Nikon D800 and Pentax 645 FA* 300mm f/4 ED

[Astrofriend (Lars)]

My latest project.

A Nikon D800 full frame camera, first thing, remove the IR filter and the others

http://www.astrofriend.eu/astronomy/...ikon-d800.html

In somehow remote control it from KStars or PC Windows with APT.

A Pentax 645 FA* 300mm f/4 ED lens

http://www.astrofriend.eu/astronomy/...5fa-300ed.html

Make them fit together with 3D printed parts

Add Off-axis adapter
Add Tilt adapter

Longtime project for sure.

Lars

[Astrofriend (Lars)]

Today I started to design the adapter that will connect the Nikon camera to the Pentax 645 lens. I have divided it in two different devices to get it easier to 3D-print.

Here is a prototype of the end of the adapter that connect to the Pentax 645 lens:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

The camera and the lens weights 2.7 kg together, I'm not sure if the strength of the adapter will be strong enough.

Lars

[Leo.G (Leo)]

This is an interesting project but I have one question regarding the D800.
How is it's live view in low light?
Silly question I know but I have the D810 and it's low light live view is beyond disgusting for an expensive camera. It becomes nothing but noise in low light use and is useless as a focusing aid for astrophotography. I run in and out with my CF card to check focus on my 27" monitor attached to my computer because I can't see a thing in live view. Then I have to hope I don't bump my lens when I put the card back in (mainly for widefield/Milky Way.

Daylight use I have absolutely no complaints but once the light levels drop so does it's quality.

[Astrofriend (Lars)]

Hi,
For daytime photo I use my Canon camera. This Nikon is bought only for astrowork. I have no idea how well the live view works. If I use live view it's only for focusing when doing time plase, ie meteor showers.

Lars

[Astrofriend (Lars)]

Last days I have done a lot of work with the adapter design. I can now connect the Nikon camera to the Pentax 645 lens system.

Latest project page:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

When skipping the Nikon bayonet I got a much bigger opening, now 46.5 mm, good for full frame sensors.

Lars

[Leo.G (Leo)]

What mount does the Pentax 645 have?


Damn, I just looked it up, I want one of those in my collection one day.

[Astrofriend (Lars)]

It's big ! Big opening and long back focus, big reason to use medium format lenses. This Pentax lens has ED lenses and this later model has two extra lenses for better correction.

I added more photos and information to my project with this lens:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

Are your astro season going towards the end now ? Our has just started.

Lars

[Leo.G (Leo)]

We're just in our last month of winter but winter doesn't necessarily shut our asto down because it doesn't ice up like many other places. Where I live in the mountains we may drop to -10 overnight and occasional light snow but the skie are usually so crisp it's a joy to be out there (in the right gear with an electric hair dryer because I don't have a good dew strap system yet). Spring is often lovely too but we've had a few very wet years, hopefully this one will be dryer. Summer is good too except for the mosquitoes.

[OzEclipse (Joe Cali)]

Originally Posted by Leo.G

We're just in our last month of winter but winter doesn't necessarily shut our asto down because it doesn't ice up like many other places. Where I live in the mountains we may drop to -10 overnight and occasional light snow but the skie are usually so crisp it's a joy to be out there (in the right gear with an electric hair dryer because I don't have a good dew strap system yet). Spring is often lovely too but we've had a few very wet years, hopefully this one will be dryer. Summer is good too except for the mosquitoes.

Leo,

Good news. You don't need a "good" dew strap system.

A really cheap mediocre one will do just fine. In 2016, I bought a $15 USB jacket off eBay. I thought I'd get a couple of years out of it, 8 years later, still going strong. They now cost the princely sum of $23 each.

https://tinyurl.com/4dj3xmbj

At a pinch, a chemical hand warmer pack held in place with a compression strap works fine as a makeshift dew heater.

Joe

[Leo.G (Leo)]

Thanks Joe!
I have one for my camera lenses, it works off a power bank and is extremely good when I get the incentive/health to take my D810 and 14mm f2.8 (Samyong) lens out to shoot the Milky Way.
I had previously made a resistor heating ring to fit one lens from online instructions and bought Nichrome wire to make a more flexible version but never got around to it.
What about the expensive dew strap/controller combinations (out of my price range)?
Stupid question most likely but are they worth the money?


One day I may find something in my price range on here in the classifieds.

I'm thinking the controller wouldn't be hard for me to to make my own using a switch mode power supply out of a computer. Since I do most of my stuff in my back yard where I have access to mains power it wouldn't be a bad idea and pick up a few dew straps when they become available in the classifieds.
They are mostly a 12 volt system are they not?


I just did some research and I already have several of the dimmer units many hobbyists seem to like for the systems. I bought them as speed controls for model trains.


https://content.instructables.com/FA...51eb0376ba742c

[Astrofriend (Lars)]

Without a dew heater my lenses fog up after 30 minutes. My latest dew heater is USB heaters. From the beginning too hig power, but I connected two of them in serial and get more normal temperature. Very cheap solution, bought from Amazon, a package of 5 inclusive 5 power regulators, maybe I payed 60 Euro for all of them.

Here is my project dew heater:

http://www.astrofriend.eu/astronomy/...ting-band.html

Here in the Northern Europe (Sweden) we have our astronomy season from October to April. Temperatures from 0 C degree to -20 C Degree. I have tested my equipment at -20 C degree and to my surprise it worked, but not me.

A lot of updates in my ongoing project Nikon D800/Pentax 645 FA 300mm f/4 ED lens:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

Lars

[Leo.G (Leo)]

I still work at -12 but thankfully never had to find out if I can survive -20.
My beard would freeze and snap off I think.

[Astrofriend (Lars)]

More updates:

I have made 3D-printed brackets, focus driver, triple DC/DC box. The computer can be a mini PC Windows or a Raspberry Pi5. Computer power by either a 12/18 volt 3 Amp DC/DC converter or a 12/5 volt 5 Amp DC/DC.

If my idea about a Nikon D800 camera don't work well for astro it's easy to convert to my old Canon 6D.

Details here:
http://www.astrofriend.eu/astronomy/...ikon-d800.html

The last thing I did was a 3D-printed dove tail and on top of that a main bracket that holds all the devices together.

Missing the stepper motor and a pivot bracket to it.

Lars

[Astrofriend (Lars)]

I have now installed the stepper motor for the tangent arm focuser. Looks to work but I haven't test it with the driver yet.

Here how it looks, most pages has updated photos and text:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

Lars

[Leo.G (Leo)]

That's looking good!
It must take you a lot of time designing all of this 3D printed stuff?

[Astrofriend (Lars)]

Hi Leo,

Yes, a very lot, but with that I can do things I only could dream about earlier.

Lars

[Astrofriend (Lars)]

Today I could do the first test to communicate with the Nikon camera. I started with the Windows system and used APT. It worked very well, none of the problem I have read about using a Nikon camera, maybe that bad reputation was for earlier models than mine.

Here is my documentation:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

Lars

[Astrofriend (Lars)]

First Light

Isn't it very exiting when testing a new device for the first time. This night I did my first test of the Nikon D800 and the Pentax 645 FA 300mm ED f/4 lens.

After some strugle I got an image, not very good because not all of the equipment is finished yet.

This is how it looks:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

It look promissing to me. After this first test I had built a new motor focuser system, based on MyFocuserPro2. Almost exact the same design as my earlier one. It worked imediately after I power it up.

My biggest problem now is to get the ASI120 guide camera to work. This camera has some problem with Linux, I had it flashed with a new software, but still it doesn't work as it should.

Lars

[Astrofriend (Lars)]

A couples of nights ago we had a clear sky. I took some photos of the galaxy M81. That galaxy I have some photos from with my older equipment and I can now compare the two systems.

The Nikon D800 & Pentax 645 FA 300mm ED f/4
vs
Canon 6D & Pentax 645 300mm ED f/4

Of course not perfect control of the environment but still very exciting to compare them. That's important for me, which camera shall I spent the time with and which lens ? One of the cameras I will remove the filters from and the mirror as well.

Here is the first images to compare and some data I have collected about the cameras:

http://www.astrofriend.eu/astronomy/...ikon-d800.html

There isn't much difference, but I prefer the Nikon D800 with the Pentax FA lens.

Do you feel the same ?

Lars

[Astrofriend (Lars)]

Every night there is a clear sky I take out my new equipment on the balcony. Take a lot of test photos, I'm on the go to build the tilt adapter, just waitng for some parts that I have ordered.

For you who curious how the the combination Nikon D800 and Pentax 645 FA 300mm f/4 ED perform I have som examples here:

http://www.astrofriend.eu/astronomy/...n-cluster.html

http://www.astrofriend.eu/astronomy/...n-cluster.html

http://www.astrofriend.eu/astronomy/...ry-nebula.html

Look at the high resolution images. Even if there is some tilt I'm impressed. But to be honest, the older version of the Pentax 645 isn't bad either, the one without "FA" letters.

The of-axis guiding help a lot compare to the older guide telescope.

The Nikon camera has a lot of pixels. What's just a dot in center can be zoomed in and then you have something there. But it eating my hard drives in a fast pace.

Lars