davhei

1 hour ago, miguel87 said:

I definitely wouldn't put acetone on my coated lenses. I'm no chemist but it doesnt sound like a good idea to me.

I’m no chemist either but Televue in fact recommends using it for cleaning optics on their website. That’s good enough for me.

3 hours ago, Waddensky said:

I'm not really sure how they're called in English, but in Dutch we call them 'ironing chairs'. They offer the same functionality as observing chairs but they are usually much cheaper. I've been using one for years. It's remarkable how expensive things can get when they're 'astronomy' branded. Just a suggestion 🙃.

A strijkstoel? Thanks for the suggestion, I will look into that!

28 minutes ago, Apprentice said:

Can anybody tell me if this would be a good choice:

https://www.astroshop.eu/lens-cleaners/lacerta-reinigungsset-fuer-optiken/p,62923

 

I am leaning towards getting this, as it contains the air blower which I would need to blow the dust and other particles from my primary mirror as well as eye pieces.

 

Thanks!

Dust blower looks fine. I personally wouldn’t use the brush and I would also stay clear of cleaning solutions that contain fragrances or other additives that might leave residue on the lenses.

For cleaning eyepieces I use acetone and the fog from my breath together with cotton swabs. Lots and lots of cotton swabs. Before going at them with the swabs I would highly recommend an air blower that you find in places that sell camera accessories. Like a rubber bulb that you squeeze to blow away bigger dust particles that otherwise might scratch your lenses.

Works well for me.

Considering the hand drawn picture by @Pixies a few posts back made it clearer to me.

Note how the same amount of rays reflect to your eye off both the small and large flat mirror. It is the size of your pupil that determines the brightness of the image in this case, since the mirror reflects most rays to the side of your eyes, not into them. For all intents and purposes it is like looking at the moon/object directly. There being a mirror inserted into the optical line doesn’t make a difference, assuming 100% reflection and a perfectly flat mirror.

The parabolic mirrors however focus many more rays to your eyes, with the larger reflecting more than the smaller.

No expert on this but it seems logical.

Welcome to the forum!

6 hours ago, Littleguy80 said:

I successfully observed SN 2020hvf this evening. I identified it fairly easily at 133x (Lunt XWA 9mm and 9mm BGO). At 200x (6mm BGO) I could see the mag 13.2 next to it which gave me confidence that it was indeed the SN I was seeing. After failing to see 2020ftl a few weeks back, I am extra pleased to get this. It took me a little while to match up the image above to SkySafari. I’ve marked up some stars below as a guide. I was using these as guides to identify 2020hvf.

 

I did hop over to M61 too. However, SN 2020jfo seems to be holding around mag 14.5, putting it out of range for me from home. 

Well done! Was it possible to see the SN2020hvf host galaxy or was it too faint?

48 minutes ago, c4llum83 said:

The BCO arrived today so the collection is now complete (for now!) and although they're not top-end high value eyepieces, I'm really happy with the selection as they all come highly recommended on these forums and didn't cost the earth!

With these and my brilliant little SkyWatcher Heritage 130p (AWB OneSky) hopefully I should have plenty to help me start properly exploring the moon and night skies over the coming years! 🚀

 

That's inspiring, adding space in the case for the evening tot 😂

All of my four eyepieces, a barlow lens, some filters in the boxes and a basic laser used for barlowing in order to check primary alignment. A collimation cap.

A small handheld plastic mirror is tucked away snugly right up to the orange case wall. I use it to view the barlow laser target in the focuser.

Also put in a laminated hand written note by the mirror to remember how the primary adjustment screws affect the alignment and other collimation related things I tend to forget.

For sundry bits and pieces and general stuff I have a large plastic box with a sealed lid. Usually have it next to the eyepiece case when observing to have everything in easy reach and in the same place.

I use a 10” f/4.7 dob.

On 01/04/2020 at 17:30, Barry-W-Fenner said:

Afternoon all,

 

I have just been searching threads on collimation and came across this one. Did you manage to resolve the issue? I ask as I have recently fitted a dual speed focuser to my 200p I to have a similar thing happening to me when I de-focus a star. It inst anywhere near as bad as yours to be fair, I am just losing a small slice on one edge, However it is the same shape as your 2nd pic.

Recently my viewing has been fine unless I go upto and over x150 Mag, Then things are getting very blurry. I thought it was down to bad seeing however I am not totally convinced it is. If i use high power on Venus or the Moon x240 they both produce excellent views. it Seems to be stars that are blurry and have 1 of the 4 defraction spikes is much more noticable almost pulling the start tear drop shaped.

I have collimated my mirrors with a calibrated laser and they seem ok, However if this is due to an issue with the focuser install then its all going to be out of line I assume.

John- Where did you purchase your concenter from? I would like one of these as they seem an excellent solution for collimation of a newt. They are a bit on the £££ side though 🙂

Davhei - I hope you managed to resolve your problem. (No pun intended) 🙂

Any advice appreciated.

 

Baz

 

 

 

Hey,

Thought I’d follow up on this. No real quick fix as such, but I spent some time positioning the secondary and getting collimation as good as I could. Perhaps not dramatically different to the way it was in my first post but certainly better. Learnt a lot in the process. Also noticed that my eye placement at the EP made a bit of difference and it was easier to see that when properly dark adapted, which I wasn’t in my first post.

All in all, I thought the star images from my dark site yesterday was as good as any I had before the focuser change, if not better. If it was secondary placement, my eye placement at the ep or just me being a bit less neurotic. Not sure. I’m quite happy though and feel comfortable with the scope now.

Had good views through bins both on Friday and Saturday, a grand sight to be sure. Thought the placement of Venus was most spectacular on Friday although the view was very striking on both evenings. Very glad to have seen it.

1 hour ago, banjaxed said:

I am no expert but if you are both experiencing similar problems after replacing your focusers then IMHO this is where the problem lies. Could you loosen the focuser screws slightly so it can be moved a little while you are observing to see if it makes any difference?

Certainly makes sense. If the issue persists after I give aligning the focuser a go then I will do that to check what happens.

Hey Baz,

I haven’t unfortunately. What I’ll do probably tomorrow is take out the secondary and make sure the focuser axis is squared, remount the secondary and fine tune the alignment as good as I can get it. Essentially a complete adjustment. Never done that before but kind of look forward to fiddling with the scope a bit.

Next clear night I’ll check and see if it is sorted. Fingers crossed.

If not, well.. let’s cross that bridge then..

If you find a solution I’d be thankful if you please post a follow up in this thread. I have a similar thread on CN in the reflectors forum, got some good input there that might help you out.

/Dave

Tried the scope against a star last night and unfortunately the same issue. In low magnifications, the out of focus image of the star has an eye shape instead of a round shape.

Moving my eye position at the EP tranformed the image into a normal round one, but when centering my eye for normal observing it ceases to be round. This causes a loss of light, and a clear darkening of the image. Vignetting?

Rotating the EP in the focuser did nothing to change it.

Does anyone recognise this? Is it a matter of squaring the focuser?

Some people (for instance a reply I saw from skywatcher that someone posted earlier) seem to insist that as long as the focuser axis is aligned with the center of the secondary it doesn’t matter that much if the focuser is not centered in the OTA. Don’t know what to think, hmm.

Tweaked the secondary a bit while installing bob’s knobs and two milk jug washers. Checked the secondary position with the cheshire combo tool and collimation cap and got the below result. Seems decent, can’t imagine it would cause the problem I described, or?

I’ll test again this evening, unbelieavably it looks like yet another clear night. Let’s see if it persists.

3 hours ago, johninderby said:

Have you checked the focuser for being square to the tube.

For checking the secondary position there is nothing better than a Concenter. Really usefull colimation tool and makes it easy to perfectly centre the secondary. It’s the first tool I use when setting up a newt.

https://www.teleskop-express.de/shop/product_info.php/info/p5506_TS-Optics-Concenter-2--Collimation-Eyepiece-for-Newtonian-Telescopes.html

I haven’t squared the focuser. Most people seem to have a smooth transition between focusers when using the moonlite installation kits with SW dobs, but perhaps that is it.

I was reading astrobabys collimation guide but couldn’t find that particular part covered. Do you have a preference for how to do it? Read that some take out the whole secondary mirror, measure on the opposite tube wall from the focuser and use a laser to adjust the focuser. Was hoping for something easier than removing the whole mirror assembly.

Yesterday I changed the stock rack and pinion focuser of my SW 250 solid tube dob for a Moonlite CR2. Went fairly smoothly but when I took the scope out in the evening (clear skies the very same night, imagine that!) to check focus distances and collimation I noticed something I had not seen before.

When star testing collimation on arcturus the star image was appearing cut off, which became more apparent when I moved it further out of focus. See picture where you can see the shadow of the secondary.

If I moved my eye slightly to the side in the eyepiece it became normal again, showing the full circle.

The usual star test looked decent though with concentric circles collapsing to a point. When collimating earlier I did only minor adjustments to the mirror alignments prior to the focuser change, just like any night. Used a cheshire combo tool and barlowed laser.

Snapped another picture through a collimation cap with colored paper behind the secondary.

My guess is the main issue is that the secondary mirror is not centered in the focuser and needs to be moved in the direction of the opening, i.e. towards the spider, by manipulating the center screw.

Would this misalignment give the error I saw? I would like to think that the focuser is ok, understand moonlite has good collimation quality control and fiddling with the focuser collimation screws would be last on my list.

I have not done any adjustments to move the secondary before so am a bit apprehensive to start messing with it if the issue is elsewhere.

Appreciate your thoughts.

5 minutes ago, John said:

Excellent sketch !

An O-III filter makes M97 pop into view quite a bit easier but thats at the expense of M108 which all but disappears so if you want to see both in the view, unfiltered is better.

 

Thanks! Didn’t think of using the OIII-filter actually, have to do that next time. Would be interested to see if it is possible to see the owl eyes.

9 minutes ago, Jiggy 67 said:

That is a fantastic sketch!!....in more ways than one. Tonight I posted a report in the Observing Report section about last night and my observations of M97. I wasn’t sure I was actually seeing it but your sketch and the prominent 2 stars to the left confirm it!!...Thanks 

That’s really cool, glad I could help! Read your report and enjoyed it, actually had M53 on my list too but never got around to it. Got absorbed by the more spectacular M3 and M5 instead. Next time.

Just back in from a nice dark sky session where I had my first look at these two messiers in UMa. Lovely pair that I thought were very prominent. Was observing close to zenith which made finding them a bit awkward but I’m glad I persisted.

Is it confirmed? I read a magnitude of 11 on rochesterastronomy.org.

So now there are two SNs in the Virgo/Leo vicinity with magnitudes of around 11-12! 

Just need the clouds to part..

Welcome! Great images, really like the widefield with Barnard’s Loop clearly visible. Keep them coming and enjoy.

20 hours ago, Martin Meredith said:

I also love reading up on objects. This is what I sometimes do: 

1. Go to Simbad: http://simbad.u-strasbg.fr/simbad/

2. Type in the name of the object in the Basic Search box. This brings up some basic info on the object.

3. To find out more, scroll down to References and press the button marked 'display'. This brings up much of the known literature in which the object is mentioned, most-recent first. You need to be a bit selective here, but it can be interesting to look at the earliest such reference as well as some of the most recent.

4. To find out about a specific reference,  after clicking on the title (which brings up an abstract), the best option is 'view the reference in ADS' (near the base of the page). 

5. Once that page comes up, nearly always you'll find a free pdf on arXiv (link on the right go the page). Often going to the publishers website you get the abstract only.

Hope this helps!

Martin

 

That's a brilliant suggestion Martin, couldn't have asked for anything better really. Thanks for posting!

On ‎11‎/‎02‎/‎2020 at 01:48, John said:

Lately I've been enjoying observing relatively straightforward targets such as open clusters and double stars etc and then finding out more about them, when they were first observed and by who, theories and discoveries relating to them, quirky information etc, etc.

Armed with a little bit more information, a familiar target seems to take on a whole new level of interest I find

Reading old accounts by well known (and not so well known) historic observers then examining the subject with your own instrument and eye is also absorbing.

 

 

John, do you have a favourite source for reading up on objects? Wikipedia is a treasure trove but I was just thinking if you had something specialised.

Welcome Tom, look forward to seeing some of your imaging work if you feel like sharing.