John

There is a noticeable difference in the views between 102mm and 127mm refractors of similar quality. Quite a difference in size as well: 150mm F/8 - 127mm F/9.4 - 102mm F/6.5:

Lovely views here - thanks for the heads up David Really clear and obvious black shadow - even a small scope will show this Your dance worked !

Triplets can be sensitive if one of the lens elements gets de-centered, ie: it's optical axis is not exactly in line with the other two. Quite a tricky thing to diagnose and fix though.

Has it had a knock ? If it used to perform and now does not, something must have changed

This is quite a neat idea. Large eyepieces laid out horizontally with an insert for smaller eyepieces to be stored vertically:

Have to make do with an unlovely one ! I've left a link in the original posting location so people can find it from both places.

I agree with all of the above ! 4mm is simply not the right eyepiece for seeing nebulae and galaxies. 30mm - 20mm eyepieces are much more useful for this task. Collimation makes little difference where such targets are concerned.

Lack of contrast on the planets. Not being able to get a clear split of double stars under reasonable conditions. Non-concentric diffraction rings on stars either side of focus at high magnification. You can also check collimation with a cheshire eyepiece and the optical alignment of the focuser and objective with a laser collimator.

The figure I found on the CN forum is 21.2mm.

Good advice from Craig Re; your 1st photo - I suppose that is a shadow on your secondary mirror rather than a felt pen line, which it looks a little like ?

When I had an 8 inch F/5.9 dobsonian, I also had the 22mm Type 4 Nagler and it is a superb eyepiece Another possibility would be the 28mm Nirvana which is also an 82 degree eyepiece.

Very encouraging 1ist light report I like to try out new-to-me refractors on some tight binary stars including those of uneven brightness. Stars such as Delta Cygni and Pi Aquilae are currently well placed for such trials. From my own experience moving from a TAL 100 to an ED doublet, the difference between the TAL 100 and the Altair 102ed-r will be mostly in the control of false colour I think. The TAL 100's that I've had have had well figured objectives so will basically show most targets as well as the more expensive ED doublets will but with some false colour around the brighter targets. The faster focal ratio of the Altair will open up options for wider fields of view than the F/10 TAL can achieve though and should be OK on a slightly lighter duty mount.

Must be something wrong with my TeleGizmo's cover. It's been through two owners and is around 8 years old and still in good shape and weather proof

You are correct of course but the term is in wide circulation throughout the astronomy world and has been for the past decade or more. I suspect we are stuck with it Do you have any suggestions for the original poster on suitable telescopes ?

Dew shield looks longer than the Messier 127L that I used to have and the objective cell looks different as well. The one above looks more like a 102mm to me This was my Bresser 127L:

I have both O-III and UHC filters. The O-III filters get used a lot more. Good advice above on not economizing on these sorts of filters as well. The low cost ones are noticeably less effective from my experience.

Great sketch Mike ! Interesting comparing one of Lowell's sketches to yours (see below). You can sort of see how he came to the "canals" idea. He just took the contrast of the linear features that bit further ! He had a scope 20 inches larger in aperture than yours though Talking of which, I was at the Lowell Observatory this time last year - what a long time ago that now seems Anyway, sketches. I've cropped and rotated yours to get a closer match, hope that is OK ?: Percival Lowell, 1894: Mike Hezzlewood 2020 (cropped and rotated):

It is probably best if this thread deals with @Steve Clay's issues with the Baader Steeltrack in his ED120 scope rather than open up a general discussion on other scopes, definitions etc. I wish I could help myself but I use a Moonlite focuser with my ED120.

I find that it's very useful to have both types of finder on the scope. The Telrad / Quikfinder type to get to the right patch of the sky and then the optical finde (I prefer the RACI types) to get much more precisely to where the target is. I make sure that the optical finder is accurately aligned so that what is in the cross hairs is in the center of even a high power eyepiece. It is quite possible to operate with just one or the other finder types but having both is the optimum in my opinion. This is the top end of my 12 inch dobsonian:

You might find these threads of interest - they both involve the same scope that you are about to upgrade to: https://stargazerslounge.com/topic/360946-preferred-focal-length-spacing-for-your-eyepiece-collection/ https://stargazerslounge.com/topic/361886-help-with-my-eye-piece-set/

They are very different eyepieces I agree. Do you have the eye cup in the "up" position ? If you wear glasses when observing though, the eye cup should be twisted down.

Mine is a TeleGizmo's but not a £200 one: https://www.firstlightoptics.com/telegizmos-telescope-covers/telegizmos_tg2d.html I bought it used for around £30 I think.

Just don't imply that other peoples choices are stupid - OK ? It's not much to ask is it ?

When I had a Bresser 127L refractor it had this type of finder shoe on the scope: I replaced it with a Skywatcher compatible finder shoe that was designed for SCT scopes which looked like this: The replacement used the same bolts and holes that the original Bresser one had used so no drilling needed. I think the above finder shoe costs around £10 if you can find one. I might still have it knocking around somewhere

Very nice session by the sound of it Mark I was using my 12 inch dob as well last night. The views of Saturn and Jupiter were OK but a bit wobbly so I turned to planetary nebulae and globular clusters instead. Unfortunately I was clouded out before Mars was in a decent observable position. I'm still hoping for glimpses of Phobos and Deimos this opposition.