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

[Manfred M]

Sony did make an f/8 500mm catadioptric (mirror) lens with appropriate electronics, image stabilization and auto focus. It was discontinued a few years ago, but I would be surprised if one couldn't find one on the used market. That being said, I suspect that it will cost more used than a new Samyang.

[rpcrowe]

The problem with a "mirror" lens and astrophotography "MAY" be that the bokeh from most mirror lenses are donut (round) shaped. This might just become confusing with the round shapes you get from astrophotography.

I had a Tokina 400mm f/5.6 prime lens (in a Canon mount) like this one which has a Nikon mount.

http://www.ebay.com/itm/Tokina-AT-X-...QAAOSwHLNZUCU7

I paid $100 USD for this lens used on eBay, used it for a couple of years and sold it for $125 USD.

The image quality was very good to excellent (better than the Sigma 400mm f/5.6 prime and quite close to the Canon 400mm f/5.6L lens). The auto focus was slow and noisy which is why I replaced it with a Canon f/5.6L lens.

However, this type of lens "might" be what you are looking for. You would need to find it on the used market.

[Manfred M]

The problem with a "mirror" lens and astrophotography "MAY" be that the bokeh from most mirror lenses are donut (round) shaped. This might just become confusing with the round shapes you get from astrophotography.

That would surprise me very much Richard. Most telescopes have the same basic design as a cat lens (in fact a lot of short telescopes are cats) and it obviously is not a problem with them. Focus would be set to "infinity", so there should be no out of focus areas anyway.

[JBW]

Sony did make an f/8 500mm catadioptric (mirror) lens with appropriate electronics, image stabilization and auto focus. It was discontinued a few years ago, but I would be surprised if one couldn't find one on the used market. That being said, I suspect that it will cost more used than a new Samyang.

Just checked Amazon, your suspicions are right on $789.00. But free shipping

[James G]

What do you know about solar alignment rather than Polar? Neither Polaris nor Octans comes above my horizon.

Brian, you got me curious so I did a little hunting......
The method I suggested should work, but when setting up and pointing your tripod "north" you really need to point it a little off to the east or west of north to "true north". The Magnetic Declination site has a map you can use to find your location and the current offset east or west from magnetic north you need to point. If you click "what is magnetic declination" there's a few images showing the appropriate compass offset.


Also, try this link... may help...

http://www.myastroscience.com/nopolarisalignment

[JBW]

Brian, you got me curious so I did a little hunting......
The method I suggested should work, but when setting up and pointing your tripod "north" you really need to point it a little off to the east or west of north to "true north". The Magnetic Declination site has a map you can use to find your location and the current offset east or west from magnetic north you need to point. If you click "what is magnetic declination" there's a few images showing the appropriate compass offset.


Also, try this link... may help...

http://www.myastroscience.com/nopolarisalignment

"This may be an easier way;
One good way is to use the Sun. Carefully level your mount with a bubble level and set the polar axis to the latitude of your site. Hang a weighted string from the mount (between the tripod legs) and lay a protractor on the ground,centered under the string. Rotate the protractor until the string’s shadow points to the Sun’s known azimuth (measured from north through east) plus 180°. Finally, swivel the mount until the polar axis stands directly above 0° on the protractor. You are now polar-aligned.

From <http://www.skyandtelescope.com/astronomy-resources/astronomy-questions-answers/polar-align-in-daytime/> "

[James G]

/One good way is to use the Sun

I suspect that will work 'better' at your latitude.... I presume sundown to darkness transition is relatively short a matter of 20 mins or so, and you can guarantee seeing the sun a bit more often than here!

Up here at 54degrees it would mean setting up and letting the tracker run for at least a good few hours (not necessarily an issue) and much more importantly for the UK ... I would need a shadow....we hardly ever see the Bl#$*ed sun.... too much cloud.

[JBW]

This is just a thought but would the Panasonic Lumix DC-FZ80 Digital Camera with a 1200mm zoom make more sense than buying a 300mm prime lens?

[rpcrowe]

The "bridge camera" is a jack of all trades and perhaps a master of none. However, the bridge camera is enough of a master to provide very decent imagery, especially if you don't need to make big enlargements.

Here are a few things that I would look into when selecting a bridge camera...

1. I would firstly ensure that the camera can capture images in the RAW format.

2. I would ensure that the aperture of the camera is wide enough to facilitate the kind of shooting I would want it for. Many bridge cameras have variable apertures which stop down pretty drastically when the lens is at its maximum focal length. The maximum aperture of the DC-FZ80 is f/5.9 at its longest focal length. However, often when you get a larger maximum f/stop (such as f/4) you are sacrificing focal length to gain that speed.

3. I would look into the image quality at high ISO. Many bridge cameras are not all that efficient when shooting at a high ISO and, with the small apertures, you often need to boost the speed. There are some bridge cameras with larger sensors such as 1-inch which "might" perform better at high ISO's but, you often sacrifice maximum focal length. And, of course, the cost of these cameras is higher!

4. The focal lengths listed for these cameras are equivalent focal lengths.

[James G]

Brian, I'd echo everything that Richard has said. It is a very long time since I have had a bridge camera, but I think the issue is the trade-offs that result from a lens system that has to cope with extremes of function.

My first thought goes back to the size of the 'ojective' lens. In simple terms it is relatively small compared to your 90mm macro for instance. Compare it to a 300mm telephoto and it even smaller in comparison.

Going back to e 'astronomy' issues, the cardinal requirement is for light gathering (stars are very faint) and that means the bigger the objective lens/mirror, the more efficient it will be at light gathering.

If you also consider Richard's comment that the bridge camera has to stop down agressively at long focal lengths then I cannot see how it could compare with a conventional lens.

PS
Take a look at Opteka mirror lenses 500mm F6.3 .... less than £100 on Amazon, Drawback no auto function, you have to focus and set shutter speed.

[JBW]

Brian, I'd echo everything that Richard has said. It is a very long time since I have had a bridge camera, but I think the issue is the trade-offs that result from a lens system that has to cope with extremes of function.

My first thought goes back to the size of the 'ojective' lens. In simple terms it is relatively small compared to your 90mm macro for instance. Compare it to a 300mm telephoto and it even smaller in comparison.

Going back to e 'astronomy' issues, the cardinal requirement is for light gathering (stars are very faint) and that means the bigger the objective lens/mirror, the more efficient it will be at light gathering.

If you also consider Richard's comment that the bridge camera has to stop down agressively at long focal lengths then I cannot see how it could compare with a conventional lens.

PS
Take a look at Opteka mirror lenses 500mm F6.3 .... less than £100 on Amazon, Drawback no auto function, you have to focus and set shutter speed.

I just looked at it and for the Sony A mount it comes with an adapter to fit the A mount and and an adapter to change it into a 1000mm. Not to sound paranoid but for 119 US dollars this seems almost too good to be true?
B.

PS just checked and B&H sells it at the same price

[James G]

this seems almost too good to be true?

Well, it is a very 'basic' lens with no frills, but you would have to focus manually anyway, and you will have to experiment with ISO/exposure....
I'm guessing that the adapter for 1000mm is a doubler which will also double the effective F No for the lens..

[JBW]

Well, it is a very 'basic' lens with no frills, but you would have to focus manually anyway, and you will have to experiment with ISO/exposure....
I'm guessing that the adapter for 1000mm is a doubler which will also double the effective F No for the lens..

I like basic. I like to experiment.
B.

[rpcrowe]

Here's another possibility...

There are converters that will adapt the older Canon FD mount manual focus lenses to your camera. I don't know how well they work because using an adapter to fit one of these lenses to a Canon EOS camera, you will lose infinity focus (unless you use an adapter with glass elements - which is another can of worms). I have not researched the viability of the FD lens + adapter on your Sony A mount camera but, it might be worth doing so.

Anyhow, you can get Canon FD lenses (which can produce excellent IQ) very inexpensively on the used market. As an example, you can find a 300mm Canon f/4 lens in an FD mount for as low as $100 from KEH

http://www.ebay.com/itm/Canon-300mm-...gAAOSwstJZUnte

Adapters are available for your camera on Amazon.com and on eBay

I have used the canon FD lens system for a long while on my Canon A1 and AE-1P cameras before I began using digital EOS gear. In some cases (namely the 50mm f/1.8 lens) the FD lenses actually produced better IQ than the Canon EOS lenses...

[JBW]

Here's another possibility...

There are converters that will adapt the older Canon FD mount manual focus lenses to your camera. I don't know how well they work because using an adapter to fit one of these lenses to a Canon EOS camera, you will lose infinity focus (unless you use an adapter with glass elements - which is another can of worms). I have not researched the viability of the FD lens + adapter on your Sony A mount camera but, it might be worth doing so.

Anyhow, you can get Canon FD lenses (which can produce excellent IQ) very inexpensively on the used market. As an example, you can find a 300mm Canon f/4 lens in an FD mount for as low as $100 from KEH

http://www.ebay.com/itm/Canon-300mm-...gAAOSwstJZUnte

Adapters are available for your camera on Amazon.com and on eBay

I have used the canon FD lens system for a long while on my Canon A1 and AE-1P cameras before I began using digital EOS gear. In some cases (namely the 50mm f/1.8 lens) the FD lenses actually produced better IQ than the Canon EOS lenses...

quick search on Ebay brings up a whole bunch of made in China adapters to mount the lens to my camera. That one on Ebay looked pretty rough

[rpcrowe]

Here are a selection of FD lens to Sony A mount and Sony E mount cameras...

https://smile.amazon.com/s/ref=nb_sb...camera+adapter

Here is some information on using various lenses with Sony A mount cameras. Looks like this is a no-go situation...
https://photo.stackexchange.com/ques...hat-are-the-di

This is the last, and most pertinent paragraph of that posting:
"Frankly, your best bet for cheap vintage glass on an Alpha body is to simply find old Minolta AF mount lenses, which are, in fact, the same mount as Sony A-mount. The dyxum website is your best knowledgebase for this, and for adapting lenses to the Sony A-mount."

Here is the dyxum web address: http://www.dyxum.com/

It looks like you have a plethora of vntage Minolta AF lenses to choose from...

Here are the Minolta AF lenses on eBay
https://www.ebay.com/sch/i.html?_fro...AF&_sacat=3323

This is a pretty good lens:
http://www.ebay.com/itm/Tokina-AF-80...AAAOSwyltZSb42

The 80-400mm Tokina replaced the 400mm f/5.6 prime lens in the Tokina lineup.

Here is a 400mm Sigma Prime
http://www.ebay.com/itm/Sigma-AF-Tel...8AAOSwAO9ZOw1-

[Mike Buckley]

I'm sure I'm not the only person who has taken with a bit of ironic humor Brian's decision to go from macro photography to astrophotography. On a more serious note, his choice is an excellent example of the breadth and depth of possibilities available to us in our pursuit of the enjoyment of photography.

[rpcrowe]

I'm sure I'm not the only person who has taken with a bit of ironic humor Brian's decision to go from macro photography to astrophotography. On a more serious note, his choice is an excellent example of the breadth and depth of possibilities available to us in our pursuit of the enjoyment of photography.

Along that line... Photography is one hobby that can be combined with, and added to, just about any other hobby. Or it can stand alone... Not many other avocations have that flexibility...

[Mike Buckley]

Good point, Richard. I hadn't thought of that.

[JBW]

I'm sure I'm not the only person who has taken with a bit of ironic humor Brian's decision to go from macro photography to astrophotography. On a more serious note, his choice is an excellent example of the breadth and depth of possibilities available to us in our pursuit of the enjoyment of photography.

Without balance in my passions how can I have balance in my life? And consider the intriguing possibilities of working with well aged light!