Camera Lens vs Refractor for astrophoto? FIGHT!! 

Bad star shapes? UNFORGIVEABLE!! jk :) My hack to get rid of those blue and red rings on the stars with the Canon 200mm (or other lenses) is to shoot with a mono camera in narrowband, remove the stars from all channels, and then only add back in the Ha stars. All stars become white, but for narrowband (bi-color or SHO) I think it's a nice look. Credit: J-P Metsavainio for this technique.

Great video, nice side by side comparison. This is such a relevant topic in our field and you did a fantastic job in sharing this info. Can't wait to get my L-Extreme filter (on backorder now).

You are answering my questions without even me asking, I can't be lazier!

So many videos in such a short period of time. Another great one for sure but I cannot keep up!! LOL. Keep'em coming. I will catch up eventually.

Hey, firstly amazing video. really helpful. One thing I notices (and you touched on) was the noise in the camera lens image. you mentioned that you got more stills from the telescope, do you think the end result of the camera lens image would be different (less noisy) had you had the same amount of stills for processing the image ?

Camera lenses and refractors was a comparison I was always wondering about. Thanks for answering this question.

Awesome video.. This is the best new upcoming astro photography channel out. You are on the rise for sure. I see you at hundreds of thousands of subscribers like Trevor Jones and all those guys. Clear skies

Excellent! Learned a lot.

Thanks for the vidéo bro, clever and usefull as usual.

Good to know about this Cuiv!

That's a very good comparison. Thank you. I was going to buy a Samyang 135. I guess I should reconsider.

Thanks very much for your videos, which are great. I have a question on camera lens vs refractor that relates to back focus (focal flange length). I purchased a new ZWO mono camera that has 17.5mm between sensor and the edge of the camera (the 2600mm). The filter wheel is 20mm thick. Canon EF lenses require 44mm of back focus, which I understand is less than [most?] telescopes that [typically?] have 55mm of back focus. After the camera and filter wheel combined, I have only 6.5mm until I hit 44mm of back focus. The 6.5mm would not be enough for an adapter that connects to a Canon lens. So, with this new mono camera, am I correct that shooting with a Canon lens is not even an option? Or, is there some workaround that I am unaware of? Thanks for any insights on this.

1 more great vid Cuiv! Also a telescope optics have 2 or 3 or 4 pieces of glass, where as a Canon L lens has 7 or 10 or 14 pieces of glass! This proves that for astrophotography less glass the better and you proved it! All that matters is what you care about.

Hey Cuiv, Great Video's, Could you please do a video explaining the working out of Gain & Offset with OSC Cameras, and also dithering settings to eliminate walking noise. These to subjects are giving me grief with my final images, Many thanks, Keep up the great work !!

Nice video, I wonder if you can do a comparison between a Newtonian vs Refractor of the same price range, and see if one of the resulting image is superior than the other.

Interesting video. I’ve recently been using my 70-200mm f/2.8 for wide field astrophotography. I’ve been using it wide open though. Guess I’ll have to see about stopping it down to f/4.

I did exactly that. Got a 2nd hand 300mm F4 L non IS off ebay (came from Japan!). 350 pounds. Much less than an equivalent 2nd hand refractor and field flattener. I've not used in anger much yet, but glad I'm not the only one that figured that was better value for money for what I need. There is quite a lot of 'you can't possibly take pictures of X without ' on the forums and it's easy to get dejected or sucked in. As you say, I doubt it helps their happiness - enjoy what you see and don't sweat little details!

Hi Cuiv, in your last vid, you mentioned USB - serial converter cables, particularly using the Prolific chipset. I had many problems with that approach (SW EQ 6N Pro) to my laptops - all resolved when I swapped to a cable with the FTDI chipset. I was told of a number of different versions of Prolific chips so it’s worth trying before buying if poss.

Excellent !!!

Nice comparison Cuiv. I use both as well - I guess I don't care about star shapes. It comes down to what you have and what you are comfortable with. I can't believe how many videos you make - certainly not Lazy. Work just started up again so I have very little time for videos and processing right now. - Cheers Kurt

Another great video. Can you just elucidate really more about your back focus. Exactly where are you measuring from. The back of the reducer glass or the edge of the reducer itself. And are you measuring exactly to the sensor in the camera. Thanks again and keep the videos coming. I love my Sharpstar 61 also but had to use an improvised dovetail bar So that I could achieve Dec Balance.

If you have Adobe Lightroom you could can display both images side by side and when you scroll around one the other will follow. It makes the comparison shots easier to see the difference.

Cuiv, Excellent, plain language comparison - good friend has gotten bitten by Astrophotography bug - he’s got a great camera and several lens - this will helpful in his journey. Please share the optical train components you used, including the filter drawer and adapters to connect a DSO camera to a camera lens. Sadly, his camera isn’t one supported by the ASIair Pro. He’s starting with a Panasonic G9 with a 300mm lens on a new/old Atlas EQG mount. Always enjoy you candor and wisdom.

what filter were you using in front of the 533 for the viel ? (Optolong L-Extreme ) lol hey Mitch finish watching the video before asking questions !!! great shot...

Thank you Yannick for this video, much appreciated.

I love your channel, it's funny how we kind of do similar tests although I never had time to create a blog (albeit a few friends insisting !). Anyhow when I saw the title, I nearly took popcorn as it's indeed a long lasting discussion; I even had that discussion with some astronomy clubs and the general agreement is: yeah telescopes are slightly better. So I agree with your message that camera lenses are still fantastic and for any beginner or hiker, that's definitely a great/better solution. The thing that I want to add though is.. are you familiar with MTF charts ? Different camera lenses have hugely different behaviors in terms of chromatic aberration and coma. So it's very difficult to generalize about camera lenses and star shapes. I love my Nikon 35mm f1.8, great color, great contrast but a lot of coma and I have to step it down to F4 so it's nice corner to corner. On the contrary, I also have the Nikon 300mm f2.8 AF-S, a gem in my opinion. It's old so this professional lens is now accessible (~$1000) and It also accepts 52mm filters (hence I love IDAS filters). The lens is much bigger than this canon, but the quality is impeccable across the frame, even at f2.8. At f4 I personally don't see any difference with a telescope and I usually only stop down the lens to show off the sharpness or when using a teleconverter as otherwise coma is starting to show. Speaking of coma, if you don't use a field flattener with a telescope, coma will actually be worse than with camera lenses, it's really terrible, so one more piece of equipment when using a scope. Lastly: triplets. I really love my nikon lens and I tested it side by side with both a triplet 80mm and triplet 102mm. The one thing that I can say is that the difference was not in coma/star shape but more in terms of contrasts and how the colors bumped out on raw images. A triplet is really extraordinary for the rendering of colors and I do believe that no camera lens can perform as good. However with a bit of post processing and play with vibrance/saturation etc, the end results are very close. So once again, yep telescopes (with field flattener) are slightly better than camera lenses but not by far.. and it really depends on which camera lens. Also if you want more than 600mm, you will have to use a scope and probably more a SCT rather than a refractor. Seems like I still need popcorn for that discussion - cheers (ps: I am French too :) ).

I don't understand why there is such controversy around star shapes. I am an older guy, but a n00b though and still impressionable. Anyone care to comment? Great video Cuiv. I learn something all the time here. My trial to Pixinsight ends in November. I'll be purchasing it. Thank you for all you do.

I am also far too lazy to stop down for stars haha. I rarely get clear skies so imaging 400mm at f/2.8 is pretty awesome, I just can't get enough of that sweet sweet light.

Great video and honest analysis, thank you! When I shoot with Canon camera and lenses I usually open the RAW files in Canon's DPP4 software. It applies lens correction algorithms to the image thus minimising the weird effects on star shapes causes by lens imperfections. Then I convert the RAW into TIFF to be stacked and further processed in other software. It is not a complete solution but it seems to help. Have you done that before?

Hi Cuiv!! I got a zwo T2 adaptor to use my sigma 70-300 apo camera lens BUT I dont get how to change f stops, on my dslr its easy you just change it but on my asi 183, how do I? Thanks and clear skies!!

What do you think is a better option Rokinon 135 mm f 2.0 vs new Raptor 61 ??? Thx !!!

I have the Same 200mm Lens. Did your shot at f2.8 of you Close the aperatur?

With regard to focusing a camera lens, I found a nice cheap trick for my Canon 200mm f2.8 lens. Assuming the lens is held by a ring and then mounted on a small dovetail, you can cut a piece of 10mm thick foamboard (around 65mm long) and wide enough to wedge very lightly between the rubber focus ring on the lens and the dovetail (in the case of the Canon 200mm and the official Canon ring, the width is about 23mm). This essentially converts rotational motion of the lens to linear motion of the piece of foamboard. This turn out to be easier to adjust precisely, partly because of the added friction but also because linear motion is easier to control. In addition, the added friction prevents the focus from being inadvertently changed. It's not quite locked like a telescope focuser but it is certainly more secure. If you cut the foamboard too thick, you can squeeze it slightly to make it narrower. A very slight wedge shape is also helpful.

I love it everytime he goes out of his way to say he's in Tokyo. The roof aesthetic is awesome there.

Well done ! I'm impressed with the comments regarding the Sigma ART 135mm. Thanks

Hey Quiv! What kind of holder do you use to mount you astrocamera + canon lens on the mount. This silvery one? Ty!

Star shapes. Phfft, ignore the soon to be trolls. Getting satisfaction from your own pics, priceless. Did you ever do a NINA polar alignment video?

I am surprised there is that level of noise with a cooled camera and stacking. Is that the zwo with the apsc sensor?

What about a Reflector Camera lens? I have an 800mm reflector lens for my Canon.

Many people let perfect get in the way of good enough and never have any fun. Keep having fun.

I recently bought a 75 - 300. Waiting for the possibility of an EQ Goto mount. ;)

Fuck the star shapes lol. Have you tried adding sulphur ii data to the oii and Ha data you get from the l-extreme?

Nice comparison, thanks. How do you know how many step down rings are required to get your lens to f4?

lens require very specific focusing routine .( ie : do not focus on center nor by HFR calculation on the whole image. Each lens has its own area for focusing . it is like a signature and you have to found it by testing .) . It seems that the best lens so far is the Sigma ART 135 mm ( same behavior as a astronomical refractor) . clear sky .

I use my 533 with a 100-400 f/4.5-5.6L Canon lens and with the small chip on the 533 in that big full frame image circle, I have zero problems at the corners because the corners of the sensor are still in the center of the image circle. Of course, that lens costs 3x what the Sharpstar costs, but then I already had it when I took up astrophotography. :) But as far as star sharpness goes, at 300mm the Canon is off the charts. So it might depend on quality of the lens as well.

the ol lextreme filter is a strict 2 color filter. to see all color abberations you should do a lrgb image...

You should match the SNR on both refractive systems ( that will rise the contrast on the Canon Lens image ), also Canon L lenses are not trully apochromatic... you should try a Zeiss Apo sonnar desing against the little Sharpstar , otherwise image will be a lot better on the telescope... thanks for share.

Nice comparison but I think there's one thing that makes the lens seem worse than it is... I have this exact lens and whenever you stop it down from the front, bright stars tend to manifest a lot of halos, plus you were using a duo narrowband filter, better to leave the lens wide open at 2.8 and enjoy those pin point stars

Just come back from a dark sky site and had my scope collimated. Not completely perfect at the edges but so close where I dont care. And I wasnt happy with my guiding, but for some reason I managed to get round enough stars where I wonder if I should care bout it. It seemed to behave well enough that things looked fine in 10 min subs. Sometimes I think we worry about things we shouldnt :)

Oh I do have one question to ask, could you please do a comparison between a one shot colour astro cooled camera and a DSLR on the same target, same mount, some scope/lens if possible? I'm always curious as to how much a difference one can see by upgrading from a DSLR to a OSC Astro camera

There is a mistake. When you close your lens to F/4 you decrease the effective front diameter light collection. So It's normal that you obtain lower SNR than with the 61EDPH. Lens has only the advantage of giving a wider field. After all the light gathered is only a question of overall effective diameter of the telescope. The issue with fast lens is that you are dramatically undersampled. A samyang 135 f/2 will be about 1.5" theorical resolution but even with a small photosite camera (3.8um) you will be on 5.7"/pix. So hugely undersampled.

Just Bought a sharpstar 61edph yersteday ! :)

Did you calibration frames for both?

I use camera lenses, ye crap pics but I still enjoy it.

Camera is still very good

Don't care about star shapes either, after all it's mostly pictures I show my wife and child. However, I feel you did not make it clear what the cost of your rig is (tripod, tracker, etc) as those are obviously required to make the shot.

It also depends on how wealthy you are. :) When you're also a regular photographer, but you don't have unlimited funds, you're probably better off getting a decent multi purpose lens though.

First like!, First comment!

Star shapes, exhausting. I think it's fine for a person to want to improve their images, but getting wildly out of shape over them is no fun for anyone.

This is a bad example for a lens. There are some apochromatic lenses from sigma and they are very good for ap

I have made a custom dovetail with adapted fixing ring from my first newtonian telescope, for a Canon 500mm f4 mark i, the brightest stars do suffer from halos when used with LP filters, besides that the shape of the stars till the corners are spotless if i focus correctly, still on the fense considering the best upgrade route to that kit..