Introduction

Astrophotography is a discipline dedicated to photographing the night sky in all its splendor.
For this exercise to be successful, there are a series of environmental conditions, equipment demands and photographic operational- plus post-production techniques that we will explore in broad lines in in this article.
Thus, people who are starting out in the discipline can have a general idea on how to achieve satisfying results and, in addition, can prepare properly for a night excursion taking the necessary precautions for their greater protection and comfort.

Environment

In Chile we are still fortunate enough to find fairly dark locations relatively close to the big cities, an essential condition for astrophotography.
Although there are many people in other latitudes whom have to cope with far worse conditions than ours, nothing beats a location with low light pollution to capture outstanding sky images.
In Santiago we can access relatively dark skies in the Cajón de Maipo, at distances between 90 (San José de Maipo) and 180 km (El Yeso Reservoir Lake), respectively, while those traveling to places like Vicuña – in the Elqui Valley – or better yet, to San Pedro de Atacama, can still find clear skies with very low levels of light pollution.
It is no coincidence that Chile’s second to fourth regions concentrate a large number of astronomical observatories, such as Tololo, Paranal, ALMA and E-ELT, among others.
The ideal nights are clear and moonless, while the best locations are as high up as possible.
My locations in the Cajón de Maipo are all well over 2.000 meters, above the flying dust and as far away as possible from major potential sources of light pollution.

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For little under a decade, the Nikon D90/D7K series has been the jumping point for those who were looking to move into the major leagues.
Or for those looking to move down and still get a DSLR with pro-akin performance at an affordable price.
Today, the price gap between the prosumer D7K series and the semi-pro Nikon D500 is in the order of 50% (USD 600) or more, while the differences in performance and operability are probably only appreciable to those of us who really put a camera through its paces.

With the launch of the D7500, Nikon has changed all that.
The marketing department, with its long-standing track record of navel staring, decided that the D7200 is too good to be true (which it is), too much akin to the D500, and ought to be stripped down.
Remember that, while the D500 is undoubtedly an outstanding camera, the company disappointed many of its fans taking close to 9 years for the D500 to replace the venerable D300, while advancing decidedly with the D7K series.
Thus placing a serious incentive on acquiring one of these, rather than shelling out for more expensive, sometimes handicapped, baby FX models such as the D600.

Although the D500 outshines the D7200 with a more sophisticated AF system (Multi-CAM 20K), inherited from the D5, a better processing engine (Expeed 5 vs. 4), a better buffer, and maybe a slightly more thorough build, the much cheaper camera has little else to envy its bigger sister. 
Least of all its odd double card set-up with one XQD- and one SDHC slot.

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Many a telescope owner, after gazing at the sky for a while, wants more; want to share what they are seeing.
There are several ways to achieve this. The most obvious is shooting through the telescope eyepiece with a small camera or cell phone. Since this is very difficult to do hand-held, you can find many economical cellphone adapters on the web (± USD 20).
The other alternative is using the telescope as if it were a long fixed-focal, fixed-aperture lens, mounting a DSLR or mirrorless (CSC) camera sans lens on the telescope focuser.
In this article we explore the different alternatives, tools, pros & cons of both methods.

Eyepiece projection

The advantage of shooting through the eyepiece, so-called eyepiece projection, is that its magnification allows you to get a high enlargement on sky objects.
The disadvantage is that a cell-phone or a point-and-shoot are not great cameras and, moreover, that image quality heavily depends on the optical quality of one’s eyepieces.
If you still use the eyepieces that came bundled with your telescope, you may want to upgrade at least one before venturing into eyepiece projection. Otherwise you are most likely going to get disappointed.
That said, in my research for this article I came across a DSLR adapter for eyepiece projection (USD 150), which could possibly overcome the low IQ issues of cell-phones and point-and-shoot cameras.
However, I have no idea how well it works. Check it out for yourself clicking here. 

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The Crayford telescope focuser design – developed in 1971 by John Wall and named after the Crayford Manor House astronomical society – has a number of important advantages over rack-and-pinion and can be home built out of wood by almost anybody with a bit of patience and the right tools at hand.
Although some prefer to build the design in metal, with the associated advantages, that approach requires specialized metal working tools, generally out of scope for most home builders.
The 2” woodshop design presented here is scalable, has proven to be sturdy, reliable and, most importantly, when built to tight enough tolerances, allows for very precise focusing, even under heavy loads.
I designed this focuser specifically to carry the weight of a Nikon D7100 camera (± 800 gr) on prime focus, which is considerably heavier than even the largest eyepieces. So far, it is holding up admirably.

Even though building this design is probably possible utilizing hand tools only, for tight tolerances the following specialty tools are recommended:
Electrical table saw and/or
Miter saw: electrical table top and/or manual
Jigsaw
Belt sander (80 grit belt)
Vertical drill stand
Drill press vice
Glue clamps
Hole saw, 54mm (2 1/8”)
Wood drill bits: 1mm, 3mm, 4/4.5mm, 5/5.5mm and 8mm
Thread tapping set

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Quite a few people end up here to try to get answers to their million-dollar questions, such as: “Is my D50 motorized or not?”, “Can my D100 focus and meter with manual focus lenses?”, “Is my D3100 geo-tagging (GPS) capable?”, and so on.
I have concocted a compatibility table that pretends to answer these questions all at once. One-stop shopping to solve your Nikon DSLR doubts, so to say.
It is so large that it does not fit my standard blog page, which is why I’m providing the table both in HTML and PDF.
Because to err is human and to forgive divine, I would greatly appreciate you dropping me a line if you find any errors.
Thanks!

For the HTML version click here, for the PDF version click here.
Note that cameras are ordered chronologically by launch date.

I’m writing this post nearly 5 years after Can I use Nikkor AI and AI-S manual focus lenses on my Nikon DSLR?, because the interest of Nikonians for legacy lenses is undeniable, while my research into the topic has added some – hopefully worthwhile – facts.
At the same time, the value of manual focus NAI and AI(S) lenses is clearly on the rise, which is good for everyone who has a few of grannies F-lenses lying around, either for proper use or sale.

The Nikon F-Mount was launched with the Nikon F camera in 1959 and has remained virtually unchanged since, making it the only camera mount still in production almost 6 decades after its introduction.
The F-mount can be found in five versions: F, AI, AI-S, AF and Non-MF (Fig. 1).
The latter made its debut in 1987 on the F-401 (N4004), is used on the D40 to D100, D3000 and D5000 series and essentially a downgrade back to the original F-Mount, because it lacks the meter coupling lever to interface with non-cpu lenses. This is why none of these cameras exposure meter with MF lenses.

The F-mount has only seen two major updates.
The first from the original Auto-Nikkor to Auto-Indexing (AI), with the addition of the meter coupling lever – introduced on the Nikon F2 Photomic A in March 1977 – and the second from AI-S to AF, with the launch of Nikon’s first flagship auto-focus camera, the F3-AF, in April 1983, followed by the popular Nikon F-501 (N2020), two years later.

Where the manual focus system update from F-Auto to AI was basically oriented at making existing technology (aperture indexing) more user friendly, the update to AF may be considered break-through.
With it, Nikon replaces mechanical camera-lens coupling with a cpu-driven, electronic camera-lens interface, allowing for many posterior innovations such as aperture control from the camera body, electronic range finding, distance metering (with D and G-type lenses), EXIF data recording, AF-S, VR, iTTL flash, etc.

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While I give them considerable credit for their thorough camera sensor testing and ranking, those of us who look to DxO Mark to help us decide which lenses are the “best” for our particular cameras have been lead astray for too long, already.
One particular testing item that has always called my attention, but had never bothered to research – until now – was the infamous DxO Mark “Best at” Score, which, without exception, suggests that lenses ought to be shot wide-open for best performance.

Shooting lenses wide open might be interesting in certain situations, but in general does not make much sense, because they are typically at their optical best at around two stops down from their maximum aperture.
It also called my attention that lenses we all know to be average keep picking up DxO score on newer, higher resolution and/or full-frame cameras, while some legendary ones keep getting below average scores, independent of the camera they are “tested” on.

As it turns out, and I quote:
“DxO Mark Score is measured for low-light conditions: 150 lux and 1/60s exposure time. Such conditions correspond to a correctly lit living room (with no daylight).
It is a difficult, but rather typical photographic use case.”

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