Once again I Need Expert Help: minimum 300mm prime lens no auto focus

[JBW]

Most of missed my first foray into Digital camera astrophotography. I managed to capture Jupiter, Io and Callisto with my Tamron 90mm macro lens. Not exactly highly detailed but it was a clear shot. This got me thinking.

I already have a massive tripod designed to carry an eight inch SC with camera gear. I've got the camera and two lenses. Once the bank balance goes up a bit I'll be ordering a Sky Watcher wedge, mount and counter weight setup.
What I need a little, make that a lot of help in is finding a good quality manual focus prime lens of 300mm to 400 mm that will fit my Sony A mount.

B&H sells 2

Rokinon Reflex 300mm f/6.3 UMC CS Lens for Sony A


Samyang Reflex 300

They may well be the same lens under a different brand.

Are they a decent lens. Do you have other suggestions?

[Ken MT]

Possibly useful information for you.


https://www.astronomics.com/why-buy-...lescope_t.aspx

[JBW]

Possibly useful information for you.


https://www.astronomics.com/why-buy-...lescope_t.aspx

I am leery about comparing apples and oranges or in this case telescopes and lenses. Unless it is legitimate to think of these two lenses as being miniature telescopes. And if they are would they work well on my camera?

[James G]

Hi Brian,
You are starting to tread another 'interesting' path

I'm not sure if you have ever been interested in astronomy before you took up photography, so I'll assume 'no' and if I'm teaching you to 'suck eggs', apologies.

Firstly, both the lenses you are looking at would be 'reasonable' for star field photography, shooting the moon, and getting some of the brighter nebulae etc in the sky.

What I am not too sure about though is how 'sharp' a focus you can get with stars (pinpoint objects). The mirror lenses are not engineered for astronomy and limiting astigmatism & abberation is more critical than in 'general' photography. I would think if you went onto some of the astronomy forums you would get a more informed feedback.

That said I have had good results with Sigma telephotos, shooting the moon and the Orion nebula. I would guess your mirror lens it would be more than adequate for the moon and 'wide' star field imaging.

Having a faster lens is preferable (i.e. f4 rather than f6.5) since it reduces exposure times and help with limiting star drift, but given the high ISO performance of most modern digital cameras this is not a great problem.

I also use a 'doubler' particularly for the moon (not for star fields and nebula) and I use a couple of 'free' astrophotography programs to assist in post processing. (Registax I would recommend)

They enable you to take multiple exposures and stack them to improve capture. (Helps to Remove noise and 'optimise atmospheric effects)
Given you intend to use a motorised tracker as well, it does look like a very nice rig. (I have an Ioptron Skyguider for tracking.)

(Harking back to your Jupiter capture, I should probably warn you that if you are hoping to get 'details' of Jupiter, using this setup you are only likely to be able to see the shape of Jupiter's disc since it will still be rather small in the frame.)

Hope this helps.

[James G]

Unless it is legitimate to think of these two lenses as being miniature telescopes.

IMO modern telephoto lenses (mirror or otherwise), are so much better than the telescope I had back when I was 16 that it is not worth worrying about.

If you want to take photos of 'faint' objects (ie invisible to the naked eye), or images of the planets showing planetary detail then you need to approach this as an astronomer and you do need a good telescope and all the observatory paraphernalia that goes with it. If however you are happy to explore the visible sky an good digital camera/lens combination is better than a 'cheap' hobbyist telescope (though can always attach a telescope via an adapter!)

I use a larger telephoto (sigma 150-500) and I posted the thread below a while back, but it does show what I could achieve then without a tracking mount. Given you will be able to track I would think your rig will give you some very nice results.... but like everything else in photography.. it will take some patience and experimentation.

Astrophotography with Digital Camer -Orion Nebula (M42)

[JBW]

IMO modern telephoto lenses (mirror or otherwise), are so much better than the telescope I had back when I was 16 that it is not worth worrying about.

If you want to take photos of 'faint' objects (ie invisible to the naked eye), or images of the planets showing planetary detail then you need to approach this as an astronomer and you do need a good telescope and all the observatory paraphernalia that goes with it. If however you are happy to explore the visible sky an good digital camera/lens combination is better than a 'cheap' hobbyist telescope (though can always attach a telescope via an adapter!)

I use a larger telephoto (sigma 150-500) and I posted the thread below a while back, but it does show what I could achieve then without a tracking mount. Given you will be able to track I would think your rig will give you some very nice results.... but like everything else in photography.. it will take some patience and experimentation.

Astrophotography with Digital Camer -Orion Nebula (M42)

Hi James, I have owned two telescopes both for visual observing. I got quite good at spotting faint fuzzies as I worked through the Messier 110 and half of the M 400. Then we got drunken neighbors and light pollution. Now our neighbors are behaving. I have dusted off the 8" Lightbridge and I'm enjoying the heavens.

But I have a hankering to combine my passions and see what I can do with the moon, the Milky Way and yes even M-42.

I am hoping that whatever I could see in the 4.5 or 8" reflector I will in time be able to capture with my Sony and a lot of tracking and stacking.

My Fujifilm S4200 takes a fair sized moonshot and if I can track and stack....

The Tamron 90 won't give me planetary detail but I'm hoping to be able to create, again in time, something similar to your M-42 shot.

Is there any chance with a good lens (suggestions) of being able to capture something like the Witch Head Nebula? I had dark enough skies to see it with averted vision in the 4.5 and nicely in the 8 on a good night.

Brian

[James G]

Brian, it's a rather strange coincidence you mentioning the Witch Head.

I'm starting to 'organise' myself for the autumn/winter when Orion will be at its best. Birmingham as for most big cities these days is very light polluted, but I have been pleased with the M42 images I got last year.

I came across the first of the links below late last year, and was intrigued by the 'apparent' simplicity of capturing the wider Orion field.

Arguably, you would be able to capture the Witch Head as part of the wider field using your setup.

Targetting the Witch Head directly as the 'main' shot though is a serious challenge but should be possible, if you are happy to try for a very long sequence of captures to build up exposure. The second link gives the details and uses a camera/lens combination (600mm) similar to mine.
7 hrs total is a long combined exposure time, but he used an ISO of 800. Reading around the subject ISO 1600 -3200 seems to give reasonable results though there is more 'noise' to be managed, and I did get good results at 1600 for M42.

So... conclusion.... I reckon your proposed rig could do what you want, but it will need you to start indulging in some extreme multiple exposures and serious stacking.

I believe Samyang do a 500mm F8 mirror lens and I've seen it on E-Bay here in the UK for less than £100. There is even an 800 mm version which is ridiculously cheap (compared to Canon/Sigma/Tamron glass), and less than £200 on Amazon.

It might be worth your while considering either of these two larger lenses as an alternative to the 300mm.

Normally, I would not be advising use of mirror lenses for general photography. I have 'tried' the Samyang series at Photo Shows over the last couple of years, and for 'wildlife' the image seemed soft with poor/bad Bokeh. In this instance though, the use is very specific and 'specialist' Since everything is focused at infinity, bokeh has no relevance.


I intend to try for the wider Orion Field this Autumn/Winter and having just reviewed the specifics for the Witch Head I'm inclined to see what I can do with my Sigma 600mm and the 7DMk II. Given your latitude and 'longer nights at present, you might be posting ahead of me! ...

Asregards the moon, you will have no probs . ( I shoot on tripod, with cable release (mirror lockup) and go for short rapid capture and then stack in photoshop. 600mm lens fills abour 2/3 of the frame .)

https://petapixel.com/2015/01/18/tut...constellation/

https://www.dpreview.com/forums/post/57119048

[JBW]

The way it looks right now my bank account will have enough in it by October. First light maybe the middle of October? Which means m42 is in my skies at about 03:00. But Andromeda is high in the sky.

I dl the version 5 of the software you suggested because it processed RAW. If RAW is not a big deal I will dl version 6.

Normally I would not dare go over ISO 200 with my Sony.

I'll look for the Samyang 500 mand 800.

Hope you won't mind if I keep picking your brain?
Brian

[James G]

Hope you won't mind if I keep picking your brain?

I'm a bear of little brain, but pick away


There is also another technique which is possible which can speed up capture .... if you can take video, it is possible to extract Keyframes and then feed them into a stacking program.

I've done it one or twice but preferred with working the raw images with about 1 sec exposure times and then stack so I simply set up a sequence in my intervalometer (electronic cable release) to automate the process.

It all gets sooooo compulsive!

[Manfred M]

Brian - both lenses you are looking at are made by the South Korean company Samyang. They produce lenses under a host of different names including Rokinon, ProOptics, Bower, etc.

Things may have changed, but in the past, their lenses were 100% manual with no autofocus / auto exposure capabilities and no electronic connections to the camera. I believe some of their newest lenses do have the electronic connections, but the lenses you are looking at have been around for a while and do not.

[billtils]

Brian

I'm certainly not an expert and can't comment at all on the specific lens you mention, but I can share my experiences with a manual focus Samyang. It's their 14mm prime and that of course makes the focus question somewhat redundant (as someone advised me, "turn it to ∞ then back a mm and everything will be in focus").

Whether or not the other electronics are manual depends on the camera. They are fully functional on my Nikon, I believe that this is not the case on a Canon and don't know about a Sony. A personal opinion is that the glass is excellent and makes it well worth the money, but I may not have felt that way if I had to turn the clock back several decades in regard to exposure settings.

[paintingwithlight]

Hi Brian,

I can't comment wrt lenses. As you are an astronomy buff you probably already know this but, in case you aren't aware, stars with low surface temperatures (e.g., red giants, surface temp. < 4000K) emit almost all of their light energy in the near infrared (see https://en.wikipedia.org/wiki/Astronomical_spectroscopy). I was amazed when I was given the opportunity to look at the night sky with a near IR sensitive device - the number of visible stars appeared to triple! I am not sure how it would affect your focus but if you had a spare camera it might be a benefit to remove the near IR filter from the sensor.

Cheers,

Michael

[JBW]

Brian - both lenses you are looking at are made by the South Korean company Samyang. They produce lenses under a host of different names including Rokinon, ProOptics, Bower, etc.

Things may have changed, but in the past, their lenses were 100% manual with no autofocus / auto exposure capabilities and no electronic connections to the camera. I believe some of their newest lenses do have the electronic connections, but the lenses you are looking at have been around for a while and do not.

I thought they might be.

[JBW]

Hi Brian,

I can't comment wrt lenses. As you are an astronomy buff you probably already know this but, in case you aren't aware, stars with low surface temperatures (e.g., red giants, surface temp. < 4000K) emit almost all of their light energy in the near infrared (see https://en.wikipedia.org/wiki/Astronomical_spectroscopy). I was amazed when I was given the opportunity to look at the night sky with a near IR sensitive device - the number of visible stars appeared to triple! I am not sure how it would affect your focus but if you had a spare camera it might be a benefit to remove the near IR filter from the sensor.

Cheers,

Michael

I'm told that's a classical astro photography mod. But as I only have one camera...

[JBW]

I'm a bear of little brain, but pick away


There is also another technique which is possible which can speed up capture .... if you can take video, it is possible to extract Keyframes and then feed them into a stacking program.

I've done it one or twice but preferred with working the raw images with about 1 sec exposure times and then stack so I simply set up a sequence in my intervalometer (electronic cable release) to automate the process.

It all gets sooooo compulsive!

M'Lady says that I'm like a dog with a bone. What do you know about solar alignment rather than Polar? Neither Polaris nor Octans comes above my horizon.

[James G]

Brian, sorry, solar alignment is something I have no idea about... in fact I can't quite see how to do it. I'd sugesst a question to one of the astronomy forums.

That said I use a polarscope on my tracker combined with a free app downloaded from IOPTRON though there are a number of other providers.

I think that aligning the tracker to true north with a compass and and setting the tracker at the lattitude angle for the Phillipenes (about 15deg North?) would work. Fiddly and you might have to build a big protractor but possible?

On another point... from some of the other responses you have had, particularly Mannfred's which is well made....I'd reinforce the point that with astrophotography you are working mostly with a wide open aperture, Infinity focus, with only ISO/Exposure to be adjusted. (Shooting the moon is the exception, but I usually do that setting the camera up manually anyway) Manual shooting is standard since most autofocus systems are incapable of 'fixing' on a star . So provide you would only want a 300 mm lens for this type of imaging, the Samyang is quite a nice option. If however you have aspirations to use it for wildlife photograghy or anything else... other than Night sky , you do need to consider if an manual only lens is suitable.

[JBW]

just for astrophotography

[Mike Buckley]

Considering your intended, specialized (relatively limited) use of the lens, you could buy a used lens perhaps of an older version that would work just as well as a new one and reduce cost in the process. I mention this because I bought a 300 mm lens a few years ago that was discontinued about 20 years ago. Like you, I use mine only for specific purposes and it fits my needs perfectly at a dramatically reduced cost compared to buying a new lens.

[xpatUSA]

Considering your intended, specialized (relatively limited) use of the lens, you could buy a used lens perhaps of an older version that would work just as well as a new one and reduce cost in the process. I mention this because I bought a 300 mm lens a few years ago that was discontinued about 20 years ago. Like you, I use mine only for specific purposes and it fits my needs perfectly at a dramatically reduced cost compared to buying a new lens.

+1

Slightly OT but I just bought a Sigma 105mm Macro for about 60 bucks US - it was cheap because the AF wasn't working - but I always use MF for close-up work.

[JBW]

+1

Slightly OT but I just bought a Sigma 105mm Macro for about 60 bucks US - it was cheap because the AF wasn't working - but I always use MF for close-up work.

excellent.