Secret Photography: Filters and Prime Focus



Wait, wait! Sit down! The magic show is not over! I still have some tricks up my sleeve, so sit back, relax—and prepare to be flabbergasted.

My last trick involved an unthinkable way of using a Barlow lens for prime focus photography. You’d think there’s nothing more that could be done, well, if you happen to think this, guess what? You’re wrong! I know of another prime focus trick that is not expressed in any book.

Here’s what you’ll need:

  • Camera

  • Telescope

  • T-Ring

  • 13% Moon Transmission Filter

  • A Set of Colored Filters


Do you remember how to Barlow Boost? No? Feel free to re-educate yourself: here. The same tactics are going to be deployed in this trick—except we’re going to use filters—instead of a Barlow lens.


Stick It Where the Sun Don’t Shine


Alright, young grasshopper, are you prepared for more training? Exhale deeply as you close your eyes and listen. This trick is subtle, but provides great power when used with supreme concentration.


Step 1: Stand telescope upright (if possible). This is not a necessity, but this method easily demonstrates how to engage the filter within the telescope barrel.

Step 2: Twist thumbscrews as seen in the image above

Step 4: Lay filter inside telescope barrel

Step 5: Re-twist the thumbscrews


** Do not ignore Step 5! It’s important that you secure the thumbscrews after the filter is engaged within the telescope barrel! Not doing so will result in a catastrophic failure. You’ve been warned.**

** I almost forgot: be cautious of fingerprints!**


Damn it, be careful! Gently glide the filter within the telescope barrel, otherwise it may decide to flip within the barrel. If that happens—you’ll break your telescope. Just kidding. All it means is you’ll have to fish the filter out with your greasy finger tips. No big deal.

I prefer to simply drop the filter and let gravity do the work, but if you don’t feel like being barbaric, ease the filter in with a cushion of caution. Don’t worry, these things aren’t made ofglass.

If everything goes right, it should look a little like this:


Yes—the filter is in there. Feel free to compare this image with the one at the beginning of this post. You’ll notice the inner telescope barrel has something in it. I wonder what it could be? Right! A 13% transmission moon filter!

After the filter is engaged: attach the camera to the telescope. Make sure thumbscrews are in as far as possible. The filter won’t fall below the ends of the screws—they stick out just far enough to clip the edge of the filter into place.


Show Me the Proof


You might be thinking: Ummmwho the hell would want to do such a thing?

Don’t be foolish, young grasshopper. This special ability is limited only by your imagination.


As we all know, the moon is obnoxiously bright. Wouldn’t it be grand if you could do something about it? Well, now you can. The image above was taken with a 13% light transmission filter at prime focus. Normally you need to expose for about 1/100 sec, otherwise the moon becomes over-exposed (at this particular phase). With the filter engaged, I was able to cut back the exposure to 1/5 of a second! I know, I know—save the applause for later.

A set of planetary filters can be experimented with as well.

Let’s see what happens when we pop in a green filter:

green moon-1

Looks like someone has gone and pissed off the moon! I like to call this “Lunar Hulk”. Luckily, humanity is buffered by at least 235,000 miles (378,195 km) otherwise we would be in, ummm, how can I say this? Deep shit.




Let’s see what happens when we pop in a blue filter:

Blue Moon-1

Oh look! A blue moon. A literal blue moon. Quite lovely how the craters are a bit more exaggerated. The green filter tends to smear out the lunar detail into a hypnotic haze.

Let’s see what happens when we pop in a yellow filter:

yellow moon-1

Ehhh, I don’t know. Looks a little nasty, but it’s somewhat easy on the eyes—if that makes sense. The yellow filter adds a subtle warmth to the image and provides enhanced contrast, especially near the Copernicus Crater (the large crater toward the middle left). Bright material is more obvious, as well as ridges of craters near the Tycho region.







Last, but not least: the red filter.

red moon1

Excuse me: now I have to go change my pants!

The red filter brings to light the moon’s evilness as if its lunar surface is saturated with blood from the sacrifice of a 100,000,000 goats.

In terms of exaggerating surface features, I can’t tell if the red filter provides any benefit. The lunar seas have a decent contrast. That’s about it.

Who doesn’t like a blood moon? Crimson moons are known to foretell unimaginable disasters. This blood moon foretells nothing. Literally. No, really—I can’t see much detail. The red filter completely stripped the moon of its cratery luster. But it looks bad-ass, right? That’s all that matters.

Colored filters can also be used for solar observation.


Humanity doesn’t stand a chance! A hulkified sun?!? Say your prayers. Kiss your loved ones goodbye. Write your obituary—the end is near.

**Warning: Colored filters are not solar filters! If you’re unfamiliar with solar observation, don’t point your telescope at the sun. Do you feel like incinerating your eyeballs? I didn’t think so.**


The End


The colored filters are technically designed for lunar observation AND planetary observation. I strongly recommend that you read the provided information about the filters: here.

Keep in mind this special trick, young grasshopper. Let your creativity lead the way into the future. Don’t be chained to the confines of your predictability. Set free your inner expression and be guided by the light of trickery.




Shooting for the Stars: Orion 102mm Maksutov

Shooting for the Stars: Canon EF 100mm Macro (Prime)

Shooting for the Stars: Opteka 500mm (Mirror / lens)

Shooting for the Stars: Canon EF 18-55mm (Kit Lens)

Shooting for the Stars: Canon EF 24mm (Prime)

Shooting for the Stars: Canon EF 50mm Macro (Prime)

Published by FlyTrapMan

I have no idea what I'm doing.

Express yourself

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: