Louis D
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Posts posted by Louis D
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5 hours ago, dweller25 said:
the Edge 8”, the Standard C9.25 and the Mewlon 180 are all within £100 of each other.
In the US (pre-tax), the EdgeHD 8" is $1600, the C9.25 is $1900, and the Mewlon 180 is $2200, so quite a spread in prices relative to the UK. It's interesting they're $300 steps apart from each other. Does performance step up accordingly?
For a visual only 8" scope, I'd probably get an 8" f/4 or f/5 GSO Newt based on my excellent 6" f/5 GSO Newt. You also don't give up wide field views like you do with any of the above CATs. Just add a well-spaced GSO coma corrector to the focuser, and you'll get nice and sharp low power views. Remove it for high power views (it adds spherical aberration at high powers).
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2 hours ago, wesdon1 said:
@Louis D Wow that's some setup! Where would I find that triple finder 'scope bracket please?
Check ebay, that's where I got mine from. Here are three listings I pulled up on ebay UK today:
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8 minutes ago, LondonNeil said:
Interesting Louis. Same ep?
At least equivalent. Most SCTs were using premium Tele Vue, Pentax, ES, or other brand eyepieces. A premium eyepiece won't correct a poor OTA's image; and on-axis, a lower end eyepiece won't corrupt a top-notch OTA's image all that much. Being that all SCTs tend to be on driven mounts at the star parties I've been to, all of the images were on-axis.
For years, I had written off SCTs as having mushy, low contrast, low sharpness images until I looked through some Edge HDs. The views were right up there with Newts having premium mirrors and Paracorr T2s. It was rather surprising. All SCTs I've looked through having been driven, I have no idea if the planetary images degrade off-axis for users of non-tracking mounts.
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On 19/06/2024 at 13:16, Don Pensack said:
Judging from the prices of eyepieces in general, £60 is a low-end price, but you are fortunate there are many eyepieces at low prices today.
I would agree that your budget puts you among what I refer to as "step-up" eyepieces, as in a step-up from what came with the typical introductory telescope. They are still quite affordable, though.
25 years ago, there weren't many good step-up choices available. Probably the Vixen LV series would have been the best choice, but at $90+ each in 1990s dollars, they still weren't very inexpensive. That's how I ended up with a 9mm LV as my first major eyepiece purchase. The various well corrected wide-field eyepieces of the day were very expensive when inflation corrected.
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Based on my anecdotal star party experience, visually, on Jupiter, I find the 8" Edge HD to be significantly sharper and contrastier than run of the mill 8" SCTs even on axis under the same sky conditions. For DSOs and non-Jupiter solar system objects, this advantage probably disappears.
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On my 127 Mak for visual observing, I prefer both an RDF (or Rigel QuikFinder) and an 8x50 RACI finder scope on a multi-shoe finder extension. Something similar to the images below on my 90mm APO, with a GLP added for good measure:
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I hope you don't mind, but I ran your TIF file through my ancient PSE 2.0 and did a bit of unsharp masking, adjusting black levels, and increasing saturation to bring up the stars and their colors while dimming the background:
The central region still has a bit of blue glow to it, but it's tolerable.
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It doesn't look at all like it increased the resolution which might be possible by microshifting the imaging chip between images. Instead, it seems to have just increased the gain to make dimmer stars brighter. However, it blows out the highlights (brighter stars) into oversized blobs. I'd be more impressed if the DSP algorithm had selectively increased gain on only the dimmest stars while leaving the highlights and background noise as-is. Basically, a form of HDR photography.
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Heavy duty aluminum photo tripods also work very well. They can be had used for very reasonable prices.
The long arm mounts tend to vibrate more because of the length of the lever arm. It acts a bit like a tuning fork. It can also twist along its length.
Mounts with the clamp close to the azimuth axis tend to be the most stable. Something like DiscMounts DM-6 is very stable, especially on a hardwood tripod:
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The sad part is, the manufacturer could include some sort of rigid tube shroud as a product improvement/upgrade, but they don't.
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3 hours ago, Don Pensack said:
The 17mm T4, though, is the only Tele Vue eyepiece I've seen EOFB (edge of field brightening) in.
The 12mm NT4 has EOFB pretty severely. It extends nearly to the center. I swapped it with my 12mm ES-92 to confirm, and all of the gradient background glow went away. I swapped the 12mm NT4 back in, and there it was again. I then examined it more closely and realized only the very central region on axis was free of it.
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On 20/06/2024 at 06:17, Gonariu said:
A rule of thumb says that the maximum magnification for a given telescope is 20-25 times the diameter of the objective in cm; then this limit is higher for refractors (in particular for apochromats) and lower for reflectors. In the user manual of my Ziel Gem 60 I found this table which I report by translating the terms from Italian.
Objective diameter (mm) maximum useful magnification
reflector refractor
60 120 150
100 210 264
120 232 300
150 262 346
200 305 412
250 343 469
280 364 500
300 377 520
350 408 566
400 437 608
I haven't seen too many consumer refractors with 10 to 16 inch objectives, though. 😉
There is this 20 inch objective if you have the money:
According to the table, you should be able to get up to about 775x. I'd hate to wrangle that OTA into and out of a trailer, though. It would be about 21 feet long and who knows how heavy. I'm trying to picture the mount for it. 🤪 Perhaps a folded design would be best.
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12 hours ago, Bivanus said:
@Louis Dmight be right , it's one of those cases of seing with one own's eye 😉 but after almost having a scratched cornea on a 16mm T6 I'll try to get by.
If you back off a bit from the eye lens and give up some FOV, as with the Meade MWA 26mm, the SAEP is tolerable in the 17mm NT4. It might also be better under truly dark skies where your iris can fully dilate and accommodate the errant exit pupil rays.
SAEP aside, the 17 Nag is a very nice eyepiece optically. It's also the only Tele Vue eyepiece that focuses at the shoulder like many non-TV eyepieces. This makes it nearly parfocal with the majority of my eyepieces.
It is a solid chunk of metal and glass. You don't realize just how dense it is until you go to pick it up.
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52 minutes ago, Bivanus said:
Still looking for 11mm T6 Nag , 17mm T4 Nag and 22mm T4 Nag with the caveat that if I get the 22 that will also get me the 11 - as far as I red everywhere the 22 barlows very good.
I can't stand my 17mm T4 Nag due to its very strong SAEP. It makes taking in the entire FOV at once all but impossible. Shadows flit all around once you get close enough to see the field stop. I retired it in favor of my 17mm ES-92. Your mileage may vary with the 17mm NT4, though.
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Unfortunately, I don't know where the commercial filter companies I've bought bare filters from get their lens tissue paper. From my online reading, I think it needs to be acid-free. Commercial suppliers (business to business) seem to be the best source.
The cling plastic appears to be called PVC cling vinyl. It has the advantage of completely protecting against surface scratches while peeling away with no residue. I've gotten some unmounted interference filters all the way from China without issue using cling plastic protection. Again, it is only available from commercial suppliers. The protected filter was then slipped into a zip closure plastic bag.
You'll still need heavy cardboard to provide stiffness to protect against bending.
Of course, you'll also want at least 3 to 5 inches of padded space around the filter(s) within the shipment box.
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I would recommend buying some cheap, older filters of roughly the same diameter off of ebay that come with their original protective cases and just swap out the old filters for your fancy new ones. Then, wrap those closed cases in closed cell foam sheeting and/or bubble wrap for shipment in an oversized box. I've gotten dozens of filters shipped to me that way by various sellers without a single broken filter.
If the filters are unmounted, you'll want to ship them in either high grade lens paper folded tight around them or covered in heavy cling plastic sheeting to protect the coatings.
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To get back to your initial alignment question, if you are trying to align your various finders to your main OTA, start at low power to get things roughly aligned. Next, jump up about 3x in power on your OTA and refine your alignment some more. If you're still not satisfied, jump up another 3x and refine one more time.
Just remember, every time your remove your finders from your OTA, you'll need to refine your alignment again when every thing is put back together. However, you can probably start at the mid-power level the next time.
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11 hours ago, Elp said:
There's a solution to this. Networking 101, to secure a device do not connect it to a network (also limit the amount of physical users).
Not possible with a lot of software that requires phoning home for license checking. My wife ran into this with Adobe products. They will not work in closed, secure rooms that have no external internet connections. This was a deal breaker for DoD (US military) contracts, so Adobe was informed they would be cut off from all DoD bidding. Low and behold, they replied "Wait, we can work around licensing issues for you". I'm not sure exactly what that work around is (security rules prohibit me from knowing), but I found it hilarious that they bumped up against a customer that couldn't be bullied (the US military).
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Speaking of old systems, every once in a while I come across old mom & pop shops still running customer ticketing on DOS and printing receipts using a pin-feed printer with carbon copies. I'm always amazed to see such setups still running in everyday use. It still meets their needs 30+ years later, so why upgrade?
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I forgot to add that many older Windows 7 and 8 machines didn't come with TPM 2.0 capabilities. I've got several Windows 10 machines built on older motherboards that don't have this, so there is no upgrade path to Windows 11 (which requires TMP 2.0 hardware support) for these machines. Again, if you're not connecting a machine to the internet, there is no reason to have TPM 2.0 capabilities.
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I've still got old 98SE, XP, 7, 8, and 10 systems around the house for old peripherals that have no driver update path and software than doesn't run correctly in compatibility mode. Does anyone know of a 1998 Minolta slide scanner on SCSI through PCI driver update? I didn't think so. How about Firewire driver support for downloading MiniDV video files? Again, I don't think so. Believe me, there are plenty of people I've helped move their old videos off of tape lately, so don't say I need to ditch that hardware just because Microsoft quit supporting it long ago.
One problem with OS upgrades is that Windows keeps taking away software access to hardware primitives to protect the user from rogue software. We ran into that at work trying to test our PCI cards in the mid-2000s. Suddenly with a particular OS upgrade, we could no longer directly access PCI hardware primitives with our low level software and had to go through OS calls that didn't do what we needed them to do for low level compliance testing. Thus, we kept an old OS machine lying around for that purpose.
I never upgrade my OS for the following reasons:
- The new OS is generally such a resource hog that it bogs down the old hardware.
- Much of the old software and drivers won't work even in compatibility mode for the reasons listed above.
- If it ain't broke, don't fix it. Why upgrade the OS when the old one is working just fine? If you're worried about internet safety, then don't access the web from your old machines. Move your files over to newer machines via flash drives for upload after you're done processing them on older machines with older software and peripherals.
I just buy or build a new machine when the latest OS becomes mature and the old machines are starting to get flaky from bad OS patches late in the support window. I'd swear Microsoft sabotages their old OS users in the last year of support to force them over to the new OS. I've had this happen to multiple OSs over the last 25 years.
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How does the average person distinguish cast aluminum from the more common cast pot metal as in the SkyTee-2 below?
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13 hours ago, Carbon Brush said:
Dewing can be a problem. In the Maldives, we had air con running in the room to keep us at a pleasant 22C.
Take the kit outside to the night 30C very humid air and suddenly the condensation you normally associate with bringing kit indoors becomes an outdoor problem!Sounds like Texas in the summer. It often doesn't drop below 90 F until 9pm. The dewpoint is up around 80 F, so dewing becomes an issue early in the early morning. I just brought my equipment in from outside tonight and left everything uncapped in the A/C with ceiling fans running to dry out everything. I took a 45 minute power nap and then capped and put away everything.
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If you're using a nebula filter, the larger exit pupil in the 32mm may improve brightness. Of course, you can push that to a 40mm eyepiece for an even larger exit pupil and brighter image.
If you're not using a nebula filter, the higher power usually yields better contrast by darkening the sky background a bit more. Technically, both the DSO and the sky background should dim at the same rate, but I find that visually, the sky seems to darken at a faster rate. It's probably something to do with the brain's visual processing capabilities.
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Pegasus SmartEye - The next phase of astro maybe?
in Discussions - Eyepieces
Posted
How on Earth does this work on an undriven mount? Can it do track and follow to present a motionless image?