$130 Telescope vs. $600 Telescope vs. $1,750 Telescope - YouTube

This is an 80mm refractor. And this is an 80mm refractor. And this, you may have guessed it by now, is also an 80mm refractor. So why does this one cost $130? This one costs $600 and this one costs $1,750. In this video, I'll explain why and I'll share everything that you should look out for when buying your first refractor telescope for astrophotography. Hey, welcome. This is Nico from Nebula Photos. This is a channel all about amateur astrophotography. And I cover everything about that hobby, including tutorials, explainers, and reviews like this video today. And since this is a review comparing these three telescopes, I need to share a few disclosures up top here.

这是一个80毫米折射望远镜。这个也是80毫米折射望远镜。还有这个，你可能已经猜到了，也是80毫米折射望远镜。那么为什么这个要卖130美元？而这个要600美元，这个要1750美元。在这个视频中，我会解释原因，并分享你在购买第一台用于天文摄影的折射望远镜时应该注意的一切。嘿，欢迎。这是Nebula Photos的Nico。这是一个关于业余天文摄影的频道。我会涵盖这个爱好的所有内容，包括教程、解释和像今天这个视频一样的评测。既然这是一个对比这三台望远镜的评测，我需要在开头这里做一些披露。

Both the Asgar 80PHQ and the SUVONI SV503 telescopes were sent to me by the respective manufacturers and that was at my request for the purpose of this review. But I'm making this video completely independently and so Asgar and SV science, I've bought myself for the channel. But with financial support from my generous patrons over on patreon.com slash Nebula Photos. And that support is really what keeps the lights on for this channel, but I'll say more about it at the end of the video.

Asgar 80PHQ 和 SUVONI SV503 望远镜都是我向各自的制造商请求后发给我的，用于这次评测。但我是在完全独立的情况下制作这段视频的，因此 Asgar 和 SV 科学的设备是我自己为频道购买的。不过，我得到了 Patreon 上慷慨的支持者们的财务支持，这些支持真正帮助我维持这个频道的运作。更多的内容我会在视频结尾再说。

So let's first jump into the design of a refractor and what makes a design well suited for astrophotography. And we will specifically be looking at the design of these three telescopes, of course. So the first thing that you want to look for is how many glass elements are actually in the tube. And then how many of those elements are ED glass? ED stands for extra low dispersion. And without at least one element being made of ED glass, you get a lot of blue, violet, or magenta fringing on your stars. And that can be really pretty distracting and hard to remove in post-processing without leaving some kind of artifact.

首先，让我们来了解一下折射望远镜的设计，以及什么样的设计适合天文摄影。我们将特别关注这三种望远镜的设计。首先需要注意的是望远镜筒内有多少块玻璃镜片。然后，要看其中有多少镜片是ED玻璃（超低色散玻璃）。如果没有至少一个镜片是ED玻璃，你会在星星周围看到大量的蓝色、紫色或品红色边缘，这会很让人分心，并且在后期处理时很难去除这些色边而不留下其他痕迹。

Now there are fringe killer or minus violet filters, and those can work pretty good for removing it optically. But keep in mind there's no free lunch. And with those filters, you'll be removing some colors from your photos. So in order to treat the symptom of the problem stars, you might get worse color reproduction otherwise. So it's always best if you can afford it to get a refractor with ED glass extra low dispersion glass. So in my comparison here, the Ryan short tube 80 is a doublet with two glass elements, but neither have ED glass. This is also a doublet, the SV bony. But one of those elements is an ED glass, an FPL, F51. And the ascar is a quadruplet, meaning four elements and two of those are ED glass. So two, one, zero. Now another word you'll see that is related to the number of glass elements and the type of glass that they're using is apple chromatic or acromatic.

现在有一些用于消除紫外光的边缘杀手或减紫滤镜，它们在光学上可以很好地去除这些光线。不过要记住，没有免费的午餐。使用这些滤镜时，你会从照片中去除一些颜色。为了处理星体问题的症状，你可能会牺牲其他方面的色彩再现。因此，如果你能负担得起的话，最好使用具备ED玻璃（超低色散玻璃）的折射镜。 在我的对比中，Ryan短管80是一个双透镜组合，但它们都没有使用ED玻璃。而SV bony也是一个双透镜组合，其中一个是ED玻璃（FPL-51）。Ascar是一个四透镜组合，其中两个使用了ED玻璃。所以，这里是2（氟镜片），1（单氟镜片），0（无氟镜片）。 另一个你可能会看到的词是“色差校正”或“消色差”，这与玻璃元件的数量和所使用的玻璃类型有关。

And this refers to the telescope's ability to focus all the colors at the same time, all the colors in the visible spectrum. And that's an important ability, especially when you're shooting with DSLRs or one shot color cameras. There's some debate online whether a doublet with ED glass can count as apple chromatic and apple chromatic telescope. My opinion is really what matters is the images. So if you can take a photo with an ED doublet and not see any obvious fringing on the stars, then we should basically consider that apple chromatic, whether it is technically or not. But of course, people will have different standards for this kind of thing. And some people are much pickier than others. So I'll be presenting a little bit later in the video, actual image comparison so you can really decide for yourself what level of perfection you need.

这指的是望远镜能够同时对所有颜色进行聚焦，涵盖可见光谱中的所有颜色。这是一项重要的能力，尤其是当你使用单反相机或一次成像的彩色相机拍摄时。 关于是否可以认为采用低色散(ED)玻璃的双镜片望远镜是"苹果色差"还是"苹果色差望远镜"，网上有一些争论。我的观点是，真正重要的是图像效果。所以如果你能用ED双镜片拍摄照片，并且看不出星星上有明显的色差，那么我们基本上可以认为这是"苹果色差"，无论技术上是否如此。当然，对于这种问题，不同的人有不同的标准，有些人会比其他人挑剔得多。 在视频的后面部分，我将展示实际的图片对比，这样你就可以亲自决定自己需要什么样的完美程度。

But general takeaways here, again, a refractor with more ED glass is going to give you better color reproduction tighter stars typically. And the worst kind of refractor for especially for one shot color camera is an acromat. Last thing about this is that with a doublet or a triplet, you'll typically want a field flattener or a flattener reducer. With this SV bony, there's a matched flattener reducer available. So I've included that in the price of $600. I didn't see one available for the Orion. And with the way this focuser is designed, I don't think there are any on the market that would work. Now the Ascar does not need a field flattener because it's designed for imaging. And so the corrector is actually built in to the telescope design because it's a quadruplet. But Ascar does offer an optional reducer. It's just a reducer only, you know, no flattening element. But I did use it for these image tests and included it in the price here.

总结一下这里讨论的内容，还是要记住，一台配有更多ED玻璃的折射望远镜通常会提供更好的色彩还原和更紧密的星点。对于一次性彩色相机来说，最不理想的折射望远镜类型是消色差望远镜。最后要提到的是，对于双镜片或三镜片望远镜，通常需要一个视场平坦器或一个平场减焦器。对于这款SVbony望远镜，有一个匹配的平场减焦器是可以买到的，所以我把它包括在了600美元的价格中。我没有看到Orion这款望远镜有类似的配置。而且根据它的调焦器设计，我觉得市场上没有适合的配件。Ascar则不需要视场平坦器，因为它是为成像设计的，其校正器已经内置在望远镜的设计中，因为它是四镜片结构。但Ascar确实提供一个可选的减焦器，这只是一个减焦器，没有平场功能。我在这些成像测试中使用了它，并将其包含在这里的价格中。

So that's a pretty cool feature of the Ascar is that you can use it at 600 millimeter focal length. If you want to go at F7.5, or you can use that 0.76 x reducer to bring it down to like 450 millimeters. Let's next look at price. I picked these three telescopes on purpose as I think it gives you a pretty good idea of what to expect at each sort of type of telescopes. So this is an acromat, not really designed for imaging. It's more designed as like a quick go to scope or guide scope. And they started around $100 go up from there. This is an ED doublet $600 with the field flattener is pretty sort of standard on the low end. And this is more like a premium astrograph kind of refractor. So 1750 is not unusual. They go up from there. There's some that are cheaper, but typically for smaller astrographs like a red cat or an FRA 300. So for an 80 millimeter astrograph, I think this ascar is competitively priced. So I'd rather not go really into the discussion of value because I think that's really subjective.

所以，Ascar 的一个很酷的功能是你可以在 600 毫米焦距下使用它。如果你想用 F7.5，可以这样用，或者你可以用 0.76 倍的减焦镜将它降至大约 450 毫米。接下来我们来看一下价格。我特意选择了这三种望远镜，因为我认为这能让你对不同类型望远镜的价格有一个很好的了解。这是一种消色差镜，不是真正为成像设计的。它更像是一个可以快速使用的望远镜或导星镜。它们的起价大约在 100 美元左右，价格会从那里上涨。这是一种 ED 双合胶镜，带有视场平坦器的价格大约为 600 美元，这在低端市场上是比较标准的。而这种是更像高端天文摄影用途的折射望远镜，1750 美元并不罕见，价格会从那里上涨。有些价格更便宜，但通常是较小的天文摄影望远镜，比如 red cat 或者 FRA 300。所以对于 80 毫米的天文摄影望远镜，我认为这个 Ascar 价格具有竞争力。我不想深入讨论价值问题，因为这是非常主观的。

It's really just about what you're looking for in a telescope. So after watching this whole review, I'm just really going to leave it up to you again, what level of perfection you're trying to achieve with like the tightness of your stars and how much fringing they have. That's the main thing that sort of differentiates these, especially these two on the higher end. The one thing I do want to say about price and cost is you really don't want to skimp on the mount. So if you could save money somewhere, save money with the telescope and the camera, I'd say, especially the camera doesn't matter that much, but the mount is very important.

这真的取决于你对望远镜的需求。看完这个评测后，我还是想让你自己决定，你对星星的清晰度和边缘的色散有多高的要求。这是区分这些望远镜的主要因素，尤其是高端的两个。关于价格和花费，我想说的是，你真的不要在支架上省钱。如果要省钱的话，可以从望远镜和相机上省，特别是相机没有那么重要，但支架非常关键。

So for something like an 80 millimeter refractor, this one's a little bit lighter than the other two. But you could go with one of these like small mounts like I have here, like the ioptron smart EQ, but I'd really suggest going up to like a EQM 35 HEQ5, an ioptron 726, something like that's going to be better. And I tested all three on my EQ6R. Again, probably overkill maybe, but I wanted to make sure that I was just testing the optical performance. So I used a very good mount so that there was no problem with tracking.

对于像80毫米的折射望远镜，这个比其他两个稍微轻一点。但是你可以选择一个比较小的架子，比如我这里的iOptron Smart EQ。不过，我建议使用像EQM 35、HEQ5、iOptron 726这样的架子，这些会更好一些。我在我的EQ6R上测试了这三款架子。可能有点过度了，但我想确保只是测试光学性能。所以我用了一个非常好的架子，这样就没有跟踪问题。

Now let's go ahead and look at the physical characteristics of these telescopes, including the weight, the focusers, the build quality, and everything that's sort of included, like the rings or the brackets and things like that. The Orion short tube 80 is 15 inches long or 380 millimeters. The dew shield does not retract, but it's already so compact that it's not really a big deal. When I bought it, I remember it just coming with this small vixen dovetail plate, bolted onto the bottom. But I looked online now and I see there's a bunch of different configurations with different accessories.

现在让我们来看看这些望远镜的物理特征，包括重量、调焦器、制造质量以及包含的所有内容，比如环和支架等。Orion短筒80的长度是15英寸或380毫米。它的防露罩不能缩回，但由于本身已经非常紧凑，所以这并不是大问题。我记得我买的时候，它只有这块小的维克森燕尾板，固定在底部。但我现在在网上查看，发现有很多不同的配置和不同的配件。

So if I were to get it today with imaging in mind, I'd probably get the rings because with this configuration, there's no way to rotate. Well, if I had rings, I could at least rotate the whole scope in the rings. And sometimes rotation is very nice to have. In terms of what it comes with, it does come with this scinta style finder shoe built into the focuser. Comes with a plastic cap for the front. And the focuser is a single speed. It's not a two inch. It's, and you can hear it makes a little bit of sort of crinkly noise that I associate with low quality focusers. It's not perfectly smooth.

如果今天为了拍摄而购买它的话，我可能会选择带环的配置，因为这种配置下没有办法旋转。如果有环的话，我至少可以在环内旋转整个望远镜。有时候能够旋转是非常有用的。就附带的配件来说，它配有一个安装在调焦器上的寻星镜支架，前面有一个塑料盖。调焦器是单速的，不是两英寸的，并且调焦时会发出一些我认为是低质量调焦器特有的那种沙沙声，运作不是很顺滑。

And so the focuser is not a full two inch focuser, so you can't use any of your two inch eyepieces or any 48 millimeters accessories with this. This also makes finding a field flattener for this very difficult because all of the third party field flatteners have 48 millimeter threads on the telescope side. But the good thing that they did with the focuser is this is 42 millimeter standard T thread. So that means you can just get standard T adapters, not the wide T adapters, but just the normal M42 T adapters to get your DSLR or mirrorless camera put onto the telescope. And I should also say that because it doesn't use any kind of field corrector, you can just put your camera on and then as soon as it reaches focus, you're in focus. There's no worry about particular back focus with this telescope. The focuser does extend quite a ways, as you can see, but you could also put on spacers as if you needed even more back focus travel. But I've had no problem with getting into focus with the Ryan short tube 80. And the telescope has a focal length of 400 millimeters and a focal ratio of F5, which is printed right on the scope right there.

因此，这款调焦器并不是标准的两英寸调焦器，所以你不能使用任何两英寸的目镜或48毫米配件。这也意味着很难为这款望远镜找到合适的平场镜，因为所有第三方平场镜在望远镜端都有48毫米的螺纹。好在这款调焦器使用的是42毫米的标准T型螺纹，这意味着你可以使用标准的T型适配器（而不是宽T型适配器），将你的单反相机或无反相机连接到望远镜上。我还要提到的是，因为这种望远镜不需要任何场曲校正器，你只需将相机连接上，达到焦点时就已经对焦完成，不必担心特定的背焦距离。正如你所见，这款调焦器的延伸范围相当大，但如果需要更多的背焦行程，你也可以使用延长管。不过，我在使用Ryan短管80望远镜时没有遇到对焦问题。该望远镜的焦距是400毫米，焦比是F5，这都印在望远镜上。

Let's move on here to the SV Boney SV 503 80 ED. It's close to around 18 inches or 450 millimeters long with the dew shield retracted. And then with the dew shield extended, it is about 24 inches or 620 millimeters long. The weight with the field flattener reducer installed back here is around 6.6 pounds or three kilograms. So not heavy by any means, but also not super light like the Ryan was. It comes with very nice rings with nice big knobs, as you can see, for loosening and tightening. And it also has a Vixen dovetail plate installed on the bottom.

让我们继续介绍SV Boney SV 503 80 ED。这款产品在收起遮光罩后长度大约为18英寸或450毫米，而在伸展遮光罩后，长度大约为24英寸或620毫米。安装了场平减焦镜后，重量大约为6.6磅或3公斤。因此，虽然称不上重，但也不像Ryan那么轻。这款产品配有质量非常好的环扣，如你所见，有很大的旋钮用于松紧调节。另外，底部还安装有Vixen燕尾板。

It comes with a metal front cap. And it doesn't actually come with a synthesized finder shoe. I installed that afterwards. I just got this off eBay, but it does come with plenty of places to put one if you so desire, but it doesn't come with this. So this is be something you have to add. It has a very nice two speed focuser. There's the course and there's the find, and it works very, very well. It's very smooth.

它配有一个金属前盖。但它实际上没有附带一个合成的寻星镜架。这是我之后自己安装上的。我刚在eBay上买到的，但它确实有很多地方可以安装一个寻星镜架，如果你需要的话。但是原装没有配这个，所以你需要自己加装。它有一个非常好的双速对焦器，有粗调和微调功能，而且运作非常非常顺畅。

So I've had no problems with that. And it does offer full 360 rotation on the focuser. You just loosen that knob right there. And then you can rotate the focuser and then tighten it back up. You see, the focuser does have gauge markings in millimeters. So that's nice for repeatable focus. In terms of installing the field flattener, it has these three thumb screws that have a compression ring inside here. And then the field flattener simply slides into the focuser like that, which works fine. And then the field flattener itself has normal 48 millimeter thread on the camera side.

所以我没有遇到任何问题。而且调焦器可以进行360度的全方位旋转。你只需要松开那里那个旋钮，然后你就可以旋转调焦器，并重新拧紧。你看，调焦器上有以毫米为单位的刻度标记，这样可以方便重复对焦。至于安装场平镜，它有三个带压环的手拧螺丝。然后将场平镜简单地插入调焦器就可以了，这样操作完全没问题。场平镜本身在相机侧有标准的48毫米螺纹。

If you do plan to get this telescope, again, this is the SV Boney SV 503, I'd highly recommend getting this 0.8 X photo reducer and field flattener, because that's going to make the stars a lot better. And with the reducer, it comes down from 560 millimeters F7 to 448 millimeters F 5.6, which is a very nice focal length and ratio for lots of deep sky targets. Alright, so that's the SV Boney SV 503 ADED in terms of its physical makeup.

如果你打算购买这款望远镜——SV Boney SV 503，我强烈推荐你购买这个0.8倍的照片减焦器和场曲校正器，因为它会让观测到的星星效果更好。而且有了这个减焦器，焦距会从560毫米 F7缩短到448毫米 F5.6，这对于观测许多深空目标来说，是一个非常理想的焦距和光圈比。好吧，这就是SV Boney SV 503在物理结构上的介绍。

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当然，请告诉我你想翻译的英文句子或段落，我会尽力将其翻译成易读的中文。

Okay, and finally, we have the Asgar 80 PHQ Q for quad. And this one is in a fairly new line of quadruplet telescopes from Asgar that all have long native focal length for their respective aperture. So this is an 80 millimeter scope, but it's at F 7.5 600 millimeter focal length. But then you can also get a 0.7 X times reducer for it. And that brings it down to 456 millimeter focal length at F 5.7. And what's really cool about this line of telescope and the reducer is that both the native focal length and with the reducer, you're corrected for a full frame sensor. And so that's actually fairly rare in a telescope at this price point that it would be well corrected out to full frame.

好的，最后我们来看 Asgar 80 PHQ Q 天文望远镜。这款望远镜属于 Asgar 最新的四镜组望远镜系列，具有相对较长的本机焦距。这个型号的口径是80毫米，光圈比为 F 7.5，焦距为600毫米。此外，您还可以购买一个0.7倍的焦距减速器，使焦距缩短到456毫米，光圈比变为 F 5.7。有趣的是，无论是本机焦距还是使用减速器后的焦距，这系列望远镜都能很好地适应全画幅传感器。在这个价格区间中，能够做到对全画幅的良好校正是相当少见的。

So that is the big reason why this one is so much more expensive than the SV Boney. This one's 1,750 SV Boney is 600 is because of that being able to have it really meant for full frame imaging. Okay, with the dew shield retracted like this, it's about the same length as the SV Boney 18 inches long or 450 millimeters. With the dew shield extended out, it's just a little bit shorter than the SV Boney. It's 22 inches or about 570 millimeters long.

所以，这就是为什么这个比SV Boney贵得多的重要原因。这个的价格是1750美元，而SV Boney是600美元，主要是因为它能够真正用于全画幅成像。好，当露水挡板缩回时，它的长度大约和SV Boney相同，都是18英寸（约450毫米）。当露水挡板展开时，它稍微比SV Boney短一些，是22英寸（约570毫米）长。

The weight of this scope with the reducer is 10.6 pounds or 4.8 kilograms, which is fairly heavy for an 80 millimeter refactor. But quads are always heavy for their size because there's big glass elements and there's four of them in this while there's only two in the other two telescopes I showed you which were doublets. And then also the reducer itself adds a couple pounds since it's a three inch reducer. So that's a fairly large reducer. The telescope comes with very nice rings with tons of tapped holes all around and a nice long green dovetail plate, fix and style.

这个望远镜连同减焦器的重量为10.6磅或4.8公斤，对于一个80毫米的折射望远镜来说，这算是相当重的。但四镜片望远镜总是比同类产品重，因为它们有大块玻璃镜片，而且这个望远镜里有四片镜片，而我之前展示的两个双镜片望远镜里只有两片。另外，三英寸的减焦器本身也增加了几磅的重量，所以这是一个相当大的减焦器。这个望远镜配有非常好的环架，周围有很多螺纹孔，还有一个很长的绿色燕尾板，固定样式的。

It comes with this top handle that I've been using to manipulate the telescope. It's a metal front cap with the name of the telescope on the front. And then one thing that is really cool, which I've never seen before, is it comes with not just one, but four different options, threaded connections for connecting your camera or your spacers or whatever you're using. So let me show you how this works.

它配备了我一直用来操作望远镜的顶部手柄。前盖是金属材质，上面印有望远镜的名字。而且有一点非常酷，我之前从未见过的是，它不仅提供了一种，而是四种不同的螺纹连接选项，可以用来连接相机、间隔器或其他设备。让我来演示一下它的使用方法。

So each of these back here is another threaded connection. We have M 76, M68, M54 and M48. So all kinds of different threaded connections are included. You don't have to go out and find those if you have a specialty connection that's needed. This is the reducer, the .7x reducer. And I just want to show you how this goes into the telescope. You use this stack of threaded connections that comes with the telescope. You thread the reducer in here like that. And then the whole thing slides perfectly into the focuser and then threads onto the back of the telescope. So I thought that was a really neat design to have the reducer have a threaded connection into this adapter that then threads onto the back of the focuser. And there's diagrams included showing you how to use all these different adapters.

所以每个这里后面的都对应一个不同的螺纹接口。我们有 M76、M68、M54 和 M48。所以包含了各种不同的螺纹连接。如果你需要特殊的连接，不必自己去找。这是一个 0.7 倍的减焦器。我想给大家展示一下如何将它安装到望远镜上。你使用望远镜附带的一组螺纹连接。先把减焦器这样拧进去，然后整个组件完美地滑入聚焦器，再拧到望远镜的后端。因此，我认为这个减焦器的设计非常巧妙，它通过螺纹接口连接到适配器，然后再拧到聚焦器的后端。附带的图示也会教你如何使用所有这些不同的适配器。

Since it is a quad, if you use it with outer reducer, you can just attach your camera to the back here and just come to focus. And as soon as you're in focus, you're good to go. With the reducer installed, you're going to want 55 millimeter back focus. In terms of markings, this both has markings for focal distance, but it also has markings for the rotator, which is really handy. I wish all telescopes had that.

由于这是一个四重望远镜，如果你使用外置减焦器，只需要将相机安装到后面，就可以直接对焦。对焦后，就可以开始使用了。安装减焦器后，你需要保持55毫米的后焦距。关于标记，这个设备不仅有焦距标记，还有旋转器的标记，非常方便。我希望所有的望远镜都能有这种设计。

So it's a 360 rotator and it has every degree marked right there. It comes with one Sintef style finder shoe standard, but it also has a place for another right there. You could easily install a ZWO-EAF or other electronic focuser and there are already mounting holes. And lastly, I'll just say this is a very substantial three inch focuser that feels nice and sturdy and quite premium. It does have two speeds, of course.

这是一款360度旋转器，上面标有每一个度数。它配备了一个标准的Sintef样式的寻星鞋，但也有另一个位置可以安装。你可以轻松安装一个ZWO-EAF或其他电子调焦器，上面已经有安装孔。最后，我想说的是，这是一个非常坚固的三英寸调焦器，手感很不错而且非常高档。当然，它有两个速度调节。

Okay, now we're on to my favorite part, which is actually looking at the images and doing some comparisons. Before I launch into that, let me just show you the stats of this imaging session. So I was shooting the Iris Nebula from Portal 4. The moon was new. I waited until the Iris was very high up in the sky, which was 2 to 3 a.m., which is also the darkest time, I think. And then I was using a Sky Watcher EQ 6R, which is a nice beefy mount, so no problems with tracking.

好的，现在到了我最喜欢的部分，就是看看图片并进行一些比较。在开始之前，让我先给你看一下这个拍摄过程的统计数据。我是在Portal 4拍摄鸢尾星云的，当时是新月。我等到鸢尾星云升到很高的位置，大约是在凌晨2到3点，也是夜晚最黑暗的时候。我使用的是Sky Watcher EQ 6R，一个非常稳定的支架，所以在跟踪方面没有任何问题。

But just to make sure I was also guiding with a William Optics Uniguide 50mm and an ASI 290mm Mini. I was using a Sigma FP full frame mirrorless camera. It does not have a low pass filter, but it was not modified. So it's a very good camera, I think, for testing for these kinds of things, because it's going to have a nice sharp image without the low pass filter to really give us a good indication of the optical quality of these telescopes. I was shooting at ISO 1600, and for each telescope, I took 4x4 minutes in terms of exposure.

但为了确保万无一失，我还使用了William Optics的Uniguide 50mm导星镜和ASI 290mm Mini相机进行引导。我使用的是Sigma FP全画幅无反相机。尽管没有低通滤镜，但它并未经过改装。因此，我认为它是一款非常优秀的相机，适合测试这类设备，因为没有低通滤镜的情况下，它能提供非常清晰的图像，从而更好地判断这些望远镜的光学质量。我以ISO 1600的感光度拍摄，每个望远镜的曝光时间为4次，每次4分钟。

So I could have tried to take more, but I wanted to really limit it to just one part of the sky as quickly as possible to try to keep the bias from changing sky conditions out of this as much as possible. So I did it all within an hour by moving very quickly. Okay, so first let's look at just some raw frames, highly stretched with the auto stretch. And the point of this is really just to look at what a single 4-minute raw looks like and how much vignetting is affecting the image.

所以我本可以尝试拍更多的照片，但我希望尽量只限于天空中的一个区域，并尽快完成，以尽量减少因天空条件变化带来的偏差。因此，我在一个小时内非常快速地完成了拍摄。好的，那么首先让我们来看一些未经处理的原始框架图片，并使用自动拉伸功能进行高度拉伸。这样做的目的是观察单张4分钟曝光的原始照片长什么样，以及暗角对图像的影响程度。

There is some shadowing of the corners, vignetting in all of these images. This is the Orion short tube 80. There's the SV Boney SV503. And then here is the Ascar 80PHQ. And the way that it has vignettes on the Ascar is interesting. And I'm not sure I'd be interested to try it with another full frame camera just to make sure that it's not some quirk of the Sigma FP that's creating this kind of vignette. I'm not really sure, but it does look sort of odd.

这些图像的角落有些阴影和暗角现象。这些照片是用猎户座短筒80拍的。这是 SV Boney SV503，然后这是 Ascar 80PHQ。Ascar 上的暗角现象很有趣，我不确定是否要试一下其他全画幅相机，以确保不是 Sigma FP 相机的某种特性导致这种暗角。我不太确定，但看起来确实有些奇怪。

These ones look more normal. But then the next question, of course, is well, how does that calibrate out with flats? That's what the Orion looks like after I calibrated with flats, darks, and bias. Here's the SV Boney a bit better. And then there's the Ascar a bit better still. Now, I'll get to this more as we go, but the SV Boney isn't corrector isn't really designed for full frame. So you can sort of see that, that it really sort of corrects out to about there.

这些看起来更正常一些。然后下一个问题当然是，这些和校准用的平场数据（flats）相比如何？这是我用平场（flats）、暗场（darks）和偏置（bias）校准后看到的猎户座样子。这里是稍微好些的SV Boney。然后这个Ascar稍微更好些。我会在后面详细讲，SV Boney 的校正器实际上并不是为全画幅设计的。所以你可以看到它大概只能校正到这里。

And then there's some weirdness. While the Ascar is a full frame corrected telescope and the reducer is also for full frame. And the Orion, we have no field corrector. So we really only have a small section here in the middle that has sharp stars. And then it very quickly gets sort of crazy. And just to show that another way, here is just the corners and the center.

然后有一些奇怪的现象。虽然Ascar是一个全画幅矫正的望远镜，且其减焦镜也是为全画幅设计的。相比之下，Orion没有视场矫正器。因此我们实际上只有中间的一小块区域有清晰的星星，其他区域的星星很快就变得模糊了。为了更好地解释这一点，这里展示了望远镜的四个角和中心的情况。

So you can see the center of the Orion is quite sharp. But then in the corners, it's pretty bad. SV Boney is quite a bit better. But if we look out into the corners of a full frame sensor, you can see we have triangles instead of round stars. While with the Ascar, they are still quite sharp and quite round. And so I've emphasized this, I think, a number of times, but that's what you're really paying for with an astrograph like the Ascar is the ability to get fairly round sharp stars all the way out into the corners of a four frame sensor, which you're not going to be able to do with a scope that's more like $600.

所以你可以看到，猎户座的中心非常清晰，但在边角处就变得很模糊了。SV Boney要好一些，但是在全画幅传感器的边角处，你会发现星星变成了三角形而不是圆形。而使用Ascar望远镜，星星依然相当清晰和圆润。我已经强调了好几次了，但这就是为什么你购买像Ascar这样的天文望远镜，因为它能够在全画幅传感器的每个角落都拍出相当圆润清晰的星星，而这不是一台大约600美元的望远镜能够做到的。

But you could just use a smaller sensor with this telescope. And it would work quite well. Okay. And then this next set is, well, how we saw what it looks like with just calibration, it looked like that. But then if we run a dynamic background extraction, how does it look after that? And you can see the Orion gets quite a bit flatter. As does SV Boney. And the Ascar looks perfect. I mean, that's a very flat field with really no problems there.

但是你也可以用一个更小的传感器配合这个望远镜使用，这样也能很好地工作。好的。然后，接下来我们来看一下校准后的效果。这是最初校准后的样子。但如果我们进行动态背景提取，看看效果会如何？你会看到猎户星云变得更平坦了，SV Boney也是如此。而Ascar的效果看起来完美无缺，视场非常平坦，没有任何问题。

And then, oh, this is just that same picture we just saw, but without the stars, and it shows you that the SV Boney is corrected. This doesn't look like quite APSC, maybe just a but pretty close to APSC. And then the full frame part is just not corrected at all. And we're getting a lot of light fall off out there. Same thing with the Orion Starless. The DBE seemed to work a little bit better though. Or maybe it's just a stretch them differently. And then here's the Ascar, again, pretty flat. Okay.

然后，这张图片和我们刚才看到的是一样的，但没有星星，显示了SV Boney已经进行过校正。这看起来不完全像APSC，可能接近但不是完全一样。而全画幅部分根本没有校正，光线衰减非常明显。奥利安无星图片也是类似的问题，不过DBE处理效果似乎稍好一些，或者只是拉伸方式不同。接着是Ascar，再次看到效果相当平坦。

And then here is the maybe what a lot of people have been waiting for. Here's my final images as I would process each one, including the crop. So with the Orion I'd crop quite a bit in, just to that sort of central portion. So again, here's the full Orion frame and I'd cropped basically right into the center to avoid all of these weird stars out on the corners. But after you do that, it looks pretty good. The one sort of thing that stands out about this image, well two things actually.

然后，这可能是很多人一直在等待的内容。下面是我处理后的最终图像，包括裁剪部分。对于猎户座图像，我会进行较大的裁剪，只保留中央部分。再看一次，这是完整的猎户座图像，我基本上裁剪到正中心，以避免边角的这些奇怪的星星。裁剪后效果不错。说到这张图像，有两个比较突出的特点。

One is we get all this sort of violet fringing on all the bright stars. And then the other thing is we're not getting a whole lot of color on the iris. And I did try to bring it out and I'm still just not really getting that sort of cool blue reflection nebula color. I'm not sure why. But we do get some of the dust around the iris. Here's the SV Boney. And again, I cropped down. It's probably around APSC, but it's a little bit square than APSC is what I just I did a pretty lazy crop. I didn't try to correct this ring. So I really just took a crop and went boom, boom, boom, boom, and cropped like that to get this.

我们遇到的一个问题是所有的亮星星上都有紫色的光晕。另外一个问题是，我们没有在星云中心看到太多颜色。我尝试过突出颜色，但还是无法得到那种凉爽的蓝色反射星云色彩，不知道为什么。不过，我们确实看到了星云周围的一些尘埃。下面是用SV Boney拍摄的照片，我进行了裁剪。虽然裁剪得比较随意，但大概裁剪在APSC大小，不过比APSC稍微方一些。我并没有试图纠正这个环，所以我就是随便裁剪了一下，结果就是这样。

And then here is the ascar. And with the ascar, I could use the full frame. Now I might still crop this down because this was just a very short integration. So there's not a whole lot going on. Yet. But if you imagine if I shot this for several hours, this whole frame would fill up with that beautiful dust and cepheus and it would look really cool. Okay. And last comparison, I just cropped in to the center of each one and registered these together just to show you sort of the deep, you know, the detail difference and the sharpness difference at the center of the frame. If that's something you're interested in.

然后这是用的 Ascar。用 Ascar，我就能使用全画幅。不过我可能还是会裁剪，因为这只是一个很短的整合，所以目前还没有很多内容。可是，你可以想象，如果我拍几个小时，整个画面会充满那美丽的尘埃和仙王座（Cepheus），看起来会非常酷。好的，最后一个比较，我把每个图像的中心裁剪出来并对齐，只是想展示中心部分细节和清晰度的差异，如果你感兴趣的话。

So I don't know how clear it is. It's clear to me that the the ascar is sharper than the SV Boney. And then it should be clear even to everyone that they're both sharper than the Orion. But let me actually zoom in a little bit just to really drive this home. Let me pick some pick a star field that has sort of a mix of smaller stars and bigger stars. That looks good. Okay. So this is pretty illustrative of what you're getting for 130, 600 and 1750. So you can see there's a pretty dramatic difference here between the 130 and 600.

所以我不确定这是否清楚。但对我来说，明显Ascar比SV Boney更清晰。而且甚至应该对每个人来说都明显，它们都比Orion更清晰。但让我再放大一点，以便更好地说明这一点。让我选择一个有大小星星混合的星场。这看起来不错。好的。这很好地展示了你在130、600和1750之间得到的结果。你可以看到130和600之间有相当大的差异。

We drop a lot of this sort of ugly fringing around the stars and we get a huge sharpness increase because you can see all of these dimmer stars that are basically invisible with the Orion. Now the difference between here and here you can see is much more subtle. The stars are a little bit sharper. But really the big thing that you're paying for is not the the center sharpness getting so much better. But the fact that the corners and full frame are so much better. It's because see here you get the triangle stars here. The corner stars are almost as sharp as they are in center. So that's what's so impressive. And that's why you pay more for a scope like the Asgar.

我们减少了很多围绕星星的丑陋光晕，并且大大提高了图像清晰度，因为现在你能看到那些用猎户座望远镜几乎看不见的暗星。现在你可以看到，差异比这里和这里更微妙。星星变得稍微更清晰了一些。但实际上，你花钱购买的并不是中心部分清晰度的提高，而是角落和全画面的改善。因为你可以看到在这里星星呈现三角形，而角落的星星几乎和中心一样清晰。所以这非常令人印象深刻，这也是为什么你会为像Asgar这样的望远镜支付更多钱的原因。

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