Baader GPC’s

[bosun21]

I have already acquired the 1.25x and 1.7x GPC’s for my Maxbright II binoviewer and have the 2.6x on order. I was wondering whether or not the 2.6x is used very much with the binoviewer and if it’s practical to own all three. I have narrowed down the eyepieces I want to buy for them also and it’s between the Delites or Panoptics. Is one better for binoviewing over the other? I can’t seem to make my mind up. Thanks.

[Neil P]

I have all three, but the 2.6 is the least used of them, it very rarely gets put in. Mostly I use the 1.25 and then change my eyepieces. I have the Mark Vs and it is a bit of a pain to have to disconnect from the diagonal each time or change the GPC. Also can be a bit scary in the dark to be fiddling about with the connector. 
 

I have had a disaster where I dropped my binoviewers while disconnecting and had to send them away to get collimated, so whatever GPC I start with I generally keep in all night. I know the 1.25 works in most of my scopes, so it gets used most. I have to use the 1.7 for one of my scopes to get focus. 

[Highburymark]

I use the 2.6x most - in fact it’s necessary for me to reach focus with my binoviewers for solar Ha. As you may know the 1.7x is actually only 1.5x, so the 2.6x is very useful if you have nice low power eyepieces that you want to use at higher mags…… or if you need a more powerful barlow element to reach focus. It’s very sharp - although all GPCs are in my experience.

[Space Hopper]

I'm the same as Highburymark : i use the 2.6x the most.

To save time, i brought a second prism diagonal, and keep the 2.6 in there permanently. The quick coupler makes it an easy swap over rather than fiddling with a gpc in the dark. I'd probably drop it otherwise.

Thats my high power option, and i mainly use 24 and 19 Panoptics and a pair of 15 APM flats if the seeing is up to it.

I don't need any more power than the 2.6x already gives.

I'm also able to reach focal natively without the gpc and mainly just use the 24's for low power viewing at around 40x mag.

I also have the 1.25 and 1.7x gpcs as well.

I don't use the 1.7x but use the 1.25x with the HW for solar work as i can't (quite) focus without it.

 

Regarding eyepieces : Panoptics all the way. Perfect for binoviewing (19 and 24mm) and i purchased some of mine second hand to cut costs.

I have tried 15mm Delite's but found eye placement and merging very tricky.

HTH, Rob

 

[bosun21]

Thank you gentlemen for your input. I’ll go ahead with the 2.6x and either the 19mm or 24mm Panoptics. Having the option of all three GPC’s available makes sense. I do like the idea of having a spare T2 diagonal with the 2.6x pre installed for an easier and safer changeover in the dark. Thanks again.

[Paz]

I have all 3 magnifications but I use the 2.6x gpc the most, so much so that I have 2 of them so that I can leave 1 permanently in my herschel wedge.

[Deadlake]

I usually use the GPC 2.6 option the most used in a dedicated Baader diagonal.

However the other option is use a Barlow to PowerMate ahead of the diagonal.

With the PowerMate gives you options of using higher power EP's, no change in exit pupil.

 

[bosun21]

2 hours ago, Deadlake said:

I usually use the GPC 2.6 option the most used in a dedicated Baader diagonal.

However the other option is use a Barlow to PowerMate ahead of the diagonal.

With the PowerMate gives you options of using higher power EP's, no change in exit pupil.

 

I thought the GPC was better as it was designed to correct for any aberrations caused by the internal prisms in the binoviewer?

[Deadlake]

36 minutes ago, bosun21 said:

I thought the GPC was better as it was designed to correct for any aberrations caused by the internal prisms in the binoviewer?

It does indeed correct for aberrations, however if you want to increase magnification then using a Telecentric lens allows this while maintaining the exit pupil.

There are also other BV which have no prisms in them such as Dennis's here: https://www.cloudynights.com/gallery/image/63529-apo-ss-binoviewer-premium-quality-apochromatic-sharpest-signature-series-binoviewer-available-for-sale/

No need as far as I know for correction in this case. 

There are quite a lot of threads on CN for this approach.