Louis D

1 hour ago, Mr Spock said:

They may be good quality but they really shouldn't be calling them orthoscopics when they are clearly a Plössl variant.

If it gives an orthoscopic view (ie., without magnification distortion across the field), then the term orthoscopic can certainly be applied.  An Abbe orthoscopic is simply one design that gets you there.  As far as I know, these Starbase orthos have never claimed to be Abbe orthoscopics.  However, there are reports that the Starbase orthos actually have some distortion which would then call into question labeling them as orthoscopic.

1 hour ago, Highburymark said:

How do people cope with 4mm Plossls and orthos? Must need cleaning after every session. And how do you clean a piece of glass so tiny?

The volcano topped ones tend to steer eyelashes away from the tiny lens.  That, and you are much more aware of how close you are, so you tend to be more aware of blinking and pull away first knowing what a pain they are to clean.

I have the 90mm version and enjoy the views through it quite a bit.  In focus, I don't see any false color.  Star images are nice and tight.  The focuser is very hefty, though a bit spongy at high loads in that the fine focus tends to require overshoot when trying to raise the tube.  I really like the camera angle adapter on the end of it to rotate the diagonal safely while heavily loaded without having to disturb the angle of the focus knobs.

All that said, it's not really a high power grab and go scope.  It takes at least 30 minutes to acclimate that hefty triplet.  Until then, bright stars are crazy spiky as if the optics are pinched.  Thus, you have to be content with low power views until thermal equilibrium is achieved.  As such, I might consider an FPL-53 or fluorite doublet next time.

8 hours ago, Don Pensack said:

If the glasses touch the eyepieces, the first thing they touch is the folded down rubber eyecup, which always sticks up a mm or two above the eye lens of the eyepiece.

Except on the 27mm Panoptic which has a broad top and an exposed metal retaining ring around the eye lens.  I pushed in too hard years ago with a pair of glasses to try to take in the entire FOV at once and put a permanent arc shaped scratch on them.  Needless to say, I never did that again.

6 hours ago, Stardaze said:

Sorry Louis, I might be playing a little dumb here but, I use all of the eye relief, preferring to nestle it into the socket with either 15mm-20mm depending on the EP used. Is that not so normal for a non-glasses user? Not that it really matters, I do find the 5 & 7mm XW eye position needing to be quite high for a comfortable placement, even hovering over the 5mm at times, so >20mm. 

I have long lashes too, so probably helps to keep the EP's cleaner for longer. 

If you needed the eye cup all the way down as I do to take in the view, then you would be using all of the available eye relief.  You, on the other hand, could get away with using eyepieces having 10mm to 12mm of eye relief quite easily, calculated from 20mm minus the amount the eye cup is twisted up.  I, wearing eyeglasses with such an eyepiece, would only see the inner part of the field.  Thus, I would be using more eye relief than is available.  Preferring to nestle into the eye cup is simply a preference and can be arrived at with shorter eye relief eyepieces if the eye cup isn't twisted upward as much or at all.

2 hours ago, Stardaze said:

I do tend to use a lot though, so have the XW's wound to the top, for example.

Quite the opposite.  You tend to use very little of the available eye relief; so as a result, you wind the eye cup to the top to eliminate the unneeded, excess eye relief.

Try smacking the eyepiece sideways into the the palm of your hand to see if you can knock it to the side.

Unfortunately, this is a well known problem with these eyepieces.  Their optical equivalents, the Meade 5000 HD-60s had no such reported issues.

About once a decade.  I always wear eyeglasses with long eye relief eyepieces, so I'm mostly just cleaning off accumulated tree sap that drifted onto the eye lens.

How about an ultralight Dob from one of the custom Dob makers?

Okay, I'm out.  I had thought about getting a Clicklock with 47mm extension to replace the eyepiece holder of my GSO CC plus 25mm M48 spacer ring since it works out to the same length.  I can't bear the thought of having multi-hundred dollar eyepieces getting stuck in a holder like that, and then having to beat on the CL with a screwdriver handle while an eyepiece is in it to get it to release.

It sounds like the CL design is really a work in progress, but Baader doesn't realize it since they have yet to recall them for replacement, or offer a consumer-friendly fix that could be applied to them.

At least with a 900mm focal length, field curvature won't be so bad.  It will still have a radius of curvature of about 300mm IIRC, so you can probably get by without a field flattener.

So, you want to try a 45mm to 180mm focal length eyepiece with it?  You do realize how bright the night sky will appear with 18mm to 72mm exit pupil sizes?  You won't be able to make out any nebulosity due to lack of contrast against the bright background.  That, and you eye won't be able to take in the entire exit pupil, so you'll be working with a 140mm to 35mm effective aperture at best.  Seems like a huge waste of effort, but go for it if you already have all the lenses.

Generally, your best bet to take in nebula at low power is night vision gear or other electronically assisted observing.

How about flourinated greases?  They're expensive, but so are astro optics.

2 hours ago, Tiny Clanger said:

However,  I recently pounced on a well priced second hand maxvision 24mm (which I believe is an old ES eyepiece design which was rebadged to avoid stocks of it being confused with the newer design ). I'll be interested to compare it with the 25mm BST !

The Maxvision were indeed leftover Meade 5000 UWA/SWA stock after Ningbo Sunny bought Meade and cancelled their eyepiece contract with JOC (ES/Bresser).  As such, they are optically identical to the the ES-82/68 eyepieces.

1 hour ago, Barry Fitz-Gerald said:

Try not to get the center spot too wet if you do ever go down the cleaning rabbit hole by the way - dont want it comming adrift as re-spotting a mirror is a pain - doable but you will always wonder how accurately placed the new spot is.

Just make a spot in the center of the donut with permanent ink or a tiny paint blob before cleaning in case that happens.  Soapy water won't generally remove either mark.

7 hours ago, Dogstar45 said:

Given that this is f10 I want to use their 6.3 reducer to increase the FoV.   Can anyone recommend a 30mm eyepiece that is compatible with this? I read somewhere that some eyepieces with wider apparent FoV's in turn have their own FoV restricted by the reducer. Which would rather neatly defeat the object of the exercise! I have read good reports about the Pentax XW 30mm.

You'll get vignetting trying to use a 6.3 FR and a widest field 2" eyepiece at the same time.  TANSTAAFL.  You can either maximize your TFOV with the 6.3 and a 32mm 1.25" Plossl or via a 40mm SWA like the Pentax XW-R 40mm in a 2" diagonal without FR.

If you really want to try combining the FR with a 30mm, 70° eyepiece, I would recommend the 30mm APM UFF or one of the other 5 or 6 rebrandings of it.  It has better correction, a flatter field, and is more compact, lighter, and less expensive than the 30mm XW-R.  However, you are likely to see some vignetting.

You're never going to get decent wide field views even with the 1500mm focal length using the FR.  A 72mm ED refractor or similar would nicely complement the 9.25 SCT.  You might even be able to mount it as a super finder with the SCT.

There are both variable length extension tubes and tilt adjusters to fine tune each.

The 40XW is nice thanks to its relatively light weight in comparison to the decloaked Meade 40mm 5000 SWA (same optics and weight as 40mm ES-68) or, presumably, the 41mm Panoptic which I haven't had a chance to use.  I'm not sure it's quite as sharp as the Meade, but it definitely isn't as flat of field.  There is a bit of field curvature in the XW, but nothing too distracting.  SAEP (kidney beaning) is less in the XW than the Meade, so it is easier to take in the entire FOV, but there is still a bit of blackout here and there.  The ergonomic conical top of the XW is very much appreciated compared to the slab top of the Meade which forces me to tilt my head to the side to use it.  Eye relief is significantly longer on the Meade, though.  I have to touch the top of the XW with my eyeglasses to take in the entire FOV while I can simply hover above the Meade.

All in all, it's hard to pick a winner between the two.

Can't you use an EQ mount as an alt-az mount by setting it to 0 or 90 degrees latitude?

I would think if you don't have it exactly level, this top mounted and counterbalanced design would be much more immune to swinging around in azimuth than a side mounted design if unclutched unless it is also counterbalanced.

Swapping out a 40XW isn't much of a challenge at 1.5 pounds to keep a mount from diving in my experience.  My 17mm ES-92 at 2.6 pounds is much more of a challenge even for my Dob.  Another problem is that tall eyepieces make a mount want to tip backward at high altitudes.  I'd be interested in how well this new mount resists turning turtle under such conditions.

So this mount doesn't have tension knobs, only locking clutches?  I like separate tension and locking controls.  Usually, one can't do a good job of both unless it were to have a push-pull locking feature so as not to disturb the tension setting.

Have you tried adding a field flattener to the front of you diagonal?  I use a TSFLAT2 with 15mm of spacing in front of my 2" diagonal in my short refractors to do a good job of flattening the curved field.

You can tell if field curvature is the issue by focusing a star in the center, and then moving it to the edge, and seeing if it focuses to a tighter pinpoint by refocusing.  Most inexpensive short tube refractors have field curvature.  The Tele Vue NP101 does not thanks to its Petzval design, though.

Only at high powers on the planets will you notice a purple fringe around an object based my experience with a 72mm f/6 FPL-51 doublet.  The rest of time, the additional aperture of the 100 will easily rule the day.

I will say the fringing was annoying enough that I popped for a used 90mm f/7 FPL-53 triplet which has little to no discernible color at high powers on planets or the moon.  However, my 8" Dob blows it away when it comes to planetary detail.  Aperture rules.

I always bring a couple changes of clothing and toiletries in my carry-on because I've had the airlines lose my checked bags for days several times.

32 minutes ago, Andrew_B said:

It's surprising how many protective cases are almost carry-on sized but are ever so slightly too big in one dimension.

Then how about starting with a true carry-on sized rolling case and then adding the foam or dividers to it?  It's much less likely to receive unwanted attention in an airport terminal, and it comes with wheels and a handle to make transport easier.  Check thrift stores for used ones for cheap.  If it's just a small scope, you can probably pack it with your clothes in a regular carry-on since most airlines only allow one per passenger.

4 hours ago, rnobleeddy said:

However, what also let me down was making the assumption that this would have the same tolerance as the Newtonian coma corrector I use, which appears to have a 1-2mm region which produce solid results. Based on what I experienced so far, the 0.79x flattener  I have will need to be adjusted much more accurately! 

I've read of imagers trying get the spacing correct to the 1/2 millimeter.  You might also run into tilt issues where different corners are flattened at slightly different distances.