Skywatcher Esprit 80, Not happy with visual, Me or the scope

[bilbo]

Hi All

Can anybody who owns an Esprit 80 tell me how they find it for visual use. I'm not at all happy with mine. Elongated stars as you move away from the centre on 26mm Panaview and 19mm Panoptic, 7mm Naglers pretty good.

I did notice that after popping in for a cup of tea, when I came back out the initial view seemed sharp then deteriorated, leaving me wondering, Me or the scope. Had a Megrez 72 for a long time never really experienced anything "off" on that but never really scrutinised it as I've always been an SCT guy.

I know f5 on an unflattened frac is pushing things, but I just expected a little better.

cheers

Steve

PS Not had a chance to try a cam on it

 

 

[Adam J]

18 minutes ago, bilbo said:

Hi All

Can anybody who owns an Esprit 80 tell me how they find it for visual use. I'm not at all happy with mine. Elongated stars as you move away from the centre on 26mm Panaview and 19mm Panoptic, 7mm Naglers pretty good.

I did notice that after popping in for a cup of tea, when I came back out the initial view seemed sharp then deteriorated, leaving me wondering, Me or the scope. Had a Megrez 72 for a long time never really experienced anything "off" on that but never really scrutinised it as I've always been an SCT guy.

I know f5 on an unflattened frac is pushing things, but I just expected a little better.

cheers

Steve

PS Not had a chance to try a cam on it

 

 

It's not a visual scope it's an imaging scope this is about what I would expect at F5. 

[Sp@ce_d]

Hmm now you mention it I can't remember ever actually looking through mine.. 🧐 

I take it you got it for imaging primarily?.. get a camera on it you'll love it.

[vlaiv]

You can easily test if it is the field curvature (and I bet it is).

Concentrate on center of the field - focus stars to pin points - edge stars will be out of focus.

Concentrate on outer field - focus stars there to be pin points - center stars will be out of focus.

If above is true - you are dealing with field curvature. If you can't do this with very well corrected eyepiece (19mm Panoptic) and outer field is still not sharp but rather small crosses or something like that - then your scope has astigmatism. You should perform star test at high power to see what might be the problem.

By the way - large exit pupil can indicate problem with your eyes as well - but in that case, stars will look elongated / distorted all over the field - not only at the edges.

[John]

Just another thing - the 26mm Panaview will be showing some astigmatism at F/5 in the outer half of the field of view - stars elongated a bit like seagulls. The Panoptic should not be showing this so will be more useful to detect field curvature as vlaiv says.

 

 

 

Edited November 27, 2020 by John

[bilbo]

5 hours ago, Sp@ce_d said:

Hmm now you mention it I can't remember ever actually looking through mine.. 🧐 

I take it you got it for imaging primarily?.. get a camera on it you'll love it.

Have you tried any 2" acc's directly on it, Mine is all over the place, tricky to get a grip unless its a perfectly uniform tube, ie no grooves or slopes.

Got a couple of Cam's, EOS 1100, 183C Pro Tec, Atik Infinity, and a collection of MV camera's, Just never had the time to use them. I thought I'd try the esprit to motivate me a little more. Problem is once I start looking, I just keep looking.

A double edge sword I think, On the one hand I should have kept the Megrez 72 on the other hand if its "orrible" to look through then that might be just enough for me to get those camera's out.

Cheers

Steve

[bilbo]

Thanks Vlaiv & John.  Just the sort of help I need, Out of my comfort zone here with this, but what you say explains a lot.

I only got a short spell at the eyepiece due to glorious weather. As soon as we get some clear sky I'll give it another go taking your suggestions into account.

Thanks a million.

Steve

[bilbo]

On 27/11/2020 at 18:13, John said:

Just another thing - the 26mm Panaview will be showing some astigmatism at F/5 in the outer half of the field of view - stars elongated a bit like seagulls. The Panoptic should not be showing this so will be more useful to detect field curvature as vlaiv says.

 

 

 

Seem to be bang on the button, Just a bit of a shock to my brain.

Had to check a starsense this eve, So I popped the 183c protec on the back of the esprit with the flattener about 1mm short from required distance. Took a couple of snapshots from sharpcap, (don't know what I'mm doing there either)

10 secs exposure on the stars with gain around 50%, Sky was terrible. I think the cental star is Denb, barely visible to the naked eye. Used the moon for an approximate focus.

I think all the stars look reasonable, nothing like my experience at the eyepiece.  Its a bit rough & ready but you guys may be able to read more from it

 

[SimM]

Images are good.

If its the Altair 183c protec - then it has a UV/IR block filter on the camera (that can be removed). I have the ASI 294C that doesn't have a UV/IR filter, so I added one. The mono version of the Altair doesn't have the UV/IR filter.

Of course the moon can look good with an IR image - removing the UV/IR block and using an IR pass filter. The problem with even good glass is that focusing visible light and IR doesn't work. The picture of the moon looks sharp and the stars are round. The moon at an early stage has light at an oblique angle and with IR can look even sharper as well as lucky imaging and stacking.

My images look bloated compared to how the look visually - that's why I bought the UV/IR filter. But here it's not required.

 

[bilbo]

Central Star appears to be 55 Cygnus, Not Deneb as previously thought,  I just assumed it was Debeb due to the brightness and nothing else could be seen.