Louis D

41 minutes ago, badhex said:

You mean like this? 

If you're referring to item at the lower right, give it a few years/decades to take on that vintage brass patina, then we'll see if it resembles a plumbing fitting. 😏  Right now, it's too shiny to be mistaken for plumbing parts.

1 hour ago, John said:

I did compare it casually with the Nagler 2-4 zoom and the 3.5mm Pentax XW but didn't notice any significant differences, apart from the AFoV.

I had to go back to my Svbony zoom write up to remind me of what I saw in the 3.5mm Pentax XW versus the Svbony zoom at 3mm:

So, I'd recommend looking for color fringing on bright stars as you move them center to edge.  The XW shows none anywhere while the Svbony zoom shows increasing amounts toward the edge.

On 21/11/2023 at 19:51, Gemineyes said:

my Stellarvue Chroma filter (MV2, which I designed for Vic Maris)

From your Stellarview filter review: I employed a special approach and sent this curve to Vic

Can you post what that curve was that you suggested?  I'm wondering how similar it looks to the Baader Semi APO curve in dark blue below:

I have that one, and it does a good job of avoiding adding a yellow cast to the image.  However, it doesn't suppress all the unfocused violet and none of the unfocused red.

I've found a Hirsch #12A Light Yellow and a Hirsch #82B Light Blue (Cyan) combine for a yellow-green view that suppresses pretty much all of the unfocused violet and red and really sharpens up planetary views without darkening the image too much like a #11 Green or especially a #56 Green does.  I recently picked up an X0 Yellow-Green filter, and it looks promising as well.

Given all the tarnished brass, I'd first have guessed it was some sort of old plumbing fitting were it not for the optics. 😁

3 minutes ago, Franklin said:

Yes I know the numbers but I see a bigger apparent difference between the SLV and HR than the Zoom and SLV. The SLV's shorter than 9mm are definitely less than 50deg as you say. Maybe my zoom is not quite as advertised?

Do the same test holding one up to each eye, but with zoom and the SLV.  It could be that if you are concentrating on the central region against a dark sky, you aren't noticing the wider FOV.  It could also be the tighter eye relief coming into play.  You really need to mash your eye into the zoom's eye cup to take in the entire FOV, especially from 3mm to 6mm.

4 hours ago, Franklin said:

Finally I set the zoom about half-way between 3mm and 4mm and compared that to the HR3.4 giving a magnification of 183x and an exit pupil of 0.44mm. This is the point where things became interesting because although the Svbony held up very well and presented an image that was still useable, despite the slight over-power, the zoom image definitely had become softer.

You need not have bothered with the in between setting.  I measured the 3mm setting to actually be 3.5mm in the central region.  It grows to 2.5mm at the edges due to distortion.  And I also noticed considerable softening at the "3mm" setting.  I consider it a bonus focal length to be used when you don't have anything better.

4 hours ago, Franklin said:

Upping the power with the SLV 4mm and the zoom @4mm, to my eye I could not see a noticeable difference between the image presented.

I noticed the 4mm setting getting slightly softer, but still quite usable.  From 5mm to 8mm, I'd rate the Svbony zoom as excellent.

3 hours ago, Franklin said:

Firstly, the fov in the zoom is a bit wider than the SLV's and considerably more than the HR with it's "orthoscopic" sized 42deg.

There shouldn't be much apparent field of view difference between the SLVs and the HR.  The LVs, NLVs, and SLVs below 9mm all have 45 degree apparent fields despite what the later versions claimed.  Check it for yourself.  Hold up a ~50 degree plossl to one eye and either the 4mm or 6mm SLV to the other eye while looking at a bright background.  The SLVs will have a smaller image circle.  The Svbony zoom has an AFOV between 58 and 61 degrees, so it should look considerably wider than either the SLVs or HR.

To build on what has been said above, I would recommend not going with a wider passband than that found in a UHC type filter.  Think of them as a more selective light pollution filter for use on nebula.

The only way you're going to see galaxies is to seek out a truly dark sky site to observe from.

The focus wheel is not to be confused with a zoom wheel.  The image is getting larger out of focus, but it is not a useful image to observe.

You might want to buy a zoom eyepiece to get started with observing if you like the idea of zooming to enlarge the image on the fly.  Once inserted in the focuser, you bring the image to focus such that it is at its smallest.  Then, you can twist the collar around the eyepiece to zoom in or out to enlarge or reduce the image size in a continuous manner.  You might need to refocus at each zoom setting because zooms tend to not be parfocal (remain in focus at all settings).

As long as the primary mirror movement lubricant is still in good shape to allow smooth focusing, it should work right out of gate.  I've had two of these Synta made Maks, one Orion and one Celestron, and both are spot on in collimation and have no focus shift or backlash.  You'll just need a decent alt-az mount/tripod and red dot finder to get started.  It looks like it was used on a photo tripod based on the still attached quick release plate.  The tripod and head are probably kicking around somewhere in that same attic.  If you can't find the tripod, you'll need to unscrew and remove that quick release plate before using it in a dovetail clamp based mount.

On 25/11/2023 at 04:22, Chandra said:

On the other hand, it must be considered that Telextenders sometimes cause intrafocus problems, especially with equipment with a short focus path as is the case with Newtonian reflectors.

Interesting, I've found just the opposite.  My old, long focus Barlows won't come to focus in refractors when used in the diagonal because they require so much in focus (up to 4 inches).  Of course, you can use them ahead of the diagonal at a higher than marked power without focus issues.  This in-focus issue doesn't arise in all but the smallest Newts because the secondary mirror is so far away from the focuser.  You simply insert the Barlow 4 inches into focuser.  Try doing that with a diagonal!  Of course, you may introduce a diffraction effect if the Barlow protrudes into Newt's light path.  In practice, I've not noticed it with even my longest Barlows.

Shorty Barlows come to focus in everything in my experience, so are generally the better choice unless going for the highest quality views possible.  I've found that the older, Japanese made long Barlows of the 90s produce the tightest images at high powers.  The difference is subtle, but it is there over shorty and mid-length Barlows of similar cost (sub $150).  I've not tried any of the super premium Barlows or Powermates because I can't justify the cost involved for how little I use Barlows.

Here's some APOD moon halo images:

https://apod.nasa.gov/apod/ap220102.html

https://apod.nasa.gov/apod/ap210201.html

https://apod.nasa.gov/apod/ap180502.html

There are many more that have been featured over the years.

Here's evidence at least the 25mm Meade 3000 went to Taiwan:

22 hours ago, JackW07 said:

I can’t seem to find this app, do you know where to find it?

 

 

If you're using an iPhone, pick up a used phone with the necessary sensors, but older or with a bad SIM card tray.  You don't need service to use SkEye.

2 hours ago, bosun21 said:

All the points you made. How accurate the lenses are cut, the quality of the glass, and high quality multi layered coatings.

I'd put polish near the top of the list.  If the lens polish isn't extremely smooth, you'll get scatter.  This scatter can easily ruin high power, low contrast planetary viewing by placing a veil of haze across the image.

I think you'll find a preference over time for an eyepiece swap to get to higher powers rather than swapping out the eyepiece, swapping in the Barlow, and then swapping in the eyepiece into the Barlow and then having to refocus quite a bit with many Barlows.  I'd recommend the Svbony 3-8mm as well.  See my write-up below:

It will probably be going on special sale price during the lead up to the holidays.

24 minutes ago, jjohnson3803 said:

If you think you have a faint fuzzy in view, but you're not quite sure, you can gently tap the side of your scope.  That should make it more apparent if you're on target.  Apparently human vision / low-light perception is such that we can detect movement more easily than see static objects.

I use that same technique to confirm or reacquire comets hidden in the twilight murk.  The latter is needed because I slowly lose sight of them while observing them.  It's bizarre, but my brain just averages them out with the sky glow over time as some sort of background noise to be ignored since it isn't moving or changing.  It's a good thing astro cameras don't behave the same way.

You could also trying using the SkEye phone app as a push-to finder to help get you in the ballpark.  I mount my phone to my scope and then center a bright star or planet and then realign SkEye to that object.  I still keep a QuikFinder and RACI finder scope on there as well.

2 hours ago, Starfazed said:

I was stunned at how much brighter Jupiter and Saturn were compared to what I'd been expecting to see at 250x magnification, and they completely blew out the image when I tried to capture it on my smartphone (just crudely through the eyepiece).

Try decreasing the exposure with the exposure compensation slider.  Slide it to the left into the negative numbers.  Your camera is trying to expose the dark background sky at 18% gray.  Try the -3 setting for starters.  That should get you in the ballpark of the correct exposure for starters.  Try other settings and see what you get.

The UHC filter would probably help to reduce skyglow so you would get better contrast of nebula against the background skyglow.  For star fields or open clusters, you probably want to avoid using a UHC filter because it throws off the star colors and would probably cause star bloat.  You can always increase contrast on star fields in post processing by adjusting levels/curves.

I was reading up on your phone's cameras, and near as I can tell, simply choose lower resolutions.  It will result in lower resolution images, but, for instance, 2x2 binning at 1/2 the linear resolution (1/4 total pixels) results in 4x as much light gathered per pixel.  Give it a try at various resolution levels to see which produces the best compromise between resolution and image brightness.  Lower resolution results in a shorter exposure time to get to the same image brightness (density) as at higher resolution.  If your mount doesn't track, keeping exposures shorter will reduce image blurring as the Earth rotates under the sky.

Pentax XLs, XWs, ES-92s, 30mm UFF, ES-82, etc.

Being an ultrawide, low power freak, I would recommend getting a GSO coma corrector first.  I demand sharp stars from edge to edge while letting objects drift across the field of view.  The inherent coma in a parabolic mirror prevents this with even the finest eyepieces.  I use the CC during all but high power observing sessions where the small amount of central spherical aberrations gets noticed.

I rarely use a Barlow.  Get a Svbony 3-8mm zoom if you want high power views in a compact pacakage.

Don't use an ultrawide angle camera lens with an eyepiece during afocal projection photography.  As you've discovered, it results in a massive mismatch in fields of view if you do.

Try using the wide angle and then the telephoto cameras to see if you get a better field of view match.  For night photography, you'll definitely want to do pixel binning with those high resolution imagers behind those camera lenses.

You could try taking ultrawide angle images of the night sky using that ultrawide camera.  Just mount the camera to a tripod and take some images of different exposure lengths to see what you get.