John

You have had some great replies already Your 16 inch dob should be providing superb planetary views from your location at 200x - 250x or more. I would suspect that a collimation check and adjustment might be in order. I find tracking at high power no problem with my undriven 12 inch dob. I do use eyepieces with wide fields of view though, which helps 200x - 300x tracking is entirely possible with my dob using the "nudge-let drift, nudge-let drift, etc, etc" approach.

The magic of 11

The Tak is an astro scope so I use it as such. I use my Vixen ED102SS with the Lunt HW as well and it's very good, but the Tak is even better. My understanding is that the Suns light passes through the objective and is bought to focus either 900mm or 633mm away and thats where the heat is and also where the componant that is designed to cope with it is located Thanks for the comments on the borders - they are my other half's doing rather than mine !

I use my Lunt HW with my Tak FC-100 DL. The views are really excellent, when there has been any detail to view

Great post Rob

No, I'm afraid not. An etalong filter plus other filtration is required to view in h-alpha light.

I think these were used on the early HEQ5 mounts. Not sure that they are available new A "wanted" advert on UK Astro Buy & Sell might be worth a try.

I think Tele Vue has said that it is safe to use their Petzval design refractors with a herschel wedge. On their website under the Lunt HW, First Light Optics advise against using it with Petzvals though so maybe it varies depending on the particular Petzval design ?: https://www.firstlightoptics.com/lunt-solar-white-light-systems/lunt-white-light-herschelsolar-wedge.html

What scope does the book recommend to get started in imaging ? Probably not a 200P dobsonian to be honest with you. There might be better choices that will enable you to graduate more smoothly from some visual experiences to imaging. The optical tube from the 200P dobsonian can be removed from the dob mount and put onto an equatorial mount but you will need a pretty heavy duty mount for imaging purposes because the dob optical tube is an F/6 wheras the one that comes on the equatorial mount is F/5 (shorter). Perhaps just hold back a little while longer from actually commiting to a scope ?. You won't get shot down in flames here, just lots of good advice

Here is one DIY approach: http://www.astro-baby.com/articles/rotating rings/Rotating Rings Project.htm I have also heard that some folk add teflon pads to the edge of one of the tube rings involved in the above to make rotation very smooth.

Just a gentle "bump" in case anyone else is interested in this event

Hi and welcome to the forum ! Do I take it that you are getting the Skywatcher 200P dobsonian ? The Telrad is extremely good and an excellent addition to a dobsonian. It does make star hopping much easier. Having a good star atlas helps as well ! Can't help you with the imaging because I'm a visual observer but many on this forum do image so help will be at hand on that soon !

Brief 1st light for both the 12mm and 17mm tonight. The eye relief is slightly longer than the eye cup. Finding the correct eye positioning seemed to be more critical than for the 21mm and 13mm Ethos but I do have years of experience with those and just 20 minutes or so with the ES 92's ! The views were very immersive, more so than both the above Ethos. The ES 92's seem to "lift" the star field towards my eye more than the Ethos does. Not sure why - perhaps the massive eye lens and longer eye relief ? The Ethos might have been a tiny touch sharper right across the field but the ES 92's seemed very well corrected in my F/5.3 dob too. As far as conditions would allow, light transmission and sky background darkness seemed to match the Ethos. Seeing conditions were far from perfect though (quite poor really) and I only had time to check out the double cluster and the M31 / 32 / 110 group before clouds intervened. It's probably fairer to compare my Delos 17.3 to the ES 92 17mm rather than the Ethos 21 as the F/L difference will impact the views so it's not quite a level playing field. Roll on a proper session under good skies !

Thats interesting. The 11mm Type 6 does not appear on the Tele Vue website now so it looks like it has been dropped: http://www.televue.com/engine/TV3b_page.asp?id=21 The 11mm is the only T6 Nagler that I have not owned ! I used to skip straight from the 13mm to the 9mm. Maybe others did the same so the 11 was not a good seller ?. I'm sure it's quality is as good as the other T6's though. All I've read on the Apollo 11 eyepiece indicates that it's a one off and not the advance guard of a new Nagler range. Time will tell of course

Coma won't be very obvious in an F/6 newtonian. I hardly notice it with my F/5.3 and that is when using 100 degree eyepieces. Diffraction spikes around beighter point sources are caused by the vanes holding the secondary support in place. It is possible to reduce their visual impact by replacing the 4 straight vane design with a curved vane design but that is quite an operation to carry out even if you can source suitable replacement vanes. Even with curved vanes diffraction is still there but it is spread over the field of view: M110 is much fainter than M31. M32 is more of a small fuzzy star. M31 looks like a brightish oval patch of light. Seeing the dust lane structure is not at all easy - you need really dark skies to pick out that.

Good report - wish that I'd been able to make it this year

A really sturdy photo tripod might work OK but as you have said, the 70mm / 900 is a long scope and these tend to pose more challenges for both mount heads and tripods than short tubed scopes of the same aperture, even if the long tubes are not very heavy. Most travel / lightweight setups involve a short tubed scope which can be handled by a portable mounting arrangement.

Hi and welcome to the forum For observing the moon, even the smallest telescopes show lots and lots of detail. Your daughter will be amazed by the lunar views that any of the scopes mentioned will give.

Useful for rubbish "Blues Brother" impersonations too

I moved from a Baader solar film filter to a herschel wedge and found the difference subtle but noticable especially if the observing conditions are calm and the scope optics very good. I also feel that the wedge is a safer way to observe the Sun. If it falls off the back of the scope the eyepiece goes with it and the damage that the heat and light could do is restricted to possibly scorching your trousers. If an over the front type filter falls off or is knocked off (eg: at an outreach event) the 1st you will know of it if observing would be rather catastrophic.

The 3.5mm is around 10mm taller than the 5mm. The eyecup sections are fully extended here:

If I didn't know it was a Tak, I might have thought that it was a Konus on a posh mount

I've seen the pup star quite a few times with various scopes down to 100mm. The Pup star follows the much brighter Sirius as it drifts across the field of view when no drive is used so it is to the east of the primary. It is around 10 arc seconds from the primary so about the same separation as Rigel. I find that I need 200x plus to split Sirius. Here is a sketch that I made some time back:

The key to getting a Moonlite or a Feather touch fitted is the flange between the focuser and the scope. Unless someone has one somewhere to fit the focuser of your choice, you may need to get one made. On the Feathertouch, the flange is this part. Moonlite use a different design but it's a similar concept, ie: focuser - scope interface.

I would contact Markus Ludes at APM Telescopes. He probably knows TMB / LZOS scopes as well as anyone now that Thomas Back is no longer with us. APM still carry a few of the original fittings for the "Classic CNC TMB" range as it's known. There is also a group of owners of these instruments on the "Cloudynights" forum who might be able to make some suggestions. One approach that I have seen is to add a Feathertouch unit to the back end of the original focuser as demonstrated in this 130mm F/7: