8" Edge HD - Wider FOV ?

[Louis D]

I'd say piggyback a 72mm ED refractor onto your SCT to achieve wide fields of view.  With a 2" diagonal and 2" eyepieces, you'll be able to achieve over 6 degrees TFOV.

No one scope is going to meet all needs.  I run with an AT72ED mounted side by side with a 127mm Mak on a DSV-2B mount for grab and go.  That way, I've got wide and narrow fields covered pretty well.

[John]

1 hour ago, Stu said:

It's a tricky one John, but actually moving  from 0.88 to 1.36 degrees does make a number of objects more comfortable in the eyepiece so if you want to stick with one scope then in my view it is worth it. I think generally having a 2" back and diagonal is a good investment anyway, I just prefer the more secure connection which helps every with larger 1.25" eyepieces.

Yes, when I've had a C8 I have tended to go down the 2" route in the end. I didn't tend to hang onto them for long - probably about time that I gave the design another chance though.

[Stu]

This kind of setup works well, widefield and high power with a bit of aperture side by side.

 

[YKSE]

3 hours ago, Stu said:

It's a tricky one John, but actually moving  from 0.88 to 1.36 degrees does make a number of objects more comfortable in the eyepiece so if you want to stick with one scope then in my view it is worth it. I think generally having a 2" back and diagonal is a good investment anyway, I just prefer the more secure connection which helps every with larger 1.25" eyepieces.

I fully agree with Stu, espeicially with Edge HD where the focal reducer is much more expensive than the standard SCT's. Besides, the 2" eyepice and diagonal are just what needed for the wide field observing in a small refractor.

[BRUN]

thanks guys, ill try a 2" EP i guess and see what its like

[Ricochet]

Have a look through the classifieds. There have been quite a few ES68/Maxvisions come up recently. 

[BRUN]

yea i check that part of the forum daily lol

[BRUN]

would a 38mm panaview be a good choice aswell ?

i do have a 40mm plossl but its 1.25" and just standard FOV

[alanjgreen]

This review says "yes" it will be good at the f10 speed of your sct scope.

I just looked at FLOs website at the 38 panaview and 40mm aero.

i would probably buy the 40mm aero of the two. Three reasons

1. The aero is more reusable if you bought a 2nd scope (faster - such as dob or refractor). The review says this worked better with faster scope speeds. Making it more of a "keeper". 

2. The 20mm eye relief of the aero will be more comfortable than the 28mm of the panaview. Eyerelief is the target distance between your eyeball and the top eyepiece glass surface. 28mm would be great if your wear glasses but otherwise may stop you getting your eye right down into the eye cup (depends how you like to position your eye?)

3. Weight. Best not to make your scope too back heavy as this may affect balance which will impact tracking. My CPC had dual fork and was much stronger than the single fork design. The evo mount is stronger than the old nexstar mount so don't worry too much about this.

[BRUN]

im starting to think i should have built up a set of these instead of the ES ive bought

https://www.firstlightoptics.com/william-optics-eyepieces/william-optics-swan-eyepiece.html

[John]

ES 68's are better eyepieces than the William Optics SWAN's. In your f/10 scope there might not be much difference but if you get a faster scope at some point the SWAN's will suffer towards the field edges.

[YKSE]

As John already said, ES 68 are much better eyepieces than WO SWAN's, the only downside of ES 68 are their size and weight in 34mm or 40mm.

I owned TS WA38mm (Panaview 38mm clone) for a very short period of time, used it as finder EPfor double-double in 80ED, when Vega was near the edge, it bloated litterally to the size of a full moon becase of astigmatism in EP and FC (in the scope, and EP too?), so I replaced with 40mm Aero directly, it works noticeable better optically, and more than 100g lighter and 20mm shorter is a bonus too.

40mm WO SWAN are the same Erfle design as Panaview, 5 lens in 3 groups, so I wouldn't expect it to be any better than the 38mm Panaview optically.

[BRUN]

guys, are these similar to WO SWAN or Panaview

https://www.explorescientific.co.uk/en/Eyepieces/Explore-Scientific-70-Eyepiece-35mm-2.html

 

is the SW Aero ED the best choice ? and would i choose 35mm or 40mm ?

[YKSE]

Those ES are the same Erfles as the WO SWAN and Panaviews.

Of the Paragons (SW Aero ED, 40mm is said by many (BillP among others) to be the best of the bunch, it has 46mm field stop (46.1mm by my measuremnt), the widest TFOV for 2" eyepieces.

[alanjgreen]

If you want 68 degree FOV for £100 then the 40mm aero sounds your best shot.

if you want almost the same FOV with more magnification then the only other choice to consider is a 30mm with 82 degree FOV such as the ES82. But at £250 they are twice as much. Also bigger and heavier.

i am sure the aero is a good place to start your widefield collection  personally I would lose a little FOV to gain the extra magnification of the 30mm 82 degree ES.

Alan

[BRUN]

i dont really have ES 30/82 money, im buying starsense lol, but thanks for all your help, id have never arrived at this conclusion otherwise

[BRUN]

guys look at this, Martin at FLO has shown me that the 40mm Aero should give the same view pretty much as my 24mm ES 68 did in my 10" dob

https://astronomy.tools/calculators/field_of_view/?fov[]=52|134|||1||&fov[]=14|124|||1||&messier=31

[Stu]

10 minutes ago, BRUN said:

guys look at this, Martin at FLO has shown me that the 40mm Aero should give the same view pretty much as my 24mm ES 68 did in my 10" dob

https://astronomy.tools/calculators/field_of_view/?fov[]=52|134|||1||&fov[]=14|124|||1||&messier=31

Yep, that looks about right, although you may get some vignetting in the 40mm/C8 combination due to the baffle tube field stop. I can't remember how big it is vs the fieldstop on the 40mm.

[Louis D]

2 hours ago, Stu said:

Yep, that looks about right, although you may get some vignetting in the 40mm/C8 combination due to the baffle tube field stop. I can't remember how big it is vs the fieldstop on the 40mm.

I doubt it would be noticeable visually.  I've used a 40mm Meade SWA 5000 in my 127mm Mak which has only a 37mm diameter rear baffle without being able to detect vignetting, though I'm sure it's there.  What I do notice is that bright stars create elliptical rings as they cross the edge of that 37mm baffle edge, growing bigger the farther off axis I push them.  It's some sort of reflection, I suppose.

[BRUN]

so how big is my baffle ?

[alanjgreen]

if you look down the front of the scope then the baffle tube is the black plastic tube coming up through the centre of the primary mirror.

You are getting into minutia now - just spend the money already!!!

[John]

11 minutes ago, BRUN said:

so how big is my baffle ?

This thread tells you the measurements of a variety of SCT's:

https://www.cloudynights.com/topic/482272-sct-baffle-tube-inside-diameters/

Also some discussion of vignetting.

[YKSE]

37mm for C8 as listed in link above.

The baffle tube is quite far away from the focus plane, therefore the vignetting is not like hard cut off (such as field stop), it grows gradually, and our eyes are very insensitive to gradual vignetting, I can only see the vignetting in 40mm Aero when I really look hard for it.

Here's a picture showing how the baffle tube (the two stops) cause the light fall off at the edge.

Here's the link to the page for detailed explanations:

http://petersonengineering.com/vignetting.htm

[BRUN]

1 hour ago, alanjgreen said:

if you look down the front of the scope then the baffle tube is the black plastic tube coming up through the centre of the primary mirror.

You are getting into minutia now - just spend the money already!!!

lol, i will !