Explorer 200P reflector damping question

[lavoisier]

Hi all,

I have just started white light observations of the sun using a 120mm refractor with an erecting diagonal. I also have an Explorer 200P which today I thought I'd use to see the sun. I found the sun quite easily in the refractor yesterday and was able to track it quite ably.

Today I couldn't find the sun in the 200P (no erecting diagonal) very easily at all and when I did I lost it quickly. Any tips on that one most appreciated.

I also noticed that the 200mm reflector caused the mount (EQ5) to wobble quite a bit and not dampen down very quickly, certainly not as quick as my 120mm refractor. In the end I got really frustrated and went back to the refractor. Any ideas as to why the 200mm reflector will not dampen down as quickly? It seems to move at the slightest touch.

Haven't tried it at night yet but if I can't use it on the sun not too happy about the prospect of using it in the dark.

All help appreciated.

Thanks

Paul

[steppenwolf]

The 200P on an EQ5 is rather pushing it to be honest so a long dampening down time is probably the price you are going to have to pay. The 120 on the other hand is a much better match for the mount.

[Ad Astra]

Vibration can come from many places, but the first thing to do is to go over your setup and check every nut and bolt. Fittings must be aligned properly and made snug. Beware of over-tightening! It isn't a lug nut on a car tire, ok? A tripod often has aluminum castings in the head where the legs attach, and these can crack if you really bear down on the wrench! Just be sure you remove the slop.

Next, check your EQ head. Are the clutches tightened properly? Again, you needn't be a gorilla about it, but they need to be snug. How about the saddle and scope rings? Are they tight and properly fitted onto the saddle?

Lastly - are you overloading your mount? (I'm an expert on this one! ) I overloaded my mounts for years and finally just purchased a proper mount that will handle my scope. Truth is, if the optical package (scope, finder, eyepiece, guidescope, etc.) is too heavy, no amount of tightening will do the job for you. This was my problem for years - but then my refractor tips the scales at 21 Kg and is 1.8 m long!

Lastly, many mounts have a bit of trouble with vibration when at the upper end of their weight capacity. Still, they can track just fine if the scope is balanced (you did balance in RA and Dec, didn't you???) and the wind isn't too bad. You really need some time in the dark to tell.

I hope this helps!

Dan

[lavoisier]

Thanks both for your replies. Everything is finger tight and I always balance my mount as i'm new to this and probably a bit over cautious. I think Steve is probably right that the scope may be on the edge of the mount limits. The other thing I'm suffering from being a newbie is that I struggle with the upside down left to right issue. I tried to use the diagonal off the refractor on the 200P but I just couldn't get focus. Maybe I'd have felt better if I'd used the 200P first and got used to a bit of 'wobble'.

Paul

[malc-c]

Can't say I've noticed any such problems with my 200P on an EQ5 pro goto. Using the 2" aperture mask of the cover with that solar film stuff I had no issues in finding, tracking and photographing the sun, even when it was at a low angle ( an hour before sunset)

Yes at high magnification it shows vibration when touched, but this soon dampens down.

[John]

Does your EQ5 have the older aluminum tripod legs or the newer 1.75" steel tube ones ?.

The alu tripod is very prone to vibrations with a heavy scope on board.

I use vibration damping pads on the feet of my CG5 tripod and those help dampen down vibrations a lot. I use the Meade ones.

[lavoisier]

Thanks Malcolm, set my mind at ease a bit now. Thought I was going to have to save up for a new mount. It's probably just me getting used to it. I do have the new steel legs John and I may yet invest in some vibration suppression pads if they really do work.

Thanks

Paul

[steppenwolf]

The other thing I'm suffering from being a newbie is that I struggle with the upside down left to right issue. I tried to use the diagonal off the refractor on the 200P but I just couldn't get focus.

Unfortunately, the back focus on these reflectors is insufficient to allow the use of a diagonal so your not missing a trick, it is simply that it cannot focus in this configuration! You'll soon get used to the inverted/swapped view .....

[malc-c]

Takes a bit of getting used to, I still get stuck with the buttons on the goto, in that when looking through the finder I have the press the up button and the object goes down ! - Direction is a bit irrelevant anyway as there is no up or down in space, and if you want say an image of the moon to look like it does to the eye then just flip it via software !

You've talked about imaging the sun - here is the result I got from the time described above.

Taken using a cheap Olympus dSLR camera (E500) body with the direct connection and a T ring -

My 1st image of Saturn below - taken using a Celestron Neximage (basically a reboxed SPC900N web cam.

and lastly Sirius using the dSLR

IMO the scope is very capable... OK I wouldn't like to see how it stands up to bolting on guidescopes and additional piggyback cameras. Maybe the length of the 200P OTA does induce a slight vibration when trying to focus at high magnification, but then use an electronic focuser and the effect is reduced. IMO if the EQ5 wasn't up to the job of supporting the 200P Skywatcher wouldn't of marketed it as such as people would be slating it rather than recommending it.

[lavoisier]

Very impressed with your pics Malcolm, nice ones. I hope to be able to pull something similar out of the bag. I'd be delighted if I did, only thing is I don't have motors or GoTo.

I like the scope and I'm hoping to give it First Light tonight so wish me luck.

Thanks

Paul