Ricochet

I own a 72ED and an Altair Starwave Mini mount, which I believe to be the same as the AZT6, although I have now upgraded to a Scopetech Zero. For a diagonal I usually use a Baader BBHS prism with a 1.25"-2" clicklock reducer for the clamp, a 2" T2 nose and two T2 extensions (15 and 7.5mm?) which weighs in a 328g. Despite the f6 focal ratio I see no issues with prism induced CA and I believe that the image is sharper than with a mirror diagonal. I tend to use three eyepieces: a 3-6 Nagler Zoom weighing 150g, a 13 Delite at 222g and a 24 Panoptic at 232g. I also own Pentax XWs, the lightest of which is the 14XW at 372g, but due to the difference in weight I never use these eyepieces with the 72ED. I've just tried the 14XW and the Starwave Mini definitely struggles more with it than it does with a 13 Delite. The suggestion of a 24mm UFF is generally a great suggestion but the listed weight is 330g so perhaps for this particular setup it might be a touch on the large side. A more lightweight alternative would be the 26mm ES62° which weighs in a 235g, basically the same as the 24 Panoptic that I use. However, I don't know how well this eyepiece will perform at f6 and I am fairly sure that the UFF will be better optically at all focal ratios.

I had to make a box for my dob OTA and so needed a massive box. I bought a large box from a storage locker shop, cut it to the size I wanted and then used contact adhesive to glue additional layers of cardboard to each face. Standard cardboard boxes aren't strong enough, hence the reason that there is a tendency for telescopes to arrive double or triple boxed. Inside I did have the original polystyrene inserts plus lots of bubble wrap. 

The carpet tube idea is a good one as the tube would be substantially thicker than a standard box and the shape would help too. However, I think I'd still be inclined to put the round tube inside a rectangular box to prevent it rolling around during transport.

How did you collimate the telescope? Can you take a photo of the collimation through a collimation cap or cheshire?

20 minutes ago, M40 said:

I thought that barlows had a focal length determined by the length of the barlow tube.

The focal length is determined by the lens(es). That is then used to calculate how long the tube needs to be to give the magnification that is desired. 

39 minutes ago, wookie1965 said:

would it be X1.5,  x1

Well I would hope that it is not 1x as that would mean it is making no difference at all. As a general rule if you screw the nose piece from a 2x barlow straight to an eyepiece it tends to work out somewhere around 1.5x but it depends on the distance between the lenses. The only way to know for sure is to time how long it takes for a star to drift from one edge to the other, or from centre to edge, with and without the barlow, and then compare the ratio. If your eyepieces have their field lenses in different positions you may have to work it out for each eyepiece. 

I would go for the 150p if I was choosing an only scope for myself. For DSOs the image will either be 33% brighter at the same magnification or 15% larger at the same brightness both of which make objects easier to see. For planetary the larger scope has a 15% better resolution and optimal magnification will probably be in the 150-180 range whereas it would be more like 130-155 for the 130p. Both telescopes have the same focal ratio so you will be looking at the same quality (=cost) of eyepieces for either scope. The advantage of the smaller 130p would be if you plan on it becoming a travel scope in future in which case the slightly smaller size would be slightly easier to transport. Similarly, the smaller scope would work better on a smaller mount/tripod should you decide to go that way in future rather than use the mini dob base.

15 minutes ago, LoveFromGallifrey said:

The metal must have contracted/shrunk somehow

There is absolutely no way that could have happened. You must have not undone the 2" clamp fully. 

The 12mm Starguider would be a good choice. My other suggestion would be the 13mm Nirvana, which is a bit more expensive with a wider field but less eye relief and probably not quite as comfortable as that is a real strength of the Starguiders. 

56 minutes ago, 9-42 said:

Thanks - forgive me, but what difference does the mirror make? Is this one easier to set up and use? I note it does not have a tri-pod?

 

Generally the larger the aperture, be that a mirror or lens, the better. However, due to your son's dyspraxia, I think that a telescope that has slow motion controls, such as the starquest suggested by @vlaiv is a better choice. The slow motion controls are knobs on long bendy rods/springs that your son can turn to move the telescope. A relatively large turn of the knob moves the telescope a small amount and the flexibility of the rods helps prevent vibrations being transmitted from the user to the telescope. 

4 hours ago, stargazer_3000 said:

the mirror has 1-1.5mm lateral movement space around it to avoid pinching the  optics-

This is significantly more movement than I have ever had on mine. I adjusted mine so that there is a gap the thickness of a piece of paper between my clips and mirror edge, the same as often suggested for between the clips and mirror face. 

10 hours ago, Nitecoda said:

Ibis Obelisk Carbon Tripod with Ball Head

I've not heard of this manufacturer before but this tripod looks the same as a Zomei tripod I have. Perhaps this is a higher quality original that the Chinese have been copying but I suspect it is much more likely just to come out of the same factory at a higher price than found on eBay and Amazon marketplace. If so it is absolutely not suitable for an astronomical telescope. It isn't sturdy enough and there is a risk that it wouldn't hold the load of your telescope. I used mine to hold a 65mm spotting scope and eventually the connection between the 3/8" pin and centre column failed just from the force of panning left and right. 

An AZ4/5 or EQ5 with steel tripod would make for a much more sturdy mount at the expense of ease of transport in terms of size and weight. As you are sharing this telescope with your children, a mount with slow motion controls may be more suitable as turning a knob to keep the object in view is a bit easier than nudging the scope. If you overshoot or go the wrong way it is easy to just turn the known the opposite direction. A motorised tracking mount would mean there is no need for anyone to master tracking while full goto would reduce the impatience of your children waiting for you to find an object for them to view. 

7 hours ago, Nitecoda said:

I can swap out the EVM SZ and take advantage of teh Baader Zoom and Barlow combination offer - at £303 - which is only a smidgen over the price of 3 x fixed length eyepieces......

Personally, I've not been overly impressed with the performance of the BHZ in my f6 scopes and so would stick with either your original zoom choice or a selection of fixed focal lengths. 

6 hours ago, Nitecoda said:

Living where I do is a bonus, dark-sky-wise, but my back garden is also surrounded by trees and nearby housing. I live in a valley so I don't have unobstructed views across the horizon. I do however have relatively access to these dark skies and 200m hills that require a short drive and then a walk. 

Views of the horizon are not necessarily useful or desirable. When you observe at low altitudes you have to look through significantly more atmosphere than at high altitudes and this massively degrades the image. As a result generally the aim is to observe an object when it is as high in the sky as possible. In addition, trees around your garden may block local light sources from direct vision while heading up into the hills means you can see them. In the end what really matters is how dark the sky is overhead and how dark adapted you can get (for DSOs). 

I think the redlines are the same as the Celestron Ultima LXs, in which case there is no comparison at faster focal ratios. Buy the 82° 28mm unless weight is an issue in which case don't buy either of your options. 

I bought a 72ED this year and have been pleasantly surprised with how good it is. The image is very sharp and I haven't noticed any real colour issues. It easily splits the double double of that gives an idea of performance, but I don't observe doubles to know if that's good or not! On Jupiter a 4mm works well (105x) and Saturn takes a bit more, around 3.5mm (120x). I think the Moon takes a similar power to Saturn but I've not particularly paid attention as I tend to vary the magnification more when observing it. 

You can't get away from the fact that it is a 3" scope and so has 3" scope performance but whenever I use it I'm never disappointed that I didn't get a bigger scope out. 

It is a very lightweight scope and I can easily carry the scope, mount and tripod with one hand which makes it easy to get out or change observing location. The downside of the lightness is that there's not a lot of weight in the objective to counterbalance the eyepiece/diagonal and so it tends to be quite back heavy. The AA Starwave Mini Az that I first tried it on wasn't up to the task of handling the imbalance but a Scopetech Zero handles it with no problems. 

However, this is actually my second 72ED. There is no facility to collimate the lens cell and so the only collimation adjustment is via the focuser alignment. Both examples needed adjustment on arrival and unfortunately the first was too far out and so was replaced. 

5 hours ago, Seoras said:

Thanks Ricochet, you’re spot on! This is the problem with my one, I’ll root around in my garage for some washers and springs and see if I can do anything with it. 

Glad I could help. Good luck with your spring hunt. 

34 minutes ago, Seoras said:

This looks just the job, hopefully the suggestions of Mark and yourself will allow me to use the red dot finder until FLO send me the Stellalyra. I suppose having both couldn’t hurt, I noticed some people have both types on their scope

You need to keep the RDF so that you can tell where the right angled scope is pointing, else you won't know which stars you are looking at in your finder. 

With regards to the RDF, I had a similar issue with a Bresser one. The problem was not in the connection of the finder to the stalk, but backlash in the horizontal adjustment mechanism of the finder. I solved the problem by adding a small spring and a couple of tiny washers I had lying around over the screw that forms the adjustment rod, as shown in the photo below. In my mind I thought the spring came out of a pen, but it looks a bit short for that, perhaps I cut it down to size. 

3 hours ago, MG01 said:

I think the 4.5" may be a tad small.

I think you are right. In addition, they are very fast scopes and I think probably not as well corrected as slower focal ratio options, and so will suffer compared to your APO. 

Is the "top" mirror clip in your second picture touching the mirror? From the picture it looks like the mirror has slipped down between the lower two clips. Is that what it looks like when you look down the tube or is it just the photo angle? 

If it is like that you will have to remove the mirror cell and then dismantle it to shift the "posts" inward so that they all just touch the mirror when it is centred. You might prefer to just it back and get a replacement. 

58 minutes ago, Cjg said:

Remember to have a look on the used section here too. A quick look tonight shows this one.  No connection with the seller, but an ED doublet for £175 , so some bargains to be found, especially as this comes with an eyepiece and diagonal.

 

That's a good option. I use a 72ED as a grab and go alternative to an 8" dob. The Altair has a nice sliding dew shield which would make it easier to transport in a camera backpack on the train/bus as required. 

A decent mount head will also be required even if a suitable photo tripod is already owned. I've ended up buying a scopetech zero but an az5 or az-gti should be a good option for less money. 

The Baader 2"-1.25" clicklock reducer has a T2 thread as well as M48 for filters. If you only need a small extension you could screw the T2 2" nose (get the safety kerf one!) directly to it. If you need any more extension you could then fit T2 extensions between the Clicklock reducer and the T2 nose. 

41 minutes ago, ClareMcMullan21! said:

that isn’t going to break the bank.

What budget won't break your bank and how old is your daughter? FLO have a Beginner telescopes page that is a good place to start. 

15 hours ago, sork said:

I am going to practice some with focusing and magnifying

There is no magnifying, the combination of a particular eyepiece and the telescope provides a fixed magnification. This is probably where you are going wrong, there is only focussing. As @Ags has said, you must adjust the focuser to make the image as small as possible. The only way to make the image larger is to use an eyepiece with a smaller focal length, i.e. the 10mm eyepiece will give a larger image than the 25mm. 

4 hours ago, Zermelo said:

Is that this one? https://www.teleskop-express.de/shop/product_info.php/info/p2757_TS-Optics-2----28-mm-Ultraweitwinkel-Okular---82--Feld.htmlMark

Also mentioned here: https://stargazerslounge.com/topic/391054-do-i-need-a-nagler-31mm-or-similar

and more discussion here: https://www.cloudynights.com/topic/810970-astrotech-28mm-uwa/

 

 

 

Yes, that's the one. 

I've got a 28mm Nirvana as my low power for my 8" dob. It's not perfect to the edge but it's good enough that I haven't bought a 31 Nagler. The new version has a redesigned eyecup but as far as I know it is only currently available from the TS brand. 

The two parts shown in your first photo are the extension tubes, or eyepiece adapters as described in the manual. One is for when you use 1.25" eyepieces and one is for when you use 2". You only ever use one at a time. In your photo you have both stacked into your focuser, which is why you can't focus. 

If you use a cheshire or concenter to collimate the secondary you can then use the barlowed laser method for the primary if you wish. If you use this method it does not matter if the laser is not fully collimated as you are effectively using it as a torch. Alternatively, the cheshire or concenter can be used for the entire process.