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  • 00:00

    today's video is sponsored by squarespace  this is the new Askar fra 300 pro the fra  

  • 00:07

    in the title of this telescope stands for  flat field refractive astrograph and for  

  • 00:12

    anyone that hasn't heard that term astrograph  it means a telescope specifically designed for  

  • 00:18

    astrophotography rather than for  visual use like with an eyepiece  

  • 00:23

    now we can usually adapt a visual telescope into  one more fitting for astrophotography by adding on  

  • 00:29

    a field corrector like a field flattener if it's a  refractor or a coma corrector if it's a reflector  

  • 00:36

    but if you're designing a telescope from scratch  specifically for astrophotography then it totally  

  • 00:42

    makes more sense to design these flat fielding  correcting last elements right into the design  

  • 00:49

    of the telescope which is why this is a quintuplet  meaning there's five pieces of glass inside the  

  • 00:55

    tube here which of course makes this telescope  fairly heavy for its size but the idea is that  

  • 01:00

    we won't need to buy anything additional with  this telescope to get a flat well-corrected  

  • 01:06

    field for astrophotography and for that reason and  also because they're more of a specialty product  

  • 01:12

    astrographs are typically very expensive but this  one the askar fra 300 pro is very competitively  

  • 01:18

    priced at just 949 us dollars so i thought  it'd be interesting to see how it performs and  

  • 01:25

    in this review i'll be putting this telescope  through its paces and seeing how it stacks up  

  • 01:30

    with another popular small telescope i have  here this is the william optics redcat 51.  

  • 01:36

    hi everyone this is nico carver and this  is a review so first some disclaimers  

  • 01:42

    both uh the askar fra 300 and this redcat 51 were  sent to me free of charge for the purpose of video  

  • 01:49

    reviews the redcat 51 from wo boys which is the  u.s online store for williams optics telescopes  

  • 01:57

    and the askar from askar directly but with  assistance from agena astro products none of  

  • 02:03

    these companies have any input into what i say  into this or any future video on these products  

  • 02:07

    and no money has changed hands these companies  may choose to share my youtube video or my photos  

  • 02:13

    taken with the products on their website or social  media but that's completely up to them throughout  

  • 02:18

    this video i'll be comparing the askar fra 300 to  the william optics redcat51 because i see them as  

  • 02:27

    competitors in that they have fairly similar specs  the redcat is also an astrograph meaning the field  

  • 02:36

    flattening elements are built in it's a quadruplet  it has a front aperture of 51 millimeters a focal  

  • 02:43

    length of 250 millimeters so that gives it a focal  ratio of f 4.9 the askar on the other hand has a  

  • 02:49

    front aperture of 60 millimeters a focal length of  300 millimeters so that gives it a focal ratio of  

  • 02:55

    f5 so f 4.9 versus f5 but this one's a little bit  longer so they're very similar in a lot of ways  

  • 03:04

    you're going to get a slightly different field of  view askar did say they added pro to the end of  

  • 03:10

    this title because this is an f5 scope while their  other fra telescopes the 400 the 500 and the 600  

  • 03:17

    are f5.6 astrographs and that small improvement  is important for uh photographs because that extra  

  • 03:25

    half stop of light means that the photos will  be brighter faster and that's why focal ratio  

  • 03:32

    is sometimes referred to as photographic speed  especially if you come from the world of lenses  

  • 03:39

    and it means that with a faster telescope one  with a smaller f number which remember is a  

  • 03:44

    ratio you can take shorter exposures but it also  means your signal-to-noise ratio will be better  

  • 03:51

    compared to a slower scope if we're talking the  same total integration okay on to the comparisons  

  • 03:57

    in terms of weight with a vixen plate a ring  and a top handle installed the red cat weighs  

  • 04:03

    1.8 kilograms or just over 4 pounds while the fra  300 weighs 3.4 kilograms or 6 pounds 11 ounces the  

  • 04:12

    red cap package includes a soft carry case but  no top handle for a guide scope if you do want  

  • 04:19

    a top handle it costs 50 extra dollars the fra  300 does not include a carry case but is well  

  • 04:26

    equipped otherwise because it has both a top  handle and a synta style finder shoe attachment  

  • 04:34

    and so for astrophotography i think most people  would put the guide scope on up top here something  

  • 04:41

    like this and then with this finder shoe maybe  put like an asi air or something like that or a  

  • 04:49

    power bank something that would be useful right  there for all the cable connections in terms of  

  • 04:55

    focusers the askar has this more traditional uh  2.5 inch rack and pinion design focuser with a  

  • 05:03

    single speed knob on this side and a double speed  knob on the other side this red knob here is a 10  

  • 05:10

    to 1 reduction which is very nice if you manually  focus like i have been with these telescopes  

  • 05:18

    if you do want to add an autofocuser the bottom  has mounting holes already for adding something  

  • 05:24

    like a zwo electronic autofocus or eaf if you want  to add auto focusing to the red cat with the zwo  

  • 05:32

    af you'll need to buy a pulley system i have  this excellent one sent to me by deep sky dad  

  • 05:38

    and the reason you need a pulley system is because  the red cat has a helical focuser like this like  

  • 05:46

    your camera lens i have heard that in version two  of the red cat that it's slightly different that  

  • 05:52

    this front element doesn't go in and out when you  move the focus ring but that it is still a helical  

  • 05:59

    focuser both telescopes have a locking device for  locking the focus this one right here this one  

  • 06:08

    underneath as well as a knob for manual rotation  which is very handy on the red cat it's right here  

  • 06:16

    and on the fra it's right there and i love  having a little locking mechanism for a  

  • 06:23

    manual rotator it's much better than having  to like rotate the whole telescope in its ring  

  • 06:28

    um it's much handier and works much better and  i'm really big into picking my rotation angle so  

  • 06:36

    that's a really good feature of both telescopes  in terms of mounts for these telescopes if you're  

  • 06:42

    pairing them with a lightweight dslr or mirrorless  camera or one shot color astronomy camera i think  

  • 06:49

    you could go with basically any uh mount including  this new sky watcher star adventure gti uh if  

  • 06:57

    you're using a mono camera with filter wheel like  i have here the red cat would be the safer bet  

  • 07:04

    because you'd be well under the weight limit of  the gti but it actually amused me that the fra  

  • 07:09

    300 with this qhy 533m and a full filter wheel  this kit that i have exactly right here put me  

  • 07:16

    right at the payload limit of five kilograms for  the gti so i actually haven't had a chance to try  

  • 07:22

    out this exact combo yet but i intend to because  i actually think this would be a really awesome  

  • 07:29

    lightweight sort of travel setup before i show  some various photo results and star tests done  

  • 07:35

    with both telescopes i'd like to tell you about  the sponsor for today's video which is squarespace  

  • 07:43

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  • 07:51

    process of setting up websites before and i  can tell you that squarespace just makes it all  

  • 07:59

    so much easier than what i had to do before it's  actually so easy to use squarespace's site builder  

  • 08:05

    and professional portfolios that i put  together my revamped nicocarver.com  

  • 08:13

    website from scratch in under an hour and i just i  love how it looks it i think it looks very elegant  

  • 08:20

    and it was just so easy that i got it done  so whether you're a photographer wanting to  

  • 08:25

    have your own beautiful portfolio  with your own domain name like me  

  • 08:29

    or a small business wanting to sell basically  anything online services products digital products  

  • 08:37

    squarespace has you covered and you can use the  link in the description which is squarespace.com  

  • 08:42

    nebula photos to get your free trial and if  you like what you see with squarespace which  

  • 08:49

    i think you will use the code nebula  photos for 10 off your first purchase  

  • 08:54

    so next up is what i'm sure many of you really  want to see which is how do these scopes compare  

  • 09:01

    when it comes to a star field and a full-frame  camera so i shot a three minute guided  

  • 09:09

    exposure with match settings on the canon eos  ra on both telescopes on the same object which  

  • 09:14

    is the blue horse head nebula here and i shot  uh this within like a 10 minute window so there  

  • 09:21

    wasn't much time between these two exposures so i  think it's a pretty fair comparison on the stars  

  • 09:28

    and this is the full field with the redcat this  on the right is the full field with the fra  

  • 09:34

    300 and the first thing you'll probably notice is  that it's a different crop or you know or it's a  

  • 09:39

    different field of view i should say uh the fra  300 is a little bit tighter in than the red cat  

  • 09:46

    but that's understandable since the red cat has  a focal length of 250 and the fra 300 it's 300  

  • 09:52

    millimeters the other thing that really stands out  from just a single exposure that's not calibrated  

  • 09:59

    is that the red cat has pretty significant fall  off vignetting in the corners while it's pretty  

  • 10:08

    well illuminated in the fra300 so you can  see that's pretty noticeable fall off here  

  • 10:16

    while on the fra 300 you can see it gets  a little darker in the corners but not  

  • 10:21

    not as bad but that fall off in the corner is  not really going to impact your astrophotography  

  • 10:29

    that much unless you don't shoot flats but i  always shoot flats and so after full calibration  

  • 10:37

    of these two frames they look quite different like  this and so you can see here now they're looking  

  • 10:45

    a little bit more similar both very flat and  i don't you know i've looked at the corners  

  • 10:53

    and i know that the theory is that you're going  to have much worse signal-to-noise ratio when  

  • 11:00

    you have that much light fall off but i don't  know i've looked in the corners of these  

  • 11:04

    shots and i don't really see a huge difference  in the noise at least visually so that gives  

  • 11:11

    you a sense of that next up let's look at some  stars really zoomed in so for this i'm going to

  • 11:20

    go into image analysis

  • 11:25

    aberration inspector

  • 11:29

    and run this on both shots here okay and  there we go and at first glance to my eye  

  • 11:38

    i mean these both look quite good i don't really  see you know glaring uh problems with the stars  

  • 11:48

    but let's go ahead and zoom in on the center  here okay um you know they're both what we call  

  • 11:56

    under sampled so it was zoomed in this far this  is probably like 400 zoom you can see a little  

  • 12:01

    bit of uh blockiness to the stars like they're  not you could you start to get a little bit of  

  • 12:06

    pixelation or whatever um but they they both look  fine i don't see a huge difference in sharpness um  

  • 12:16

    let's look at the corners now okay so

  • 12:21

    this left upper left corner i can think i can  see just a little bit more chromatic aberration  

  • 12:28

    a little bit of like red separation on that star  um but unfortunately these aren't like perfectly  

  • 12:36

    matched fields so i don't uh have that same star  here to compare like a big star right on the edge  

  • 12:46

    uh so i don't know if that's the best comparison  but i think i see a little bit of red fringe  

  • 12:52

    there while on the red cat stars i don't really  see much of anything now i mean this level of  

  • 13:02

    chromatic aberration wouldn't bother me  i don't think but it might bother some  

  • 13:06

    people so i just that's why i'm noting it yeah  and i think you know here let's see if there's a

  • 13:13

    okay so here's a fairly good test like that's a  bright star fairly close to the edge there's a  

  • 13:19

    bright star fairly close to the edge and i i  still feel like i see just a little bit more  

  • 13:23

    of that like blue and red um separation here  with the ascar than i do with the red cat  

  • 13:35

    but let's keep looking so in this corner this is  the bottom right corner the star shapes look a  

  • 13:43

    little bit um off on the red cat and a little bit  more circular a little bit more round on the ascar  

  • 13:53

    there could be a tilt issue there so it might not  be the optics fault let's go to the upper right  

  • 14:01

    corner yeah same thing in the upper right  corner a little bit not as extreme as that  

  • 14:07

    that bottom right corner but in the upper  right corner i see a little bit more um

  • 14:16

    malformed stars on the red cat that i do  on the ascar i think but you know what this  

  • 14:24

    is all sort of nitpicking because i think all  of these stars look very good um i'm you know  

  • 14:32

    i'm suitably impressed that these are 250 and 300  millimeter focal length on full-frame camera that  

  • 14:43

    i think these are both quite impressive uh for  you know scopes that are under a thousand dollars  

  • 14:49

    i don't i don't know what other people think  but uh for me this this is a very impressive  

  • 14:53

    performance uh to wrap up here i i haven't had  the best luck with weather with this scope yet  

  • 14:59

    um but i did get this finished image done here  at home in somerville this is with the qhy 533  

  • 15:08

    m mono camera and a hydrogen alpha filter  and an oxygen three filter and it's just  

  • 15:14

    eight uh exposures with the h a filter and five  exposures with the o3 filter so not a lot of data  

  • 15:20

    um but it just i think it shows you the potential  of pairing the fra 300 with the 533m uh it's an  

  • 15:30

    interesting combination i think i think a good  combination of gear i i just think this this  

  • 15:37

    field of view 300 millimeters with that one-inch  square sensor is going to work well for a lot  

  • 15:44

    of these sort of nebula scenes like the jellyfish  here with the extended uh nebulosity and the two  

  • 15:51

    bright stars in in gemini and uh you can see that  i don't see any issues with you know star haloing  

  • 16:01

    or anything like that with that's with this setup  so uh hopefully this review of the askar fra 300  

  • 16:11

    was helpful and if you have any questions  you can always leave them in the comments  

  • 16:17

    and i'll try to answer them all until next  time this has been nico carver clear skies

All

The example sentences of EXPOSURES in videos (15 in total of 63)

they personal pronoun include verb, non-3rd person singular present the determiner number noun, singular or mass of preposition or subordinating conjunction drug noun, singular or mass exposures noun, plural , taking verb, gerund or present participle drugs noun, plural without preposition or subordinating conjunction a determiner good adverb set verb, past participle or coordinating conjunction setting verb, gerund or present participle ,
eight cardinal number uh interjection exposures noun, plural with preposition or subordinating conjunction the determiner h proper noun, singular a determiner filter noun, singular or mass and coordinating conjunction five cardinal number exposures noun, plural with preposition or subordinating conjunction the determiner o proper noun, singular 3 cardinal number filter noun, singular or mass so adverb not adverb a determiner lot noun, singular or mass of preposition or subordinating conjunction data noun, plural
exposures noun, plural must modal be verb, base form much adjective longer adverb to to gather verb, base form enough adjective light noun, singular or mass but coordinating conjunction then adverb the determiner speed noun, singular or mass of preposition or subordinating conjunction the determiner
our possessive pronoun materials noun, plural also adverb have verb, non-3rd person singular present a determiner variety noun, singular or mass of preposition or subordinating conjunction interior adjective and coordinating conjunction exterior noun, singular or mass exposures noun, plural and coordinating conjunction a determiner precise adjective location noun, singular or mass
consequential adjective photos noun, plural at preposition or subordinating conjunction different adjective exposures noun, plural , in preposition or subordinating conjunction order noun, singular or mass to to combine verb, base form them personal pronoun as preposition or subordinating conjunction an determiner hdr proper noun, singular in preposition or subordinating conjunction post noun, singular or mass
light noun, singular or mass with preposition or subordinating conjunction the determiner camera noun, singular or mass this determiner is verb, 3rd person singular present just adverb under preposition or subordinating conjunction an determiner hour noun, singular or mass just adverb about preposition or subordinating conjunction thirty noun, singular or mass sub noun, singular or mass exposures noun, plural
the determiner exposures noun, plural i personal pronoun just adverb made verb, past tense at preposition or subordinating conjunction 140 cardinal number at preposition or subordinating conjunction 2 cardinal number minutes noun, plural are verb, non-3rd person singular present completely adverb noise noun, singular or mass free adjective .
this determiner caused verb, past participle the determiner surface noun, singular or mass exposures noun, plural which wh-determiner resulted verb, past tense from preposition or subordinating conjunction the determiner impact noun, singular or mass event noun, singular or mass to to partially adverb shift verb, base form into preposition or subordinating conjunction
if preposition or subordinating conjunction you personal pronoun have verb, non-3rd person singular present other adjective risk noun, singular or mass factors noun, plural like preposition or subordinating conjunction having verb, gerund or present participle a determiner history noun, singular or mass of preposition or subordinating conjunction certain adjective exposures noun, plural certain adjective illnesses noun, plural
where wh-adverb it personal pronoun 's verb, 3rd person singular present using verb, gerund or present participle multiple adjective exposures noun, plural and coordinating conjunction a determiner lot noun, singular or mass of preposition or subordinating conjunction what wh-pronoun the determiner pixels noun, plural magic noun, singular or mass is verb, 3rd person singular present is verb, 3rd person singular present
when wh-adverb niosh proper noun, singular evaluates verb, 3rd person singular present possible adjective hazards noun, plural in preposition or subordinating conjunction a determiner workplace noun, singular or mass , we personal pronoun use verb, non-3rd person singular present samplers noun, plural to to measure verb, base form workplace noun, singular or mass exposures noun, plural .
samsung proper noun, singular tends verb, 3rd person singular present to to brighten verb, base form exposures noun, plural , especially adverb when wh-adverb there existential there is verb, 3rd person singular present a determiner person noun, singular or mass in preposition or subordinating conjunction frame noun, singular or mass , but coordinating conjunction i personal pronoun m proper noun, singular
you're proper noun, singular gonna proper noun, singular get verb, non-3rd person singular present about preposition or subordinating conjunction 12 cardinal number exposures noun, plural per preposition or subordinating conjunction roll noun, singular or mass , and coordinating conjunction there existential there 's verb, 3rd person singular present no determiner meter noun, singular or mass , so adverb be verb, base form prepared verb, past participle .
it personal pronoun might modal use verb, base form the determiner hdr proper noun, singular option noun, singular or mass , combining verb, gerund or present participle several adjective shots noun, plural with preposition or subordinating conjunction varying verb, gerund or present participle exposures noun, plural into preposition or subordinating conjunction one cardinal number ideally adverb
exposures noun, plural that wh-determiner may modal have verb, base form - - and coordinating conjunction we personal pronoun can modal look verb, base form at preposition or subordinating conjunction multiple adjective exposures noun, plural - - that wh-determiner may modal have verb, base form led verb, past participle to to the determiner condition noun, singular or mass in preposition or subordinating conjunction this determiner case noun, singular or mass of preposition or subordinating conjunction green adjective hair noun, singular or mass and coordinating conjunction

Use "exposures" in a sentence | "exposures" example sentences

How to use "exposures" in a sentence?

  • Thirty-six satisfactory exposures on a roll means a photographer is not trying anything new
    -Freeman Patterson-

Definition and meaning of EXPOSURES

What does "exposures mean?"

/ikˈspōZHər/

noun
state of being exposed to something harmful.
other
States of experiencing some things directly.

What are synonyms of "exposures"?
Some common synonyms of "exposures" are:
  • subjection,
  • submission,
  • vulnerability,

You can find detailed definitions of them on this page.