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