After two sessions with stock 200P - eyepiece upgrade advice?

[Louis D]

4 minutes ago, vlaiv said:

Not sure why would it be so?

If you place camera lens at exit pupil - all light from EP will certainly hit camera lens without any issues.

Try it yourself.  I keep an old Olympus C4000 with adapter tube that couples nicely with my 22mm AT AF70 for digiscoping.  No camera lens for my Canon DSLRs will couple with any of my eyepieces (except maybe the ES-92s with their 43mm eye lenses and the two Meade 40mm eyepieces).  Part of the problem might also be that the entrance pupils for most DSLR lenses are buried deep within the lens, so you can never get it to correspond to the exit pupil of most eyepieces to capture all the rays because the eyepiece would have to be inside the camera lens.  Perhaps those with 30mm+ eye relief might work.  I'm speaking from real world experience, not theory.  I would have loved to have used my high resolution DSLRs for this experiment, but it just isn't possible for 90%+ of eyepieces.

[Louis D]

2 minutes ago, vlaiv said:

That is not going to help much - it's a 12mm eyepiece - means that field stop is about 17.1mm - that is only about 8.6mm from axis - about a third of a distance from field center compared to edge of 46mm field. Even if you introduce large distance error for flattener - that part of the field will not be significantly distorted.

So this aberration doesn't scale linearly with magnification like coma in a Newtonian?

[Louis D]

2 minutes ago, vlaiv said:

In any case - I think that we can use your comparison as a good indicator of edge performance of eyepieces - all issues discussed above will probably have rather small impact at these magnifications.

I wouldn't have spent days captured and compositing images if I thought it wasn't representative of the reality I was seeing with my own eyes.  Until the advent of the most recent generations of phone cameras, I had neither the field width nor resolution nor edge correction to do this well.  I'll bet the latest generation of phone cameras are even better than what I was using.

[vlaiv]

2 minutes ago, Louis D said:

So this aberration doesn't scale linearly with magnification like coma in a Newtonian?

I'm not sure, it is interplay of scope curvature and "expected" curvature of flattener - it usually manifests itself in the corners of the image and can't be seen when you move towards the center - this is on sensors with diagonal of about 20-30mm - so affected area is usually 10+ mm from optical axis.

[heliumstar]

To the OP.

Read your post a few times and I feel that whatever compromise you make now you will not be happy. You have issues with 'high power' eyepiece. Just get one 8-10mm eyepiece that will be your high power eyepiece for now - something like Baader Morpheus 9mm - with that one there are no compromises. If you stretch a little 9mm Nagler for example. Spend all the budget on that one eyepiece. Save and buy more later.

[estwing]

Can we keep on topic guys pls...

[Deisler]

@Louis D @John

Hi I wonder if you have used Baader Hyperion Aspheric 2'' 31mm? Seen people recommended it as wide field low-power EP a lot.

More specifically, how is it compared to Aero 2'' 30mm or even APM UFF 30mm? 

Cheers

[John]

I have owned and used a Hyperion Aspheric 36mm. I was disappointed with it's correction to be honest with you, even in quite slow scopes such as my ED120 F/7.5. I didn't have the chance to compare it with the Aero ED 30 though but my guess would be that the Aero ED 30 is better corrected.

I did not keep the Hyperion Aspheric 36mm for very long.

 

[Louis D]

12 minutes ago, Deisler said:

@Louis D @John

Hi I wonder if you have used Baader Hyperion Aspheric 2'' 31mm? Seen people recommended it as wide field low-power EP a lot.

More specifically, how is it compared to Aero 2'' 30mm or even APM UFF 30mm? 

Cheers

Here's a comparison between the 30mm/35mm Aero EDs and the 31mm/36mm Hyperions.

[Deisler]

Cheers both @John @Louis D

And with John's review back in 2010

 I am leaning towards Aero 2'' than Baader Aspheric 2''. 

I assume 30mm is better than 35 or 40mm, as 30mm is near the 'upper limit'?

[Deisler]

3 hours ago, heliumstar said:

To the OP.

Read your post a few times and I feel that whatever compromise you make now you will not be happy. You have issues with 'high power' eyepiece. Just get one 8-10mm eyepiece that will be your high power eyepiece for now - something like Baader Morpheus 9mm - with that one there are no compromises. If you stretch a little 9mm Nagler for example. Spend all the budget on that one eyepiece. Save and buy more later.

Baader Morpheus 9mm looks a great EP! Unfortunately I dont think I will spend that much on a single EP as my first EP. Maybe as my next upgrade.

[Ruud]

3 hours ago, Deisler said:

I assume 30mm is better than 35 or 40mm, as 30mm is near the 'upper limit'?

About the upper limit: This is determined by the effective field stop of an eyepiece. The stop can't be wider than the barrel.

In a 1.25"  barrel you can fit the field stop of a  32mm 52° eyepiece, or that of a 24mm 68° one. Both are at the upper limit of what will fit. 

See the diagram.

The eyepieces on the blue line all show the same maximum true field of view that can be obtained from a 1.25" focuser.  Any combination of focal length and afov on and below the blue line will fit a 1.25"  focuser. Combinations above the blue line blue line need a 2" focuser (or larger).

Occasionally you'll come across a 1.25" eyepiece that lies above the blue line, like say a 30mm 60° eyepiece. Such an eyepiece  has an excessive amount of pincushion distorting due to positive angular magnification distortion (amd) which blows up the apparent field of view.

I love the Morpheus and Delos. Their angular magnification distortion is very close to zero.

A small amount of positive amd (5%) is often used by designers  because this makes it easier to correct an eyepiece for astigmatism. The 24mm ES68 and 32mm GSO Plössls are examples. I've taken this into account when calculating the blue line.

If you know the size of the field stop you can very accurately calculate the true field of view of an eyepiece. The first sheet of the attached spreadsheet is for the 200p and calculates true fields of a few eyepieces mentioned in this thread.

ScopeCalculator-2019-06-16.xlsx

Scope Calculator Formulas.pdf

I plan to make a new version that runs using macros. This will be more versatile and  self explanatory. In the current version (no macros), put the cursor over the commented cells in the spreadsheet  to read the explanations there and consult the pdf if you want to know what is calculated and how. Edit only the yellow cells.

 

 

 

Edited November 15, 2019 by Ruud

[Louis D]

16 hours ago, Deisler said:

Cheers both @John @Louis D

 I am leaning towards Aero 2'' than Baader Aspheric 2''. 

I assume 30mm is better than 35 or 40mm, as 30mm is near the 'upper limit'?

I'm not really sure what you mean by upper limit in this context.  The 30mm Aero ED is a 2" eyepiece and has about a 35.5mm field stop, so it is 10.5mm smaller than the 2" maximum field stop of 46mm as found in the 40mm Aero ED (which is no longer in production and sold out worldwide).  The 35mm Aero ED has a 44.5mm field stop, so it is much closer to the upper limit for 2" eyepieces.  If you meant upper limit for exit pupil, that would be 7mm*6=42mm for most dark adapted observers, so no issues with even a 40mm eyepiece.

The 30mm is slightly better corrected than the 35mm, but it is narrower in field of view at 68 degrees versus 73 degrees for the 35mm.  If you were to compare well corrected true fields of view, the 35mm would probably slightly win out, just showing it at a slightly lower power.  I don't think you can wrong with either one as long as you concentrate on the central view and allow the edges to remain in your peripheral vision.

[John]

If you want to try a low / wide 2 inch eyepiece for a smallish outlay, this has just popped up in our classifieds and seems a decent deal:

 

[Deisler]

5 hours ago, John said:

If you want to try a low / wide 2 inch eyepiece for a smallish outlay, this has just popped up in our classifieds and seems a decent deal:

 

Bought it. Thanks!

Now will order my BST EPs (5mm and 15mm) from FLO and they should make me happy for a while.

[Louis D]

4 hours ago, Deisler said:

Bought it. Thanks!

Now will order my BST EPs (5mm and 15mm) from FLO and they should make me happy for a while.

Be sure to let us know your thoughts on your purchases.  Every equipment report helps fine tune everyone's understanding of the pros and cons of each item.

[Deisler]

Back to my previous question regards filter, if I may -

Last two sessions when I viewed the moon (close to full moon), I felt very uncomfortable as my left eye was left with a bright white spot even 30 mins after I came back in. I know it is not ideal to view full moon, but I think I might have to buy a filter to make sure my kids feel comfortable with the brightness.

It would be great the same filter would work for planetary view too. Even greater if galaxy/large DSO, but not essential.

I have seen many people recommended "Baader Neodymium Filter" which "Intensifies surface details on Mars, Jupiter and Moon – and enhances many Deep Sky galaxies and nebulae against the background sky.. ''. Sound ideal for me.

Is it a OIII or UHC, or neither?

Any recoomendation you can give for the problem I have.

Regards

Deisler

[Raph-in-the-sky]

11 minutes ago, Deisler said:

Back to my previous question regards filter, if I may -

Last two sessions when I viewed the moon (close to full moon), I felt very uncomfortable as my left eye was left with a bright white spot even 30 mins after I came back in. I know it is not ideal to view full moon, but I think I might have to buy a filter to make sure my kids feel comfortable with the brightness.

It would be great the same filter would work for planetary view too. Even greater if galaxy/large DSO, but not essential.

I have seen many people recommended "Baader Neodymium Filter" which "Intensifies surface details on Mars, Jupiter and Moon – and enhances many Deep Sky galaxies and nebulae against the background sky.. ''. Sound ideal for me.

Is it a OIII or UHC, or neither?

Any recoomendation you can give for the problem I have.

Regards

Deisler

I just got my baader neodymium and it s great! This filter is mostly used for jupiter, mars and the moon. Some say it improves some DSO but people tend to disagree on this point. 

It is by no mean a UHC or OIII filter which are much more restrictive.

[John]

The Baader Neodymium is a useful filter but is not a narrowband (eg: UHC) or line (eg: O-III) filter so does not have anywhere near the sort of impact that those do on nebulae.

If you find observing the moon rather bright a neutral density filter might help or alternatively a polarising filter.

I don't regard the Neodymium or a neutral density / polarising filter by any means essential but I would not be without a good O-III filter

 

[SpaceWalker]

21 hours ago, Deisler said:

I have seen many people recommended "Baader Neodymium Filter" which "Intensifies surface details on Mars, Jupiter and Moon – and enhances many Deep Sky galaxies and nebulae against the background sky.. ''. Sound ideal for me.

Is it a OIII or UHC, or neither?

Any recoomendation you can give for the problem I have.

The former is true except the Moon, the latter is false.  If you like observing Mars and especially Jupiter the Baader Moon & Sky Glow filter is a must, IMO. Although, for Mars a Magenta #30 works better. For the Moon you'd better observe at least halfmoon and pump up magnification significantly that reduces brightness. Any filter, neutral or polarizer, bounces/disperses some light and reduces sharpness, do you want this trade off?  As John explained above the Baader M&SG is a broadband filter and doesn't work on nebulae etc. IMO, for the emission nebulae you'd better get Astronomic OIII or at least Baader visual OIII filter.  For the reflection nebulae and galaxies no any effective filter exists other than "gasoline filter" (fill up gas tank and drive to a dark area 😀).

 

[wookie1965]

I had the full set of BST'S when I had my 200p great eyepieces for the money the 15mm is my goto eyepiece now.

I have 2 refractors now and have kept the 25mm 15mm and 8mm sold the others I bought a 11mm and a 20mm televue plossl second hand.

Get the best for your money the BST'S are a vast improvement over the stock eyepieces.

[Louis D]

On 16/11/2019 at 02:10, Deisler said:

I felt very uncomfortable as my left eye was left with a bright white spot even 30 mins after I came back in.

The most comfortable views of the full moon are with binoviewers because both eyes see the same brightness.  The discomfort you're feeling isn't because the moon is bright, it's actually as dark as asphalt at noon.  However, one eye sees noon-lit asphalt and the other eye sees blackness.  Your brain goes into overdrive trying to combine these two vastly different views and leads to all sorts of weird artifacts.  With two eyes, I can see details quite clearly across the face of the moon that elude me entirely with one eye no matter what sort of filtering I try.

For cheap, you can get a "moon" filter that has about a 13% transmittance to cut down on the brightness imbalance for starters.  If that's not enough, stack a second one for 2% transmittance.  Or, you could get a variable polarizer filter or both and combine them to really knock down the transmittance.  Check ebay for the cheapest prices on basic filters like these.

[Deisler]

Thank you guys. Very useful advice!

I have ordered my BST EPs as early Christmas gift. I will look for some 2nd hand filters, which I don't think are essential to me now. I will probably buy a few , 2nd hand, so if I don't like them, I can re-sell them without losing too much money.

I have also bought a phone holder from Amazon, inspired by @Stu and his luna images. Hope to do some with my Huawei phone.

Cheers,

Deisler

[bingevader]

Hello Deisler,

Sorry, only just got around to posting on here.

You will enjoy the Panaview, a bit soft around the edges, but the wide field views are lovely.

It's also great for star hopping.

The 5mm will be lovely on the moon.

When the planets are a bit better placed, I think you'll be hankering after a bit more magnification if you are not happy with the 10mm.

The 15mm and a 2x barlow would do this, or you could just get the 8mm!

I've looked through the 8mm BST and it's very good.  

[Deisler]

Just to report back to you guys:

Today I received my Panaview 30mm 2'' used, bought from a fellow stargazer here and tried it this evening (-3 degree outside  ). Gave my telescope 1 good hour to cool down. Good clear sky condition.

Here is my take on Panaview 30mm 2'':

Pro:  Had a look through Panaview - the wide field view is amazing, much wider than my stock 25mm EP. I really enjoyed just randomly pointing my 200P to the sky and viewing those stars. I spent 30 mins or so, trying to find Andromeda galaxy - to my disappointment I did not manage to see it. But I did see a faint 'galaxy' near there - I suspect it was M110 but it could be M32 I am not so sure. Then I found M45 - with Panaview I can include entire M45 in my view - very nice indeed. I also saw the double star, Mizar/Alcor, although the flare (see below) was not ideal.

Con: The view quality is not much better than stock 25mm (at least I cannot tell). I do find at the outer 20% view, the stars tend to have 'wings', which is completely expected as many people already mentioned that. However most bright stars also tend to have 'cross' flares, even when they are at the centre of view. I found it quite annoying. Not sure it is the EP or something else? Checked collimation, it looked ok.

Conclusion: I am very happy with it, but could be happier if the flare issues can be resolved?

BTW - I think I will need a height-adjustable bar chair - Finding andromeda definitely hurt my back! Also, my telrad got dew after a few minutes and I could not see anything through it, but I can already tell it is far better than my stock finder!

Regards

Deisler

 

Edited November 18, 2019 by Deisler