[diazemmanuel]

I am interested to start digiscoping. I now use a Nikon D90 DSLR. I plan to buy and attach the DSLR to a Celestron C90 Mak (new 2010 model) spotting scope. What are advantages and disadvantages of such a setup?

Using scope's lens, the I know I will have to focus manually (or use aperture-priority settings, if possible (?)). Question: what max aperture will be available to me, i.e., in 35mm camera terms?

I read through the C90's manual and it says I have to remove eyepiece, use available scope's T-adapter thread and use T-adapter to attach the D90. Question: what's the focal length of the spotter scope in 35mm camera terms? I read from some threads in this forum that you can directly attach a DSLR without removing eyepiece. Is this also possible with this setup? How do I go about it? What equipment will I need to buy?

I already have a lot of questions. I appreciate answers. Your responses will be of great help as I will use the proposed setup on my work on biodiversity conservation, including birds.

Best regards to all.

[Paul Corfield]

There's not many advantages to using a Mak as a photographic tool. The downsides are the high starting f ratio which is around f14 and this will mean very slow shutter speeds on days that aren't sunny. The 35mm equivalent is around 1875mm which is a lot of magnification for anything at closer range, say under 30m (100 feet). The high magnification also means that vibrations will be greatly enhanced and this tends to be a problem with most mirror lenses. With mirror lenses you get quite bad bokeh, they call it doughnut rings, see attached example.

Advantages are that they are small, lightweight and inexpensive for the amount of magnification. If image quality is important then the bad points outweigh the good points in my opinion.

Paul.

[diazemmanuel]

Many thanks Paul. I understand your technical misgivings about the C90 Mak. But I can also foresee of the possibilities of using the C90 Mak as a long telephoto...Will it be the same technical considerations for a refractor scope like the Celestron Ultima series and variants? Any recommendations?

Regards.

Emmanuel

[Paul Corfield]

What sort of range are you going to be photographing things at?

Paul.

[diazemmanuel]

200-300 m max. will include hard to go near plants and shy animals, including birds on limbs probably.

[diazemmanuel]

sorry i mean 200-300 ft not m.

[Paul Corfield]

Hard to know what to suggest really. Digital slr's on the back of spotting scopes comes with it's own problems, mainly the size/weight of the camera with lens and mounting it all to the eyepiece. To get the best images you need a scope with ED glass and one with a good quality eyepiece. The budget quickly starts to spiral at this point.

Going back to the Maksutov type of scope, have a look at this link and see if the images would meet your needs. He's using an Orion 150mm Mak which is a better option due to its better light gathering abilities.http://www.billmajoros.com/photoalbu...ens/index.html

I'm generally of the opinion that a digital slr is best mounted to an astronomical type of scope, either a refractor or mirror type. I use a 600mm refractor personally. Spotting scopes are better suited to small digital cameras which is why I wouldn't recommend a spotting scope as your best course of action if the Nikon D90 is to be the camera you are going to be using.

[Paul Corfield]

Also look at the Celestron C5 as it has a better focal ratio at around f10 and 1250mm or 1875mm in 35mm terms.

Good selection of bird photos with the C5 in the gallery section at http://www.birdforum.net/gallery/sea...earchid=151860

Paul.