jetstream

Great post and I know this isn't quoting you Neil but I wanted to mention something. This mention of the "blocking filter" in the nose of the Quark is misleading IMHO. This front filter is the induced transmission filter (ITF) which serves a completely different role than the blocking filter. As the etalon is a "comb" filter the actual blocking filter isolates one line for us to see or image. To me this ITF is the fail safe energy reducing "broadband" filter and not the actual blocking filter. I thought it might be worth mentioning this.

Some make choices and hopefully they are informed ones.... A few have tried the reflective filters but the con to this is the reflected light- I wouldn't want to inadvertently look at a D-ERF while its tracking the sun. BTW there are more choices for the full aperture ERF and not all are reflective I believe.

Very true- but having a filter that "rattles" ( a bit loose in its cell) and figuring out the energy from the solar disk size can prevent this. My 120ED has no issues with this filter (with my diags). I chose KG3 because the nature of the KG3 allows it to filter IR regardless of coating. If the KG3 breaks I'll know it immediately vs a coating failure with the other types which may go un-noticed. The reflective filters shoot light out the objective... I guess its all about choices-to each their own. Edit- I use this filter for keeping IR from reaching my eye as well as protect the Quark or wedge...

Thanks for this Doug, great point. In general I do not use super large exit pupils and have bought a scope (200mm f3.8) that brings along many benefits for specialized nebula observing, including the avoidance of the super large exit pupil (ie 42mm LVW/standard reflectors) to increase the TFOV ...

BTW I use this filter for solar use. Mr Smie did calculate if it was safe based on the f ratio (solar disk size) at the distance inside the tubes using my diagonals. It is an absorptive IR filter (KG3) vs a reflective (Baader UV/IR). http://beloptik.de/en/left/if-uv-ir-cut-on-kg3-infrared-blocking-filter/

People can do whatever they want- its a free country (ies) so to speak. I personally like the metallic ITF features better (ie they block more light when they fail).

It's more complicated than this IMHO. After hearing Alans (Alien13) experiences a while back I tried super large exit pupils with success on a few objects, but in general I stick to a 5.5mm maximum for general dark sky use. The goal here is to help members get into a reasonable "ball park" in terms of exit pupils and we can explore other options once experience is gained.

Whatever we do here we must not ever consider removing the "little silver" filter (ITF) from the bottom of the Quark. I believe the goal of a true front mounted ERF and a "mini ERF" (UV/IR,35nm Baader 2") is to keep heat (energy) from the Quarks filters. https://www.andovercorp.com/products/bandpass-filters/standard/600-699nm/

This is my minimum exit pupil for objects like the Veil etc using 100 deg EP's. I also find that widefield (82 deg) and hyperwides (100 deg) seem to offer more "contrast" (yeah I know its the wrong use of the word) than 50 deg EP's -possibly through engaging more of the eyes receptors. In other words my 32mm plossl goes unused for this type of observing. For many an exit pupil of around 5.5mm is very good- under truly dark skies. Your own eye plays a big role here too... honestly I think that 3.4mm exit pupil is small for what you want to observe but I would go with 2" eyepieces to get larger ones. If your scope doesn't take 2" I'd buy one that does down the road. Just my thoughts,Gerry

The Quarks filters let deep red-656.3 nm through (in "steps down to it") so the wide Baader 35nm Ha filter will not cause a color difference. Be very careful when considering and using filters ahead of your diagonal for solar.

I can see you have got the UK seeing figured out Piero!

Could it be that owners of some brands are more open to report problems than others? It might seem like some astronomers don't want to jeopardize the value of their equipment IMHO.Wandering quality control could hit anywhere really. https://www.cloudynights.com/topic/574698-delites-never-seen-this-before/

One of the very best IMHO- and when you view it crank up the mag using a widefield. Once done warming up on M37 wander over to the Flaming Star neb and spend time with the UHC there under dark skies. The Eskimo neb is a must see and really up the mag on this one as well. This show case neb will show a 2 toned green with fine filaments under the right conditions.

Sorry to hear the issue John. My own Leica zoom hasn't developed this problem after extensive use-puzzling. As I was going to sell it I contacted Leica concerning warranty transfer to the new potential owner...they told me it was not transferable. It must be different here. The cleaning wouldn't cost much anyway I suspect.

Piero, congrats for a fine purchase! Great scope!