Come back Genesis, all is forgiven!

[Stu]

Just thought I would post up about this. You may have read that I was not happy with the views I was getting through my TV Genesis scope.

It was hard to define what was wrong, just didn't look sharp at medium and higher mags and there was too much CA.

Well, I got brave (or stupid) today, and took the lens cell apart. This is not something I would recommend doing at all by the way!!!!

I found a diagram giving me an indication of how the elements should be arranged, and found that the front one was the wrong way round. I marked the elements so I could make sure I avoided rotating them, although if the cell had been apart before then I guess that didn't matter.

I gave everything a clean as there was some gunk on the internal surfaces too, and re-assembled it all carefully!

I've just given it a quick try out tonight, and delighted to say it is now performing far more as it should. The collimation is out, but I know how to sort that. Fundamentally though it is working very well now. Allowing for the mis-collimation, stars are sharp and CA much reduced even at higher mags.

Even Jupiter and Mars looked ok, I could see the ice cap on Mars and some detail in the belts on Jupiter. Castor and Algieba both split very nicely. This was all at x166 which is as high as I could go without getting the Barlow out. Finally, M44 looked very nice in the 24mm Panoptic showing the lovely flat field (at 3.4 degrees with this eyepiece)

So, notwithstanding the collimation issue (which I am comfortable I can sort once I get it onto a sturdier mount) I am happy that the scope is fixed and looks like it should give the lovely views I expected of it when I bought it. Feeling quite happy about it! :-)

Cheers,

Stu

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[John]

Well done Stu 

It's a tough decision to take to do "open optic surgery" like that but it sounds as if it has paid off. I wonder who put the objective element in the wrong way around ?

Glad it's well on the way to being the classic 4" refractor again 

[nightfisher]

Nice one Stu, its a brave man that strips a high end frac but sounds like it paid of 

the problem you descibe is like i get with my swift 839, its a stunner at lower power but seems to lack high mag sharpness, i have had the lens elements out and its a little better

[m.tweedy]

brave man. Glad it worked out well for you. Sadly no TV Genesis coming up on the classified in the near future now.

[Stu]

Thanks John. Maybe I was feeling reckless, anyway was just fed up with it not performing and knew that it had to be something like that.

The scope has been resprayed at some point so perhaps it was did-assembled at that point?

Anyway, seems to be sorted now so am happy.

Stu

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[Stu]

Nice one Stu, its a brave man that strips a high end frac but sounds like it paid of

the problem you descibe is like i get with my swift 839, its a stunner at lower power but seems to lack high mag sharpness, i have had the lens elements out and its a little better

Thanks Jules. I certainly won't be taking the Vixen apart that's for sure!!!! Bit scared to even clean the optics myself, Paul-CI kindly did it for me the other day, looks lovely now :-)

Is your Swift sorted now? Did you find anything amiss?

Stu

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[nightfisher]

Thanks Jules. I certainly won't be taking the Vixen apart that's for sure!!!! Bit scared to even clean the optics myself, Paul-CI kindly did it for me the other day, looks lovely now :-)

Is your Swift sorted now? Did you find anything amiss?

Stu

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i think the lens were out of orientation, still work in progress to get it right............just need to some clear skies

[Stu]

brave man. Glad it worked out well for you. Sadly no TV Genesis coming up on the classified in the near future now.

'Fraid not Michael ;-)

I wouldn't have felt comfortable asking too much for it as it was so was a bit stuck with it until I could get it sorted! Shall be hanging on to it even more now :-)

Stu

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[ChrisLX200]

They are beautiful scopes and built to last. I would hate having to take my SDF apart though! Sadly mine sits neglected in the shadow of its big brother - the 127is and so hasn't been out of its case for 6 months.

ChrisH

[Peter Drew]

Excellent news! 

[Stu]

They are beautiful scopes and built to last. I would hate having to take my SDF apart though! Sadly mine sits neglected in the shadow of its big brother - the 127is and so hasn't been out of its case for 6 months.

ChrisH

That's a shame Chris, perhaps you should lend it to me to do an indepth comparison between f5 and SDF Genesis' ;-)

Stu

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[HumptyMoo]

My immediate instinct was "Jesus he knows me" No. All is not forgiven.

Thankfully, it turns out the thread was interesting instead

[A McEwan]

One day (night) I'd really like to try one of those classic old Genesisises (either version)! I remember getting really excited at the adverts in Sky & Telescope Magazine a long time ago...

Ant

[Stu]

One day (night) I'd really like to try one of those classic old Genesisises (either version)! I remember getting really excited at the adverts in Sky & Telescope Magazine a long time ago...

Ant

Ant, it's funny, they are by no means an apo, though mine now seems to be close, but they have a definite appeal. I think it is the short focal length and flat field which makes widefield viewing so rewarding. You can use a smaller exit pupil and still have a decently wide fov so the contrast is very good.

I'm hatching a plan to take it somewhere nice and dark to take in some lovely widefield objects like the Veil and NA nebulae, with a 21mm Ethos giving a 4.2 degree field and 4.2mm exit pupil it should be spectacular.

Stu

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[Merlin66]

Definitely worth trying to find one - to at least look through!

My Genesis is serial #1007 - this is the one that split the double double at x49...

Still in regular use for spectroscopy.....majic!!

[Joves]

Great news, Stu. I was so disappointed for you when I read that you were less than impressed with what should have been an excitedly enjoyable first light. Glad to hear you've finally got it sorted. Will be good to hear when you also have it collimated.

I got lucky with mine. Collimation seems fairly spot on and all elements appear to be oriented the way they're supposed to be. Thank god for that, as I don't know I'm as brave (reckless?!) as to take it all apart

[Stu]

Thanks Aaron. I am sure reckless is the right word!! I certainly wouldn't recommend it.

I believe that now the elements are correctly orientated, it is 'just' a matter of loosening the Allen bolts that hold the whole assembly to the tube and gently adjusting it to bring the collimation in.

The de focussed star test actually looks pretty much spot on, but when you bring it towards focus it is clearly out. Mars looked good on one half but not the other!

The only other thing it could be is rotation of the elements with respect to each other but as the de focussed star test looked pretty round I don't think that is an issue.

I will perhaps get a chance this weekend, quite keen to give it a go because I reckon the performance will be great once it is sorted. I was beginning to doubt the reputation the scope had but not any more :-)

Stu

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[ChrisLX200]

The original Genesis was not perfectly colour corrected - probably similar to a good ED doublet today. The SDF was better (the mods mostly addressed colour correction), and the 101 better still, but the neutral 'white' colour in the latter was apparently less well received by visual observers than previous versions! Funny old world. I guess it's the same with analog audio recordings and digital - some swear by the snap, crackle and pop of vinyl

ChrisH

[Stu]

The original Genesis was not perfectly colour corrected - probably similar to a good ED doublet today. The SDF was better (the mods mostly addressed colour correction), and the 101 better still, but the neutral 'white' colour in the latter was apparently less well received by visual observers than previous versions! Funny old world. I guess it's the same with analog audio recordings and digital - some swear by the snap, crackle and pop of vinyl

ChrisH

That's correct Chris, there are a wide variety of views around about the original f5 version, some stating 'this is not an apo', whilst other opinions are that visually it is.

From what I've seen now I would say it has good colour correction in focus but obviously not perfect. It is effectively an f10 ish scope reduced and flattened to f5 by the Petzval doublet. I do like the ultra wide fields the 500mm focal length gives though :-)

Stu

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[Stu]

I was just re-reading my first light report on the Genesis, and wondering why I didn't pick up the issues sooner? I think I concentrated on low magnification/widefield objects where the issues didn't not show up as much. I think the level of CA, which I described as 'in line with expectations', was based upon various 'this is not an apo', reviews. What I am seeing now is far better colour correction which is great.

Stu

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