# Tips on using Tokina 500mm Mirror Lenses with Lumix gH4?



## Katsi (Feb 10, 2015)

I have recently bought a Tokina 500mm f8 mirror lens. I plan to take advantage of the gH4's x2 crop factor and give myself a decent equivalent 1000mm focal length in the hope that I might be able to get some decent shots of our moon and solar system. 

I have heard that focusing will be a problem. Does anyone have any tips to using this lens and camera combination? Does anyone have experience with this particular lens? Thank you. 

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## tirediron (Feb 10, 2015)

Since you're shooting astro, focusing shouldn't be an issue, just make sure you know where 'infinity' is on that lens, since it's not always exactly where it's marked on the lens.  Be clear on how the crop factor applies.  Your 500mm lens will have a field of view equivalent to a 1000mm lens on a full-frame camera, BUT...  there's no increase in "magnification".


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## Katsi (Feb 10, 2015)

Thanks Tirediron. Aha, so sorry, the field of view of the lens will be the same as it would be on full frame but it doesn't effect the focal length? Please forgive my ignorance. Trying to get my head around the concept. So what is the difference in what I will see between this lens on the gH4 and this lens on a full frame camera...?

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Please check out my new photography blog should you have time... 
BLOG - Isle of Wight Photography- Two People. One Camera


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## Katsi (Feb 11, 2015)

Just so you know it all clicked into place after your comment yesterday. I now understand the restricted field of view due to the crop factor but that it doesn't change the magnification. Thanks for your help...!


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## astroNikon (Feb 11, 2015)

Watch the bright stars for focusing. They'll look like Donuts or slightly elongated/blurry if they are out of focus.  I used to use a Nikon 500mm Reflex (mirror) lens, along with the telescopes which are essentially the same thing just a tad bigger.  It was a great trainer for technique for the scopes.
Have fun.


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## Katsi (Feb 11, 2015)

Hey astroNikon, thanks for the tip! I have seen people making cardboard aperture rings and and strange things out of guitar tuning pegs to help focusing more accurately! I would love to get into using telescopes. I assume you capture images using your scopes too or do you just observe? I'll try and master the mirror lens before I have a bash at anything else I think...


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## 480sparky (Feb 11, 2015)

Katsi said:


> ........I have heard that focusing will be a problem. Does anyone have any tips to using this lens and camera combination? Does anyone have experience with this particular lens? Thank you........



Best attempted during night of good 'seeing', meaning as little turbulence as possible.  A good sturdy tripod is mandated.  Try bracketing your focus.  Can you tether that camera to a computer and operate it remotely?


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## Katsi (Feb 11, 2015)

Cool! Yeah thanks for the tip. Absolutely, I will try a nice still night. What do you mean by "bracketing"? The gH4 can be operated remotely by phone or iPad, something I intend to do....


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## 480sparky (Feb 11, 2015)

Take a series of shots, changing the focus _ever so slightly_ for each one.  Maybe for astro stuff it isn't all that required as it is for terrestrial photography.  But that's my method for using reflex lenses.


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## astroNikon (Feb 12, 2015)

I still do it the way Sparky does & digital zoom .. but I'll ordering a Bahtinov mask for my scope.
Info on it here ==> Bahtinov mask - Wikipedia the free encyclopedia
and other solutions ==> Focusing Methods

for instance, this is a neat picture.  But if you zoom in ALOT you can see the out of focus donuts



20140923-01 Orion Nebula by stevesklar, on Flickr


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## Katsi (Feb 12, 2015)

Thanks so much. AstroNikon that is a spectacular photograph. Its awesome, I love it. I hope to be able to achieve something like this. It blows my mind! Some great focusing tips in the link, can't thank you enough!


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