches of solid tube). If I keep it out of the wind and space my rings out on a longer dovetail, will the mount struggle. I appreciate the size is an issue, but if distribution of weight is calculated, will the HEQ5pro still struggle, or should I simply give up on the idea as it will cost me a mount in the near future.

I figured I wouldn't be the first to think about this possibility, I just don't want it to end in tears :sadeyes:

Dutch

[ballaratdragons]

That's why we say cut giant holes in it, or build one like in Asi's post.
The tube is the problem.



1. Keep it out of the wind, but you still need to slew. Bad.

2. You can put the tube rings at the far ends of the tube and it won't make a scrap of difference. No matter where the tube is held it still all pivots on the same points on the RA and Dec axis. Bad.

It isn't too hard to lighten your tube with big cut-outs, or turn it into a 'light frame' truss-style scope.

Google for some plans and ideas from others that have done it :thumbsup:

[mangrovedutch]

Thanks Ken, I'll see what I can come up with tomorrow. I know you are giving me good advice, just to stubborn to accept it at times. Never thought about cutting it up to reduce its weight, sounds drastic, but has its merit.
Thanks to all who have offered advice. I appreciate it.

Regards, Dutch

[asimov]

It's not all about the weight Dutch, it's about wind/breeze catchment area & lever arm action.

[asimov]

I'm buying a 14" collapsible DOB soon & want to EQ mount it. I have the CGE mount to mount it on. Ya reckon it'll ride it as is? No way! However I'll make it do so with a bit of persuasion I assure you...

[mangrovedutch]

G'day John, You'll have to send me a before and after picture mate, that sounds like a mission.

Dutch