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07-20-2011, 01:41 PM   #46
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QuoteOriginally posted by littledrawe Quote
are there any issues with focusing on your DSLR, is it as simple as focusing a manual lens?

Yup - but instead of having the focusing barrel on the lens itself, its a pair of wheels near the end of the scope - see my photo. Also, you WILL need a tripod, or the very least, a monopod

QuoteOriginally posted by littledrawe Quote
Wildman, in your set up, the stuff between the camera body and the scope itself is extension tubes to improve your minimum focus distance? Am I understanding that correctly?

If I were to just use the adapter "Squier" linked what would the minimum focus be?
The tubes do both - infinity and close focusing. The compromise is only how much extension tube you actually fit. Too much tube and you lose infinity focus, and depending on how much tube, you lose infinity focus to a BIG degree, like I posted above.

If you have no ext. tubes at all, and just the adapter, you wont be focusing on anything, be it near or far


Last edited by Squier; 07-20-2011 at 01:46 PM.
07-20-2011, 05:05 PM   #47
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I recommend you start with the sigma 170-500, gain experience with heavy lenses antd if you like it, move to 300 mm f2.8 + 1.4x Tamron TC. Read my rerview of the sigma first.
07-20-2011, 06:47 PM   #48
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Thats where I'm at

"I recommend you start with the sigma 170-500, gain experience with heavy lenses antd if you like it, move to 300 mm f2.8 + 1.4x Tamron TC. Read my rerview of the sigma first."

I don't remember hearing good things about the sigma when I started this journey. I had a 400mm f5.6 and a Kenko 1.5X TC, It was alright but just didn't give me what I want. I now have the Pentax 1.7X AFA + Tamron 300mm f2.8 which I shoot handheld and with a monopod.
I am not, at this moment, in a position to buy one of these but I like the Idea of something longer than what I have and with equal or superior image quality, that is readily available and affordable. I personally would love to have an A*600 but the chances of me finding one for sale and being able to drop that much coin right at that moment are slim at best.
I think it is totally silly that pentax doesn't have one current lens in production in the super telephoto range.
07-20-2011, 06:52 PM   #49
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I am following this with a lot of olinterest, although I lucked out in a quest for a long lens just 2 weeks ago, a tamron 200-500f5.6. What it has is good sharpness and good speed for the FL and focuses from infinity to 2.5 meters that is really really close for a 500mm!

07-21-2011, 01:55 AM - 1 Like   #50
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QuoteOriginally posted by littledrawe Quote
Wildman, in your set up, the stuff between the camera body and the scope itself is extension tubes to improve your minimum focus distance? Am I understanding that correctly?
Yes.
That photo shows an atypical setup for closeup work. I was shooting butterflies that day. It works well for this purpose because I can change the extension on the fly because the tube slides back and forth about 60mm as well as adding additional fixed extension. Squier is right you can lose collimation if you are not careful and add too much. See close up shot of pecker and butterfly with this setup.

For normal shooting the amount of extension is much shorter and more simple - see pic.

A note:
There is a big difference between spotting scopes and astro scopes. Astro scopes are simple two or three elements affairs with nothing between the front objectives and the focal plane of the camera except air. In other words they are used at prime focus.

A spotting scope has an added prism. This prism leads to a noticeable loss of IQ compared to shooting at prime focus. I can and do shoot using a spotter but only when extreme magnification is more important than IQ. It gives me an equivalent of about 2000mm (40x) at f12 set up this way. see eagle pic at about 300 feet.

Last edited by wildman; 08-01-2011 at 01:57 AM.
07-21-2011, 05:44 PM   #51
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QuoteOriginally posted by wildman Quote
Yes.
That photo shows an atypical setup for closeup work. I was shooting butterflies that day. It works well for this purpose because I can change the extension on the fly because the tube slides back and forth about 60mm as well as adding additional fixed extension. Squier is right you can lose collimation if you are not careful and add too much. See close up shot of pecker and butterfly with this setup.

For normal shooting the amount of extension is much shorter and more simple - see pic.

A note:
There is a big difference between spotting scopes and astro scopes. Astro scopes are simple two or three elements affairs with nothing between the front objectives and the focal plane of the camera except air. In other words they are used at prime focus.

A spotting scope has an added prism. This prism leads to a noticeable loss of IQ compared to shooting at prime focus. I can and do shoot using a spotter but only when extreme magnification is more important than IQ. It gives me an equivalent of about 2000mm (40x) at f12 set up this way. see eagle pic at about 300 feet.
love the shots

a quick question regarding the difference between a spotting scope and the astro scope, as you define them.

For me, I see no relevence to adding a prism, in calling a scope an astro scope or spotting scope. all a prism does is give non inverted correct left to right image. It does nothing for magnification on it;s own, and magnification is not defined by just the main objective group, BUT the combination of the main objective group and an eye peice.


As you state what you call an astro scope (i.e. the prime lens without eyepeice ) is just that a prime lens.

unless you have an eyepeice adaptor and shoot using the eyepeice adaptor as well, the lens is the lens, regardles sof whether you put the prism in or not
07-21-2011, 06:24 PM   #52
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QuoteOriginally posted by wildman Quote
Yes.
I can and do shoot using a spotter but only when extreme magnification is more important than IQ. It gives me an equivalent of about 2000mm (40x) at f12 set up this way. see eagle pic at about 300 feet.

I had almost considered Digiscoping, but its just not as fast as a prime focus/scope set up. Besides that, the huge magnification ( say 2000mm used at distance of 200 metres ) , is subject to every bit of atmospheric disturbance going.
It would become increasingly important that the right time of day ( assuming its bright and not hacking down with rain/ coudy or whatever ) when trying to shoot birds at such distance. Cold bright still air of early moring or early evening would be prime time, and for the subject to be still

Of course you dont have to use a 2000mm lens only for distance work, so i was still in 2 minds about it. The trouble is for me, is that i was avoiding big FL glass from Canon ( when i was Canon shooter ) and Pentax big glass too, or even Sigmas monster lenses, because of price. I wanted the reach without the coin, so prime focus scoping was the choice, therefore another nail in the coffin for Digiscoping, because the quality is really in the costly Digiscopes, from Kowa ( TN 884 and similar ) Nikon ( EDG 85 Fieldscope - ED82 Fieldscope ) Swarvoski etc etc etc. The point for me was not to pay this sort of money, so didnt go that route.

I'd love to try it, but i wouldnt be happy unless i had some serious quality kit
07-22-2011, 01:42 AM   #53
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QuoteOriginally posted by Lowell Goudge Quote
all a prism does is give non inverted
correct left to right image.
A prism adds back focus. The refractive index of the glass prism slows
down the light passing thru it compared to air. So the light cone
doesn't converge on the focal point quite as fast. The focal length of
the scope is not changed but the light path is lengthened.

Also what I was talking about, with respect to photography and
especially digital photography, is that introducing a prism into the
light path introduces aberrations of it's own. Notably spherical
aberration, color fringing and field aberrations when placed in a
converging light path.

If you are a gear head and really want to get into it, and God only
knows I don't, I suggest you go over to the Cloudy Night forum. This
sort of stuff is raw meat to those folks.

Suffice to say that my practical empirical experience is that
introducing a prism into the light path always substantially reduces IQ
in my final images. Particularly so when the focal plane is a digital
sensor rather than visual (the eye).

QuoteOriginally posted by Lowell Goudge Quote
magnification is not defined by just the
main objective group, BUT the combination of the main objective group
and an eye peice.
You don't need an eyepiece to determine magnification:

If we accept the convention that a "normal" lens (zero
magnification-neither a wide angle nor a telephoto) is defined by the
diagonal of the focal plane (sensor) then in the case of my K20 that
would be 28mm.

Then divide the the focal length of the lens by the diagonal of the sensor (28mm)
and you get the magnification.

So a 100mm lens = 100mm/28mm=3.57x mag. Or to put it another way on my
K20 I get 3.57x mag per 100mm of FL. Thus a 600mm FL lens would give me
3.57x6=21x mag. I just round it off to 3x mag per 100mm so 3x6=18x mag.
Close enough for me.

Anyway get out there in the field and look for birds that's what it is
really all about.


Last edited by wildman; 07-22-2011 at 01:56 AM.
07-22-2011, 02:25 AM   #54
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QuoteOriginally posted by Squier Quote
Besides that, the huge magnification ( say 2000mm used at distance of 200 metres ) , is subject to every bit of atmospheric disturbance going.
Yep. I have found that as little as 60ft and I start to see the effects of air trubulance at the magnifications I shoot at.

QuoteOriginally posted by Squier Quote
The trouble is for me, is that i was avoiding big FL glass from Canon ( when i was Canon shooter ) and Pentax big glass too, or even Sigmas monster lenses, because of price.
I hear you! The price of a conventional 800mm tele is just not practical for most folks.

Here's a shot of my spotter setup. It's a 100mm (objective size not FL) Pentax with the Pentax CA-35 SLR camera adapter. About $1500 for the scope and $400 for the adapter. The adapter is not just a passive mechanical adapter but also has optics in it that acts as a 2x TC. Image is correct (not upside down or reversed right and left) with no vignetting etc etc that you usually got kludging together the typical Digiscoping setup - it's all worked out for you by Pentax and works well together.

Last edited by wildman; 08-01-2011 at 01:57 AM.
07-22-2011, 04:54 AM   #55
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Thats serious ! Now if was going to get into Digiscoping , that'd be the type of kit i'd be gunning for

I guess thats the Pentax 100ED. The price of that adapter is more than i paid for my SW 120 scope :-) What is the camera you use for that set up?

I've heard good things about Pentax digi scopes too, up there with Kowa Nikon Swarvoski Vortex Zeiss TV etc.

I see you're using what looks like a Manfrotto 393 - best bang for buck gimbal on the market. I had one for my previous Double SW 80ED. Excellent piece of kit

How do you find having to focus the scope AND the camera, when shooting ?

Last edited by Squier; 07-22-2011 at 05:02 AM.
07-22-2011, 05:35 AM   #56
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wildman

the only point I was trying to really clarify out of your post regarding the prism and spotting scope, was that it seemed to imply that using a scope with a prism some how gave you more magnification than a scope without. as for the distortion the prism offers, I agree, if it is done with rear reflecting mirrors, then the result can be badly impacted. Personally my preference is the less glass in the light path the better.

as for the magnification calculation, fl/diagonal, that is really only if you consider a focal length of the diagonal of the sensor as "normal" magnification is not really defined in that manner when dealing with cameras, magnification is Image sice / subject size, which for distances much greater than the focal length is focal length / distance.

but enough of the tech talk,

as I said, you have some great images, so the one thing no one can dispute is your set-up produces.
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