Franklin

I've had several old Vixen 60mm F15 scopes and the optics were very good and I'd try and fix up the Carton and also take apart the Sun diagonal and show us what's inside it😁.

I've seen an old Unitron herschel wedge that had a metal flap at the back to direct the sunlight down to the ground and it was completely open at the back. This one had a prism inside but not a 45deg, more like a thin wedge.

Not a real laser beam😁but a strong beam of concentrated sunlight no less and if a small child were to stand behind the scope it could end bad! Not sure if it's a prism, I thought it was a 45deg un-silvered flat mirror and most of the light just passed through?

The problem with the original SXW Sphinx mount with regards tracking for imaging purposes is that the mount not only tracks in RA but also in DEC and the reason it does this is to make up for inaccuracies in PA and also to keep the Goto model correct. I think for visual use this is not a problem but I've read that these steps in declination can cause problems when imaging.

That is one of the old Japanese herschel wedges, it was intended to be used with those .965 Sun filters in conjunction with the scopes aperture stop cap. I personally wouldn't chance using one these days and will stick with my Lunt. There are folk over the pond who still use these and post on CN about their findings. The design is actually safe to use but the lack of a heat-sink at the rear means that a dangerous laser beam shoots out and it is this that is the danger. They were known as "Tie burners"! Enough said.😁

I personally wouldn't put anything larger than a 4" refractor, 6" newt or a 5"CAT on an EQ5. They are rated at 9kg but that's a bit ambitious imo, after all the EQ5 is a clone of the GP which is rated at 7kg. You note they put 8" newts on them and they also put 6" fracs on them. A recipe for a wobblefest! edit. There are many people who do put 8" newts and other larger scopes on their EQ5 mounts and claim to have success and that may be so but in my experience, which is just from a "visual use" perspective, I'd stick to scopes weighing no more than 5 to 6 kg.

Obviously I'm a bit slow on the uptake but a 185 APO for 5K..... Really? Can't wait to read user reviews on the optics.

Still listed on RVO but doesn't say in stock, I got one from Opticstar (Meade UK distributor) a couple of years back but not listed there now, so it looks like the used market for both. I did read on the Baader website that they are taking orders for the Microguide from interested parties and if there are enough they will be producing some more.

Vixen rate their Porta mount at 4.5kg which is half that 20lb claim. This misunderstanding has it's roots over the pond when the Vixen distributer, at the time, started selling Porta mount heads but paired with the heavier duty HAL130 and HAL150 tripods. Yes the HAL is a better and sturdier tripod than the light-duty tripod supplied with the Porta but in no way does it magically transform the Porta head into a mount capable of handling double the payload as recommended by Vixen. The Porta, when used with a small scope such as an ED80 is an excellent little mount but it is just a lightweight and portable mount, hence the name "Porta"😁. Also The Tak FC100-DC is super light and nimble, in fact it is about the same size as some 3"ED scopes. When I had a DC the Porta carried it just fine, though I now have the APZ which is very nice. A few firms just copy and paste their advertised specs and some of them are giving out false information because of it. From the Vixen manual for Porta.

The Meade Astrometric with your 2.4m scope and x2PM would get you up to 400x, which is the kind of silly high power you need to be using.

Yes, the Baader Polaris is 25mm so you would need a 5x barlow at least to use it for this purpose. The Meade Astrometric is still in production but the Baader/Celestron MicroGuide would have to be found used.

These illuminated reticle eyepieces have a 12mm and 12.5mm focal length and it is recommended to use them with a minimum 2000mm focal length scope, so you may need to use a barlow to get the image scale large enough to take the measurements and this means that the drift will literally fly across the field of view. The book "Observing and Measuring Double Stars" ed. by R.W. Argyle is the definitive resource on all this stuff and is highly recommended, though it does get quite technical in places.

Here's another good explanation from a fellow SGL member.

Interesting article, thanks for posting.

The rate of sidereal drift is 15 arc seconds per second of time, so by timing the E-W drift of a star across a scaled line you can work out the size of the scale for a given magnification. Once you know the size of each mark on the scale, in arc seconds, you can use it to measure separations, just like using a ruler. The method is to set the scale in line with the E-W drift and with the star at one end, turn off the drive and time the drift of the star across the whole length of the scale. Do this many times and then take the average, then multiply this average by 15 to convert to arc seconds and then divide the result by the number of marks on the scale. If you change scopes or use a barlow then you must re-do the timings for the different optical configuration. There are also more accurate methods which take into account the cosine of the declination of the star but if you make your calibration timings with a star close to the celestial equator the simple method works fine.

A Meade Astrometric reticle eyepiece or even better a Microguide (Baader/Celestron). You calibrate the scale for a given optical setup by timing transits with a stopwatch, Once this is done you can use the scale to measure separations and also use the protractor on the reticle to measure position angles.

Wouldn't knock the WO scopes but also wouldn't describe the FC as a side-grade either, the Takahashi is a couple of rungs up the ladder imo. DC, DF, same scope different focuser and DZ F8. I had the DC and it was a perfect telescope, very nice and light with outstanding optics.

I know this thread is about 4" ED F7 scopes and they are great but there is something in an F9 4"doublet that works and the DL combines this, not only with fluorite glass but Takahashi's legendary optical figuring, definitely a keeper if you do downscale, I would think.

You have a great collection of extremely fine refractors John and the DL must be something very special.

The Vixen ED102SS F6.5 was released in 1999 and production continued until 2004 which makes it quite a rare bird these days.

Same here but I found that each click makes only a very subtle difference. I wish there had been a bit more info in the instructions on this.

👍Same here, for use with my ED70 travel scope, I've been using a 2x barlow with my LV8-24 zoom but the 3-8 SVBony zoom has been getting glowing reviews and at that price it seems silly not to.

The price is going down, AliExpress will deliver one to the UK for a grand total of £73.14 right now. I've seen reviews comparing these favorably to some tasty eyepieces.

I got a Quark Chromo earlier this year and it's been very impressive. When you've had a chance to play around with it, you'll have to post your findings on what you think is the best setting. The instructions say to start in the middle at 12 o'clock but with mine I find 2 o'clock position seems the best for surface and prominence details together.

Some designs have the retaining ring on the inside, behind the rear element, so it is still possible to do the "slap the tube" thing but the problem then is checking to see if you've got it right. You have to keep putting it all back together and cheshire testing. Quite a faff, I'd just live with slight off-collimation and keep the scope for low-power wide field stuff.