Inspire me about visual astronomy

[bomberbaz]

3 hours ago, RobertI said:

Thanks for your help Steve, appreciated. I hadn’t really considered the exit pupil aspect, that’s a good thought. I have always worked on the basis that I didn’t really want to go below 68 degrees FOV which limits me to a 24mm eyepiece in an SCT, but what I didn’t really consider is the limitation on the exit pupil. Your excellent suggestion of a 32mm Plossl gets around that, at the cost of a narrower field of view of course. And I do have a 0.63 reducer which I use most of the time. Before I rush out and buy a 32mm Plossl, do you think my 38mm 2” eyepiece might also work? There will be vignetting at the edges but I’m assuming the central 50 degrees will be no worse than a Plossl?

I( would suggest trying it. The exit pupil is a little on the large size at 5.7mm, but try that on a dim nebula, (M57 etc are far too bright) and also an eyepiece around the 25mm range to see what results you yield. I would expect the 38mm to be brighter than the 25 but the darker background would help the smaller exit pupil.  It could possibly a little washed out depending on your eyes response to darkness, none of us are the same.

What filters do you use/have?

Edited May 3, 2023 by bomberbaz

[RobertI]

50 minutes ago, bomberbaz said:

I( would suggest trying it. The exit pupil is a little on the large size at 5.7mm, but try that on a dim nebula, (M57 etc are far too bright) and also an eyepiece around the 25mm range to see what results you yield. I would expect the 38mm to be brighter than the 25 but the darker background would help the smaller exit pupil.  It could possibly a little washed out depending on your eyes response to darkness, none of us are the same.

What filters do you use/have?

I have an OIII and a UHC, I believe the OIII works well on the Crescent? As far as the 38mm 2” eyepiece goes, I recall that I found it would not focus with the reducer, so that combination is out. I’ve tried the C8 with a 21mm eyepiece plus reducer, but I now have a 24mm too, which I could try, but I suspect the 32mm will give the jump I need in exit pupil size to make a difference on the Crescent. I will give it ago this summer! 
 

Sorry to the OP for diverting the thread, but hopefully of interest.  

Edited May 3, 2023 by RobertI

[bomberbaz]

On 03/05/2023 at 22:27, RobertI said:

I have an OIII and a UHC, I believe the OIII works well on the Crescent? As far as the 38mm 2” eyepiece goes, I recall that I found it would not focus with the reducer, so that combination is out. I’ve tried the C8 with a 21mm eyepiece plus reducer, but I now have a 24mm too, which I could try, but I suspect the 32mm will give the jump I need in exit pupil size to make a difference on the Crescent. I will give it ago this summer! 
 

Sorry to the OP for diverting the thread, but hopefully of interest.  

The 21 and 25mm will be ok for UHC as typically they are still useful down to an exit pupil of 2mm and sometimes less on very bright objects, the crescent does respond to UHC as well as OIII but when I tried both on it, the OIII won. (Both were at 5mm EP)

The OIII is not restricted to 5mm exit pupil but my testing just showed that it responded best to one of that size. FYI I could not see the crescent in my dob at 3.5mm EP, that's the difference.

A 32mm plossl in FLO'S AE  range is 29 quid, bargain. And it still give your C8 plus reducer a very nice 1.27 degrees true field of view, big enough for most DSO nebula. I think that would cover nearly all your bases and as remarked, won't bust your bank either. Let me know how you get on as I would be interested to hear about it!

Also apologies to OP, all useful stuff this though.

Edited May 5, 2023 by bomberbaz

[RobertI]

11 hours ago, bomberbaz said:

A 32mm plossl in FLO'S AE  range is 29 quid

Thanks for the additional info, I’ll order the Plossl and let you know how it goes.  

[Agerskov]

On 28/12/2022 at 00:17, mikeDnight said:

 

Hi Mike
Great and fantastic sketches. 

As far as I know most referre to HD 192579, 30 and 31 Cygni (omicron Cygning) as the Patriotic Triple - but I can't recall your sketch above as of these stars. 

Have you found another three red, white and blus stars in Cygnus to resemble The Patriotic Triiple? 

If you have - I like yours better that the omicron version. 

[mikeDnight]

3 hours ago, Agerskov said:

Hi Mike
Great and fantastic sketches. 

As far as I know most referre to HD 192579, 30 and 31 Cygni (omicron Cygning) as the Patriotic Triple - but I can't recall your sketch above as of these stars. 

Have you found another three red, white and blus stars in Cygnus to resemble The Patriotic Triiple? 

If you have - I like yours better that the omicron version. 

I've never checked their individual identities, but have attached the pic's below for easy identity. The orientation of my sketch is a little different, but the stars are the same.

 

Edited May 10, 2023 by mikeDnight