Birding with Pentax (1 Viewer)

Paul Corfield · Nov 2, 2007

Sout Fork said:
Paul,
I wonder if you have considered using a barlow instead of a teleconverter in that astro scope?

Because a telephoto already has negative focus group in the rear of the lens a teleconverter is made to correct for this group. On an astro scope at prime focus no such group is present.

Because of this you might want to try to use a barlow in place of the teleconverter. It MIGHT, and I'm not sure, give better performance in an astro scope than a teleconverter which is made to correct for a conventional telephoto lens.

In any case a barlow is cheap and wouldn't cost a lot to try one out on your setup.

SF

A few shots taken with an 80mm Astro-Tech APO triplet with a 2x barlow.

Sout Fork, you are the man. :t:

Initially I had tried a 2X barlow but I could reach focus on anything throughout the range. I needed like a couple of extra inches of travel. What you said today got me thinking and with a little swapping around of optics I go it to work. What I did was unscrew the chrome barrel containing the optics from the barlow lens and I screwed that into the t-mount. The t-mount originally had a standard 1.25" chrome barrel. I've now screwed that onto the barlow. To get it to work I have the camera+t-mount with barlow+old barlow housing with old t-mount chrome barrel. Mounting them in that order gives me the extra couple of inches I needed on the focus.

Here's two photos, just cropped/resized and nothing else done, no sharpening etc. One on the left taken with the barlow configuration and the one on the right with the 2X teleconverter. There's very little in it but the barlow does have the edge. Took another one with the barlow combined with the teleconverter (approx 2880mm equiv). The sun had gone in and it was a struggle but on a bright sunny day it would be usable if you needed the extra long range.

Cheers Sout Fork.

Paul.

Sout Fork · Nov 3, 2007

Paul said:
"Initially I had tried a 2X barlow but I could reach focus on anything throughout the rangeInitially I had tried a 2X barlow but I could reach focus on anything throughout the range. I needed like a couple of extra inches of travel.. I needed like a couple of extra inches of travel."

This is normal. An Astro scope assumes you are going to use it with a diagonal or a prism. So when shotting pictures you need to make up for the 50-60mm of focal length lost when not using a diagonal. Get a 50mm two inch extension tube and a 2" to 1.25" ep adapter with a T thread and you should be in business.

NOTE: a barlow works best when it's positioned as close to the sensor of the camera as you can get.

I use a draw tube thing. Push it in and I get normal focus range. Pull it out and I can focus down to 10 feet for close ups. See pics

SF

Sout Fork · Nov 3, 2007

Neil said:
Sout Fork,
Very nice. Which camera were you using? What was the eyepiece?
Neil

I use a Pentax *istDL and never shot through an ep.

As to which scope is best as I explained to Paul they all have their limited use.

However If I was starting at square one with no money invested in optics and knowing what I know now and thinking in terms of one killer all around scope for photography...

... I would look for a scope similiar to the Celestron 102mm f/5 wide field but with vastly improved mechanicals and optics.

So here's the specs for my ideal wildlife long lens:

Focal length=500mm
Objective size=100mm
Focal ratio=f/5
Lens glass=Ohara FPL-53 or Schott (Zeiss) florite in a triplet configuration (this should give you the highest level of color correction at the present state of the art).
Focuser=Feathertouch crayford dual speed or similiar fully rotatable

Something like this is not too far off the mark:
http://www.optcorp.com/product.aspx?pid=1-600-576-1095-1489

I know this is more than you asked but you got me to thinking which is always dangerous. As you can see there is no free lunch when it comes to quality.

Take care,
SF

Paul Corfield · Nov 3, 2007

What sort of quality barlow are you using Sout Fork? Is it an apo or achromat design? Mines a simple cemented doublet and the image is a little off at the edges of the photo. With the 2X teleconverter however the image is sharp from edge to edge and I find it renders colors better than my barlow. My teleconverter is a cheap one from ebay and is a simple 4 element design so I'm going to get hold of a better 7 element design and see how it improves the image quality compared to my barlow, they are so cheap on ebay that it will be an inexpensive experiment. When funds allow I may get a better barlow but the good ones are pretty expensive.

Paul.

Herou · Nov 3, 2007

Hello all fellow pentaxians!

To go back to the original thread,here's what I use nowadays:

Bodys:*ist D,K100D and k10D
Teles:Fa 200/2,8,F 300/4,5,A 400/5,6 and Sigma AF 400/5,6 Apo

They're all very sharp and contrasty,but my favourite is the F 300/4,5.
This is one of the best lenses I've ever had,and I've had lots of them.(Ive used Pentax since 1975)
I'm really looking forward to the new DA 300/4.I hope its as good as the F 300.And with the SDM too!Nice!
I also got the 80mm scope,but I haven't tried it with the dslr yet.

I'm attaching some samples.The lenses are (from left to right):
1:F 300/4,5 2:F 300/4,5 3:F 300/4,5 with Soligor 1,7x converter
4:FA 200/2,8 5:Sigma AF 400/5,6 Apo macro

Regards

Thomas

mooreorless · Nov 3, 2007

I use a draw tube thing. Push it in and I get normal focus range. Pull it out and I can focus down to 10 feet for close ups. See pics

SF[/QUOTE]

Hi Sparrow is this what they call a variable tele-extender? Have you ever used a variable universal camera adapter? I am going to get a Pentax K100D camera for Christmas and was wondering what you use. Thanks for any information.

Sout Fork · Nov 4, 2007

Thomas is right.
We sort of high-jacked this thread.
If anyone wants to start a new thread I'd be glad to carry on from there.

SF

187 · Jan 11, 2008

I own an ist DL, and a leica scope. I want to take a few bird pictures. I thought that I found the proper adaptors from a company called Scopetronix but they are out of business. Can anyone on this thread give me any advice? I am on the verge of going crazy with all the home built stuff and a piece from here and a piece from there. Do I really have to get into that much detail just to fasten my camera to my scope?

Sout Fork · Jan 11, 2008

187 said:
I own an ist DL, and a leica scope. I want to take a few bird pictures. I thought that I found the proper adaptors from a company called Scopetronix but they are out of business. Can anyone on this thread give me any advice? I am on the verge of going crazy with all the home built stuff and a piece from here and a piece from there. Do I really have to get into that much detail just to fasten my camera to my scope?

If you really want to avoid all the hassles, and have the MONEY, get this along with a 15 buck k mount t ring:

http://www.bhphotovideo.com/c/product/89463-REG/Leica_42300_SLR_35mm_OR_Digital_.html

SF

Neil · Jan 12, 2008

Sout Fork said:
If you really want to avoid all the hassles, and have the MONEY, get this along with a 15 buck k mount t ring:

http://www.bhphotovideo.com/c/product/89463-REG/Leica_42300_SLR_35mm_OR_Digital_.html

This is the best way, but you can use a 50 mm lens as well to match to the scope eyepiece. You need a support (Manfrotto have one ) for the DSLR and scope as the weight of the camera would be too much for the connection ( the 50 mm normally has a 52 mm thread ).
Neil.

bkrownd · Jan 24, 2008

K20D and DA*300 announced today. Any of you going for it?

MGT · Feb 21, 2008

I use the following:

Pentax K10D.
SMC Pentax-DA 1:2.8 40mm Pancake Lens.
SRB Griturn S49-52 & 52mm Step Rings.
SRB Griturn Digiscoping Threaded Sleeve.
SMC Pentax Zoom 8-24mm.
Pentax PF-80EDA Scope.
Manfrotto 701RC2 Fluid Head & 055MFV Tripod.

See photo's attached:

I'm new to digiscoping and possibly a relative exception with this set-up in the UK as far as SRB Griturn are concerened. This "Junkfisher" was recently taken approx 40-50yds away and is the first opportunity I've had to tinker with the aforementioned set-up.

It appears that my positive vibes are not unfounded and despite good hand to eye co-ordination I must admit I'd benefit from a Red Dot Sight. I see South Fork (compliments on the snaps) is displaying a fairly large Dot Sight. However, it must be up to the job if South Fork's snaps are anything to go by.

South Fork may well get away with said Dot Sight on a 100mm scope, but what are fellow Pentaxians using on your 80/65mm scopes? I'm interested in the following:

Pentax Gameskeeper HS10 Red Dot Sight Matte
Pentax Gameskeeper RD10 Red Dot Sight Matte

Any advice and/or views on the aforementioned and how does one attach a Dot Sight to their scope?

Birding with Pentax (1 Viewer)

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