RDF annoyances

[wibblefish]

I have a short refractor with a standard skywatcher rdf mounted towards the rear. My skies are supposedly bortle 4 but I am in an urban area with a few streetlights and near neighbours who have windows illuminated late into the evening plus some security lights.

The RDF works fairly well (though obscures the target as its bright dot) but I struggle with it when there isn’t a very bright target on some nights  and also when angling upwards (my garden has some tall trees around it so I often have to have a steep angle) I get issues aiming correctly (parallax?). 

I have a couple of thoughts but not sure what may help or if it’s something to put up with:

- Get an RACI finderscope and combo it with the RDF on a multishoe - would this be overkill and / or cause weight / balance issues on  a short tube?

- Replace RDF with telrad (maybe to big?) or a rigel mounted further up the tube?

- move the RDF up the tube (somehow its fairly light so guessing a sticky pad)

Any suggestions / opinions would be appreciated I imagine I am just being annoyed by something small that needs to be put up with! 
 

On the plus side my BST EP will be here soon so I am hoping the wider field of view will help when the RDF yoga is happening 🤔

Edited January 11, 2021 by wibblefish

[Ricochet]

I am a big fan of 9x50 RACI finders, but you are right that it might cause balance issues as it is a significant size compared to your telescope. I don't think there is really any way to know how it affects the scope except to try it. You can get a smaller 6x30 right angled finder, although I can't recall if RACI is an option, but obviously this has both less magnification and light gathering ability. 

If you do get some sort of right angled finder, my preference would be to relocate the red dot. The Telrad in particular is a very large finder and could even obscure the optical finder on an scope of that size. 

Also, which BST have you ordered? 

Edited January 11, 2021 by Ricochet

[NGC 1502]

Many RDFs are too bright even when turned to the dimmest setting, this certainly makes them harder to use.

Solutions include - if you’re ok with electronics you could insert into the circuit something to dim the red dot. A lower tech idea that I’ve done myself is to use red nail varnish on the source of the dot.  Let it dry then test, you can add more nail varnish.  Best to test in the dark to get a better idea if it’s ok.  I tried using red cellophane from sweets but the dot turned into a large blob.

Ed.

[NGC 1502]

PS - please don’t let on that Ed from Essex uses red nail varnish 😁

[wibblefish]

@Ricochet there is a 6x30 raci which I guess would be lighter. Aye I did wonder about balance and weight, there seems to also be a school of thought that the short tube is wide enough you dont need a finderscope. Maybe ill just trying moving the RDF further forward first and see if that makes a difference.

I have 25, 18, 12 BST with a barlow coming so hoping those will help as they are 60 degrees.

@NGC 1502 thats a good idea, I dont mind tinkering with electronics but maybe the nail polish would be less invasive 😎

[Ricochet]

The 25mm BST would give a field of about 2.3°. The 5° of a 9x50 RACI is quite an improvement on this. 

[wulfrun]

1 hour ago, wibblefish said:

 

@NGC 1502 thats a good idea, I dont mind tinkering with electronics but maybe the nail polish would be less invasive 😎

Not sure nail polish is actually a good idea, on plastic components the solvents may well dissolve things. Glad to hear I'm not the only one who finds the RDFs too bright. I have (probably) the same one and I'll be tinkering with the electronics for sure. I also have a Celestron one that projects circles and that's also too bright.

[Tiny Clanger]

Apart from it being smaller than the telrad (which would have taken up pretty much the entire length of the 127 mak tube) I specifically bought the Rigel Quick finder because it not only has circles rather than one spot ( half a degree and two degrees, not the same as the telrad's ) and adjustable brightness, but it also has an inbuilt pulsing option. Bythe way, both Rigel and telrad come with sticky pads to fix their bases on your telescope tube : don't know about the telrad, but the rigel has two bases included for different tube diameters (very handy, one for my mak one for the dob) The telrad and Rigel bases are not the same as a standard finder shoe, so you can't just slot them in .

On the Rigel QF , just by the on/brightness/off knob is a second, smaller one which lets you adjust it from steadily on through a range of speeds of blinking on/off.  The slowest on/off pulse is about 2 seconds on , the same off( I just checked !).  You can select whatever combo of brightness and blink speed (or none) that you find convenient Very handy, I've the Rigel and a 6x30 RACI , and having both available has made the few viewing sessions I've managed since mid December much easier.

I believe you can buy an add on for a telrad to make it pulse, but it comes built into the Rigel .

Heather

[wibblefish]

@Tiny Clanger thanks, I need to read a few more reviews about the Rigel, I could probably mount it on the objective end of the scope so I dont have to squat down so much and then use the finder shoe for either a 6x30 or 9x50 RACI ... I guess I need to work out how much difference in weight their is (not easy as nowhere seems to have that info on the sale sites nor skywatcher main!) between them (and price!). Either way I'll wait till I get the BST and see how it looks.

Edit: looks like according to amazon the 6x30 is 204g and according to skyatnight the 9x50 is 450g so maybe the 6x30 + Rigel (80g) is the way to go to keep things light and easier to balance on a very small scope - especially as the BST eye peices will add more weight also to the same end

Edited January 12, 2021 by wibblefish

[wibblefish]

I swear its a slippery slope, I went from trying to find any information on the weight of finder scopes to looking at upgrading the tripod from the aluminum az3 basic one to something more sturdy with an extension pillar  

@Tiny Clanger I  noticed FLO only has the RA version of the 6x30 skywatcher finderscope, what one do you have / where did you get it if you don't mind me asking?  

Also I have BST starguider EPs arriving today and my weather app is fluctuating between clear and cloudy ... I suspect it will be the latter just to thwart me!

[Zermelo]

6 hours ago, wibblefish said:

looks like according to amazon the 6x30 is 204g and according to skyatnight the 9x50 is 450g so maybe the 6x30 + Rigel (80g) is the way to go to keep things light and easier to balance on a very small scope - especially as the BST eye peices will add more weight also to the same end

If you're looking at the Skywatcher 6x30 RACI, the figure I found was 308g including the bracket?  I'll find out soon - mine is due imminently (🤞). I considered the 9x50 but decided it would be too heavy.

I've been through a similar process as you, but with a 750mm long reflector. The scope was designed to be as light as possible to go with the Star Discovery mount's limit of 5kg, but there's still a decent degree of leeway. The other consideration, as you say, is balance. So I ended up replacing the red dot with an optical finder (but soon to be upgraded to the RACI) in the front shoe, and adding a Telrad (300g including batteries and base) at the back end. My heaviest EP is about 160g, (of course on my Newt that's near the front end), and overall the shift in centre of mass can be accommodated within the (quite short) limits of the fixed puck. So far, I've not noticed any degradation of the goto or tracking with the extra weight. With hindsight I might have gone with a Rigel instead of a Telrad, being lighter and having the built-in pulser (which I think I will end up making for the Telrad).

19 minutes ago, wibblefish said:

FLO only has the RA version of the 6x30 skywatcher finderscope

True, more's the pity.  I ordered mine from Bristol Cameras, though they don't keep stock. Rother Valley list them on their web site but when I called, they were out of stock. I suspect the same everywhere.

 

 

[Zermelo]

Also listed here, though hard to trust availability without checking.

[wibblefish]

@zermelo yeah I am going to see how the BST EPs affect the weight on mine at the back end and then think about finder scopes (which are rear end mounted), tripod its a light weight aluminium thing (though the AZ pronto head is very good) to go with the short tube being light so don't want to risk an overbalance - I think my weight limit on the tripod is only about 3kg max(?) but there are so scant details about the telescope / tripod weights  so that its all guess work.

At the risk of sounding a bit silly I assume if I purchased a more substantial tripod such as (https://www.firstlightoptics.com/tripods/sky-watcher-38-stainless-steel-tripod.html) it would improve the load carrying significantly or is it more to do with the mount head?

The Rigel is only 80g I think so not worried about that (plus itd be further forward). Appreciate the links I am not overly worried about availability in all honesty as everything is out of stock everywhere I was just looking for a retailer recommendation as I haven't used anyone bar FLO  

 

Edited January 12, 2021 by wibblefish

[Tiny Clanger]

Quick reply while having a brief coffee break : the 6x30 RACI I got in the summer was from a camera shop , I've dealt with Bristol Cameras  and Carmarthen Cameras, not sure which one was the RACI vendor, both gave good service . Just popped the RACI on the kitchen scales, it  weighs 263g, I have the shoe for it placed close to the established balance point on the Heritage tube so having it there vs having it on my mak will not mean faffing with the heritage's balance.  The Rigel weighs 66g,  it doesn't make a significant difference to the balance of either 'scope.

I found swapping  from BST to the stock EPs messed up the balance of the heritage, you really notice the difference with a dob base, what I did was find a big hefty magnet ( removed from a damaged audio speaker) , stick some felt on the side to stop it scratching the 'scope, and that sticks on the bottom end of the tube when using a BST to balance it . My BST 15mm weighs 173g, the stock 20mm 40g !

Heather

[wibblefish]

19 minutes ago, Tiny Clanger said:

Quick reply while having a brief coffee break : the 6x30 RACI I got in the summer was from a camera shop , I've dealt with Bristol Cameras  and Carmarthen Cameras, not sure which one was the RACI vendor, both gave good service . Just popped the RACI on the kitchen scales, it  weighs 263g, I have the shoe for it placed close to the established balance point on the Heritage tube so having it there vs having it on my mak will not mean faffing with the heritage's balance.  The Rigel weighs 66g,  it doesn't make a significant difference to the balance of either 'scope.

I found swapping  from BST to the stock EPs messed up the balance of the heritage, you really notice the difference with a dob base, what I did was find a big hefty magnet ( removed from a damaged audio speaker) , stick some felt on the side to stop it scratching the 'scope, and that sticks on the bottom end of the tube when using a BST to balance it . My BST 15mm weighs 173g, the stock 20mm 40g !

Heather

Appreciate all the measurements Heather! Yes I managed to find somewhere that BST EP is about 170g each, my stock ones are light as anything so I would reckon probably similar to yours. I have (at the moment but it seems to change every hour) clearish skies tonight so I might get a chance to chuck the BST on and see how it affects the scope balance etc (also add the barlow for more weight!), I can always re-center on the dovetail as I think I copied how it was set in the demo pictures as I figured that would be a good start lol 

Edited January 12, 2021 by wibblefish

[Tiny Clanger]

Forgot to say, my 6x30 RACI is the skywatcher model, altho' there is no branding anywhere in sight on it , just a small sticker on the box it came in.

I don't have direct experience of the az3 tripod , but when I was investigating az mounts found that the az5 is rated to carry 9kg itself, but paired with the aluminium tripod (which I guess is the same one as yours)  the combo is rated at 5kg.

I already had a strong , stiff , photo tripod ( a Manfrotto 055, it weighs about 3kg itself) which has a weight rating of 9kg, and would cost about £150 new if bought now (Ive owned it for about 25 years ) , so that's what I put the mak & az5 on. The mak 127 is a substantial little lump of metal and glass and weighs around 3kg, it works really well on the tripod & mount combo.

If I needed to use the big Manfrotto a lot for photography ( I have travel tripods which are fine for most purposes) I'd be really torn between the skywatcher steel one , or seeking out a second hand manfrotto . I suspect the photo tripod closes up smaller (it has 3 sections vs the skywatchers 2 ) and I've always liked the click locks which are a fast and positive way to extend the legs. On the on the hand, the skywatcher has a larger platform to seat the mount on, weighs more ( hard to find specifications, but I've seen around 7kg being quoted ) more mass is good for stability,  and it is simpler ...  I like simplicity, less to break or go wrong .

Heather

[PXR-5]

I recommend the 6x30 raci finder, the 50 is a big boy and heavy.

 

You will still need the RDF to get you in the neighbourhood though. 

[John]

I use 6x30 RACI's on my 4 inch refractors and 9x50 RACI's on my larger fracs and my 12 inch dob. I seem to have developed a collection of these things !

 

[Ricochet]

2 hours ago, Tiny Clanger said:

I found swapping  from BST to the stock EPs messed up the balance of the heritage, you really notice the difference with a dob base, what I did was find a big hefty magnet ( removed from a damaged audio speaker) , stick some felt on the side to stop it scratching the 'scope, and that sticks on the bottom end of the tube when using a BST to balance it . My BST 15mm weighs 173g, the stock 20mm 40g !

That doesn't sound right. You should easily be able to add or remove an eyepiece as small as a BST without needing counterweights. Have you got the friction set right on the altitude axis? 

[NGC 1502]

19 hours ago, wulfrun said:

Not sure nail polish is actually a good idea, on plastic components the solvents may well dissolve things.

Always a good idea to check if modifications could cause a problem, so thanks to wulfrun for mentioning this. It would be easy to try the nail varnish on a hidden area of the RDF.  But I’ve not had a problem myself and it worked to dim the red dot to an acceptable level.   Low-tech solutions are my favourite 👍

Ed.

[wibblefish]

Thanks all I actually managed to get a good play with my new BST EP last night (including barlow briefly) and I don't seem to be seeing any issues with balance that I can tell (other than if you fully loosen the ALT and tilt the scope up but that is fairly normal I presume as it was doing this with the old EP).

I will definitely be looking into an RACI 6x30 and Rigel setup sooner rather than later as I had similar issues last night with the RDF just not being able to see anything. I ended up using some bino's are a guider till they fogged up and then reduced to guessing vaguely where in the sky to place the RDF due to the light pollution and being dazzled repeatedly in various directions  

Sidebar: the BST 25 and 18 are really an amazing improvement on my stock 25mm, ridiculously so, the 18mm seems the better of the two but there is something nice about being able to have the whole of Pleiades in the view at once. I also got some amazing detail on views in M42 in Orion (one of my favorite targets atm) with the 18MM and barlow which I was surprised at. I am awaiting my BST 12 today though I fear I won't get a chance to test it for a while looking at my weather apps for the next week!

Edited January 13, 2021 by wibblefish

[KP82]

8 hours ago, wibblefish said:

Thanks all I actually managed to get a good play with my new BST EP last night (including barlow briefly) and I don't seem to be seeing any issues with balance that I can tell (other than if you fully loosen the ALT and tilt the scope up but that is fairly normal I presume as it was doing this with the old EP).

I will definitely be looking into an RACI 6x30 and Rigel setup sooner rather than later as I had similar issues last night with the RDF just not being able to see anything. I ended up using some bino's are a guider till they fogged up and then reduced to guessing vaguely where in the sky to place the RDF due to the light pollution and being dazzled repeatedly in various directions  

Sidebar: the BST 25 and 18 are really an amazing improvement on my stock 25mm, ridiculously so, the 18mm seems the better of the two but there is something nice about being able to have the whole of Pleiades in the view at once. I also got some amazing detail on views in M42 in Orion (one of my favorite targets atm) with the 18MM and barlow which I was surprised at. I am awaiting my BST 12 today though I fear I won't get a chance to test it for a while looking at my weather apps for the next week!

6x30 RACI is definitely a good choice for smaller refractors. I used to have a SW one until I moved to GOTO mounts exclusively for my refractors. I still have a RDF and 8x50 RACI for my dob.

25mm BST is the weakest among the bunch, very obvious astigmatism towards the outer region. When I had my BSTs, the 12mm was my favourite. The 3.2mm wasn't bad either but I had ghosting issues with my 5mm when viewing Mars and Jupiter.

[Carbon Brush]

Going back to the RDF. I have suffered with a few of these in times past.

I think it was a Skywatcher that was so bright it washed out Jupiter when centred. OK as a a daytime RDF!
Somewhere (years ago) I posted my mods to make it usable.
A large fixed resistor, and a variable resistor for brightness control. Also a switch to go back to original brightness.
After this I got on OK with it.

Another (unknown make) had a tinted (rather than reflective) window.
This time you struggled to see Jupiter - because it was dimmed so much.
Not much you can do about that.

If you can find a decent example, they are OK.

HTH, David.

[Pixies]

8 hours ago, wibblefish said:

Thanks all I actually managed to get a good play with my new BST EP last night (including barlow briefly) and I don't seem to be seeing any issues with balance that I can tell (other than if you fully loosen the ALT and tilt the scope up but that is fairly normal I presume as it was doing this with the old EP).

I will definitely be looking into an RACI 6x30 and Rigel setup sooner rather than later as I had similar issues last night with the RDF just not being able to see anything. I ended up using some bino's are a guider till they fogged up and then reduced to guessing vaguely where in the sky to place the RDF due to the light pollution and being dazzled repeatedly in various directions  

Sidebar: the BST 25 and 18 are really an amazing improvement on my stock 25mm, ridiculously so, the 18mm seems the better of the two but there is something nice about being able to have the whole of Pleiades in the view at once. I also got some amazing detail on views in M42 in Orion (one of my favorite targets atm) with the 18MM and barlow which I was surprised at. I am awaiting my BST 12 today though I fear I won't get a chance to test it for a while looking at my weather apps for the next week!

The 12mm BST is noticeably better than the 18mm - so you'll like it.  What scope do you have?

[wibblefish]

@KP82 I did like the 25mm and didnt notice that but my scope is a bit “soft” towards the edges I think  mostly due to being a short tube so it doesn’t bother me to much.

I am kinda hoping the RACI will help me when (like last night in certain directions) I had periods where I was just placing the dot roughly where I thought the object was as the sky as it was just purple with no stars I could see to start hopping off from. When viewed through the binos I had no issues finding stars to guide, I did a lot of sweeping to with the 25mm and then switching to the 18mm when on target which was good fun and will likely do that until I sort a finderscope.

@Carbon Brush thanks for the advice, whilst I do definately think the RDF is to bright (it basicall ly covers an area over the target and you cant really see mich through the tint (I assumed you arent meant to - more like focus one eue on the target dot and the other eye to overlay it?) I think maybe moving it forward or possibly changing to a circlular ringed RDF might help me more I will have a play with it!

@Pixies it arrived today but I feat no clear skies for a while now to test it! I am impressed with the 25 and 18 (in particular as it was also good with the BST barlow) especially the eye relief so I am hoping the 12 will be good also. Looking forward to trying it on the moon in particular as I imagine it will be a massive improvement on my old 10mm! 

My telescope is an Evostar 90/660   (f7.3) short tube refractor. I dont have any knowledge for comparison but I am quite happy with it so far, a little soft at the edges but not enough to worry me. It works well as a grab and go out rather than having to faff to much. I should probably write a review eventually as I have not seen anyone mention this scope anywhere online but I guess thays fairly standard for a random beginner level telescope 🧙‍♂️

 

 

 

 

 

Edited January 13, 2021 by wibblefish