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Would like some advice on lens and camera choices

Astrophotography Beginner CMOS DSLR Equipment Imaging Optics
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#1 JanSpace

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Posted 22 October 2021 - 06:52 AM

Hi folks, first post here, nice to meet everyone.

 

I've been dabbling in astrophotography with a fixed alt-az tripod and a dslr, and I'm now thinking of moving up in the hobby a short step. My budget is a bit restricted (~1100 usd) so I've sort of narrowed it down to a few possible routes.

 

First off, I'm planning on getting a SkyWatcher Star Adventurer for about 425$ as a mount. This is partly budget related but also portability related, as I'm travelling somewhat nowadays as a student so lugging around a go-to mount is just not an option for me at the time being; barring one exception which I'll mention at the end. I'm aware of its limitations but I'm quite excited to see what I can do with it especially with guiding, as some folks report good results. This also applies to why I'm looking at lenses and not scopes, as most seem a little too bulky for me at the moment.

 

My main interests are in imaging nebula, some bright galaxies and star clusters (perhaps I would say everything except very wide-frame photography), with a focus on using narrowband filters to get past most of the light pollution that I'll have to deal with, as even though I'm travelling its still mostly between cities and my dark sky time is currently very limited. I currently have a DSLR, which I will talk about below (I'm scared of astro-modding it). I've allocated about 150$ for a ZWO Ha filter for starting off with.

 

Option 1: DSLR + Lens + Guiding

This seems like the cheapest approach as it doesn't involve getting two cameras (one for guiding one for imaging) but currently I'm quite hesitant to astro-mod the DSLR as I'm worried about breaking it and being stuck without any form of imaging for some time. As such I'm not too convinced about its performance with Ha, though I've heard that its still "alright" stock so to speak (especially with longer subs).

I'm looking at the ASI120MM (either -S or Mini) for guiding.

 

Option 2: Astrocam + Lens + Guiding

With this route I'm looking at the ASI178MM Mono for imaging and the same ASI120MM as mentioned above for guiding. I've narrowed down the accessories I'll need getting it to work with a DSLR lens and they won't add too much budget-wise for me. The DSLR is also used of course as a secondary, so this is more of an Option 1.2 in a way...

This does however open up the possibility of me bucking up and trying to astro-mod my DSLR later as if something breaks I'll still have the 178MM. It also lets me do Narrowband Ha or maybe duo-band Ha/OIII with a monochrome camera and its extra sensitivity.

I understand its uncooled and that its main use is for planetary imaging, but the results I've seen so far in pictures some folks have shared have been stellar and honestly more than good enough for me. I'm aiming more for a wide amount of targets to image with decent quality at the moment rather than supreme image quality, as I'm guessing that will require a cooled astrocam and a sturdier mount (someday).

 

Lens Options:

As for the lenses, I'm keeping things extra limited on budget to about 200$, though if you've got any good alternatives under 300$ I would very much like to hear about them. The top two contenders are the:

 

Canon EF 75-300mm f/4-5.6 III: https://www.bhphotov..._Autofocus.html

 

Mitakon Zhongyi Creator 135mm f/2.8 Mark II: https://www.bhphotov...f_2_8_mark.html

 

I'm leaning toward the Canon lens at the moment as the variable zoom seems like it will be handy for framing versatility. If I go with the ASI178MM the equivalent focal and fstop at 70mm would be 318.5mm f/18.2. Veeery high F stop I know, but the focal length frames a lot of targets well. It does lead to a rather broad pixel ratio of 5-6"/px though which is a bummer. If I zoom in all the way though to 300mm I get 1365mm f/25.48 and a much better pixel ratio of 1.6"/px.

 

So this gives a focal length range of 318.5-1365mm and a focal ratio range of f/18.2-25.48 and a variable pixel ratio of 6"-1.6"/px. I'm aware though that those higher focal lengths would be demanding on polar alignment, but I'm hoping that with a good polar alignment using PHD2 SPA and Drift align along with the guiding camera I can track efficiently enough for perhaps 60 seconds at 135mm (615 equivalent) or (on a windless night) 200mm (900 equivalent) and perhaps lots of shorter subs at 300mm (1365 equivalent). I would really like to hear some thoughts on this, as though it seems to make sense in my head I'd like to know about its practicality. I am very curious to hear what you guys think of the very high f/stop; by my understanding it doesn't limit the amount of light coming in, just the clarity right, as it is an equivalent value?

 

The alternative competitor the Mitakon makes me think of the Samyang 135mm (which I really can't consider, at 500$) though I've heard that it suffers from some CA and Coma. I'm sure the Canon would also have similar hurdles, but I'm assuming that due to higher fstop they might be less pronounced? The fixed zoom is a bit of a bummer and honestly I'm 80% convinced on going with the Canon at this point just for the variable zoom.

 

But yea I understand that none of these options are optimal, but moving up in the hobby is an itch I need to scratch and I really can't stall until I save enough for a sturdy go-to. This obviously hasn't stopped me from thinking about it however, i.e blowing the whole budget on a light go-to... something like an iOptron cem26 does barely fit in the budget and its very light at 5KG for the mount (I can't consider the SW EQ-35m since its way too heavy for me right now). My hesitance to go down this route is that it will most likely be some time until I can save up to buy anything else for the setup, so for quite some time it will just the mount, the DSLR and a cheap lens I can squeeze in.

 

Tldr;

1- Canon DSLR+Guiding or DSLR+ASI178MM+Guiding?

2- Canon EF 75-300mm or Mitakon Zhongyi; or your best bet for under 300$

3- Blow the budget on the Go-To (iOptron Cem26)?



#2 Delta608

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Posted 22 October 2021 - 07:06 AM

  Take a look at this....  The new Askar Astro Camera Lens (ACL) 200mm f/4 APO  vs Canon 200mm f/2.8 L ii..  By Nebula Photos, a great source..He also frequents here on CN..

 

 https://www.youtube....h?v=dVEbOdn0qh0


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#3 JanSpace

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Posted 22 October 2021 - 07:13 AM

  Take a look at this....  The new Askar Astro Camera Lens (ACL) 200mm f/4 APO  vs Canon 200mm f/2.8 L ii..  By Nebula Photos, a great source..He also frequents here on CN..

 

 https://www.youtube....h?v=dVEbOdn0qh0

Ahh that's interesting. The Askar could be a good choice, makes the budget a tiny bit tight if I'm still adding guiding but it seems like a quality scope; thank you Delta. The lens seems very portable too. Though I guess it would take imaging with a monochrome camera off the table as that would stretch outside the budget, though maybe that's alright for now.



#4 JanSpace

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Posted 22 October 2021 - 07:16 AM

Ahh that's interesting. The Askar could be a good choice, makes the budget a tiny bit tight if I'm still adding guiding but it seems like a quality scope; thank you Delta. The lens seems very portable too. Though I guess it would take imaging with a monochrome camera off the table as that would stretch outside the budget, though maybe that's alright for now.

Though it does mean a larger portion of the budget going into the lens, stretching it a bit.



#5 Delta608

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Posted 22 October 2021 - 07:19 AM

  I think you will find your budget is blown the instant you took up this hobby !!   One of the more experienced members here has said.."Buy once, cry once !!"..(but you 'll buy multiple times till you settle in to what you like..) Good luck and keep us posted...



#6 JanSpace

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Posted 22 October 2021 - 07:22 AM

  I think you will find your budget is blown the instant you took up this hobby !!   One of the more experienced members here has said.."Buy once, cry once !!"..(but you 'll buy multiple times till you settle in to what you like..) Good luck and keep us posted...

Well if anything its motivating me to study harder so I can afford more stuff, so that's good in that way :) Thanks Delta



#7 JanSpace

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Posted 22 October 2021 - 07:41 AM

I would like to include an extra contender in the running:

 

Astro-Tech AT60ED: https://www.astronom...ed-doublet.html

 

So this would be option 3, with:

Mount: SW SA

Lens: AT60ED

Imaging: DSLR

Guiding: ASI120MM Mini

 

Baaarely snags the budget, but the scope seems not that bad in terms of portability and pretty great in terms of quality.

 

Though now I'm also considering a portable cheap scope, which goes against what I said about a 300$ max for the lens. I may consider shifting the scope/lens budget to 400$ with a focus on a good quality/portability mix.



#8 Andy Lucy

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Posted 22 October 2021 - 01:42 PM

You could also consider the Askar FMA135 telescope (focal length 135mm, f/4.5).  It’s tiny, light, inexpensive and should give you much better Astro image quality than a lens at equivalent price.  I have some example images in my gallery taken with this telescope and various cameras:  a Nikon Z50, ZWO ASI462MC and ZWO ASI2600MC (fitted with an Optolong L-extreme filter).

 

An advantage of using a focal length a short as 135mm is that you can get reasonable image quality using an unguided Star Adventurer mount.  Even so, I’d recommend guiding:  with my Askar FMA135 on an SA I guide with a ZWO ASI120MM-mini and mini guide scope combination:  this works well.

 

Andy



#9 jonnybravo0311

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Posted 22 October 2021 - 02:12 PM

Hi JanSpace,

 

The Star Adventurer is a nice little tracker, and its ultra-portability is what makes it so attractive. You can throw it, your tripod, your camera, some lenses and more into a backpack. The SA is a tracker and it works best with lenses up to about 200mm. The SA with a DSLR and a 135mm lens is a fantastic choice for a very portable kit. Once you start thinking about longer focal lengths and longer exposures...

 

This is where the portable trackers start to show their limitations. You can help yourself out a bit by guiding, which you do mention. However, you did not mention (or include in your budget) that not only do you need a guide camera, but also a guide scope (or off-axis guider if you choose that route). Further, you will need some kind of computer with software to control it. You're also adding weight to your system, which already has quite a limited capacity.

 

One more thing to consider with the Star Adventurer is that you're finding and framing your targets manually. There is no GOTO functionality, so you're stuck fiddling around manually adjusting the RA and Dec until you are on target. Every time you fiddle with things on the mount, you chance knocking your polar alignment out of whack.

 

I hope I'm not sounding too disparaging. On the contrary, I am happy you want to pursue astrophotography as a hobby. I'm just trying to set your expectations and outline the potential limits and pitfalls of choosing a small tracker. Full disclosure: I bought a Star Adventurer last year as my first real "astrophotography" purchase. I was very quickly frustrated with it and bought a CEM40 (a guy local to me was selling his). My Star Adventurer has been sitting in its box in a closet since then.

 

Plenty of people are happily using this kind of a setup. One I can think of off the top of my head is a member here who goes by the name of matt_astro_tx. Perhaps reach out to him for some first-hand experience. He's been thoroughly enjoying it :)



#10 JanSpace

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Posted 22 October 2021 - 04:43 PM

You could also consider the Askar FMA135 telescope (focal length 135mm, f/4.5).  It’s tiny, light, inexpensive and should give you much better Astro image quality than a lens at equivalent price.  I have some example images in my gallery taken with this telescope and various cameras:  a Nikon Z50, ZWO ASI462MC and ZWO ASI2600MC (fitted with an Optolong L-extreme filter).

 

An advantage of using a focal length a short as 135mm is that you can get reasonable image quality using an unguided Star Adventurer mount.  Even so, I’d recommend guiding:  with my Askar FMA135 on an SA I guide with a ZWO ASI120MM-mini and mini guide scope combination:  this works well.

 

Andy

Oh that looks excellent! The form factor is amazingly compact, and you make a good point that it would track quite well at that focal length. Thank you Andy! I'm definitely adding this high up on my considerations. Coupled with guiding, as you mentioned, the performance could be quite wonderful. And it has an 1.25" filter thread which is just.... its everything in one, like wow.

 

I had a look through your gallery and those shots of the veil nebula and North America nebula look wonderful; seems like the lens does its job as an apochromat quite well, since there doesn't seem to be much in the way of CA. Do you post these to Astrobin as well? If so could I have a look, as a full-size image?

 

Hi JanSpace,

 

The Star Adventurer is a nice little tracker, and its ultra-portability is what makes it so attractive. You can throw it, your tripod, your camera, some lenses and more into a backpack. The SA is a tracker and it works best with lenses up to about 200mm. The SA with a DSLR and a 135mm lens is a fantastic choice for a very portable kit. Once you start thinking about longer focal lengths and longer exposures...

 

This is where the portable trackers start to show their limitations. You can help yourself out a bit by guiding, which you do mention. However, you did not mention (or include in your budget) that not only do you need a guide camera, but also a guide scope (or off-axis guider if you choose that route). Further, you will need some kind of computer with software to control it. You're also adding weight to your system, which already has quite a limited capacity.

 

One more thing to consider with the Star Adventurer is that you're finding and framing your targets manually. There is no GOTO functionality, so you're stuck fiddling around manually adjusting the RA and Dec until you are on target. Every time you fiddle with things on the mount, you chance knocking your polar alignment out of whack.

 

I hope I'm not sounding too disparaging. On the contrary, I am happy you want to pursue astrophotography as a hobby. I'm just trying to set your expectations and outline the potential limits and pitfalls of choosing a small tracker. Full disclosure: I bought a Star Adventurer last year as my first real "astrophotography" purchase. I was very quickly frustrated with it and bought a CEM40 (a guy local to me was selling his). My Star Adventurer has been sitting in its box in a closet since then.

 

Plenty of people are happily using this kind of a setup. One I can think of off the top of my head is a member here who goes by the name of matt_astro_tx. Perhaps reach out to him for some first-hand experience. He's been thoroughly enjoying it smile.gif

Hi Jonny! Yup I'm starting to agree with you (and Andy) that perhaps going with 135mm would be the best decision.

 

And yup I forgot to mention the guidescope. Currently I'm eyeing the SVBONY SV165 mini scope, which I can get here (currently in Asia) straight from China for around 25USD :D. According to several reviews and testimonials I've found regarding this little scope, it's quite the solid performer and very similar to the popular ZWO 30mm guidescope (this one is 30mm/120fl as well).

 

As for software, when I was doing untracked photography I was making use of N.I.N.A and have gotten rather comfortable with it. I do have a laptop with N.I.N.A, a seperate platesolver (I forgot the name, though it is offline which is great) and soon PHD2 for guiding. As far as I can tell I can make everything work with free software, which is excellent for now. And when it comes to the weight, I am trying to keep it under 5lb (the SA has an 11lb limit, so trying to stay under half of that). The DSLR is 1 pound, the guidescope should be half a pound and the guidecam around the same weight; and should I go for a 135mm scope I think the weight will end up safely under the 5lb target; fingers crossed!

 

And I agree that the SA will probably have a bit of a learning curve; I'm getting the pro pack so at least the Dec bracket will help a bit with alignment. Maybe I'm just new but the act of star hopping and manually finding targets is a lot of fun for me, it's just nice being under the stars piecing things together bit by bit. Avoiding bumps will take a bit of practice certainly. The cem40 seems great; as mentioned I was eyeing the cem26, its younger sibling. Unfortunately the more I think about it, the weight of a go-to is just not something I can put up with right now when competing with the 3 pound star tracker.

 

Thanks for the reply; it's not disparaging at all no worries.  Right now at least, I'm excited to figure things out one step at a time.

 

Btw that shot you took of the tulip nebula on your astrobin looks stellar; wonderful contrast and color.


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#11 jonnybravo0311

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Posted 22 October 2021 - 05:26 PM

Oh that looks excellent! The form factor is amazingly compact, and you make a good point that it would track quite well at that focal length. Thank you Andy! I'm definitely adding this high up on my considerations. Coupled with guiding, as you mentioned, the performance could be quite wonderful. And it has an 1.25" filter thread which is just.... its everything in one, like wow.

 

I had a look through your gallery and those shots of the veil nebula and North America nebula look wonderful; seems like the lens does its job as an apochromat quite well, since there doesn't seem to be much in the way of CA. Do you post these to Astrobin as well? If so could I have a look, as a full-size image?

 

Hi Jonny! Yup I'm starting to agree with you (and Andy) that perhaps going with 135mm would be the best decision.

 

And yup I forgot to mention the guidescope. Currently I'm eyeing the SVBONY SV165 mini scope, which I can get here (currently in Asia) straight from China for around 25USD laugh.gif. According to several reviews and testimonials I've found regarding this little scope, it's quite the solid performer and very similar to the popular ZWO 30mm guidescope (this one is 30mm/120fl as well).

 

As for software, when I was doing untracked photography I was making use of N.I.N.A and have gotten rather comfortable with it. I do have a laptop with N.I.N.A, a seperate platesolver (I forgot the name, though it is offline which is great) and soon PHD2 for guiding. As far as I can tell I can make everything work with free software, which is excellent for now. And when it comes to the weight, I am trying to keep it under 5lb (the SA has an 11lb limit, so trying to stay under half of that). The DSLR is 1 pound, the guidescope should be half a pound and the guidecam around the same weight; and should I go for a 135mm scope I think the weight will end up safely under the 5lb target; fingers crossed!

 

And I agree that the SA will probably have a bit of a learning curve; I'm getting the pro pack so at least the Dec bracket will help a bit with alignment. Maybe I'm just new but the act of star hopping and manually finding targets is a lot of fun for me, it's just nice being under the stars piecing things together bit by bit. Avoiding bumps will take a bit of practice certainly. The cem40 seems great; as mentioned I was eyeing the cem26, its younger sibling. Unfortunately the more I think about it, the weight of a go-to is just not something I can put up with right now when competing with the 3 pound star tracker.

 

Thanks for the reply; it's not disparaging at all no worries.  Right now at least, I'm excited to figure things out one step at a time.

 

Btw that shot you took of the tulip nebula on your astrobin looks stellar; wonderful contrast and color.

Thanks for the compliment. A 135mm lens is a great focal length for a star tracker, and I think if you're going to stick with the Star Adventurer, you'll be quite happy with the combo. As I wrote, the biggest advantage of the SA is its portability. it's probably why I haven't sold mine yet... I keep telling myself I'm going to use it for some wide field work... like a Milky Way shot over the ocean :).



#12 Andy Lucy

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Posted 22 October 2021 - 07:13 PM

I had a look through your gallery and those shots of the veil nebula and North America nebula look wonderful; seems like the lens does its job as an apochromat quite well, since there doesn't seem to be much in the way of CA. Do you post these to Astrobin as well? If so could I have a look, as a full-size image?

I don't have any posts on Astrobin.  However, my gallery contains a couple of Pixinsight "aberration inspector"  FMA135 images taken with the Nikon Z50 (which has an APS-C size sensor).  These are a mosaic  of the centre, four corners and four outer edges of an image (all viewed at 100%)  and allow you to judge the performance across the frame.  You'll see that the corners are a bit soft with slightly mis-shaped stars but - as you have noticed - colour fringing is very low. 

 

I could send you a file of a full size APS-C image:  if you'd like this please send me a PM.

 

Andy


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#13 JanSpace

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Posted 23 October 2021 - 08:12 AM

Thanks for the compliment. A 135mm lens is a great focal length for a star tracker, and I think if you're going to stick with the Star Adventurer, you'll be quite happy with the combo. As I wrote, the biggest advantage of the SA is its portability. it's probably why I haven't sold mine yet... I keep telling myself I'm going to use it for some wide field work... like a Milky Way shot over the ocean smile.gif.

Yup I agree that keeping one portable option like that handy could turn out very useful on short notice. Then again the cem you have is far from being bulky too, but yea not nearly as portable as the SA.


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#14 jonnybravo0311

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Posted 23 October 2021 - 09:27 AM

Yup I agree that keeping one portable option like that handy could turn out very useful on short notice. Then again the cem you have is far from being bulky too, but yea not nearly as portable as the SA.

The size/weight was the primary reason for the CEM40 purchase. When I was looking to upgrade, I had narrowed it down to three choices: the CEM40, the EQ6-R Pro and the Losmandy GM811G. Even though both of the other mounts have a higher payload capacity, it boiled down to how easily I would be able to setup and tear down. I know myself - after all, I've been living with myself for a while now :p. As such, I knew that if I had to completely setup and tear down my rig every time I wanted to image... well, my rig would be collecting dust instead of photons. With the CEM40, I carry the entire assembled rig from the garage to my "observatory" (i.e. the end of my driveway).




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