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Old May 7, 2003, 6:50 AM   #1
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Default telescope for nikon camera

Has anyone tried a telescope with a nikon camera. I have a D100 and was thinking of getting a telescope for it, a Soligor MT800
with a visual power of 400x, whats the visual power of a 500mm lense?

is it useful or does it has extreme distortions? focusing problems?
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Old May 7, 2003, 8:37 AM   #2
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I would suggest posting this question in the digiscoping fourm here. There are some very knowledgeable people there who can give you all the info you need. Its the 4 or 5th from the bottom of the fourm list.

The general answer is that if a compatable T adapter is made you could do it, but you'll loose autofocus and have a fixed aperture. Kinda annoying. The easier/better way to do it is to use a camera like a CoolPix 4500 and attach it via a mounting system. You'll find more in those forums.
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Old May 7, 2003, 10:59 PM   #3
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Eric,
Magnification is not a good metric. You can have high magnification in a scope - but the image will look like crap. Magnification for a scope is calculated by dividing the focal length of the scope by the focal length of the eyepiece. In this case - they supply a 9mm eyepiece - for a mag of 800/9= 89. I'd doubt you could ever use smaller than a 6mm eyepiece with this scope. Surely not the 2mm required for 400x magnification.
A reflector telescope is a very poor choice for terrestial photography. Most 500mm reflector lenses work VERY poorly with a D100. I've have tried one - what a waste of money!
The scope will probably give you mag in the 1000-1500 MM range - but the images will lack contrast and be severely distorted by atmospheric disturbances - like heat waves. The scope is made for astronomical photography, and is probably good at that. I have several reflector scopes and do a bit of astrophotography. The D100 is a pretty good choice for a digital-astro camera as it will fit on a t-mount just like all good 35mm cameras have done for years. Scope adapters - such as flip mirrors and off-axis guiders are readily available. The D100 has a noise-reduction feature which subtracts a black frame automatically - just like you do with a manually CCD. So if you're getting the scope for astronomy - then great. Otherwise - spend that money on a good fast super tele lens.

Mark
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Old May 8, 2003, 7:44 AM   #4
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Default Magnification vs. Focal length and Reflex lenses

50mm is usually considered 1x mag. meaning its close to how the human eye sees the world. Using this assumption, 500mm lens is approx. 10x mag.

I recently bought a Rubinar 500mm f/5.6 Reflex (mirror) lens to go with my D100. It came with a M42x1 (not T mount) to Nikon F adapter. First problem, the built-in flash interferes with the barrel of the lens preventing mounting. Solution: a Tamron 1.4x TC. It seperated the lens from the body and increased the focal length to 700mm f/8 (with D100 FOV factor its like a 1050mm f/8 - 21x). I am currently having a custom adapter made to replace the TC. A newer Nikkor 500mm Reflex (or Tamron, Tokina, Sigma etc) should not have this mounting issue, but check it out first if you can. Next issue, on a D100 the metering (focus & exposure) do not work and its manual focus. You are left in full manual mode. I figure on using the Sunny 16 rule and calculating from there.

As to the quality and contrast of the Reflex lens, below are 4 pictures (2 reduced images each with a 1:1 pixel crop)
All were taken with this combination:
D100 (JPG, Large, 1/250 sec, Manual Mode, WB Cloudy -2, Crop only, no additional enhancements)
Rubinar 500mm f/5.6 Reflex Lens (circa 1994)
M42/Nikon adapter ring with lens element
Tamron 1.4x AF-D Teleconverter
Bogen Jr. 3405









Just to give some hint of the PULL this lens has, here are two more shots. Both were taken from the same location. One using a Nikkor 28-105mm (at 35mm - 52mm after crop factor) and the other using the Rubinar 500mm with the 1.4x TC (1050mm after crop factor). The Close-up was enhanced as I completely underexposed the shot. My fault!





You make the decision.
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Old May 8, 2003, 6:22 PM   #5
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wow.. thanks.. that's alot of extremely useful info!

seems like it has alot of power to give, lacking focus a bit but that can be excused some...
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Old May 8, 2003, 8:06 PM   #6
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A mirror lens is a very cheap way to get yourself a lot of reach. The only downsides I remember are that they are usually manual focus (I've never seen an AF one, but I am ignorant about the possability of their existance) and many people find the unfocused background unattractive or distracting.

Personally, I find the background on the first image distracting (for example.)

I know others that like it, thought, so make your own judgements.
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Old May 12, 2003, 12:02 PM   #7
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A side note on the photos above:

As stated the 500mm reflex lens was used with a 1.4x TC. After doing some shooting this weekend, I noticed a minor loss in sharpness when using it with my Nikkor AF-D 28-105 f/3.5-4.5 IF, usually a very sharp lens. So keep that in mind when judging the photos for sharpness.

I am having a custom adapter so I can use this lens without a TC. This will probably cause me some other issues (loss of infinity focus) but there are ways around that too. I will cross that bridge when i get there. I will post some photos when available.

I wouldn't call them a VERY cheap solution. Less expensive maybe... A used Nikkor 500mm f/8 runs about $250-500 on ebay. I know of a shop in Philly that has one for $300. You can find some for $100 but they are usually cheaply built and have very poor sharpness and contrast (Kalimar, Soligor, Starblitz, Samyang, etc). The best are Nikkor (Nikon), Tamron, and Sigma. I went with the Rubinar because I read good things about them on astronomy sites. It cost me $120 and I still had to buy $130 TC just to use it. For $250 I could have gotten a Nikkor.

As far as I know, reflex/mirror lenses are all manual focus. Some newer ones allow for the use of shutter and/or aperture priority, but most are strictly manual exposure on newer cameras. On older bodies, the meter usually works.

The background on these lenses is very different due to how the lens works. Instead of being fuzzy spots, they are fuzzy donuts. Whether it makes the background distracting or interesting is in the eye of the beholder.

All in all, I am quite satisfied with it.
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Old May 12, 2003, 10:26 PM   #8
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Well, I really meant very cheap in comparison to the 400, 500, & 600mm Auto Focus lenses you can buy. Those are large, heavy, and cost as much as a decent used car (>$3,500USD) That makes $300 look cheap.

I realize what causes the differences in background/bokeh. Some people like it, but I know many who don't. Personally, I'm in the "don't" group. It's something that the buyer should be aware of and pick the lens knowing it will yield a "different" background than they might be used to.

I hadn't heard that they added support for some Priority modes. Good to know. I don't mind the loss of manual focus, personally.
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Old May 13, 2003, 11:28 AM   #9
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Now here is one last shot of what it is suppose to be used for.



Rubinar 500mm Reflex lens
Tamron AFD 1.4x TC
Nikon D100
1/100Sec, f/5.6 (f/8 w/TC)
Manual Exposure

Adjustments:
Cropped from Horizontal to Vertical
Color corrected
Resized for posting

IMHO, Not too bad for my first moon shot...
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