Quarrelling with Quark

[Stu]

Thanks, Joves. Now that I've got my head in the right place, literally and figuratively, things can only get better. It's like one of those so-called 'light bulb' moments - when it comes on, everything is clear.

You have a signature list that reads like the stock of an astronomy shop, but most relevant is that you've got it together with the Quark and a TV102. That encourages me to think I can get that combo working, too.

I'm sure I'll get to know and love my 32mm plossl. I just need to live with it a little bit longer ... However, I'm only just achieving full disc when using the x0.5 reducer. Are you getting full disc without any reducer?

Now that I have things sorted out a bit better I'm looking forward to playing around with some spacers and different configurations of the optical train, but have only a 2" UV/IR cut filter, so constrained in some way. Also not sure if it's safe to put the reducer first in the optical train - i.e. on the Quark before the diagonal?

Whatever, the only way is up ...

Thanks for your response. Clear skies!

Gordon, I think a safe rule is always keep everything behind either the Quark or the UV/IR cut filter. I certainly would not put a reducer in front of the Quark unless it was protected by a D-ERF or UV/IR ahead of it.

I've been using a x0.5 reducer in the eyepiece barrel of my Plossl and do enjoy the lower mag it gives. The contrast certainly seems better in surface features.

[Floater]

There you go again guys ... Straight answers straight away!

Kinda figured that the first thing in the line should be a filter of some kind but glad to have that confirmed.

Shaun, you're a rascal. :-))

[Joves]

Pleasure Gordon. Absolutely, try the Quark in your TV102. Make sure you use the UV/IR cut filter though. The view was amazing. It's awesome with the TV76, but the extra resolution of the TV102 was most impressive.

I get full disk views in the TV76 without any reducer. There's not a heap of swimming space around it, but it's definitely full disk. With a reducer, there is a heap of space (akin to the view through a PST with 15mm eyepiece, but with a heap more resolution). Here's the thing though... I do use it first up in the optical path. When used directly on the eyepiece, the result is minimal when compared to without it. After speaking with Shaun from Daystar, he said it's not ideal as it changes the bandpath, but is not unsafe to do so.

[Stu]

That's very interesting Aaron, I would not have thought that to be the case but I stand corrected.

I agree about the use of the focal reducer ahead of the Quark not being ideal though. I have used a x0.8 reducer ahead of the Quark to get full disk views on the TV85. It does work but it reduces the contrast because it takes the focal ratio further from the ideal; the light 'beam' is less parallel so the bandpass is not as tight.

After much experimenting, I now only use the reducer after the Quark. It doesn't increase the fov but it does improve contrast by lowering the mag

Stu

[Joves]

Totally, Stu. The view with the reducer ahead of the Quark definitely still provided better views than the little PST though. I'd suggest not necessarily doing it on the back of my advice though. If something were to happen due to it not actually being safe, I'd hate for it to be on account of my suggestion.

That's interesting that you find the reducer after the quark doesn't change the FOV so much as it ups the contrast. I hadn't considered it that way, but it makes sense. I usually just do without the reducer in the TV76. In the 102, I was more than happy yesterday with the non-full-disk views. I'd love to get an ERF for the NP127 and try the Quark in that.

[Stu]

Totally, Stu. The view with the reducer ahead of the Quark definitely still provided better views than the little PST though. I'd suggest not necessarily doing it on the back of my advice though. If something were to happen due to it not actually being safe, I'd hate for it to be on account of my suggestion.

That's interesting that you find the reducer after the quark doesn't change the FOV so much as it ups the contrast. I hadn't considered it that way, but it makes sense. I usually just do without the reducer in the TV76. In the 102, I was more than happy yesterday with the non-full-disk views. I'd love to get an ERF for the NP127 and try the Quark in that.

I reckon the 127 with a D-ERF would be pretty amazing. I often thought the Genesis would have been great in the same way.

The limitation with the Quark is the 21mm etalon aperture which effectively forms a field stop limiting the field of view. Putting a focal reducer in front of the Quark generally won't increase the fov because it just gets blocked by the etalon. You can see this effect in the eyepiece, you can see the eyepiece field stop, then inside this the etalon field stop which is the limiting factor.

[Pig]

The Vixen 40mm NPL does a pretty good job of lowering the mag and at £43 new its quite a steal. It works better with proms than it does with the surface detail. However, the surface detail is still fab. It is also a lot easier to look through than the TV32mm.