Louis D

1 hour ago, Mark at Beaufort said:

I did not appreciate that SVbony produced 3 different zoom EPs. I wonder what the 10-30mm would be like? 

Quick initial impressions and first light on CN here and here by member LDW47.  There are also more user impressions further down by LDW47.

3 hours ago, JeremyS said:

I saw on another Forum that a German company sells XW eyepiece caps

Anyone know if they also fit the Pentax XL series?

https://astrogarten-shop.de/en/accessories/eypieces/pentax/pentax-eyelens-cap-smc-xw-eyepiece.html?language=en

2 hours ago, markse68 said:

Hi Jeremy, no they don’t unfortunately- the hole is quite a bit smaller on the XLs

Yes, the eye lens on the Pentax XLs are 30mm in diameter versus 35mm for the XWs.  The XW eye cup's hole must necessarily be larger to allow the entire eye lens to be seen.

I think it's pretty clear from this image I took that the 3.5mm XW on the far left has a larger eye cup hole than does the 5.2mm XL second from the right.  The XL cup's conical taper also appears to be noticeably taller as well.

I would start with the SV171 and see if you like using a zoom eyepiece at all.  Some people just don't care for them on a day to day basis.  I mainly use a pair of Celestron/Olivon Regal zooms in my binoviewer because it's such a pain to change two eyepieces to change powers and to make sure they aren't tipped in their holders causing merging issues.  In general, I prefer monoviewing DSOs with premium wide field eyepieces.  Planets and the full moon demand binoviewers, though.  I just see so much more detail with two eyes with them.

The only other galaxy (core) I found to be super easy from Bortle 6+ skies besides M31 was NGC253.  However, I don't know if gets high enough for UK observers to see.

On 09/11/2020 at 10:59, John said:

That was why I had to use the 28mm Baader FT rings. The 14mm gave insufficient clearance for a 2 inch filter. The ideal length would be 17mm-20mm I reckon, just clearing the end of the 1.25 inch barrel.

I have a 20mm TPO spacer ring from OPT on my 12mm Nagler.  It doesn't thread on all the way, so it's more like 22mm or so of extension.  As a result, I've got 7mm of gap between the bottom of the 2" extension and the bottom of the 1.25" barrel.

I just found a snapshot of this eyepiece that I had forgotten about:

15 hours ago, BrendanC said:

I pretty quickly gave up on observing when I realised that most of the things worth seeing were only viewable when imaging. Planetary is possible, but so rare. given the suitable position of a planet and the weather in the UK. I like 'seeing what is unseeable', which is pretty much most of the sky, at any time of the year weather-willing, but only through imaging.

I think this is why EEVA is gaining popularity.

8 hours ago, Dantooine said:

I have also thoughts about putting the extenders on a lathe (Hence the tv instead of the baader rings) and making them exactly the same length as where the 1.25 barrels end. There seems to be no manufacturer that makes the perfect fitting extenders. 

If they were exactly the same length, would 2" filters safely clear the 1.25" barrel?  It would be mighty close.

I bought a couple of parfocalizing rings, but decided not to use them when I saw the sharp points on the set/grub screws.  I didn't want to ruin the resale value on my eyepieces by digging divots into the chrome on the lower barrels.  That, and they had to be secured into the lower taper of the safety undercut which wasn't going to be very secure.

Instead, I used rubber O-rings to bring my 12mm Nagler T4 into parfocalness with the rest of my eyepieces that focus at the shoulder.  I think I used a stack of five 4mm thick ones with a 50mm inner diameter.  It works well enough that I need only a small focuser adjustment now to bring it into focus relative to my ES, Baader, and Pentax eyepieces.

2 hours ago, climbingmagnet said:

What's a good binoviewer please?

I have the Arcturus branded one which I believe is sold as OVL in the UK.  The same base unit is sold with different eyepiece holders by Williams Optical (WO).  Most folks prefer the collet lock (OVL) over the set screw/compression ring (WO) versions.  There are other brandings out there.  Do a search and check back on SGL for user opinions on whatever you find.

There are of course higher end binoviewers, and they have larger prisms to allow for wider views, better eyepiece holders, greater attachment flexibility, and system accessories such as power switches.  However, for starting out, the basic models with smaller prisms are fine performers for planetary viewing.  You'll need to budget for a pair of decent 50 to 60 degree eyepieces and possibly for a Barlow nosepiece (or dedicated GPC/OCS) to reach focus if the included one doesn't work for you.

I would avoid that pedestal mount unless it can be bolted to the ground.  It's going to tip over at some point unless there's a 100+ pound iron or lead weight at the bottom.

Personally, I would start out observing and not worry about astrophotography for a while.  Learn the sky and enjoy finding objects.

3 minutes ago, VaderAG said:

Thanks for the FLO suggestion. They have a beginner telescope section and seems to tally with suggestions here.

One they mention which isn't mentioned above is the Sky Watcher Mercury 707 - is there any reason to go for the dobsonians over this at this price point?

70mm achromatic refractors don't have much light gathering power and suffer from chromatic aberrations.  So, they tend to be a bit disappointing to look through.  That, and that mount isn't all that great.  It tends to be wobbly and difficult to track objects with.

That's not to say all 70mm refractors aren't great.  I love my 72mm ED refractor for wide field views.  Its short focal length and low chromatic error make viewing large swaths of the sky very enjoyable.  However, I have it mounted on a very capable alt-az mount that I purchased separately.

I used one of those 76 Dobs at a star party.  It's pretty close to impossible to aim it at a target while perched on a table due to it super short length.  I've been observing long enough that I was able to aim it by "shooting from the hip" so to speak.  However, I wouldn't expect a beginner to be able to do this.  In the central 25% of the field, the view of Jupiter was enough to see banding once it was on target.  It's not a great view since it uses a spherical mirror instead of a parabolic mirror.  As alluded to above, these show up in thrift stores for about $10 to $20 after Christmas because they tend to be underwhelming.  That's where the advanced observer at the star party had picked up his two examples.  He puts them out on a low table for kids to try and use.  However, none of kids or their parents could get anything in the field of view until I came along.  They were astounded I could get them to work when they had had no luck with them.

I keep my eyepieces stored upright in the case with only the top above the foam.  I've never had trouble with the XL caps in this orientation over the last 22 years because gravity keeps them in place for the most part.  Sure, they don't lock on, but short of a gale wind, they don't come off of their own accord between uses.  I just toss the cap down the empty hole when I go to use the eyepiece and then grab it back out of the hole and put it back on when I'm done.

The annoying caps are those packaged with the AstroTech AF70 and similar lines.  The cap fits so snugly on the rigid eye cup that you have to work your finger around the edge of the cup to push it all up into the cap.  It's such a pain that I just unscrew the eye cup and use it sans-cup with eyeglasses.  That way, the cap stays on the cup between uses.  I just place the cup/cap combo loosely over the top of the eyepiece between uses.

You should be able to see the Pleiades (M45) and the Orion nebula (M42) at the least.  You might need to pan around a bit to see M45 due to its size and your scope's long focal length.  They trail Mars by several hours in a similar region of the sky, so you might need to stay up late enough for them to be visible.  Uranus, though tiny, should also be visible between Mars and the Pleiades as a tiny green dot once magnified enough.  The Andromeda galaxy (M31) should at least show its cigar shaped core and possibly its two companion dwarf galaxies' cores.  The Double Cluster (NGC884 and NGC889) should also be obvious once you can see M45.  Once the moon is back in the evening sky, take an evening to tour around it.  On each successive night, note how the terminator line changes as different features are side lit.

My point is, not every object is easy to see.  There are certain showpiece objects that are large and bright enough to be visible under just about any conditions.  Learn what these are, use planetarium software to determine when they will be visible and where on the sky to make sure you have an unobstructed view, and then use the software on your scope to go after them.  Much of the joy of astronomy is hunting down objects and confirming you at least detected them.  That's how I approach comet hunting in particular since they mostly tend to hang out in the twilight murk near the sun.  You may need to manually slew your scope back and forth a bit to detect faint fuzzy patches once the computer puts you on target.  Your brain's ability to pick out a moving target is much better than its ability to pick out a static target.  Ever notice how much easier it is to see a camouflaged animal when it moves or at least flinches?

8 hours ago, Matt61 said:

I've found Mars too bright to discern detail and will be trying filters next time I view.

Invest in an entry level binoviewer.  I also couldn't adjust to viewing Mars at opposition without heavy filtration using monovision.  However, once I switched to my binoviewers, I had no issues with brightness and could see loads of details with ease.  It has something to do with splitting the brightness in half, presenting the same view to both eyes, and allowing your brain to image process as it was intended to do, from two eyes.

13 minutes ago, Trentend said:

Televue extender eyeguards

I'm pretty sure they fit the 32mm Plossl, but you should contact a TV vendor for confirmation.

16 hours ago, Trentend said:

Wonder if there’s another 32mm on the market with a a bit less eye relief and wider FOV?

You're already maxed out on true field width in a 1.25" barrel with the 32mm Plossl.  Many of the Chinese made 32mm Plossls have the eye lens recessed much more than the TV version, so they have less eye relief as a result.

If you want to go wider, you'll need to add a Mak to SCT thread adapter, a 2" visual back, and a 2" diagonal.  Bright stars do exhibit a weird oval reflection as they pass the edge of the rear port and there is 30%+ vignetting of the edges, but works really well to bring in wider views.  The 24mm APM UFF has roughly the same TFOV as your 32mm Plossl.  Notice how much more field is visible below with only moderate vignetting?

That's a massive 2", 35mm eyepiece on my 127 Mak below:

Don't try to mount an SCT threaded 2" diagonal directly to the rear threads.  It won't fit next to the focus knob.

On 04/11/2020 at 13:32, climbingmagnet said:

2. If I want to get greater magnification to see the rings of Saturn more clearly or see Mars better, what's the best approach. A magnification accessory or another eyepiece (or both)?

Buy a large Dobsonian.  In my second year of observing 21 years ago, I bought a second hand 15" Dob to get increased image scale without sacrificing detail or contrast.

On 03/11/2020 at 12:44, Rusted said:

Don't forget that you have to mount a refractor so you can get under it at high altitudes.

This is even an issue with smaller refractors.  I have an adjustable height stool so that I can sit mere inches above the ground with my legs straight out when the scope is pointed near zenith.  It makes me wonder why people complain about the "contortions" it takes to view through a Dobsonian by comparison.

4 hours ago, Deadlake said:

Agreed, a lot of unknowns about glass used even if it's cited by name, for example:

• Quality of glass from a batch
• Matting element used with ED element.

It's how it works in the field, however the above two can be implied by cost, no free lunches.

To add to that:

• Quality of lens polish
• Quality of lens coatings
• Quality of lens cell design and execution
• Quality of factory collimation and lens cell's ability to hold it
• Quality of stray light control (baffling, etc.)

Don't despair too much about the 6mm Delos.  It will prove very useful in an f/7 or faster scope.  I use my 5.2mm Pentax XL all the time in my ~f/6 scopes, so a 6mm would also find a good home in such a scope.  I mention this because I'm sure you'll be wanting to invest in a 72mm to 100mm ED refractor in the f/6 to f/7 range in the next year or two just so you can get to lower powers with their concomitant wider fields of view.

I have the 10mm Delos and really like it.  I also looked through one in an 8" EdgeHD at a star party.  It was showing incredible detail on Jupiter, so I know it does well when coupled with an 8" SCT.  I also find 200x in an 8" a particular sweet spot for observing planets and planetary nebula when conditions allow it and for resolving large globular clusters like M13 and M22.  Going to higher powers doesn't usually yield much improvement in resolution and often degrades low contrast features.

6 minutes ago, Paz said:

Are those figures assuming a focal length of about 3030mm rather than 2032mm, e.g. 10mm x 303 = 3030.

Having said that I use Delos with a C8 and I agree that it usually maxes out in practice at around 12mm or 10mm, being about 179x to 203x.

Corrected all values.  Thanks, I had clicked 3032 into my computer's calculator and stored it in memory.  I never caught it.  I was wondering why all the powers seemed too high.  I'm a bit off today what with our election turmoil.

4 hours ago, Don Pensack said:

I FIND IT VALIDATING THE PICTURE RESULTS MATCH MY FIELD IMPRESSIONS.  THE CAMERA AND THE EYE MUST NOT BE TOO DIFFERENT IN THAT REGARD.

Look at the size of the taking lens on most cell phone cameras.  They're very similar in size to the human eye and react very similarly to eyepiece exit pupils.  Once I realized this, I decided to embark on my AFOV imaging odyssey.

3 hours ago, chrispancho said:

Thanks for your reply!  Taking what you say about the 31 and 22 being complimentary, if I had to pick one of the two to get right now, should I go 22 first?  I just bought a 6mm Delose as my high power EP, and I currently have the Nagler 17mm, so I’m thinking a good progression would be to go 22mm. 

Total amateur here!

Let's work the numbers here.  You've got a 2032mm FL scope.  That equates to 66x, 92x, and 120x for the 31mm, 22mm, and 17mm Naglers.  That's actually not a bad progression of ~30x per jump.

Most nights, around 250x or so will be the upper limit due to seeing conditions.  Your 6mm Delos at 339x is unlikely to ever see much use except to split doubles.  The 0.6mm exit pupil will also be at the limit of comfort.  You might battle with floaters in your eye at that tiny exit pupil.

I would have gone with a 10mm or 12mm Delos instead.  They would be much more likely to see extensive use at 203x and 169x, respectively.