Quite reQuarkable! ;-)

[Stu]

I would be interested in how the Opticstar f5 80mm frac works with the Quark. Certainly in normal use its poor above 30x unless its stopped down to 60mm or 50mm - but Ha is different.

It would be good to try it out some time before considering another better quality refractor.

I know I have a 102mm f6.95 APO but I do like to view the whole solar disc.

Would the performance with something like a Baader Continuum filter give any indication? This is narrowband and removes any CA so will show the basic performance of the optics.

My assumption is that the figure of the objective would be most important with the Quark, so perhaps cheap achros may not perform aswell as the optically superior ones. I would assume something like an ED80 has a pretty good objective so may outperform a cheaper achro for reasons other than colour correction?

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[michael.h.f.wilkinson]

I think the Opticstar is a mechanically improved ST80, so I should think it is OK, given the results I have seen elsewhere.

[John]

I think the Opticstar is a mechanically improved ST80, so I should think it is OK, given the results I have seen elsewhere.

It's mechanics are improved but I'm not convinced it's optics are, or at least there is some wide quality variation. Neil English ended up putting an ST80 objective in his Optistar 80mm F/5 as the original was poor. Mark's does not sound great either.

Presumably a decently figured objective would benefit the Quark as it does anything else. I appreciate that CA control is not going to be an issue but SA, coma etc might well be.

[Davey-T]

I have an ST80 that I use as a guide scope, optically and mechanically it's pretty pants especially the focuser but will try it with the Quark when I get the chance.

Dave

[Mark at Beaufort]

I have used the continuum filter plus binoviewers with barlow in the 80mm Achro. I still only get sharp views (sunspots etc) when I stop down to 60mm. So I think the jury is still out with this frac and using the Quark.

I will be interested in Dave's result with his ST80.

[Mark at Beaufort]

The Quark/ barlow is optimised for 656nm, full disc up to 450mm f/l as you're only dealing with a small part of the spectrum does this not mean an expensive scope is wasted on it ?

Dave

I just did a calculation on my 80mm frac. The frac with the Quark will give a FL of 1720 or f21.5. With a 25mm plossl with a 52 degree FOV this corresponds to 69x and a true field of 45 arcminutes (a full Sun being visible).

The only way to find out is to undertake a field test.

[Qualia]

Mark, if I have grasped what you're getting at I raised a similar kind of idea the other day in another thread and was politely informed that the Quark's 21mm etalon will act as a field stop and so any eyepiece's field stop larger than that won't add to the true field of view.

In your own case above, the 25mm Plossl with a 52º FOV will probably surrender around 0.7º TFOV, but if others are thinking along similar lines but not taking the 21mm etalon into account they may be in for a surprise.

If this is correct, I imagine to obtain a full disc with a quark eyepiece and the 21mm etalon 'compromise', one needs a focal length scope of around 400mm

[michael.h.f.wilkinson]

The situation with the etalon acting as a field stop is similar to that of the blocking filter acting as a field stop in the case of my LS35. The B1200 I have acts as a 22 mm field stop. This does not prevent the use of my MV 24 mm with its 27 mm field stop. It just limits the effective FOV. Daystar states the Quark will show the full disk in scopes with a focal length of 450 mm or less, which corresponds to what people observe.

[Stu]

One thing I need to check out more carefully is the 1.25" barrel. I briefly tried to fit it into the 1.25" adaptor on my 2" diagonal, but it wouldn't fit so I quickly gave up. It is not a major issue for me as I only use 2" diagonals but may be for others. I'll check it further today and confirm

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[michael.h.f.wilkinson]

Others have reported similar issues with Quark barrels. A bit strange as it would seem to be one of the easiest parts to get right in something a complex as a quark

[Moonshane]

Unfortunately a desire to get incorrectly constructed units out quickly, with inadequate quality control is not just a characteristic of one single company. I have learned my lesson in buying an out of stock item with FLO from another company and put it this way, assuming FLO stock it, I'll be using them for all my new purchases in future even if I have to wait for stock to come in.

[John]

One thing I need to check out more carefully is the 1.25" barrel. I briefly tried to fit it into the 1.25" adaptor on my 2" diagonal, but it wouldn't fit so I quickly gave up. It is not a major issue for me as I only use 2" diagonals but may be for others. I'll check it further today and confirm

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If they are like the Tele Vue dual fit barrels, it will depend on the design of your diagonal as to whether the 1.25" barrel can be used. The TV ones work well with the Tele Vue diagonals with the hi-hat adapter but won't work, or at least won't fully insert and feel secure, with other "fatter" types of adapter.

Maybe the "hi hat" design would work with the Quark ?

[Stu]

This is more than that John, it looks like the barrel has been machined slightly too large and physically won't fit into the 2" to 1.25" adaptor as shown here.

I've tried with four different adaptors and it is the same with each so it is not just a tolerance thing with one of them.

For me this is not an issue because I use 2" diagonals but it certainly would be for anyone with a 1.25" diagonal.

I have fed this back and await a reply. I may post this separately so it doesn't just get lost on this post.

Stu

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[michael.h.f.wilkinson]

It would be a concern for me, because I probably would be using it in a 1.25" focuser.

[Stu]

Apparently this was caused by a bent CNC tool. Should still have been picked up in QA though.

I understand that I should get a replacement at some point, just trying to establish if I will just get sent the barrel to change myself. I'm happy with my Quark so don't want to change it.

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[michael.h.f.wilkinson]

Interesting info. It should mean that future quarks should be OK in this respect at least.

[Stu]

Interesting info. It should mean that future quarks should be OK in this respect at least.

Yes, that seems to be the case. They are promoted as being compatible with 1.25" and 2" and seems little reason why this shouldn't be possible, looking at the construction

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[John]

The slight problem for future Quark purchasors though will be to be sure which one they are getting and, if it's used, has it had the barrel replacement ?.

Is there any "gubbins" inside that 1.25" barrel to complicate replacement ?

[Stu]

The slight problem for future Quark purchasors though will be to be sure which one they are getting and, if it's used, has it had the barrel replacement ?.

Is there any "gubbins" inside that 1.25" barrel to complicate replacement ?

Very true. I've been told by my retailer that he is contacting anyone who purchased an affected unit from him to get them sorted. Still not totally sure if the barrel is user replaceable. It doesn't look it!

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[michael.h.f.wilkinson]

It is not user replaceable, I heard on Solarchat. A comment from Daystar suggest that items inside the quark are under pressure and opening one would cause serious problems

[Moonshane]

Blimey.

[Stu]

It is not user replaceable, I heard on Solarchat. A comment from Daystar suggest that items inside the quark are under pressure and opening one would cause serious problems

I'm sure that's correct Michael. Difficult to know what to do. I don't need the 1.25" and am happy with the performance of the unit I've got.

Will wait and see what the retailer says

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[Davey-T]

You'll need 1.25 if you're going to try it in the LS60.

Just tried mine and it's the same, no hope of it fitting into a 1.25 diagonal, don't think I like the idea of returning it, may just get an 1.25" / 2" adaptor machined out and keep it for the Quark if I need one.

Dave

[Moonshane]

I suppose you could get a machinist to turn a 1.25" extension enough to get the quark in but it's a lot of money hanging off a small extension.

[Stu]

I've now been told it IS user replaceable.....

....awaiting the part so will let you know.

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