Louis D

I had a Thousand Oaks glass solar filter years ago, but because the coating is just on the surface, not throughout the glass, it's super susceptible to pinhole damage.  I eventually trashed it and went with BSF.  I can't say that the image was any better with the BSF, just white instead of orange as with the TO filter.

1 hour ago, DarkAntimatter said:

Regarding wedges, is there any danger to the scope in having the filter at the eyepiced end?  With an aperature filter, the light intensity is attenuated before it gets into the scope at all.  With filters at the other end, do we need to worry about heating of secondary mirrors, etc?

Even with a refractor, I'd be concerned about not keeping the sun centered as with an unattended alt-az mount.  As such, I always cap my frac when walking away from it with a wedge in place.  I have no idea what all that solar energy would do to the side of the interior of the focuser, and I'm not about to find out.

I have a 90s era Lumicon UHC that I rarely use.  I use my 90s era Lumicon OIII quite often.  Do you already have a premium OIII filter?  If not, I'd get one before a premium UHC.

7 hours ago, ollypenrice said:

Few amateurs use derotators but Alt-Az with derotator has been the professionals' choice for some time. These are, though, two different worlds.

Olly

Agreed, but the original posting I responded to said EQs are essential to AP.  This is an absolute statement which is simply not true.  Perhaps if it had said NEARLY essential, I wouldn't have bothered replying.

For me, I have a feeling eye relief will be the deal breaker.  As I've stated earlier in this thread, the spec'ed 26mm eye lens diameter will limit absolute eye relief to 17mm if the AFOV is 75 degrees and the lens is flush mounted to the top.  That is barely enough with eyeglasses.  More likely, it will be a few millimeters less, so the actual AFOV visible with glasses will be somewhat less than 75 degrees.

8 hours ago, teoria_del_big_bang said:

I don't have one but I have seen quite a few threads about repairing them on SGL and other forums.
Most seem to use Jubilee clips.

Steve

 

I had to look up Jubilee clips.  We just call them hose clamps here in the US since no one brand dominated the market.

Apparently, the Jubilee brand name became genericized in the UK over time, sort of like Kleenex over here for facial tissue.

6 hours ago, AstroMuni said:

As the mirror is spherical the sharpness of close up shots of planets is not that clear. Thats my theory anyway

If the OP can keep the object exactly centered at high power, that's probably the best use case for a spherical mirror.  It's still not great, but it's better than trying to use it for wide field views.

I took a hard pass on one of these tripods when I checked it out in person and noticed one of the leg clamps had broken.  It appeared to be made of plastic of all things.

When you say clamps, I'm assuming radiator hose clamps:

They're great for holding things tightly together.

2 hours ago, Alan64 said:

For astrophotography however, to "see" galaxies and nebulae, an equatorial mount is essential.

Not necessarily.  A lot of good work has been done with alt-az mounts and field derotators.  In fact, many professional observatories have been going this route lately.

5 hours ago, Emdeejay said:

Also it's just a cheaper .5x svbony f/r it just screws on the back of the lens

I use one in conjunction with a 2x Barlow nosepiece and 45mm of extension between them to create a home brew OCS/GPC to reach focus at about 1x power in my Dob.  However, the 0.5x adds loads of field curvature, so only the central region is sharp.  They are mostly intended for use with cameras with small imaging chips to fit large objects onto them or to reduce exposure time.  They don't see the blurry edges due to their small coverage area.  The Celestron 0.63x R/C not only reduces the focal length, it also flattens the field.  However, it also adds a bit of spherical aberration at high powers that is not visible at low powers.  Thus, you shouldn't use one at high powers to get the best views.

3 hours ago, johninderby said:

From eBay. Pretty easy to cut using a very fine saw, just wear a mask while cutting and sanding though as you don’t want to breathe in carbon fibre dust.

Amazing what you can get from ebay.  I buy a lot of new old stock (NOS) stuff from there as well as new and used items.

59 minutes ago, johninderby said:

One thing I’d like to know if these diagonals can be sold at such a low price why aren’t  the likes of Celestron, Skywatcher and Bresser suppying their scopes with them. 🤔

Probably because those OEMs can purchase those throwaway diagonals for even cheaper in bulk increasing their profit margins further.

The focal reducer is doing its job, reducing the focal length and thus the magnification.  This is why everything looked smaller (super zoomed out).  You really only need it for observing objects too large to fit in your lowest power 1.25" eyepiece.

The double image is most likely caused by one or both eyepieces sitting tipped in the eyepiece holders.  This is usually caused by the eyepiece undercut.  Try holding the eyepiece firmly down in the eyepiece holder while tightening the locking collet.  If it still tips, you may need to fill the undercut with narrow tape (auto pin-striping tape works well for this purpose).

The eyepiece "focus knobs" are actually diopter adjusters to allow for different focus positions for each eye if you're not wearing eyeglasses.  If you have the same diopter power in each eye or are wearing eyeglasses, both should be all the way down.  The reason they merged the images for you was because by spinning the eyepiece, you were able to rotate one tipped eyepiece's optical axis to match the other eyepiece's optical axis.

I have no idea what could be causing the bright spot in the center of the FOV.  Perhaps you're actually seeing massive edge vignetting.  It might also be stray light from somewhere in the optical train.

1 hour ago, Tiny Clanger said:

One caution : I've bought a few things where the vendor sent something not quite as per the photo, sometimes they seem to just rip off an existing ad.s illustrations even if their item is different in a detail you particularly wanted, I doubt the middlemen who source the stuff appreciate the importance of some details , like which side the eyepiece locking screw is on ...

In that case, make sure to screen shot the original ad when ordering so you can provide it during the return process if asked to prove "not as advertised".  I've had vendors update the images and/or description later to try to avoid having to accept a return on these grounds.

23 hours ago, Emdeejay said:

You're suggestion of an extension tube might help, I was thinking maybe it needed a tube with a few inches since everyone says how the binos create a 100mm optical path etc, but I didn't know if you can just get an extension tube that isn't a Barlow.

I suggested the extension tube to REPLACE the binoviewer's optical path length while trying to figure out why you can't reach focus.  Often, you can simply unscrew the optical section from a Barlow and use the tube alone as an extension tube to get a couple of inches of extension for focus investigations.

Do NOT use the Barlow with the SCT.  You should be able to reach focus without it after turning the focus knob many times in the proper direction.  Sure, the focal length will increase some, but not nearly as much as adding the Barlow will increase it.

During the Mars opposition, I found I was getting far superior views through my Arcturus binoviewer with a pair of vintage B&L SWA microscope eyepieces.  I use the nosepiece from a Meade 140 2x Barlow screwed into the front of the binoviewer to reach focus in my Dob.  I swapped back and forth with various Pentax and Televue wide fields in mono-mode, but the overwhelming difference in brightness made it impossible for my aging eyes to see any significant details.  With two eyes, the view suddenly looked with those images taken by astrophotographers who stack hundreds to thousands of frames.

I watch our local Craigslist for such items (tripods, cases, fluid heads, etc.) that are cast offs from local film and music production companies/groups.  There are some good deals to be had if you don't insist on cosmetic beauty.

11 hours ago, nephilim said:

Thanks for the heads up mate. I'm looking more towards these type of cases 🙂 https://www.absolutecasing.co.uk/waterproof-cases/max-cases/standard-cases/max300.html

I have a couple of these Chinese made cases, and they're quite tough.  I have a small one to hold my six Paradigm (BST Starguider) eyepieces vertically that I picked up for $10 on sale a few years ago.  I also have a large one from a wholesale club to hold my collection of large, yet seldom used, eyepieces.  I also have a couple of vintage Doskocil cases as well that were American made.  I prefer the denser foam in them, but the lower density Chinese foam works well enough.  All can take quite a beating.

1. Are you using a 1.25" diagonal?  This will help minimize the amount the mirror will need to be moved forward.
2. Have you tried both with and without the Barlow?  It should work either way.  I'm sorry to read it's not working with the Barlow, either.
3. Have you tried achieving focus in the daytime on a distant object?  This can help sort out what's going on.
4. Does the image appear to be converging to a focus, and the focuser just runs out of travel before reaching focus?
5. Do you need to use a Barlow with the 4" refractor to reach focus?
6. Have you tried racking the focuser all the way from one end to the other of its range of travel while looking through an eyepiece to ensure the mirror appears to be moving the entire distance?
7. Have you tried adding a 4" extension tube in place of the binoviewer to see if you can reach focus.  The binoviewer adds about 4" to the optical path length.

I've had no trouble reaching focus with my 127 Mak without a Barlow, and I've read numerous places that 8" SCTs should also have no trouble reaching focus natively.  Keep trying to narrow down the issue.

The 25mm eyepiece is considered decent, but everyone pans the 10mm eyepiece.  Folks on here usually recommend upgrading the 10mm with an 8mm or 12mm BST Starguider.

What eyepieces do you already have before you rush off and buy a 2x Barlow lens?

A shroud around the struts would be helpful to block stray light.

Just make sure to avoid the really cheap "aluminum" flight cases which are actually made entirely of thin, textured, metal-colored plastic.  The sides puncture quite easily.  Not even the edges or corners are made of metal despite the look.

I finally got around to trying out the SVBONY 68° UWA 20mm eyepiece in my 127 Mak.  As expected, it cleans up nicely to the edge.  I also snapped a picture through the Orion Centering SWA 20mm which is wider with poorer correction for comparison.  The SVBONY is a bit cleaner to the edge, but not by a huge margin.  If you have a slow scope, the SVBONY 68° UWA 20mm will probably work quite well in it.

The Astro Essentials 9x50 RACI from FLO is reportedly a GSO-sourced finder sold under many other brandings.  I have a version under a US brand and find it to be terrific.  If you defocus a bright star, you can make it easier to see the reticle crosshairs.  I find I don't miss having illuminated crosshairs in a RACI.

I haven't had a chance to try my recently acquired 20mm SVBONY 68 degree in my 127 Mak yet, but it does reasonably well in the central 50% of the FOV at f/6.  It should perform very well at f/12 for 75x.  They're £29.99 shipped from ebay UK.

Although the 6mm and 9mm SVBONY 68 degree eyepieces are well regarded for sharpness, field of view, and eye relief, they have a lot of kidney beaning (SAEP) going on, so keep that in mind if you're sensitive to it.

I'd recommend the 8mm BST Starguider for highest power viewing (188x) with the 127 Mak.  It does quite well in mine without SAEP for a bit more money.  I'd pair it with the 12mm for a bit lower power (125x).  Bought together, FLO offers a 10% discount.

At the low power end, a 32mm GSO/Revelation/Astro Essentials Super Plossl works fine to provide the max field of view at 47x in a 1.25" eyepiece without breaking the bank.