Which Eye Piece

[Bino Pete]

2 hours ago, GavStar said:

I agree that 170x and 120x are nice magnifications to have. I think I’d also like to have a 50x mag option as well for more extended objects. So I’d keep the 42mm eyepiece if you can (do you like this one?)

I like both my 2" pieces but I have nothing else to compare them with so to you more experienced people they might be a load of rubbish!

[GavStar]

1 hour ago, Bino Pete said:

I like both my 2" pieces but I have nothing else to compare them with so to you more experienced people they might be a load of rubbish!

Maybe get one of the recommended eyepieces that sounds good to you - I think  around 17-20mm looks good giving 100 to 120 x and then compare with your 30 and 42mm. At f10 your scope is relatively forgiving on eyepieces and from a quick google the revelations get good feedback particularly for longer focal length scopes. 

Eyepiece preferences do depend on the individual imo - eg televue ethos get rave reviews by most people but I prefer the Es 92 (just!)

[Bino Pete]

16 minutes ago, GavStar said:

Maybe get one of the recommended eyepieces that sounds good to you - I think  around 17-20mm looks good giving 100 to 120 x and then compare with your 30 and 42mm. At f10 your scope is relatively forgiving on eyepieces and from a quick google the revelations get good feedback particularly for longer focal length scopes. 

Eyepiece preferences do depend on the individual imo - eg televue ethos get rave reviews by most people but I prefer the Es 92 (just!)

Have you got the ES 92 in both 12mm and 17mm?

[GavStar]

Just now, Bino Pete said:

Have you got the ES 92 in both 12mm and 17mm?

Yes fantastic eyepieces BUT very heavy. You need a strong focuser. I thought your budget was £150 ?

[Bino Pete]

Just now, GavStar said:

Yes fantastic eyepieces BUT very heavy. You need a strong focuser. I thought your budget was £150 ?

lol I think my budget has gone out of the window!

Is a CPC 800 focuser strong enough?

[GavStar]

5 minutes ago, Bino Pete said:

lol I think my budget has gone out of the window!

Is a CPC 800 focuser strong enough?

?

Sorry i don’t know about the cpc 800 focuser - but I’m sure you will get an answer soon. If it can handle an ethos 21 or a nagler 31 then it can handle the ES. They are pretty large (in comparison to a standard eyepiece like the APM UFF 10mm - the little thing on the bottom right of the second photo)

 

[Bino Pete]

16 minutes ago, GavStar said:

?

Sorry i don’t know about the cpc 800 focuser - but I’m sure you will get an answer soon. If it can handle an ethos 21 or a nagler 31 then it can handle the ES. They are pretty large (in comparison to a standard eyepiece like the APM UFF 10mm - the little thing on the bottom right of the second photo)

 

They look very smart! Are the ES 12 and 17 both 2" and are they both threaded for filters?

[GavStar]

1 minute ago, Bino Pete said:

They look very smart! Are the ES 12 and 17 both 2" and are they both threaded for filters?

Yes and yes ?

[Louis D]

1 hour ago, Bino Pete said:

lol I think my budget has gone out of the window!

Is a CPC 800 focuser strong enough?

Unless you put a crayford focuser on the back of any SCT, the focusing is done entirely internally by moving the primary mirror, and the diagonal and eyepiece are directly attached to the back of the tube, so the connection couldn't be any stronger.  Nothing external moves during focusing, which is quite nice for heavy eyepieces.

I would start with 70-ish degree apparent field of view eyepieces like the Delos and Pentax XWs and learn the sky with them before going for 80 degree and up eyepieces.

[alanjgreen]

1 hour ago, Bino Pete said:

They look very smart! Are the ES 12 and 17 both 2" and are they both threaded for filters?

I would be more worried about the eye relief of the ES. They state 22mm for the 17mm but are well known for "overstating" and it looks like 5mm is lost in the curve of the EP so it's an "real" eye relief of 17mm.

- do some research on cloudynights to see how glasses wearers get on with them?

Having never used one I can't comment on the performance. These are 92 degree FOV so expect to pay more than 72 degree FOV eyepieces.

The weight is a hefty 38 oz which is nearly 2.5lb.

The Delos weighs 14.4 oz or 0.9 lb.

you would have to do some tests with this weight on the back and try slewing to see if the motors could cope...

[Ags]

2 minutes ago, alanjgreen said:

The weight is a hefty 38 oz which is nearly 2.5lb.

The Delos weighs 14.4 oz or 0.9 lb.

If I was a Dalek invading the USA my battle cry would be Metricate! Metricate!

[alanjgreen]

1 hour ago, GavStar said:

 

Makes the ethos21 look like a compact package. Especially considering it has 100 degrees and a lower power wider fov!

The effort to grab TWO more mm eye relief really has made the ES a bit fat (and heavy).

[alanjgreen]

4 minutes ago, Ags said:

If I was a Dalek invading the USA my battle cry would be Metricate! Metricate!

I'm from UK and I still use lbs for weight. It's all down to what you were brought up with.

I've certainly got no intention of learning metric

You will be telling me to travel in kilometres next but I will prefer to stay miles ahead.

[GavStar]

42 minutes ago, alanjgreen said:

Makes the ethos21 look like a compact package. Especially considering it has 100 degrees and a lower power wider fov!

The effort to grab TWO more mm eye relief really has made the ES a bit fat (and heavy).

Alan, as you note earlier the ‘official’ eye relief of the ES 92 is 22mm, ie 7mm more than the ethos. I’m not sure what is the accurate figure but in actual use it does feel a lot more than just 2mm over the ethos. And for me a lot more comfortable to use and be able to see the whole fov. Not that I don’t like the ethos 21mm - it’s a toss up which one I grab when I go to the eyepiece bag. Sometimes I want extra fov and sometimes I want comfy! ?

I would note though that I don’t wear glasses when observing.

[Bino Pete]

On 23/01/2018 at 11:19, alanjgreen said:

I used to own a Mk3 Baader zoom.

At 24mm setting its not very good due to loss of fov (see the tfov text I wrote above!)

Would a 24mm fixed focal length (Baader Hyperion 68 Degree Eyepiece) have the same problem as my Baader mark3 zoom eyepiece at the 24 setting with the loss of fov?

I'm not interested in this eyepiece but just wondered! 

[alanjgreen]

13 minutes ago, Bino Pete said:

Would a 24mm fixed focal length (Baader Hyperion 68 Degree Eyepiece) have the same problem as my Baader mark3 zoom eyepiece at the 24 setting with the loss of fov?

I'm not interested in this eyepiece but just wondered! 

No it does not have a lack of FOV issue. It is 68 degree FOV.

the 24mm lack of FOV issue (50 degrees) is perculiar to the zoom only.

[Louis D]

17 minutes ago, alanjgreen said:

No it does not have a lack of FOV issue. It is 68 degree FOV.

the 24mm lack of FOV issue (50 degrees) is perculiar to the zoom only.

The zoom peculiarily is mostly due to the eyepiece having a fairly constant true field of view that gets magnified and spread out over a larger apparent field of view with decreasing focal length.  It's not linear (3x AFOV at 8mm vs 24mm), but it is there (60 to 70 degrees at 8mm vs 45 to 50 degrees at 24mm).

[Louis D]

2 hours ago, alanjgreen said:

I would be more worried about the eye relief of the ES. They state 22mm for the 17mm but are well known for "overstating" and it looks like 5mm is lost in the curve of the EP so it's an "real" eye relief of 17mm.

I measured 17mm of usable eye relief for both of my ES-92 eyepieces.  My 5.2mm and 14mm Pentax XL, 10mm Delos, 9mm LV, and 3.5mm Pentax XW all have 18mm of usable eye relief, so it's a difference of 1mm.  I don't consider it to be that big of a deal.

This has been discussed elsewhere, but there is no physical way the Ethos can have 15mm of eye relief, 100 degree AFOV, and a 30mm eye lens.  The best it can hope for is 12.6mm of eye relief before subtracting a couple of millimeters for packaging as in the case of the Delos/XL/XW/LV, so figure on 10.6mm or generously 11mm of eye relief for the Ethos.  That means the ES-92 has 6mm more usable eye relief than the Ethos.

[Bino Pete]

12 hours ago, alanjgreen said:

No it does not have a lack of FOV issue. It is 68 degree FOV.

the 24mm lack of FOV issue (50 degrees) is perculiar to the zoom only.

Does the new mark4 Baader zoom have this same problem or is it restricted to the mark3?

[Paul73]

It (fov) is the same issue in all but the most expensive zooms. Optically, the Baader Mk111 and IV are very very similar. The MkIV is a bit more compact and has a smoother working eye guard (I have one of each on my desk as I type).

I would not recommend these for an SCT.

If eye relief is a concern, steer clear of the longer Ethos. You will loose a good chunk of the fov and most of your bank balance. I use the Delos range (I believe the Pentax cow to be similar). You won’t find better.

Paul

[alanjgreen]

1 hour ago, Bino Pete said:

Does the new mark4 Baader zoom have this same problem or is it restricted to the mark3?

Yes, it's in the description. Paragraph 4

https://www.firstlightoptics.com/baader-planetarium/baader-hyperion-zoom-eyepiece.html

a zoom will have varying eye relief at the different magnifications. I personally wouldn't recommend them for a glasses wearer.

You would be better off with eyepieces with 20mm eye relief if you observe wearing glasses.

[Stu]

1 hour ago, Paul73 said:

I use the Delos range (I believe the Pentax cow to be similar)

I may be misreading this Paul, but were you thinking of some udder eyepiece when you wrote this?

[John]

Out of interest, the actual AFoV of the Baader 8-24 zoom varies a bit from the specs. It has been measured at around 42 degrees at 24mm to nearly 70 degrees at 8mm.

When I've had them I've treated them as 20-8 mm zooms because I didn't like the constrained AFoV at the 24mm end and the slightly "mushy" field stop that also seems to occur at that focal length.

 

 

[Louis D]

11 hours ago, Paul73 said:

It (fov) is the same issue in all but the most expensive zooms.

I've read there was an expensive Leica spotting scope zoom with an iris that contracted as the magnification increased to maintain a constant AFOV of about 50 degrees.  Effectively, it threw away the extra AFOV by blocking it with the iris.  Be careful what you wish for.