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C6/C8 on AZ4: Managed it?

CraigT82

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CraigT82

CraigT82

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Hi All,

I've been searching the forum for info on using a C6 or C8 on a steel-legged AZ4 mount. I've found several posts alluding to how mounting this type of scope on an alt-az mount would require either relocating the dovetail or using tube rings to get the finder and focuser knob in the right positions.

Has anyone out there actually managed to get one of these scopes mounted satisfactorily on an AZ4? Did you use tube rings or move the dovetail? Or just stuck it on and hoped for the best?!

Also, if you've managed to get a C8 on there, how does the AZ4 cope with the fatter tube and extra weight? Would a C6 be a better set-up on the AZ4?

Thanks in advance,

Craig

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  • 4 months later...
CraigT82

CraigT82

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Ok... For anyone who may be interested!

I recently bought a second hand 1994 (ish) classic C8 and with some initial testing it looks like it's going to work well on the AZ4 Steel legged mount*

The only thing I had to do was to move the dovetail clamp from one side to the other (I had to remove the finder shoe in order to do this but have ordered a telrad to replace the 8x50 Orion finder the scope came with)

I've only had it set up in the day and pointed it a some far off trees with my 5mm BST (giving x400) and it came into a nice, almost pin-sharp sharp focus (so I think the collimation isn't too far off).

Whilst looking through at this high mag i tried tapping the OTA and tripod legs and also moving the scope around to roughly simulate tracking an object... The mount seems to be able to handle these high mags without too much vibration and moves in alt and az fairly smoothly, so I'm chuffed!!

For the benefit of anyone interested I'll report back after using it in anger!

Craig

*Bear in mind this set-up is going to be used purely for visual use!

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John

John

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I'll be interested to see how you get on Craig. I've used my ED120 refractor on my AZ-4 a few times and it's been OK for a short session but I've not used it at high powers(ie: over 180x) with that optical tube. Your C8 is a shorter tube than the ED120 but more than twice the focal length so it will be interesting to see how the AZ-4 fares. Will you be using a dew shield ?. That will add to the length of the OTA of course.

My little 4" Vixen F/6.5 ED refractor rides on the AZ-4 very solidly and I have exceeded 200X with that but it's a much lighter and shorter scope than the ED120.

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CraigT82

CraigT82

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Yes II'll be using a dew shield so that extra weight and length may cause some issues, but If I can get it up to around x200-250 comfortably on the decent nights with this set-up then I'd be happy.

You can see that it doesn't quite get up to the zenith before the bottom of the tube contacts the mount, but again I'm not too bothered about that as if I really needed to look straight up I could just move the OTA forward on the dovetail an inch or so.

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John

John

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If you put the mount on 2" steel legs it would help - thats what I do when I use my ED120 on my AZ-4. Taller than the 1.75" tripod too. I'd not recommend the setup that you are trying to be honest but I hope it works out OK though.

A 2" diagonal can certainly be put on a C8 without any problem.

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  • 2 weeks later...
CraigT82

CraigT82

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Ok so finaly managed to use this setup in anger!

An initial issue was a kind of 'rebound' effect in the altitude when using high mags...when trying to make small adjustmens in altitude the scope would rebound slightly, so that I would have to nudge the scope past the object and let it come back onto it. The first thing did was to strip the altitude clutch and remove the expensive bicycle hub grease that I applied not long after first getting the mount, and replaced it with a much lighter weight silicon lube, that seemed to help a lot. Next thing I did was to spend a bit of time getting the scope as perfectly balanced as I could, and then mark on the dovetail this balanced position so I could quickly find it again. A combination of lighter lubricantand proper balance seems to have all but eliminated this rebound effect

Anyways it actually works quite well... certainly up to x200 which is the highest power I can realistically get from this scope with the eyepieces I have. Tracking at x200 can be tricky at first but with a little practice and some time spent finding the right tension on the clutches it becomes easy... little and often is the way forward! It also helps to have a bubble level handy as getting the mount nice and level also helps. I found that having a bit more tension on the alt clutch made things easier and also the more tension here the quicker the vibrations damped down.

My opinion so far is that the AZ4 handles the C8 tube fairly well... it's by no means perfect but it's certainly usable and I am happy to use this setup to get out there and point 'n' nudge for a couple hours or so when I get the chance. I think it'l serve me well until such a time as I can sneak the purchase of a Skytee past the other half... Damn you joint bank account!

Craig

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ollypenrice

ollypenrice

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I think that for me the issue would be using a manual alt az at this kind of FL, irrespective of how good and stable the mount were to be. However, if you're getting the hang of it then that's great. I do have a Dob with this kind of FL but it's a light bucket generally running at only about 80x. 200x is possible but kind of busy!

Olly

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Tyr

Tyr

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Thanks for the pictures and report, this combination of scope of which I like the size / FL / cost and mount which I already have is something I was interested in.

Observing mars with this mount and my 127mak at 214x magnification was interesting, I found positioning the view ahead of the objects path through the field of view and then observing it as a sort of fly by the most effective method for me as it allowed the view to remain steadier.

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CraigT82

CraigT82

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Thanks for the pictures and report, this combination of scope of which I like the size / FL / cost and mount which I already have is something I was interested in.

Observing mars with this mount and my 127mak at 214x magnification was interesting, I found positioning the view ahead of the objects path through the field of view and then observing it as a sort of fly by the most effective method for me as it allowed the view to remain steadier.

Yup that's pretty much the way I do it with the C8! The extra weight on the AZ4 does make it more difficult to move the scope by small precise amounts so by anticipating the path of the object you minimise the amount of nudges you have to make!

BTW the weight of the my C8 plus dew shield, finder and diagonal is about 6.3kg.

Craig

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John

John

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I'm glad you are finding the C8 / AZ-4 combo usable if not perfect.

I've had a go with a C8 on a SkyTee II recently and that works pretty well. Having ultra-wide eyepieces helps somewhat with the tracking though which is a challenge at high power even with the SkyTee II's slow motion controls.

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Stargazer_00

Stargazer_00

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'get out and grab half an hour when can'!

I can definitely understand this. I have my 6" 150p on AZ4 for these days. I have different options when a longer session is on the cards.

I would not expect a C8 to come to ambient in 30 minutes or less though, even if stored in a shed (which are usually a degree or 5 higher than proper outside.

Do you/have you found any issue with tube currents on the short sessions? I'd expect the view to get markedly better after the scope had been out for an hour.

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CraigT82

CraigT82

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Yeah I did notice tube currents when I used it last week, but the ambient outside temp when I took it out was about 16 degrees and the scope was usable but not great straight off the bat, and after about 20 mins it had settled down nicely.

Mind you, I've only had the C8 for about a month, so long cooling times haven't really been an issue! You're right though, come winter time i'm going to have to get much better at anticipating clear nights and putting the scope in a cool place before I leave for work.

Craig

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ollypenrice

ollypenrice

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'Busy' is a great way to describe it! Definitely not a setup with which you'd want to spend hours at the eyepiece, but it suits my style of observing... which is 'get out and grab half an hour when can'!

Craig

Yup, that makes perfect sense. When I retire (fat chance!!) I might enjoy not being up all night!! :grin: :grin:

Olly

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