SW Skymax 150 - First Light, First Thoughts

[iPeace]

1 minute ago, 25585 said:

Have you tried swapping diagonals, and with none? 

Also different eps. 

 

I was using identical diagonals which I know to work equally well; I tried every eyepiece I own in the Mak - at least, those with a sensible focal length. I didn't try straight-through without a diagonal. Perhaps next time.

[avtaram]

1 hour ago, nightfisher said:

I still wonder if the GSO 150 F6 newt is the perfect Luna scope, would love to get one and try it........

I have the Skywatcher 150 f8 Newt which gives jawdroping views of the moon. It's also very good on planets and double stars.

I was viewing Jupiter some days ago when the seeing was pretty rubbish, the 150 f8 newt easily beat the 12" dob on that occasion, although when the seeing is good the 12" wins hands down.

[nightfisher]

4 hours ago, iPeace said:

Is this the one you mean?

https://www.teleskop-express.de/shop/product_info.php/info/p2679_GSO-150mm-f6-Newtonian-Telescope-with-2--Crayford---optical-tube.html

 

Yes thats the very one

[iPeace]

Just now, nightfisher said:

Yes thats the very one

All right; I'm game. I can appreciate the irony of it costing less than a bag of chips - and might include free cod.

Just don't tell anybody I'm getting one.

[nightfisher]

14 minutes ago, iPeace said:

All right; I'm game. I can appreciate the irony of it costing less than a bag of chips - and might include free cod.

Just don't tell anybody I'm getting one.

Are you getting one, if so i really want to know what you think of it, soo very tempted to get one myself

 

[iPeace]

5 minutes ago, nightfisher said:

Are you getting one, if so i really want to know what you think of it, soo very tempted to get one myself

 

Sure, I might as well. I'll save the box in case I have to ship it to you later on.

[nightfisher]

Might hold you to that my friend 

[iPeace]

3 minutes ago, nightfisher said:

Might hold you to that my friend 

I'll get the 1:10 focuser upgrade just in case

[Captain Scarlet]

Interesting the Mak150 failing a test vs an 85, even a TV. I wonder, the 85 collects 57 sq-cms of light. The Mak collects 177 sq-cms, three times more. The Moon is an extremely bright source for any telescope, but I wonder if 3 times the concentration for the Mak150 will affect night-adaption enough to make your seeing of it actually worse than a smaller scope? I need to think about this some more...

Cheers, Magnus

[iPeace]

21 minutes ago, Captain Magenta said:

Interesting the Mak150 failing a test vs an 85, even a TV. I wonder, the 85 collects 57 sq-cms of light. The Mak collects 177 sq-cms, three times more. The Moon is an extremely bright source for any telescope, but I wonder if 3 times the concentration for the Mak150 will affect night-adaption enough to make your seeing of it actually worse than a smaller scope? I need to think about this some more...

Cheers, Magnus

I'm still assuming it was the "seeing" - or something like that. But there will be other nights, so we'll see.

[Stu]

14 hours ago, iPeace said:

I'm still assuming it was the "seeing" - or something like that. But there will be other nights, so we'll see.

Cooling and collimation are the other two possibilities. They can take a long time to cool although I think you store it in a garage? Did a defocused star look stable or could you still see tube currents?

Worth checking collimation too, they are generally very stable but it's possible it took a knock in transit.

[iPeace]

2 hours ago, Stu said:

They can take a long time to cool although I think you store it in a garage?

Yes, in an unheated shed. It comes out cold to the touch. We were out for a total of five hours, so at the end of the session, I guess I could expect that it was certainly as cool as it was going to get?

2 hours ago, Stu said:

Did a defocused star look stable or could you still see tube currents?

Well, I didn't know to check. Plus I'm not sure I would recognize a "tube current" if it appeared at my front door singing "tube currents are here again".

I certainly will check this next time out. Can you give me a hint as to what a "tube current" looks like - or do you know it when you see it?

2 hours ago, Stu said:

Worth checking collimation too, they are generally very stable but it's possible it took a knock in transit.

I'll do some research on how to check a Mak's collimation - but I won't be in any hurry to fiddle with it; have read a few accounts of those who in hindsight should have left well alone.

 

Thanks, Stu!

[25585]

A stop-down mask or 2 would be a good test. One with aperture same as your frac, the others 100 and 125. The comparisons would be interesting, and could possibly be revealing as well.

[Chris]

If you defocus a bright star then a collimated scope would show concentric rings forming a doughnut shape. If the smaller inner circle isn't central inside the outer circle then collimation would likely be out unless the primary mirror is flopping a bit, therefore check this inside and outside/either side of focus. 

Tube currents look like heat waves shimmering over a defocused star, make the star nice and big/defocused to see this. 

I'm not the best at trying to explain things but I hope you get the jist  

EDIT: this might give you an even better idea:

 

[iPeace]

6 minutes ago, Lockie said:

I'm not the best at trying to explain things but I hope you get the jist  

That's brilliant, thanks!

[Timebandit]

 

Interesting 3rd edition 

I must say this does not completely surprise me. You are comparing a very high quality refractor on lunar. A quality refractor does really take some beating on lunar and planetary targets. I know aperture is king, but only on certain objects and only if supported by superior Optics. Stanley has shown that a small quantity refractor can go up against larger aperture scopes and still edge it.

A quality refractor is a formidable scope and will give crisper and sharpness, that aperture advantage of other scopes will not necessarily be beat. You just need to have a look at the Tak club threads lately and claims of superior Optics on their 100mm scopes beating larger aperture scopes. Why, because on lunar and planetary IMO aperture is not always king, but quality and superior Optics can be.

 

 

[RobertI]

In a recent observing post, I documented how my 100 mm achromat could split a double that my C8 (double the aperture) could not. I would not have believed it if I hadn't seen it with my own eyes. The object in question was over a shimmering rooftop so turbulence was present. Last year I observed Jupiter with both scopes under very good seeing and the C8 was the clear winner. I guess this confirms that smaller scopes can outperform larger ones under certain atmospheric conditions but not all the time.

Good video @Lockie, interesting to see how much the tube currents died down after two minutes.

[martinl]

Since I also have a lovely TV85 and have considered a 150/180 Mak for planetary/lunar I follow this thread with interest.

One strategy for dealing with tube currents that hasn't yet been mentioned is to insulate the tube. As long as the optics and air in the OTA are at the same temperature it doesn't really matter if the scope is not fully cooled down. There is a long thread on CN discussing this approach at the moment, might be worth looking into.

[iPeace]

1 minute ago, Timebandit said:

 

Interesting 3rd edition 

I must say this does not completely surprise me. You are comparing a very high quality refractor on lunar. A quality refractor does really take some beating on lunar and planetary targets. I know aperture is king, but only on certain objects and only if supported by superior Optics. Stanley has shown that a small quantity refractor can go up against larger aperture scopes and still edge it.

A quality refractor is a formidable scope and will give crisper and sharpness, that aperture advantage of other scopes will not necessarily be beat. You just need to have a look at the Tak club threads lately and claims of superior Optics on their 100mm scopes beating larger aperture scopes. Why, because on lunar and planetary IMO aperture is not always king, but quality and superior Optics can be.

 

 

Thanks, that's another interesting take on this. Naturally, if the TV-85 is "that good" and this 150 Mak is "as good as it gets", then there we are.

My main question is, of course: is this the best the Mak can do? If not, what's going on?

I'm not yet prepared to accept that this is all the Mak has to give. It doesn't seem to make sense to me.

So I have the following on the 'To Do' list:

• Get more nights observing with the Mak
• Summary check of the Mak's collimation;
• Check the Mak for tube currents;
• Get a Newt and lob it into the fray.

[Ags]

I can't imagine the Newt being competitive with the Mak! Interested in what you make of it though... But you should have played to the Newt's strengths and got a 250mm dob at least. 

[nightfisher]

Regards the newt.....a few years back i picked up a 114mm 900 f/l skywatcher tube cheap on astroboot, this was the proper newt not a bird jones one and the Luna views simply stunned me, i only sold it on as it had the horrid plastic/metal floppy focuser that would not dare hold the weight of a DSLR, i could not find any focuser that would fit it so reluctantly sold it on, but after seeing what this £30 tube could do it has left me thinking a half decent 150 F6 would be a rather interesting option, being half the F/L of the Mak its more of an alrounder but can barlow up to F12, and not being quite as long as the skywatcher 150 F8 its a more manageable tube, BTW a lot of owners rate the 150 F8 as something rather special 

[spaceman_spiff]

I like the idea of insulating the ota to reduce air currents. A while ago I covered my Skymax 150 with kitchen foil to help reduce radiative cooling. I have recently removed it because it was looking pretty haggard. I didn't noticed any difference without it but tbh I wasn't out for too long.

[Alfian]

11 hours ago, nightfisher said:

has left me thinking a half decent 150 F6 would be a rather interesting option, being half the F/L of the Mak its more of an alrounder but can barlow up to F12, and not being quite as long as the skywatcher 150 F8 its a more manageable tube, BTW a lot of owners rate the 150 F8 as something rather special 

I've looked at this scope a few times Jules, equipment curiosity never seems to be too far away! Interestingly, according to the TS Optics website the the GSO 150 f6 is a heavier OTA than that of the 150 f8 skyliner, but the shorter focal length would I assume be less of a sail. 

[nightfisher]

11 minutes ago, Alfian said:

I've looked at this scope a few times Jules, equipment curiosity never seems to be too far away! Interestingly, according to the TS Optics website the the GSO 150 f6 is a heavier OTA than that of the 150 f8 skyliner, but the shorter focal length would I assume be less of a sail. 

Yes, the F8 is a right sail, and up here it would be hard work, hence the shorter F6 would be more practical

[iPeace]

1 minute ago, nightfisher said:

Yes, the F8 is a right sail, and up here it would be hard work, hence the shorter F6 would be more practical

We'll soon know.