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That’s exactly why I’m doing these reviews, give people the info they need before shelling out the $$$

Yeah, it’s too bad the cost is so high for astrophotographers. Albeit, the astigmatism will degrade image quality in daytime use as well. Oh well, like you said, can’t win them all

So there’s a small misunderstanding here that I can clear up, which will be good news. For Canon full frame DSLRs, the only way for a clip-in filter (from Astronomik or any other brand) to work is to be inserted into the mirror box which ends up holding the mirror up. This prevents one from using the optical viewfinder, which I think is what Astronomik was referring to. Focusing needs to be done in live view. However, as soon as you are done focusing you can switch off Live View and take your photos normally. The mirror being held out of the way does not affect the taking of photos in this case, since you aren’t using the optical viewfinder.

@@FerventAstronomy thanks so much....your video helps me a lot.... i did the astromodification by myself and when i saw the lights in my pictures i thought i had broken the sensor and then i bought another one....and with the second sensor on the camera i thought again i broke the sensor one more time.....thanks to you and to your video i havent bought a third sensor....

Well, I am at least glad that I was able to help before you ended up with a third sensor!

The product that I use (in part because my shop stocks it) is the William Optics Diffraction Spikes Bahtinov Mask. They have distribution in most parts of the world, so if you don’t have a dealer in your specific locale it’s likely that you have one within a reasonable shipping distance. Edit: it comes in various sizes, I believe there’s currently 4 to choose from, with adjustable collets to fit basically any optic.

👍 Same concept, clear Bahtinov mask with etching, albeit the WO variety are designed around sizing for larger optics due to the fact that they make telescopes. They also have cutouts which I believe accentuates the diffraction spikes, but I’ve never side-by-sided things to know if there’s a real difference. Honestly you can probably just hold the Lonely Speck product in front of the 14mm lens while you focus, it’s not critical that they be mounted to the lens, nor edge to edge (more convenient though). With a bright enough object like Jupiter you should have no problem seeing the diffraction spikes, they showed up fine even when I used the Bahtinov mask from my RedCat 51 on the 10mm Laowa lens.

@@FerventAstronomy Thanks. I can order it online. However, I might try the Lonely Speck Sharpstar first as I have a 100mm square filter holder which attaches to a 82mm thread diameter, so I won't even have to use a stepdown ring. The sharpstar comes in 100mm square filter with laser etching forming a very tight set of lines. I will be able to use that on any of my other lens that have filter threads. Unfortunately, I won't be able to use it on the Sigma 14mm f/1.4 I just purchased. But trying to use a Bahtinov on a 14mm might be rather difficult anyway, though Ian Norman claims you can with his product.

@@FerventAstronomy Just tried my Nisi filter holder on the Sigma 40mm...fits perfect. Then I tried holding one of my 100mm square ND filters in front of the Sigma 14mm f/1.4. Yeah, it does cover it...with almost no overlap, but hey, if it works, it works. Worth a shot. Nisi makes a 150mm filter holder that will fit the new Sigma 14mm, but it costs a small forture. Lonely Speck makes a 150mm version of their sharpstar. However, it would be so much cheaper if I can get the 100mm square version to work on both Sigma lenses.

@@evenhandedcommentor6102 holding the lonely speck filter in front of the lens gets my vote. If you end up wanting something you can mount to the lens, then the WO mask for ~$50 is by far a better solution than spending hundreds on a 150mm holder and 150mm LS mask.

Thanks much! This has a fairly clear explanation: Lenses designed for digital cameras are designed around the fact that there is a set of filters in front of the sensor, filters that in your modded camera are now different. While you might not expect it to have much of an effect given that it’s just thin glass, there are situations where their refractive index comes into play. Namely, fast wide angle lenses. Something like Sony’s 14mm F1.8 is designed to factor in the refractive index of the sensor filters in Sony’s cameras. Those filters are actually part of the lens’ optical formula. Nikon Z cameras have a thinner filter stack from what I understand, but normally that’s not a significant enough difference to cause an issue. Given the modded nature of your camera however, it’s likely that whatever filter situation you’re using is the culprit. If you can expand on how the mod was done and what if any replacement or clip in filters you’re using I can provide some suggestions.

@@FerventAstronomy gotcha! I didn't know the differences of the sensor filter could effect the image quality. So this is good to know! My Nikon Z6 II is modified by Spencer's camera. From what I understand is he took out all the factory filters and replaced them with his visible + Ha spectrum filter

@@leezheng8161 I hear you. I'm not sure what filter thickness he uses, but I'm going to imagine that it's somewhat less substantial than the OEM Sony filter stack. I can't guarantee it, but it's likely that adding a clear glass filter between the lens and the sensor will improve the situation, albeit I can't say by how much. If you're game to spend some scratch on a potential fix, then I would recommend trying a magnetic clip-in filter from Kolari Vision. The "Kolari clear" is optically clear glass so it won't filter out any wavelengths, but it'll add a little more refraction back into the system and that might do the trick. Plus, it's only 80 bucks so it's not too painful of an experiment, and it's reversible so if you have any lenses that prefer a thinner filter stack you can just pop it out.

@@FerventAstronomy gotcha! Good to know. I will definitely look it up. Thank you very much for your suggestion and explaining everything! I appreciate it.

My pleasure, it’s literally why I’m doing these reviews!

Thanks for the comment! Expanding on a couple of things: Some of what is commonly thought of as de-centering is often irregularities in field curvature due to either variation in the production (grinding or molding) of an element or a misalignment of its tilt. In this case, I’d wager the top right hand corner actually has less field curvature than the rest, at the cost of more noticeable tangential astigmatism. The fact that the sagittal astigmatism is worse in the right hand corner supports the theory that it’s more in focus. As far as DSLR lenses on Sony cameras, the physical flange distance will have been compensated for in this case as it’s the “built for Sony” version and not adapted. But what I can’t guarantee is that the refractive index of the sensor’s filters has been taken into account by Sigma. Sony’s filter stack tends to be on the thicker side, which gives it a higher level of refraction compared to most thinner stacks like, say, Nikon Z. This usually manifests as an issue only when using wider angle lenses built for a really short flange distance where the light comes in at a steep angle. It’s a problem when using an astro modified Sony camera with Sony’s own ultra-wides, for example, as the refractive index of the sensor filters is actually built into the lens’ optical formula. Or it can be an issue using stock cameras when adapting vintage rangefinder lenses as those lenses were designed to be really close to the film plane, and film has no sensor filters! In this case, being a DSLR lens, the optical formula was probably designed for Canon EF mount primarily. But that means quite a loooong flange, which precludes the possibility of a steep angle for the light to travel. I’m inclined to think it’s not going to be an issue, but I suppose I might want to start taking a parallel set of samples with a modded camera from now on to elucidate any of these effects. If I get a chance to test this lens in this way before finding it a new home I’ll try to remember to report back. Cheers!

Thanks, Alan! The cause of the aberration had been vexing me, and I was elated when I was out shooting one night with @AbdurAstro and he pointed me to a post on Cloudy Nights that touched on it. There’s something so satisfying about finally finding the answer to a mystery. Re: the lens - gotta be honest, wishing this one had lived up to the hype, haha

I have a Canon EF version and it's awesome

@MrJcalais glad to hear it! What camera do you pair it with, pray tell?

@@FerventAstronomy Good old Canon 6d

@MrJcalais Ah! One of my old loves! Still such a workhorse for so many people. Definitely a good pairing for this lens.

Welcome to the world of DIY modding! I think that’s the best way to go about things: older camera as your first victim lol

It’s a unique lens for sure! Luckily, there’s nothing to worry about with the tracking, I wouldn’t have included trailed images, as can be seen with the samples used. As it turns out (thankfully) the wider your field of view the more resilient an optic is to any shake, trailing, etc. It becomes more of an issue (more noticeable) the more telephoto you get, so you’d actually notice shake (or just regular star trails) more at 24mm than at 10mm given the same input: either the same shake or the same untracked exposure time. That’s one of the reasons why it’s not really necessary to track when using extreme wide angle lenses, but I do it to ensure good exposure and zero trailing so that we can clearly assess the true unspoiled performance of any given optic!

I'm afraid not, albeit as a lens designed for full frame with somewhat sub-par performance it's not a huge loss. MFT is tough when it comes to fast ultrawides, but there are at least two options that can provide F2.8 apertures at reasonably wide fields of view: the Leica DG 8-18mm f2.8-4 will give you a decently wide FOV at 8mm, and the Olympus 7-14mm f2.8 Pro even more so. There may be others but I'm not as in tune with the system. Given that both are older optics, there's a decent chance that one can be found used for a reasonable price.

I’m always a fan of trying what you have first!

Hah! Well I hope you enjoy it!

@FerventAstronomy I am going to try it with a tracker.

Clear skies!

Just think of all the money you’re SAVING by not buying the AF version! 😜

It’s a little bit of both, but stopping down will fundamentally change many aberrations due to the knock-on effects of increasing the collimation of the light you’re letting in. With astigmatism, when the shape changes it is actually changing the pattern picked up by the sensor, but you’re correct that decreasing exposure value will hide some of the fainter parts of said astigmatism. It’ll vary by lens. If you’re curious about any given lens you can always download the samples and check for yourself to see if the results are acceptable to you!

😂

No doubt, eh?

Hmm, that’s a tough situation if you’re using an EF-S camera. It’s virtually impossible to find an astro-appropriate ultrawide for Canon APS-C cameras, especially one with such a high resolution sensor. One option might be to look for a Tokina 11-16mm F2.8. It’s rubbish on the edges and corners, but if you down sample your images it might help mask some of the aberrations. From experience I can tell you that unless your modded camera’s sensor was re-adjusted to make up for the change in refractive index that you’re going to have trouble getting most wide angle lenses into focus. If you’re going the Samyang/Rokinon 14mm f2.8 route you’ll end up with a ~22mm equivalent field of view, which isn’t too bad, but if you’re really hoping for capital W wide angle then it does leave something to be desired.

Honestly, the best thing would be to save for a Sigma 18-35mm, if that is wide enough for you, or Tokina 11-16mm or 11-20mm

The Sigma 18-35mm F1.8 is a good suggestion for speed, albeit it does edge close to a 30mm equivalent FOV

@@FerventAstronomy Thanks guys!!

@@matej.mlakar Great recommendations, I'll look into all of them!!

I suppose it makes sense, as they advertise the lens as having low distortion. That’s typically their schtick. I’m definitely curious to see how (in)consistent the performance may be, feel free to send me a sample if you do take it out one night!

some tested the distortion is like 0.1%, so it is not going to help anything

Indeed, not surprising since it’s a “D-dreamer” It’s just unfortunate as distortion isn’t really as relevant for astro as things like astigmatism

Quick update: so far I had 50kt winds and solid 200% cloud cover while chasing auroras in Iceland…

Oof, that’s rough 😅

That’s the confusing thing, it appears to be their first crack at this focal length and aperture.

Yes, link in the description

Indeed they did! I have the Pentax and Nikon V2 adapters from Monster Adapter, and they work pretty well. I’m sure the same is true of the Vectis adapter

That's great to hear! Outreach is so important, and that's a very inventive use for that lens. I might have to try something similar.

Glad you're finding them useful. I've left IG behind for a number of reasons, so I'm glad you found me here on YT!

Happy to help!

Cheers, Alan. Yeah, nothing pops the hype bubble like the stars, hah! The field curvature and astigmatism cast a bit of doubt for me about its claimed corner performance in non-astro applications, but such is the state of lens marketing these days. I still need to get my hands on Canon’s RF 135 and Nikon’s Plena, then I think I’ll have exhausted this focal length. Unless Sigma graces the market with a mirrorless successor to its old 135.

Yeah, Astro performance is seldom top of mind for manufacturers it seems

You're welcome, glad you found it useful!

It’s too bad eh?

Cheers! Glad you found it worth your time!

con mucho gusto 😄

definitely not much of a splash for astro lol

Zed club!

Aww, thanks for the kind words! My goal is to fill an information gap for people, in admittedly a niche topic, so I don’t foresee the channel becoming huge. It’s kinda unfortunate though, since being small makes it hard for people to find the information. I’m hoping if I just keep doing my stuff it’ll work itself out

Glad it saved you some disappointment! As far as those Samyang lenses go I don’t have personal experience, but I know a lot of people use the 14mm.

Thanks for the kind words! It's a bit disappointing to hear that I'm not showing up in the results, but TH-cam is as TH-cam does. At least you found me! haha

good to know, didnt try that!

I have both, and ultimately they each have their own strengths and trade-offs. As I’ve reviewed them both, you can download samples from each off my website and let that help guide your decision. If you’re travelling then you’d probably enjoy the Sony’s more compact nature.

Well, after testing I can unfortunately confirm there is an IR source inside the lens for some blasted reason. Guess I have a new metric that I'll have to add to my testing regimen.

Thank you for the follow up!

@@bukcity9790 glad I could help, wish the results were better tho!

@@FerventAstronomy Can you elaborate on what you saw as far as an IR light leak? I just used this lens under dark skies on an astro modded A7RV and found that I was getting a glow in the bottom left corner when stacking a bunch of frames, but that went away with the use of dark frames. Is this the same issue you encountered. Thanks so much for all these reviews; they are really well done and informative.

@astrotennessee I can’t recall offhand where it was and how bad it was, but the best way to see for yourself is to crank your ISO up to 12800 -ish, and take a 30 or 60 second dark frame with the lens cap on. IR leak won’t usually stack out unless your frame shifts significantly from shot to shot.

As Bill writes in the explainer text below the graph: “These raw values are not appropriate for comparing camera models because they are not adjusted for gain or area.” One way to think about it is that while all cameras use the same units on the X-axis (ISO), what’s being measured on the Y-axis is not scaled the same between different cameras. The graph isn’t representing the amount of read noise as compared to a standard scale, rather it’s showing the amount of read noise at any given ISO relative to any other ISO within the same camera. Does that help?

@FerventAstronomy Yes, but I'll have to look into it some more.

👍 I recommend reading about analog to digital converters (ADC) and Digital Numbers (DN), that should put you in the right area.

I think that would be a medium to dark Bortle 3, albeit that's directly overhead as there are light domes on the horizons. Thanks for watching, I hope the review helps with your decision.

@ it did, thank you. I’m going to buy it.

Yeah, it's a total bummer. My local astronomy club has made some strides in getting some light pollution under control at various areas locally over the years. In all cases the thing that makes a difference is convincing the decision makers that it's in their own personal interests to tamp down the lights. This spot might be one convincing conversation away from meaningful change, its hard to know.

It’s definitely a boon across the board for astro work. I’m glad they reworked it

No pinched optics here, in fact I’m not quite sure which aberration you’re referring to? Pinched optics necessitate pinching, which in a telescope occurs if a compression force is placed on a lens element, typically due to over-tightening of the set screws which hold the given element in place. As there are often a set of three screws used, the corresponding aberration will exhibit a 3-lobed pattern that is geometrically aligned with the locations of the screws, whereas most other aberrations (such as astigmatism) are almost always oriented relative to the optical axis. As the elements in your typical consumer lens are mounted quite differently, pinching isn’t really something you’re likely to come across (I certainly never have). The closest aberration that I can think of that might demonstrate a visual similarity to pinched optics is called aperture vignetting, and it’s something I’m looking forward to doing an explainer on. It’s the in-focus manifestation of what people experience as “cat’s-eye-bokeh” on specular highlights with conventional photography, but it’s a bi-polar aberration and not a tri-polar aberration like pinched optics.

I don't understand what the goal of your comment is. Can you explain?

Yeah, I'm with Lindon, I also don't know how to interpret this commentary.

@@FerventAstronomy I think he's saying that $1800 is a lot of money. It's all relative. Look up the Canon RF 600mm f/4 L IS USM lens.

@@javaman4584 That gets at one reason why it doesn't make sense: $1800 *isn't* a lot of money for a mid-range telephoto zoom. A 600mm F4 like you mentioned is more akin to the Bentley, although I would suggest the EF 1200mm F5.6 is more accurately Bentley territory. The 200-600mm is more like a Toyota Corolla, which (ironically) costs almost double what a 600mm F4 costs. But the crux of it is that the original comment wasn't really constructive. I love chatting with folks in the comments, but I'm not fond of the drive-by nonsense some people leave me.

OK I managed to re-create your issue: If I open in lightroom and crank the clarity I also get a square. This only happens in a single exposure and not in a HDR merge. Not sure 100% what is going on as I don't see the issue through other manipulations

Yep, cranking the clarity is what's "causing" the issue, but there's definitely something in the way that Lightroom is debayering the file that seems to be linked to the artifacts. The clarity is the magic that really brings out the field lines though haha. Haven't tried Pixinsight, the price has always scared me away given the CAD exchange rate, but I might give Siril a try. I tried Capture One and Darktable, couldnt get the same detail with C1 and Darktable was just a usability disaster so I gave up on it.

@@FerventAstronomy if you want top tier astro you need pixinsight and BlurX + StarX. Unfortunately it's $500-600 for really specialized software but it really is next level.

I’m glad it’s got you out there experiencing the sky!

I have not enjoyed the STC duo for wide angle stuff due to Oiii vignetting and star halos (admittedly using it at f2.0). Any issues with it at 600mm 6.3?

@@matthewholt7858 the halos around bright stars are very strong at 600mm too unfortunately. But it depends on the subject. There are no halos in the image of the Rosette Nebula for example, because there are no bright stars in that area.