Skywatcher 200p daft question

[spaceboy]

Can't see there being any problem. The 200P is 1200mm so there may be a little flex in the OTA. I have seen pics of the larger 250PX mounted on an EQ6 but I think this was for visual only.

[muttley]

I can see why you think there was a cover missing - I built mine yesterday and had the very same thought when I was looking at Astro Baby's collimating guide which shows and instructs the removal of the cover.

Yes, it was astrobaby's guide which started me wondering too. I can see some logic in having it exposed for cooling, but I will have to cart mine in/out of the house or garage each time I want to view, so there is plenty of opportunity for the mirror to get damaged. Maybe a small 'wheely' trolley is required - it is quite a big thing to move (if you are too lazy to remove the base). Still waiting for a clear night to use it for the first time. Given my extreme lack of patience, maybe astronomy is not an ideal hobby!

[spaceboy]

Still waiting for a clear night to use it for the first time. Given my extreme lack of patience, maybe astronomy is not an ideal hobby!

No it isn't if you don't have patience. Watching a video at Leicester's Space Centre it said that the skies are clear for roughly 3 months a year. That is often only the odd night here and there with the occasional 4-5 nights in a row. Out of those 90 nights you can almost guarantee it will be on a night you have to get up first thing in the morning, you stripped your mount /scope to do mods, the new eyepiece you wanted to try hasn't arrived in the post yet, the neighbours are having a garden party, you cannot find your collimator for love nor money or it's the middle of summer and you can at best only get in 2hrs during the small hrs of the morning before the birds start a chirping again. But for most of us it is all worth it on those nights the skies eventually do clear and the seeing & transparency is perfect. (probably 30 day of the year)

[Mr Q]

My DS-10 (10" newt) has an opening of about a 1/2 inch between the mirror holding cell and the OTA to facilitate cooling down of the primary mirror.

I decided to tape up the gap to keep bugs/dust from getting on the primary during storage (a great help).

So the cool down time is increased some but when I set the scope up for cool down, I place the OTA in a horizontal position at a 90 degree angle from any breeze present. This allows the heat from the primary to rise to the top of the OTA and migrate out the other end as cool air enters the bottom side of the OTA to replace the escaping warm air. This works out nice and adds only a few minuets to the whole cool down process and prevents the primary from dewing up.

I'd rather have a little time added to the cool down for the added protection of the primary (dust, dirt, etc.), which should only be cleaned when really needed. Using this method, I only have to clean the primary once every couple of years on average. The scope is now 30 years old and the mirror(s) are as pristine as the day I assembled it - always looking clean with a torch shined down onto the primary - a method of detecting any bit of dust/grit on the mirror's surface.

If anyone does not want to use this idea, a shower cap over the primary end will be sufficient to keep the mirror clean during storage.