michael.h.f.wilkinson

9 hours ago, Elp said:

My understanding is if you're using 100mm+ it needs a derf to reduce the energy (thus heat) entering the front objective as the derf will reflect a lot of the light. This also protects the quark somewhat. When I tested the SF102 I used one of my photographic HA filters in front of the diagonal, but kept the scope pointed at the sun for only a few seconds as it's not recommended to do this. Some people have been using wide bandpass ha filters to the same end prior to the quark but anyone whom does this is likely doing it at some risk, a 2 inch filter isn't as thick as a derf I'd presume and no filter manufacturer will recommend such use, only a derf will be recommended.

Most likely, the view would be a lot better with an ERF of some kind. Apart from being safer, the thermal currents in the tube caused by the heat will be massively reduced. BTW, the thickness of the filter isn't really an issue in a D-ERF. In this case, the coatings do the filtering, the glass is merely there to hold the coatings in place. A smaller aperture requires thinner glass to do the job.

Just had them out under hazy skies, with some reasonably clear patches. Orion's belt stood out nicely, the stars pin sharp across the field of view. M42 could be spotted, but other DSOs like M65 and M66 were not visible in the haze. The optics seem very sharp, but deserve better skies to work properly. I did find eye placement a bit trickier than in daytime viewing, but a slight twist of the eye cups sorted that out. 

Normally I would use the bigger binoculars for astronomy, but it is nice to have a portable travel option.

I should add that using an ERF, which isn't required for a quark or Ca-K module, cuts down tube currents a lot. Imaging in Ca-K without an ERF in place causes considerable reduction in sharpness, I find. With my tri-band ERF (which transmits Ca-K, H-alpha, and the solar continuum band) gives much better results. It may be that the larger aperture scopes suffer from similar issues more than a 60 mm would when using a quark.

I certainly feel my 80 mm consistently outperforms my 60 mm. I have also use an 8" Tri-Band SCT (a modified C8 with coating on the corrector plate acting as a tri-band ERF), and there the effects of seeing are visible, but under good conditions, it shows a great deal more detail, both in white light and H-alpha. In Ca-K seeing is much more of a problem than in H-alpha, I should add. Both images below were taken with the tri-band SCT

2 minutes ago, josefk said:

Hi @michael.h.f.wilkinson - i have a daft question 🙂 Are those three images of increasing scale and resolution with increasing aperture relatable to what would be seen as "betterness" visually or is the greater capability of the larger apertures most apparent when captured by a camera?

I actually like all three BTW and would be over them moon if anything like the LS35THa view was achievable visually with a solar scope at the lower end of the scale for aperture (and cost)...I've never observed H-Alpha and like the OP and like many others i've read in threads like this i'm wondering at what level to "buy-in" to something i have no experience with...

It is always tricky to compare images with the visual impact in H-alpha. The H-alpha image itself is a uniform shade of red, and it takes a while to get used to that. I very often have people looking through the scope and first just seeing a red disk, and then suddenly gasp as the detail pops out. When imaging, I always use a monochrome camera, as I would be wasting 75% of the pixels otherwise. I then stack about 10-20% of the best shots, sharpen, and apply a colour look-up table which runs from black through red, to orange, then yellow and finally white, to bring out detail.

Regarding the image quality, aperture of course plays a big role, but the bandwidth of your etalon has a major role to play as well. The LS35 THa and SolarMax have a bandwidth of 0.7 Å (0.5 Å if double stacked). The Solar Spectrum filter is much narrower, and gives more contrast (at a lower apparent brightness).

I have used various H-alpha scopes for imaging, starting with a second-hand Lunt LS35THa. Despite this not being intended for imaging, I got some pretty neat results (with a planetary camera attached).

I then got a Coronado SolarMax-II 60mm, to which I later added a double-stack unit. I still have this one at work for visual purposes, after I got a second-hand Solar Spectrum H-alpha filter with telecentric lens (sort of similar to a Quark) which I use in my APM 80mm triplet refractor. The difference between the three systems in imaging is shown below (click for full resolution)

Left to right: Lunt LS35THa, Coronado 60 mm single stack, APM 80mm with Beloptik Tri-Band ERF, Solar Spectrum 0.3 Å H-alpha filter and Baader TZ4 telecentric

I have spotted it quite easily with my C8. At magnitude 12.9 it should just be doable in a 130mm scope

Very nice indeed. If clear outside is right and I get some clear skies I might well go for this target tonight and/or tomorrow night

Very nice first result! Good detail showing

Brilliant idea, might well give that a go!

I have had the Helios Apollo 15x70s and they were excellent, but then the Helios LightQuest 16x80 came along, and it is slightly better and somewhat lighter than the Apollos. The Helios Apollo is a clear step up compared to the generic type, the LightQuest 16x80 is just as easy (or difficult) to hold as the Apollo 15x70, and a marked step up again.

11 hours ago, PeterW said:

I picked up some secondhand Leica 8x20 trinovid, the smallest of this class of binos. Views narrower than I prefer, but they take up no space in my jacket pocket, so easy to carry all the time, never know when they might come in handy.

peter 

Interesting. The FOV in the Zeiss Victory is pretty good (7.45 deg vs 6.4 for the Trinovid), and clearly better than the cheaper Zeiss Terra 8x25 (6.8 deg). I assume the FOV in the Leica was in part due to restrictions imposed by the narrower optical tubes, given the smaller aperture.

14 hours ago, Captain Scarlet said:

Very nice.

I’ve been thinking about a pocket pair too, I’ve narrowed it down to your Zeiss’, and the Swarovski 8x25. Did you consider those? They seem to be similarly priced.

Magnus

I did consider Swarovski, but like my comparison of 10x42 roof prism binoculars from Zeiss, Leica and Swarovski, I found the Zeiss just a touch more comfortable. Otherwise they are very close in optical performance. The store I went to didn't have similar Leica in stock this time, so I just compared two. Eye placement in binoculars is a very personal thing, so your mileage may vary.

4 hours ago, Nakedgun said:

~

You may find compatible caps via Amazon.

 

 

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Found some Opticron ones that seem to fit the bill exactly

https://www.opticron.co.uk/our-products/accessories/rubber-objective-lens-covers/31027-rubber-objective-lens-covers-25mm-og-l-pair

Yesterday I bit the bullet and got myself an ultra light pair of binoculars (because of course I need more binoculars).  The aim is to have a quality pair that I can keep in my coat pocket, so it can travel with me without adding much weight to my luggage.

I settled for the Carl Zeiss Victory 8x25 pocket binoculars, given the stellar reviews, and the stellar performance of my other Zeiss Victory binoculars (10x42).

These bins have a curious asymmetric design.

and fold up to a tiny package.

They come with a handy protective case

but sadly lack lens caps of any description. I have found 33.7 mm eyepiece caps fit snugly over the eyepieces of these bins, but don't quite fit over the objectives. 

Optical quality is outstanding, as you would expect, and the eye relief is sufficient for me with my glasses. Hope to bring them to Texas for the eclips, and intend to make some solar filters for them shortly.

11 hours ago, Flame Nebula said:

Hi Michael, 

A red filter. Interesting. I've not heard of that approach before. 

Seeing tends to be better at longer wavelengths, hence the trick

I have picked it up once with my Celestron C8, using a red filter to punch through the rather lively seeing. Even then it was difficult to spot, as a more-or-less constant bright dot in the sparkling mess surrounding Sirius A.

5 minutes ago, Ouroboros said:

I think you should try observing after the sun goes down.  

Or take up solar astronomy

It helps me select which objects to chase on the night. I live in a Bortle 4-5 (6 on a bad night) suburban setting, with Bortle 2-3 skies fairly close by.  I use my biggest scopes (Celestron C8 and Meade SN-6) on planets and moon on bad nights, but gun for fuzzies on good nights. I have visited Bortle 1 and 2 sites on holidays, and everything performs better there.

Regarding the usefulness of the Bortle scale for imagers: I can punch through much of the light pollution with narrow-band filters, and capture stuff that is terribly hard to spot visually, so it seems to affect my observing more.

Even without narrow-band filters, I can subtract the sky background in ways an observer could never do, so the horsey is an easy target for my 80 mm in imaging. You do need much longer integration times to reduce the photon noise of the sky background, but long exposures can get neat results.

13 h 2 min 30 s total integration time on the Dumbbell Nebula

1 hour ago, John said:

I've compared the 3mm and 4mm settings of my Nagler 2-4mm zoom with the Svbony zoom quite a few times now. With the exception of the slightly wider AFoV of the Svbony, I've seen little difference in optical performance so far. The Nagler zoom has more refined "click" detents and in .5mm steps, which can be useful. I don't think the Svbony quite gets to 3mm focal length - 3.4mm at the shortest, maybe ?

I was looking for a 3-6mm Nagler zoom (which would be my 3rd 🙄) but I've put that on hold for the time being as the Svbony generally seems to be holding it's own.  

I sometimes wonder if at this very high magnification range the atmosphere isn't the limiting factor, certainly in the centre of the FOV. You will need near perfect atmospheric conditions for differences in optics to show up. I am not knocking the Svbony EP in any way, it is just that as optics have improved, other limiting factors come into play.

21 hours ago, Gonariu said:

I'm spoiled for choice, living in Sardinia I was thinking about the August 2026 eclipse in Spain or the August 2027 eclipse in Tunisia, both are quite close. Certainly for the language Spain is better for me as Spanish can be understood by those who speak Italian and Sardinian, for the duration of the whole Tunisia is better.

I have friends in Leon, Spain, and they would love to have me over for the 2026 eclipse 

The blue ellipse in the paper is due to H-I (neutral hydrogen at 21 cm wavelength). I am not sure how much that region would show up in the optical wavelengths. I would certainly not expect star-forming regions there, but there may be stars, of course. 

I do not know about Sirilic, but I have stacked results from different sessions in Astro Pixel Processor without issues. Note that I stacked the non-stretched versions, with background subtracted.

You don't necessarily need a long focal length for lunar, I use my 6"F/5 Schmidt-Newton happily on the moon, I just use short focal length EPs (like a 5mm). It can also handle wide field. Schmidt-Newtons are few and far between, but something like a 6" Dobson fits the bill as an all-round observing scope that will not break the bank. Even an 8" Dobson would fit the bill.

Best of luck. 81-100% cloud predicted for my neck of the woods, so still can't test guiding with the HEM15. Curious to hear about your experiences