First light report - SkyWatcher 300P Flextube in Diamond Black (MKII?)

[MikeP]

I had some collimation problems initially because I had not adjusted the collimation bolts correctly. This meant the mirror was not held in place firmly and could "bounce" slightly on the springs. Could you have a similar problem?

I loosened the locking bolts and tightened the collimation bolts to compress the springs a bit more, then collimated and finally re-tightened the locking bolts. The locking bolts were then able to contact the mirror cell, which they could not before, and now hold the mirror firmly in place.

Mike

[Tim]

Hi,

I have one of these too, bought back in April.

Couple of points,

If it is going to be outside much, esp. in wet/dew, then a replacement base made from marine ply would be a valuable addition. The chipboard it is made from will swell and distort in the wet.

To achieve focus with a DSLR the flextubes have a massive advantage. Simply dont extend the thing all the way. This gets around the problem of their not being enough inward travel.

Also, pop your webcam into the eyepiece holder for avi's of the moon etc, i've even done Jupiter through mine, and will be doing saturn very soon.

I took the photo below on my first night out with the 300P. I dont use it much, but when I do, I LOVE it!

TJ

(Dont click, its huge, and doesnt add much)

[rusirius]

Having just bought one of these its been good to hear someone Else's opinion and thoughts on the scope. I had the same problem with the instructions for the base, only found them after I had finished construction

Ah! Not just me then!

I think regarding collimation the difficulty is going to be the accuracy of these laser collimator's, my own seems to be slightly out and I too see flaring on stars with my own eyepieces - I'm presumed the cause is the poor quality of my eyepieces and the collimation being slightly off, I've still to do a star test .

I'm going to make up a rig to test the accuracy of the laser collimator (this weekend hopefully) as described in Star Ware. The supplied eyepieces don't seem to be coated very well but I still see a little distortion with the Orthos and the Nagler. I don't think its far off and I can still get great views. Is a cheshire any more accutare than a laser collimator? I'm thinking of getting a proper one.

I really like this scope and once I nail the collimation and get some good eyepieces I know I'm going to be very content for a long while.

Yes, same here. I'm generally pleased with the scope particularly in conjunction with with the Nagler, just need to fine tune that collimation.

The flaring of stars can also be produced by internal reflections and I have a feeling this is a scope that would benefit from flocking.

Yes I believe Ade flocked his too. I can't see anything in the tube that might be too reflective, but if anyone has any ideas on where flocking could/should be applied then I'm all ears.

I collimate mine with a laser collimator everytime I set it up. It does not hold collimation very well, which after reading Ade Ahsford's report was a little disapointing, but I've got pretty good at collimating so no bother there. I replaced the finder scope with a red dot from the 130PM. I found that its easier to use than the finderscope, but I intend to fit both at some point. I've also fitted a cooling fan to the primary mirror just shorten cooling down times.

So I'm not the only one that found this to be the case. The ipression given was that one could take it down and move it around and it would still hold collimation when being extended again. I have found this emphatically not to be the case. The collimation seems be lost every time one colapses and the extends the upper section. Its quick enough to reset using the Laser Collimator so as you say, no real problem there. I'm also thinking of installing a coolling fan at some point. Can this be done without drilling or otherwise defacing the OTA?

I couln't get on with the red dot finder on my LX90 but I've also just purchased a Telrad finder on the used market and I'm thinking of using it in conjunction with the finderscope rather then in place of it. The theory is that the non-magnified view of the Telrad will be used initially as a course finder and the existing optical finder for finer adjustment.

I had some collimation problems initially because I had not adjusted the collimation bolts correctly. This meant the mirror was not held in place firmly and could "bounce" slightly on the springs. Could you have a similar problem?

I loosened the locking bolts and tightened the collimation bolts to compress the springs a bit more, then collimated and finally re-tightened the locking bolts. The locking bolts were then able to contact the mirror cell, which they could not before, and now hold the mirror firmly in place.

Mike

Mike, its a fair point and I think the mirror might need to settle on its springs after the OTA has been unpacked. I did get a couple small jolts the first couple of times I adjusted it, but its since adjusted quite smoothly. I'm following the same procedure as you outline. I first loosen the locking bolts slightly and then adjust the collimation bolts. I then re-tighten the locking bolts just enough to make firm contact with the mirror. I've not had the situation as you have whereby they don't make contact at all though.

If it is going to be outside much, esp. in wet/dew, then a replacement base made from marine ply would be a valuable addition. The chipboard it is made from will swell and distort in the wet.

That's put the dampeners on things somewhat! I'm not planning to be outside in the wet too much but only time will tell how it handles the elements.

To achieve focus with a DSLR the flextubes have a massive advantage. Simply dont extend the thing all the way. This gets around the problem of their not being enough inward travel.

Also, pop your webcam into the eyepiece holder for avi's of the moon etc, i've even done Jupiter through mine, and will be doing saturn very soon.

Interesting. Will give that a go.

I took the photo below on my first night out with the 300P. I dont use it much, but when I do, I LOVE it!

Wow! That's brilliant.

[FLO]

If it is going to be outside much, esp. in wet/dew, then a replacement base made from marine ply would be a valuable addition. The chipboard it is made from will swell and distort in the wet.

That's put the dampeners on things somewhat! I'm not planning to be outside in the wet too much but only time will tell how it handles the elements.

Yes, wet grass is the real problem, the wet can get behind the white laminate and soak into the board.

The solution is Interlocking foam exercise mats. We put all our Dobsonians on them and they work a treat

[MikeP]

Mine only goes on paving. I've screwed three lockable castor wheels on the bottom so it is well clear of anything wet and it is easy to roll it around the patio to different observing positions.

Mike

[kev1204]

Mike,

I already checked that the mirror wasnt bouncing about but no matter how many times I try the scope doesnt hold collimation when lowering and extending the tube, even when the scope isnt moved. Like I already said its only a small adjustment with the laser collimater and its sorted.

TJ, the fan mounting holes were already drilled and tapped with M4 holes at 80mm centres.

[Sam]

This is a very comprehensive review and also very useful, as it's a scope I'm seriously looking at buying. Thanks you for taking the time to to do the first light and for sharing it with us.

Sam

[FLO]

I already checked that the mirror wasnt bouncing about but no matter how many times I try the scope doesnt hold collimation when lowering and extending the tube, even when the scope isnt moved. Like I already said its only a small adjustment with the laser collimater and its sorted.

The 300p Flextube normally holds its collimation quite well, our own kept the laser spot within or very close to the centre-circle of the primary. How far out is yours? Are the tubes/bars/whatever fastened tightly? (It might be worth letting your supplier know so he has your concerns on record).

[MikeP]

Kev,

I'm sure you probably do the same thing but I'll mention it anyway. When I extend mine, I make sure that I pull each support tube firmly against its stop as I tighten the screw thing that holds it in place. That seems the best way to get the upper part of the tube into the same position each time.

Just a thought - your secondary isn't slightly loose is it? Raising and lowering could cause it to move slightly.

Since you can do a quick adjustment with the laser I realise it isn't a big issue to you but it would be good to get it sorted.

Mike

[rusirius]

Yes, wet grass is the real problem, the wet can get behind the white laminate and soak into the board.

The solution is Interlocking foam exercise mats. We put all our Dobsonians on them and they work a treat

Ah! So that's where you get them from! I did notice them in the pictures on your thread and wondered where to get them from. Thanks for pointing out the solution.

Kev,

I'm sure you probably do the same thing but I'll mention it anyway. When I extend mine, I make sure that I pull each support tube firmly against its stop as I tighten the screw thing that holds it in place. That seems the best way to get the upper part of the tube into the same position each time.

Just a thought - your secondary isn't slightly loose is it? Raising and lowering could cause it to move slightly.

Since you can do a quick adjustment with the laser I realise it isn't a big issue to you but it would be good to get it sorted.

Mike

Your point to Kev is noted. I do check that the trusses are pulled up firmly agaist the stops but even so, the collimation does seem to drift out a bit each time. Its not out by much and is quickly corrected using the laser collimator so its not a major problem but it doesn't seem to stay put as the review implies.

Although I didn't think that my secondary was loose, I did check and found that athough the secondary was attached to the vanes firmly, I had to tighten the thumb screws securing the vanes to the OTA tube. I'm not sure how tight they're supposed to be but a couple of them were just slightly less than hand tight so I tightened them up accordingly. I will let you know how I get on.

[beamer3.6m]

I am sure that there is one of these on Ebay at the moment.

£580 I think.

[kev1204]

Mike,

Last night I gave the scope a thorough going over. I collimated it using the laser and then lowered and extended the tube several times. It was out by about 10mm when looking at the Laser return on the secondary which on the Laser collimator pushed the Laser return to the edge of the 45 degree return plate. I feel that its the primary moving slightly, but its quickly adjusted. Im not sure how much "out" this puts the collimation as far as the image goes.

One other point that I noted that was the laser drifted out slightly from the centre of the collimater target when the tube was moved to the horizontal position (Primary moving slightly)

Overall Im very pleased with it all. Its a lovely bit of kit - looks great and performs brilliantly. I wanted one for ages and would definitly recommend it.

As for the Ebay price of £580, I payed only 9 quid more for mine brand new.

[beamer3.6m]

As for the Ebay price of £580, I payed only 9 quid more for mine brand new.

Typical Ebay.

[rusirius]

The laser beam on mine tends to land around 1-3mm outside the circle on the primary. The return does usually still hit the etched screen on the collimator well away from the edge and maybe 3-5mm away from the centre opening.

To quote Steve;

The 300p Flextube normally holds its collimation quite well, our own kept the laser spot <B>within or very close to the centre-circle</B> of the primary.

It sounds like some minor drift is therefore to be expected and that maybe mine might well be within acceptable tolerance after all?

£580 on e-bay - no doubt plus delivery or cost of fuel to collect - does not seem reasonable. I also paid £589 and delivery was included.