Question from a member

Hi guys, can anyone help me with a response to this question please:

I have had my K10D converted to IR. The auto focus is a bit off. Can I adjust the auto focus? If so, how?

Thanks
Dan

And this as well!

As a long-term Pentaxhead, I am trying to further my Birding interest with a Pentax solution. I have a K10D and a D ist and want to know what is available to be by way of attaching these to a bird-watching scope. I keep getting offered Nikon solutions!!!

Hi Dan,

Ref the K10 focus issue. There is a debug facility that can be downloaded from a Russian site for free and there are several threads on this forum explaining how it can be utilised.

As a keen birdwatcher myself, I don't believe there is a Pentax equivalent to the Nikon DSLR adaptor for mounting a Nikon DSLR to a Nikon Fieldscope. Have you considered digiscoping with a compact? There are several good adaptors available that fit most scopes.

Dave

I'm afraid this has nothing whatsoever to do with the K10 issue on back focusing.

Infrared light focuses on a different plane to UV light. Until relatively recently Pentax lenses had an IR focusing index; you focus in the normal way and then move the focus distance on the lens focusing ring from the UV index to the IR one.

For example, on a 50mm lens when focusing in the normal way visually at infinity, you would shift the focusing ring to 10 meters for it to focus at infinity using IR light.

I can only suggest buying lenses with IR indices or stopping down as much as he can.

There are all sorts of bird watching scopes other than Nikon, in fact I see quite a few Leica ones about in particular.

You probably need some sort of eyepiece adapter and the place to find adapters of all kinds is a company called SRB. (Not SRS!) If needs be they can make you virtually any adapter that you can imagine, but a Pentax K adapter for your purposes will probably be "off the shelf".

Telescope adapters are also used widely by astonomers. There are also microscope adapters.

I think I'm right in thinking that the standard diameter for these items is 25mm.

http://www.srbfilm.co.uk/ is the link for all thing Adapter!

As gartmore said, infra red light focuses at a different point to the visible sepctrum and lenses are not usually corrected for this. The point of focus changes and old manual focus lenses have an IR mark to move the lens to after focusing.

As IR photography needs a very measured approach, usually on a tripod, then I'd suggest the purchase of some inexpensive manual focus lenses. Focus, move to the IR mark, put the IR filter on and expose the image, a slow process but it will work.

And just to add to John's comment, Pentax F autofocus prime lenses have the IR index as well but you would, of course, have to use them in manual focus.

Hey folks,

Thanks for all the responses, your a great help especially with Pete no being in so much these days.

Thanks
Dan

I think you might get lucky if you google "T" mount adaptors for both the scope and the kmaount.

of course there are better photos to be had from the 200 or 300 mm Pentax telephotos..

certainly in terms of astronomy I get better results with my 300mm F2.8 lens than I do attempting prime focus photography with an 8 inch Newtonian.

However, if you want to attach a camera to any telescope with a standard interchangable eyepiece (usually 1-1/4 inch or 2 inch), this is easy. My Dad's Newtonian has a screw thread built into the 2inch focuser to allow T-thread mountings to screw straight on. I also have a T to 1-1/4 inch adaptor somewhere although I rarely use it. Pentax K to T thread adaptors are widely available and should cost around £6 - £12.

I bought my T mount adaptor from London Camera Exchange in Norwich. I got the adaptor for the scope as part of the kit. A bargain Konus scope for a £100. (New). I tried my K10 on it but it was well heavy. However I tried a W80 attached to a Viking adaptor bracket. A good balance but iv`e yet to give it a try. The other issue with using a DSLR is the probable ingress of debris without the lens mounted.

Cedric

You are quite right to suggest SRB, John. I have used one of their digiscoping adaptors on my Leica scope with a Sony compact. Leica, Swarovski, Zeiss, Kowa and Opticron all make digiscoping adaptors for compacts but none fit any brand of DSLRs. The only one that does is manufactured by Nikon and it has not been well received by birders because of the limitations it makes on useable aperture. Also, the weight of a DSLR makes considerable demands on the strength of any adaptor.

Dan have you check out Bird Forum? There are endless threads on this subject!

Opticron do make an SLR adaptor (at least they did last time I looked, this year some time - here's a link) but your comments on aperture and stability are very true, often the working aperture is f/11, with an effective focal length of 680mm or similar. It all depends on the scope, the objective lens diameter etc.

Digiscoping with a compact camera can be very succesful, but I think with a DSLR it's likely to be less so. Even the Opticron website has a warning about it:

Bearing in mind a decent scope, eyepiece, adaptor and mount is going to cost around £1,000, I'd much rather go for the flexibility and quality of a DA*300mm and a 2x teleconverter, for not much more.

Dan