First light with my new Altair Astro 102ED-R.

[RobertI]

First light is an important moment, so despite so-so conditions, I thought I'd relate the first observing session with my new Altair Astro 102ED-R.

I didn't really have a plan and the session was a mix of trying to test out the optics and trying to do some observing. I think I achieved neither very well, but I got the opportunity to observe a very low Jupiter, a slightly wobbly Mars, the Dumbell nebula, a couple of nice coloured doubles and the rising moon. The main takeaways from the session were:

• At F7 (FL=714mm) the scope was a lot easier to observe with than the F10 Tal (FL=1000mm), with the eyepiece in more convenient locations.
• The focuser, which seemed stiff to start with, actually worked really well and was a joy to use.
• There was no noticable CA on the brightest stars and the moon and nicely defined diffraction rings around brighter stars.
• I did push the magnification to 200x on Mars, but was not really seeing much detail apart from the polar cap and the dark southerly region.
• There did seem to be a certain amount of 'scatter' around bright objects, but I really don't know if this is worse than any of my other scopes, and to be honest could be due to my modest eyepieces or even my eyesight, so I'm not worrying about that for now.
• The dumbell was lovely at x72, very bright with hints of structure when viewed with the OIII filter. I think this scope could really excel at deep sky.
• The 38mm Panaview worked nicely for wide fields, but there was distortion on a significant part of the outer FOV - to be expected I guess.

So overall pretty much as I expected from a cursory intial session. Optically I suspect I will find it marginally better than the Tal but without the CA, yellow cast and long tube. I am expecting it to be much better on deep sky though. I guess I was slightly disappointed that I was not 'blown away' by the views, but I also knew that this was only a 100mm scope and I had tried to manage my expectations beforehand! Also conditions were not perfect at all, and I know that it takes several sessions to really get to know a scope.

By the way, I avoided doing a star test after reading several articles about the pitfalls if star testing apo's! However I did establish that the collimation seemed good. I should add that the build quality is superb, very hefty rotatable focuser, good focus lock (which locks the pinion rather than the tube), and a huge sliding dewshield which stays in place!

So over the next few sessions I will either stick to some proper observing with the scope, or do a head to head with the Tal, which is really the benchmark I am hoping to beat with this scope.

Watch this space!

[Adam J]

38 minutes ago, RobertI said:

First light is an important moment, so despite so-so conditions, I thought I'd relate the first observing session with my new Altair Astro 102ED-R.

I didn't really have a plan and the session was a mix of trying to test out the optics and trying to do some observing. I think I achieved neither very well, but I got the opportunity to observe a very low Jupiter, a slightly wobbly Mars, the Dumbell nebula, a couple of nice coloured doubles and the rising moon. The main takeaways from the session were:

• At F7 (FL=714mm) the scope was a lot easier to observe with than the F10 Tal (FL=1000mm), with the eyepiece in more convenient locations.
• The focuser, which seemed stiff to start with, actually worked really well and was a joy to use.
• There was no noticable CA on the brightest stars and the moon and nicely defined diffraction rings around brighter stars.
• I did push the magnification to 200x on Mars, but was not really seeing much detail apart from the polar cap and the dark southerly region.
• There did seem to be a certain amount of 'scatter' around bright objects, but I really don't know if this is worse than any of my other scopes, and to be honest could be due to my modest eyepieces or even my eyesight, so I'm not worrying about that for now.
• The dumbell was lovely at x72, very bright with hints of structure when viewed with the OIII filter. I think this scope could really excel at deep sky.
• The 38mm Panaview worked nicely for wide fields, but there was distortion on a significant part of the outer FOV - to be expected I guess.

So overall pretty much as I expected from a cursory intial session. Optically I suspect I will find it marginally better than the Tal but without the CA, yellow cast and long tube. I am expecting it to be much better on deep sky though. I guess I was slightly disappointed that I was not 'blown away' by the views, but I also knew that this was only a 100mm scope and I had tried to manage my expectations beforehand! Also conditions were not perfect at all, and I know that it takes several sessions to really get to know a scope.

By the way, I avoided doing a star test after reading several articles about the pitfalls if star testing apo's! However I did establish that the collimation seemed good. I should add that the build quality is superb, very hefty rotatable focuser, good focus lock (which locks the pinion rather than the tube), and a huge sliding dewshield which stays in place!

So over the next few sessions I will either stick to some proper observing with the scope, or do a head to head with the Tal, which is really the benchmark I am hoping to beat with this scope.

Watch this space!

Nice,

I dont think there are any pitfalls to star testing APO scopes so long as you understand that you can expect some under / over correction in red and blue, or perhapse you are thinking of another effect?

Adam

[RobertI]

19 minutes ago, Adam J said:

Nice,

I dont think there are any pitfalls to star testing APO scopes so long as you understand that you can expect some under / over correction in red and blue, or perhapse you are thinking of another effect?

Adam

Yes, I read this article which linked to some others and the takeaway for me was not to bother testing in White Light! Another factor is that I star tested my 150PL and the results were abysmal, but the scope has performed faultlessly, so made me wonder whether it was of value anyway.  However, with the 102ED-R  I did try a quick test on a bright star using an OIII filter, and the diffraction rings were perfect and identical inside and outside of focus (though faint), so promising. I didn’t mention this as I was not sure how valid an OIII filter is for testing but I can’t see why this would be a problem? 

[Adam J]

4 minutes ago, RobertI said:

Yes, I read this article which linked to some others and the takeaway for me was not to bother testing in White Light! Another factor is that I star tested my 150PL and the results were abysmal, but the scope has performed faultlessly, so made me wonder whether it was of value anyway.  However, with the 102ED-R  I did try a quick test on a bright star using an OIII filter, and the diffraction rings were perfect and identical inside and outside of focus (though faint), so promising. I didn’t mention this as I was not sure how valid an OIII filter is for testing but I can’t see why this would be a problem? 

The ideal is to use a solar continum filter. But you can use a green filter too if you are struggling with the diffraction rings being too dim.

However, yes white light is not a good test for an apo as too much is overlapping to be able to make anything out.

Adam

[RobertI]

17 minutes ago, Adam J said:

The ideal is to use a solar continum filter. But you can use a green filter too if you are struggling with the diffraction rings being too dim.

However, yes white light is not a good test for an apo as too much is overlapping to be able to make anything out.

Adam

I do have a green filter so I’ll give that a go. Thanks for the help. 👍

[John]

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.

 

 

 

[RobertI]

10 hours ago, John said:

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.

 

 

 

Thanks for sharing your experience John, I am looking forward to comparing against the Tal, I'm really not expecting much of a performance difference, but will be a bit disappointed the ED scope is not as good! I enjoy observing with two scopes, it's all part of my scope education and is good fun!

I managed a second light last night, in very similar conditions to last time (bright sky, poor to average seeing). Mars was a little better in terms of detail, but still not fabulous. I think it's going to take a while to get a good night for a proper test run.

I did try a tight double - Mu Cygni with mag 4.8 and 6.2 components separated by 1.4"  - I managed to split it (black line between) at around x180 I think, so that's promising.

I also tried a star test with a green filter, and it looked much better than in white light. But I understand a proper star test requires excellent seeing, a well corrected eyepiece and no diagonal - I had the opposite of all three, so probably a pointless test.

Wide field viewing was not much fun with such a bright sky, so again better conditions required.

[RobertI]

18 minutes ago, RobertI said:

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 other thing I don't like about the Tal is the yellow colour cast to everything - I assumed this was a result of lower quality glass but is apparently deliberate to reduce the effect of the CA. Not many people seem to mention the yellow colour cast so I guess is not bothersome to most.

I am fully expecting to realise how good the Tal is when I do a side-by-side test with the ED-R!

As a side thought, in retrospect I could probably have met most of my requirements (shorter tube, wider fields, reduced CA, removal of yellow cast) with the cheaper AA Ascent 102ED F7 with FPL-51 glass and costing half the price, but I think would have forever wondered what the ED-R would have been like, and I'm also  hoping to do some sneaky imaging in the future. 

Edited September 12, 2020 by RobertI

[Chris]

Hey Rob, you sound a tiny weeny bit underwhelmed but just to try and re assure you, the detail you described on Mars is what I've been getting by stacking lots of frames. Deep sky sounds good. Maybe things will improve with subsequent sessions, test it on some doubles!  

[RobertI]

Thanks Chris, that's good to know, I probably should have got the Tal out to confirm it was the conditions and not the scope. I really should know by now that sky conditions are everything and I shouldn't be judging yet. Am I underwhelmed? I shouldn't be because I already know what a 4" frac can do from the Tal, and I had already restrained my expectations (it's only 4" after all), but you can't help hoping for an unexpected surprise, especially when so many people rave about how good 4" ED apos can be. But I've managed to split Mu Cygni (1.4" sep) which is a good start and I am sure under good conditions it will be fab.