Anyone digiscoping with DSLR at prime focus? (1 Viewer)

I bought my Nikon D70 digital SLR a while ago (mid 2004) and used it successfully with big scopes for astronomy at prime focus. Now I'm quite happily using it with my new much smaller 500mm FL f6 scope (effectively a 500mm f6 manual lens, instead of the Tamron 28-300mm).

Just wondering if anyone else here uses the prime focus technique, rather than the much more commonly used afocal projection (with eyepiece and adaptor to camera) ?

Hi David,
I use it now and then with the Celestron C5 scope. Focal length is about 1200 mm, and even though the scope is quite big, it's not heavy enough to balance well with my D2X or D200 cameras. With very long exposures and very short exposures it's fine and outputs nice results.
There's some vignetting though at the edges. I've added recently the reducer and vignetting is gone. Focal length is shorter (700~800mm) and the results are very nice. However, the bulkiness of the scope prevents me from walking around with it.
On top of that, I fell in love lately with the Leica SLR adapter mounted on my Apo 77 - providing the same focal length with stellar results (I've uploaded some samples in this site).
That said, I usually prefer the safe way - the 200-400 AFS VR F/4 + TCs and a P&S camera with scopes for the ultra long range...

g8ina said:

I bought my Nikon D70 digital SLR a while ago (mid 2004) and used it successfully with big scopes for astronomy at prime focus. Now I'm quite happily using it with my new much smaller 500mm FL f6 scope (effectively a 500mm f6 manual lens, instead of the Tamron 28-300mm).

Just wondering if anyone else here uses the prime focus technique, rather than the much more commonly used afocal projection (with eyepiece and adaptor to camera) ?

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I use a Skywatcher ED80 on my D70, bare or with converters. The results are very good even with converters.

Here's a page with shots from it, most have a kenko 1.4x converter on, and some even a stacked Sigma 1.4x too:
http://www.smugmug.com/gallery/1489917

Nice work Fernando !

What ISO settings do you use if you are running the scope and converter (at what must be f10 or so ?)

Thank you for the compliment.

Yup, F/10.5 with one converter.

Mostly between ISO 400 and 800, depending on the situation. Flight shots I allways do at ISO800 to keep the shutter speed high. With the scope alone I'm allways at ISO400 unless the light is very very poor.

FernandoBatista said:

I use a Skywatcher ED80 on my D70, bare or with converters. The results are very good even with converters.

Here's a page with shots from it, most have a kenko 1.4x converter on, and some even a stacked Sigma 1.4x too:
http://www.smugmug.com/gallery/1489917

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Congratulations, your pictures are absolutely stunning ! How can you take such perfect pictures of birds in flight with a manual focus lens ?
Your setup is not common and very interesting. Did you compare it with "standard" disgiscoping or "standard" telephoto ?
The main problems with long AF lenses are the price and the weight. And they are not "that" long... With digiscoping, the focal is much higher and it is very difficult to get a precise focus, especially on far subjects. Is the focus very precise on this scope ? Do you use a tripod or monopod or can it be used without it ?

SuperNo said:

Congratulations, your pictures are absolutely stunning !

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Thank you.

SuperNo said:

How can you take such perfect pictures of birds in flight with a manual focus lens ?

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Well, first don't compare manual focusing a telescope with manual focusing an AF lens. AF lenses are much tougher to focus, the focusing travel is much shorter and faster therefore making small and precise adjustments is very dificult. In a telescope this isn't the case.
Second, practice, my keepers rate as been improving more and more through the time I've been using the scope, an year and a half now. Right now in ten flight shots maybe two or three are out of focus but not by much.

SuperNo said:

Your setup is not common and very interesting. Did you compare it with "standard" disgiscoping or "standard" telephoto ?

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Yup, this setup is not seen everyday, in fact the only two times I met someone online trying this was the original poster and last week at Nikonians, I don't know why as this is an excelent setup, light, cheap and impressive image quality. Even with stacked converters the quality is very good, this shot (100% crop straight from the camera) was done with the Sigma 1.4x+Kenko 1.4x from my car window, with a Tshirt wrapped bellow the scope (Forgot the beanbag)
http://www.smugmug.com/photos/65421586-O.jpg
You can see moiré in the pic, that shows that even with stacked converters the lens is reaching the camera's full resolution.

About comparing it with other systems, not really, only with my own telephotos, Sigma 400 APO Macro, Tokina ATX400, Sigma 100-300. But the scope is much better than any of these in any level.
I wish I could get the opurtunity of comparing it to other systems or big lenses but so far I hadn't.

SuperNo said:

The main problems with long AF lenses are the price and the weight. And they are not "that" long... With digiscoping, the focal is much higher and it is very difficult to get a precise focus, especially on far subjects. Is the focus very precise on this scope ?

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Yes, the focus is very precise on this scope and it's also very easy to see where the focus is, even far away.
About the reach of the scopes VS telephotos, in this case the reach is the same as a 600mm lens, as this is a 600mm scope at prime focus, alltough the 600mm lens is much brighter. Off course you can add converters to strech the reach but you also can do that with a 600mm lens.

SuperNo said:

Do you use a tripod or monopod or can it be used without it ?

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Most of the shots I do are from my car window, the others from a tripod. Using this scope without suport at all is not an option. On a monopod it's ok, but the quality wont be the same and don't even think about using two converters.

Hi Fernando ,

Thanks for all these answers ! Your pictures (and others from a French photographer) are so convincing that a friend of mine is about to order the scope !

I have a last question : I've read that the minimum focus distance was pretty high (15m ?) . Even if the purpose of such a setup is not to make macrophoto, this can be a problem. Do you use an extension tube to reduce it ?

SuperNo said:

Hi Fernando ,

Thanks for all these answers ! Your pictures (and others from a French photographer) are so convincing that a friend of mine is about to order the scope !

I have a last question : I've read that the minimum focus distance was pretty high (15m ?) . Even if the purpose of such a setup is not to make macrophoto, this can be a problem. Do you use an extension tube to reduce it ?

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I depends on the scope, the adapter and how you set everything together.

In my scope the 7.5cm focusing travel is enought to focus from infinity to +-6m witch is more than enought with this focal lenght. Make sure you set the adapter in a way that the scope is focused at infinity when the focus barrel is retracted.

I'm using a homemade adapter made from an unused Nikon lens, I took out every piece of glass from inside it and also the mechanical parts, I only left the electronic gear, this way I get to keep the metering on the lens. I stuck a 2" focus extender (for telescopes not photography) inside it and it's done.

Here's a pic from the gear:
http://www.smugmug.com/photos/53578989-L.jpg
This is not the color of the scope, I repainted it as I hated the original color.

BTW witch scope is your friend gonna buy?

Hey Fernando, that is a great idea using an old Nikon lens to use the metering!!!

You should try selling them, I'd buy one for sure ! Guessing the exposure timing is OK but you only need the sun to go in or come out, and your guesswork is way off. I reckon I get only 20% of my scoped shots coming out with OK exposures.

FernandoBatista said:

BTW witch scope is your friend gonna buy?

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The same as yours ! In fact a famous french nature photographer (Gerard Therin) recommands it and says it's optically better than a premium 600AF lens that costs at least 10 times more. My friend has a Canon 20d and the 100-400L, and wants extra reach. The first review made her hesitate, then she saw your pictures... and finally ordered the scope !

g8ina said:

Hey Fernando, that is a great idea using an old Nikon lens to use the metering!!!

You should try selling them, I'd buy one for sure ! Guessing the exposure timing is OK but you only need the sun to go in or come out, and your guesswork is way off. I reckon I get only 20% of my scoped shots coming out with OK exposures.

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I've been told that before but frankly I don't want to make a business out of this. The lenght of the adapter changes from scope to scope so I wouldn't be able to do a model that would fit on every scope, on some scopes the user couldn't reach infinity others he couldn't reach the closest focus.
For example the adapter I have works from infinity to about 6m on the ED80 but on a Vixen 80SS I had it would only work from infinity to about 15m or so, for the Vixen the adapter needed at least 5cm more lenght.

But if you really want one made, find a lens you don't want/need and we'll discuss the price for the mod

FernandoBatista said:

I've been told that before but frankly I don't want to make a business out of this. The lenght of the adapter changes from scope to scope so I wouldn't be able to do a model that would fit on every scope, on some scopes the user couldn't reach infinity others he couldn't reach the closest focus. For example the adapter I have works from infinity to about 6m on the ED80 but on a Vixen 80SS I had it would only work from infinity to about 15m or so, for the Vixen the adapter needed at least 5cm more lenght. But if you really want one made, find a lens you don't want/need and we'll discuss the price for the mod

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Thanks for that - After thinking about it for a while, I don't see why I couldn't do this myself, so I'm looking into getting a broken or scratched lens from e*ay, and have asked Nikon for pin connection info. I doubt if they'll give it to me, but even with my limited knowledge I *might* be able to suss it out (I only have a degree in electronics). If I can't do it myself, I'll get back and we'll talk turkey

Thanks for the concept at the very least !

SuperNo said:

The same as yours ! In fact a famous french nature photographer (Gerard Therin) recommands it and says it's optically better than a premium 600AF lens that costs at least 10 times more. My friend has a Canon 20d and the 100-400L, and wants extra reach. The first review made her hesitate, then she saw your pictures... and finally ordered the scope !

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I guess I have to call skywatcher/orion and ask for a fee then )

Tell her to show some photos when she gets it.

g8ina said:

Thanks for that - After thinking about it for a while, I don't see why I couldn't do this myself, so I'm looking into getting a broken or scratched lens from e*ay, and have asked Nikon for pin connection info. I doubt if they'll give it to me, but even with my limited knowledge I *might* be able to suss it out (I only have a degree in electronics). If I can't do it myself, I'll get back and we'll talk turkey

Thanks for the concept at the very least !

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You can even get a working one, I got one quantaray from ebay (witch I used on the other scope because I made it longer) for about 30€ with shiping. It worked perfectly.

Why would you need to know the pin connection? Just make sure you don't damage the electronics while disassembling the lens. There's no need of messing with pins.

FernandoBatista said:

I guess I have to call skywatcher/orion and ask for a fee then )

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Yes :t: And if the results were good for real, maybe you could double the fee, as I would probably get one too

FernandoBatista said:

Tell her to show some photos when she gets it.

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Her gallery is here

Her English is even worse than mine, so she prefers me to ask the questions... If you speak a little French, you can write to her directly !

David

Sorry to drag you back to the start of this thread, but I am a beginner and trying hard to catch up. In my earlier thread I asked for advise on using a D70, Nikon FSA-L1 and a suitable Nikon 'scope. As the FSA plugs directly into the 'scope (i.e. no eyepeice) and bayonets directly into the body of the D70, is this not prime lens working? I agreed the adapter is not cheap, there is a commitment to use a Nikon ED 'scope and a support for the camera is probably required, but would it match Fernando results?

Go preparing your wallet then, you'll sure like it.

I took a look at her gallery, the deer shots are great.

And no, unfortunately I can't speak French at all.

James Walker said:

David, Sorry to drag you back to the start of this thread, but I am a beginner and trying hard to catch up. In my earlier thread I asked for advise on using a D70, Nikon FSA-L1 and a suitable Nikon 'scope. As the FSA plugs directly into the 'scope (i.e. no eyepeice) and bayonets directly into the body of the D70, is this not prime lens working? I agreed the adapter is not cheap, there is a commitment to use a Nikon ED 'scope and a support for the camera is probably required, but would it match Fernando results?

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OK James no prob. Yes, it is what we call prime focus - ie, no eyepiece between the scope and camera sensor. I didnt realise that the adaptor was a prime adaptor. Most digiscoping uses an eyepiece between the scope and the cammera and thats what I thought you were asking about. I use prime a lot now, but it has it's disadvantages in that the system is totally manual, focus and exposure. Fernando has a Skywatcher 80ED which has, I believe, about 650mm focal length. His technique is one I will be investigating over the next few weeks as a better solution to using my own scope in manual mode.

The biggie here with say a Nikon spotting scope is the focal length and focal ratio of the scope, as it is taking the place of the lens. My scope is a 500mm f6.2 with an 80mm objective lens. If the Nikon is an 82mm, check its overall length - that may give you an idea of the focal ratio. I think the smaller spotting scopes must have a much shorter focal length, therefore, not *that* much better at prime focus than say my 28-300mm zoom lens.

example of the sums :
diameter x focal ratio = focal length
80mm x f6.2 = 496mm focal length

Fernando does take some damn fine images but he has a lot of experience and has the advantage of metering with his special modded lens adaptor, so he does NOT have to guess his exposure times as I do. However, if you can gain that experience with a bigger scope, then there is no reason why you too could not achive similar results.

To summarise (sorry, Ive just been thinking out loud here) -

How much can you afford ? (my scope and T2 mount adaptor was about £250)
What level of convenience do you want ? (my setup is fully manual only)
What weight are you prepared to lug about ? (mine weighs in with camera and scope & tripod at over 10KGs, NOT really portable if out walking !)

Feel free to contact me by PM or email and we can arrange a chat on the phone if you like, I'm always happy to try and help. Bear in mind my background is astronomical photography, so my knowledge of scopes is slightly different to most in here (not meaning to sound big headed guys !)

Still confused ?? Hope not
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Fernando, thanks for the last message. I assumed that the AF system would need to be disabled.

James Walker said:

David

Sorry to drag you back to the start of this thread, but I am a beginner and trying hard to catch up. In my earlier thread I asked for advise on using a D70, Nikon FSA-L1 and a suitable Nikon 'scope. As the FSA plugs directly into the 'scope (i.e. no eyepeice) and bayonets directly into the body of the D70, is this not prime lens working? I agreed the adapter is not cheap, there is a commitment to use a Nikon ED 'scope and a support for the camera is probably required, but would it match Fernando results?

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Spotscopes like the Nikon are very good, and more than capable of excelent
images, but I still prefer the system I'm using for many reasons:

- Price, a Nikon 82ED cost +-1000€ +350€ for the FSA adapter. The ED80 costs 400€ and the homemade adapter costs around 30€ to 50€ at best. You can add two kenkos converters for more 350€ to have the same focal lenght more or less. Anyway it's around 800€ for the SKywacher system VS 1350€ of the Nikon system.
- Optical quality, the spotscopes are nice and resolution wise they can probably outresolve the D70 anyway so in this department they're both very good, but the bokeh I've seen from this systems is really harsh nothing at all like what I'm getting from the skywatcher even with converters, witch is very smooth.
- Focal lenght options, with the skywatcher I have 600mm F/7.5, 840 F/10.5 or 1200 F/15 depending on the converter used, so I can pretty much adapt to every situation. With the Nikon system you're stuck with 1000mm at F/13, in some situations this is too much focal lenght and more important too dark.
- If I want to change my camera brand I can still use my scope just have to redo the adapter, with the Nikon you're stuck.

For DSLRs the only advantage I find on the Nikon system or any similar system is the size, the scopes are very compact and easy to put on a backpak, the Skywatcher on the other hand is huge. For compact cameras spotscopes are the best choice though.

g8ina said:

Fernando, thanks for the last message. I assumed that the AF system would need to be disabled.

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Yes and no, with the converters on (F10.5 and F15), the autofocus is useless so switch it off or you wont be able to realease the shuter (in shutter priority), but with the scope alone (F/7.5) the AF still sees perfectly well and can help focusing, half press the shutter button and when you reach the focus point you'll ear a beep that's when you should fully press the button.

Of course the gears of the lens should come off.