Ian McCallum

When I was out a few evenings ago with my SW Evostar 120, I noticed some play when I was trying to focus on Jupiter.  I'm guessing this is focuser slop.  Any ideas how to cure it , without buying a whole new focuser?🤔

7 minutes ago, vlaiv said:

According to this:

it would not be very good - it would start too "early" at 470nm - about same place as #8 but would have gentle slope - ending the same as #12.

Evostar 120 is rather nice scope for this sort of thing. You can use its 5" (or rather 4.72") of aperture on deep sky and then switch it to be 4" F/10 for planets. Just make 100mm aperture mask for it. You can also have 80mm F/12.5 if you want - by making 80mm aperture mask. With about 70mm - you won't need filter as you'll be hitting Conrady standard (F/ratio divided with aperture in inches >=5 - minimal/no visible CA), but you'll be limited to say x100-x150 magnification.

3d printed ones will likely be the best, but I've made them out of PVC pipe plugs as well.

I'd like to add some more Wratten filters to my collection, but for different things (not CA) - mostly to enhance planetary views, etc.

4 minutes ago, vlaiv said:

Wratten #8 is closer to 495 long pass in its characteristics.

Both start at 450nm and raise up to 500nm, but Baader hits 500nm at 95% transmission - with steeper curve and higher general transmission reaching 97-98%.

Wratten #8 reaches only 60% at 500nm and peaks at 525nm.

Wratten #12 starts beyond 500nm and reaches peak at 550nm.

As cutoff filter - 495 is the best as it has the steepest curve.

@Ian McCallum

What scope do you have and how much are you bothered by CA? Have you considered stopping the scope down a bit together with wratten #8 filter?

Where would a Wratten #9 fit in there?  I'm using the Sky-Watcher Evostar 120 Achro.  I've only managed one night with the #8 and was impressed. I've still to stop down the telescope.  I found the CA was pretty obvious, after coming from a SW 200P Dob...

I see that the Wratten #12 cuts light of 500nm, therefore seems close to the Baader 495.  Would it do the same job as the Baader 495?🤔

Revisiting an old thread...

Now I've got a SW Evostar 120 refractor and decent mount (EQ5 Deluxe), would Orthos be any good for me? I'm contemplating motorising this mount.

49 minutes ago, strayring said:

I received my BST Starguider 12mm from First Light Optis. The FLO package sticker warns "MAY CONTAIN CLOUDS" and true to form that's exactly what I got!

Post by Royal mail took only 3 weeks UK to Cape Town which in our world ain't bad at all.

The reviews are all good, many recommend the eyepiece punches above its weight at its price. 

I'm really looking forward to some clear skies so I can give it a run on the xt8.

At least you didn't get this one! 😂

I tried the Wratten #8 on Jupiter , this evening.  It did reduce the CA and also seemed to bring out the N and S equatorial belts, making them easier to see.  The yellowish colour wasn't unpleasant, actually quite nice.

1 hour ago, John said:

It is a whopper - 2.2 lbs !

When I'm using it with my dobsonian I do need a heavier counterweight.

 

 

That's an unexploded hand grenade!🤣

On Jupiter, this evening.  The Wratten #8 made a difference to the CA, making some of the features on the Jovian disk easier to see. I think it made the North and South equatorial bands stand out more. 

Then the clouds rolled in and the neighbour's floodlight came on. 🤬

I was observing Jupiter, a bit earlier. Then the clouds rolled in and a neighbour's floodlight came on. 🤬

5 hours ago, Franklin said:

I see you have X2 5kg weights on your EQ5 with the Evo120. I think I only used one of the weights when I had that set up. SW120 = 6kg?

Absolutely, spot on. 👍

I'm trying to set up the new SW EQ5 Deluxe mount, I got a few days ago. 

Do I need to polar alignment using the scope, etc, just for visual use? 🤔 I can't see Polaris from my backdoor, due to houses in the way. 

The old Meade EQ-1B mount was a bit easier to set up. 

I bought a customer returned EQ5 Deluxe mount from @FLO, the other day.

I've found a few loose washers inside the boxes, so am unsure where exactly they came from. There's at least one that's 10mm and the rest are probably 6mm. I'm not sure if they are for the dovetail. 

Has anyone with a EQ5 Deluxe know what they are for? 🤔

This arrived from Auntie @FLOyesterday evening. It's a customer returned EQ5 Deluxe mount.

Excuse the mess of the spare room (including the washing drying). 🙄

Courtesy of Auntie @FLO, a Wratten  #8 filter. 

13 minutes ago, TBRHussaR said:

Obsession telescopes has a video on YouTube about how to clean mirrors. I’m not sure if I’m allowed to post a link, but if you google it , it’s there. 
I also get dew when moving my stuff in. I also just let it dry overnight. I think a cap helps prevent dust settle on the wet surface .

Like this?

https://youtu.be/tQrkJubzyP0

Are they like this?

https://web.archive.org/web/20050923061253fw_/http://www.trutek-uk.com/truetech/filters.html

1 hour ago, Franklin said:

That will do the job. When used on the moon the filter will give a slight yellow cast, but all the fancy minus violet filters do that as well. At the end of the day there is only a small number of objects that you would want to use such a filter on anyway. Moon, Venus, Jupiter, Saturn, Mars and anything brighter than around mag2.

And a lot cheaper too!

I've ordered a Wratten #8 filter from @FLO, their own brand Astro Essentials in 1.25".

12 minutes ago, vlaiv said:

It is better to make your own, it can be as simple as cardboard cutout or fancy like 3d printed part. If you make one - you'll control diameter of opening (say go for 80mm or 100mm) - and it is best if opening is in the center of the lens rather than to one side.

Newtonian scopes often use off axis aperture mask due to central obstruction, but for refractors - it is better to go on axis.

That photo was taken from another website, it was just to use as an example.  My refractor has a centre hole in the dust cap.  Agreed about making my own...

24 minutes ago, vlaiv said:

Did I get this right, you have Evostar 120 with you right now?

Why don't you use that one to get the sense of 80mm F/12.5 scope?

If you make 80mm aperture mask for that scope - you'll get 80mm with 1000mm FL - which gives F/12.5.

Btw, that is effective way to get planetary scope out of larger achromat. You can try different size masks to see which one gives you best view as aperture too stopped down will impact level of detail, and not stopped enough will leave some CA. Depending on how sensitive you are - you can hit balance between the two for the best views.

You can even combine aperture masks with filters (say Baader Contrast Booster).

I was thinking of using the Evostar 120 with the dust cap on, but with the small hole in it to stop it down.

So recapping, I'm back to looking at the Scopetech 80mm offers from Aunty @FLO.  Will I notice the difference between the F15 and F12.5 versions?  What difference will the single verses multi coating make?

The reason for the renewed interest is, I've got a SW EQ5 Deluxe mount coming.  Also, @FLO has a price drop on a ex-display model of the F12.5 version.

https://www.firstlightoptics.com/offers/offer_scopetech-stl80a-l-80mm-f125-classical-refractor_155968.html

I'm glad someone else saw that 'extra' moon too!😄 I saw it quite clearly the last few nights. Not tonight though, as we're clouded out!

Last night, the moon looked great in the 8" Dob, using the 28mm 2" LET eyepiece.  Tonight, clouded out!

I used the 28mm 2" SW LET and 8" Dob on the moon, last night.  It was breathtakingly sharp in it's clarity!😮