Should i buy 200mm or 300mm lens?

[TheDadure]

Hi guys,

This christmas i planned to buy a portable and not that expensive tracker for my dslr,and after some research i found sky watcher star adventurer(big version,not mini) is available in my country,so i don't need to order it on amazon.

I am not exactly new in astronomy nor astrophotography,i have 8 inch dobsonian and canon EOS 1300d(t6) with kit lens and 50mm f1.8 and i took some milky way and andromeda shots on a tripod but they were not that good because of low focal lenght and short exposures.

I am pretty tight on budget so if i buy star adventurer i have 200 bucks left.I looked online and found that tair 3 300mm f4.5 and SMC takumar 200mm f4 are pretty good and cheap so they fit in my budget when i add the cost of shipping .I also found some zoom lenses which i taught were good,but on some other forums they say the zoom lenses are bad for astrophotography unles they are 600$ or more.

So what do you guys think is tracker good enough,should i buy 200mm lens or 300mm lens considering my crop sensor,which one is better for astrophotography(they are pretty much the same price) and which one will better fit my setup.

I decided to buy star adventurer because it is portable,for the same price i could buy neq3(motorized) but it is too heavy for me and my friend to bring it outside the city where we take pictures(we don't have a car and have only a moped).

I should also point that maybe,but just maybe i will sometimes in the future buy a small apo refractor , so can it be mounted on star adventurer?

I am going to take pictures of nebulas,galaxies,comets... with this lens and maybe just for fun some small nebulas like m57.

Considering everything i wrote,what lens do you thinks is better for me,i dont really need something for wide field for that i have other 2 lenses.It is pretty hard desicion,300mm has better focal lenght but it is heavier and i do not know how long my exposures will be with it.

I looked everywhere but could not find good answers for my questions.

That'it guys,sorry if i the post was too long or my english is bad(it is not my first language).

Clear skies!!!

[catburglar]

Out of the two you mention, I think I’d probably go for the 200mm. The shorter focal length will be more tolerant of tracking /polar alignment errors meaning that you get more good frames to stack in your final image. If you plan to add guiding to the setup in the near future then the 300mm might be a better bet, but guiding adds complexity and kit that would tend to limit portability- if that’s important to you. 

You may also want to consider a Rokinon/Samyang 135mm ED F2- I’m not sure if you’ll get one within budget, but it’s a good lens to start out with.

Just one word about your choice of targets- most planetary nebulae and galaxies will be too small for either of these lenses to give great images. There are plenty of targets in the winter sky that will suit these shortish focal lengths including M31, M42, M45, Rosette Nebula for starters.

[TheDadure]

Thanks man, i will consider your lens too,and thanks for advice on objects.

Will m57 will be any visible with these lenses and what do you think about sigma 70-300mm apo lens?

 

[ollypenrice]

I agree with Catburglar and for the same reasons.

I would also forget the term 'crop sensor' when thinking about astrophotography. It leads some people into the mistaken belief that a crop sensor effectively extends the focal length when it absolutely does not do so.

It's a good idea to focus on a star located at one of the four intersections of the one third lines, by the way. This will give you the best compromise focus across the chip.

Olly

[gorann]

Whatever you do stay out of zoom lenses. Even those that costs more than 600 USD, like the Sigma APO 70-200 mm f/2.8 APO that I have give terrible stars in the corners, so it is only usable for daytime photography. Takumars are among the better cheap lenses that you can get used. I paied 100 USD for my Takumar 200 f/4 on ebay three years ago. Here are two links but I seem to remeber that I once also found an extensive review of the old cheap lenses but I cannot find it right now.

https://www.cloudynights.com/articles/cat/articles/the-best-telephoto-lenses-for-astrophotography-r2993

http://www.astropix.com/html/i_astrop/lenses.html

[TheDadure]

Thank for your advice guys i really appreciate it.

Just if someone can tell me which lens is better overall(in terms of optics) it would be great.

 

 

 

[catburglar]

I think the Rokinon 135mm is  likely to be a better lens than the Super Takunar 200. But what’s best for you may depend on a couple of different factors....cost and field of view. I’ve attached a couple of images I’ve taken with the EOS1300 and Rokinon 135mm. (I’ve still got a lot to learn), but I was quite pleased with them. I find it quite tricky to get rid of all the vignetting with flats, but because the short FL and wide FoV it means you’ve got  a little bit of scope to crop the image.

The 200mm will get you a bit closer in but because it’s operating at F4 vignetting/field flatness might be less of a problem.

Id you can find one within budget I’d get the 135mm, but if you can’t the 200mm is a good lens too.

[TheDadure]

Thanks man i think i will buy 200 for start and maybe later something better or bigger.

clear skies

[SteveNickolls]

Hi,

Sorry to be late for this party. I would add a +1 to the Samyang 135mm f/2.0 lens, you can read the review about this here-https://www.lenstip.com/index.html?test=obiektywu&test_ob=442, and the site has plenty of other lenses suited to astronomy reviewed. Don't forget you can pick up good second hand lenses from places such as mpb-https://www.mpb.com/en-uk/used-equipment/used-photo-and-video/used-lenses/used-canon-fit-lenses/

This site gives ideas for lenses-http://www.astropix.com/html/i_astrop/lenses.html

Good luck with whatever you decide to go for.

Don't forget to post your images on SGL. ?

 

Cheers,
Steve

[Icesheet]

I’ll add another +1 to the Samyang 135 and you should be able to get it in or around budget. 

 

Ive experimented with a few lenses, Sigma 70-200 APO f2.8, Nikon 300mm f4.5  to name two. I’ve had to compromise with them all. Stopping down and cropping images to remove bad stars commonly.

The Samyang works wide open and is at an ideal focal length for the Star Adventurer especially if you plan to add a small APO telescope later in the 300-400mm range. I guarantee you will still use the 135mm whereas you may be less inclined to use say a 200- 300mm lens, especially one you have to compromise with. 

 

Whatever you do keep it simple and have fun!